Ion-selective nanopore systems and methods for single-molecule polymer profiling.

Abstract

The invention relates to means and methods for analysis of target analytes using nanopore-based sensors, more in particular to methods, nanopore systems and devices for single-molecule profiling of biopolymers. Provided is a method of improving the sensing properties of a protein nanopore having a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, the method comprising increasing the net positive charge at the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance.

Description

[0001]P137280PC00 Title: Ion-selective Nanopore systems and methods for single-molecule polymer profiling. Cross-Reference to Related Applications This application claims benefit of European Patent Application No.24173397.1, filed April 30, 2024, which is herein incorporated by reference in its entirety. Background The detection and characterization of analytes has been a critical piece of scientific studies. There is a need for better systems of capture and determination of analytes. Summary Recognized herein are compositions, systems, and methods for improving the characterization of analytes. In an aspect, the present disclosure provides a method comprising: (a) providing a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 1.4 nm; and (b) contacting the engineered biological nanopore with a biopolymer. In some embodiments, the first region is more net positive than the second region. In some embodiments, one or more amino acids in the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids. In some embodiments, one or more amino acids in the first region is mutated to one or more positive amino acids. In some embodiments, when one or more amino acids in the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids, then one or more amino acids in the adjacent region is mutated to one or more positive amino acids. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective region of a wild-type biological nanopore. In some embodiments, the first region comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective region of the wild-type biological nanopore. In some embodiments, the mutated at least one amino acid in the first region is at most 10 nm away from a mutated at least one amino acid in the second region In some embodiments, the first ring of charge comprising the mutated at least one amino acid in the first region is at most 10 nm away from the mutated at least one amino acid in the second region. In some embodiments, the first ring of charge comprising the mutated at least one amino acid in the first region is at most 10 nm away from the second ring of charge comprising the mutated at least one amino acid in the second region. In some embodiments, the second region comprise a C(alpha)-C(alpha) diameter of at most 5 nm. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, a monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to a neutral amino acid or a positive amino acid to exhibit the increased net neutral charge or increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, the at least one mutated amino acid in the first portion of each of one or more monomers (or less than all monomers) forms the first ring of charge, wherein the at least one mutated amino acid in the second portion of each of one or more monomer (or less than all monomers) forms the second ring of charge, wherein each monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, each monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to a neutral amino acid or a positive amino acid to exhibit the increased net neutral charge or the increased net positive charge, respectively, as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, in the at least one mutated amino acid in the first portion of each monomer forms the first ring of charge. In some embodiments, the at least one mutated amino acid in the second portion of each monomer forms the second ring of charge. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, one or more amino acids in the second portion is modified to one or more neutral amino acids or one or more positive amino acids. In some embodiments, when one or more amino acids in the second portion is modified to one or more neutral amino acids or one or more positive amino acids, then one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, the engineered biological nanopore generates an electro- osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel generates the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in the nanopore system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positively-charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the method further comprises measuring a signal generated by translocating the biopolymer through the engineered biological nanopore. In some embodiments, the measuring the signal comprises measuring a signal for a state of (a) an open channel of the engineered biological nanopore; (b) capture of the biopolymer by a first opening of the engineered biological nanopore; or (c) exit of the biopolymer through a second opening of the engineered biological nanopore. In some embodiments, the measuring comprises detecting differences in the signal between states (a), (b), and (c). In some embodiments, the signal comprises an ionic current, a change in ionic current, or derivations thereof. In some embodiments, the measuring comprises detecting a presence of the biopolymer, a concentration of the biopolymer, or any combination thereof. In some embodiments, the measuring comprises detecting one or more characteristics of the biopolymer. In some embodiments, the one or more characteristics of the biopolymer comprise a shape of the biopolymer, a structure of the biopolymer, one or more mutations of the biopolymer, a surface charge of the biopolymer, one or more post-translation modifications of the biopolymer, one or more ligands coupled to the biopolymer, or any combination thereof. In some embodiments, (b) comprises contacting the biopolymer with the first side of the fluidic chamber. In some embodiments, (b) comprises contacting the biopolymer with the second side of the fluidic chamber. In some embodiments, the nanopore system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a method comprising: (a) providing a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 3 nm; wherein the engineered biological nanopore is not FraC; and (b) contacting the engineered biological nanopore with a biopolymer. In some embodiments, the engineered biological nanopore generates an electro- osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel generates the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in the nanopore system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positively-charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the method further comprises measuring a signal generated by translocating the biopolymer through the engineered biological nanopore. In some embodiments, the measuring the signal comprises measuring a signal for a state of (a) an open channel of the engineered biological nanopore; (b) capture of the biopolymer by a first opening of the engineered biological nanopore; or (c) exit of the biopolymer through a second opening of the engineered biological nanopore. In some embodiments, the measuring comprises detecting differences in the signal between states (a), (b), and (c). In some embodiments, the signal comprises an ionic current, a change in ionic current, or derivations thereof. In some embodiments, the measuring comprises detecting a presence of the biopolymer, a concentration of the biopolymer, or any combination thereof. In some embodiments, the measuring comprises detecting one or more characteristics of the biopolymer. In some embodiments, the one or more characteristics of the biopolymer comprise a shape of the biopolymer, a structure of the biopolymer, one or more mutations of the biopolymer, a surface charge of the biopolymer, one or more post-translation modifications of the biopolymer, one or more ligands coupled to the biopolymer, or any combination thereof. In some embodiments, (b) comprises contacting the biopolymer with the first side of the fluidic chamber. In some embodiments, (b) comprises contacting the biopolymer with the second side of the fluidic chamber. In some embodiments, the nanopore system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a method comprising: (a) providing a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein the second region of the channel has a neutral charge; and (b) contacting the engineered biological nanopore with a biopolymer. In some embodiments, (i) the first region is modified to be more net positive than the respective region of the wild-type biological nanopore and (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore. In some embodiments, the first region is modified to be more net positive than the respective region of a wild-type biological nanopore. In some embodiments, the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore. In some embodiments, the first region is more net positive than the second region. In some embodiments, one or more amino acids in the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids. In some embodiments, one or more amino acids in the first region is mutated to one or more positive amino acids. In some embodiments, when one or more amino acids in the second region is modified to one or more neutral amino acids or one or more positive amino acids, then one or more amino acids in the adjacent region is mutated to one or more positive amino acids. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective region of a wild-type biological nanopore. In some embodiments, the first region comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective region of the wild-type biological nanopore. In some embodiments, the mutated at least one amino acid in the first region is at most 10 nm away from the mutated at least one amino acid in the second region. In some embodiments, a ring of charge comprising the mutated at least one amino acid in the first region is at most 10 nm away from another ring of charge comprising the mutated at least one amino acid in the second region. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, a monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or an increased net positive as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to at least a neutral amino acid or at least a positive amino acid to exhibit the increased net neutral charge or the increased net positive, respectively, as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, the at least one mutated amino acid in the first portion of each of one or more monomers (or less than all monomers) forms one or more rings of charges. In some embodiments, the at least one mutated amino acid in the second portion of each of one or more monomer (or less than all monomers) forms an additional one or more rings of charges. In some embodiments, the one or more rings of charges is at most 10 nm away from the additional one or more rings of charges. In some embodiments, each monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, each monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or the increase net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to a neutral amino acid or a positive amino acid to exhibit the increased net neutral charge or the increased net positive charge, respectively, as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, the at least one mutated amino acid in the first portion of each monomer forms one or more rings of charges along the engineered biological nanopore. In some embodiments, the at least one mutated amino acid in the second portion of each monomer forms another one or more rings of charges along the engineered biological nanopore. In some embodiments, the one or more rings of charges is at most 10 nm away from the another one or more rings of charges. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, one or more amino acids in the second portion is modified to one or more neutral amino acids or one or more positive amino acids. In some embodiments, when one or more amino acids in the second portion is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids, then one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, the engineered biological nanopore generates an electro-osmotic force (EOF) greater than an EOF of a wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the neutral charge of the second region of the channel generates the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to another region adjacent to a constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positively-charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the method further comprises measuring a signal generated by translocating the biopolymer through the engineered biological nanopore. In some embodiments, the measuring the signal comprises measuring a signal for a state of (a) an open channel of the engineered biological nanopore; (b) capture of the biopolymer by a first opening of the engineered biological nanopore; or (c) exit of the biopolymer through a second opening of the engineered biological nanopore. In some embodiments, the measuring comprises detecting differences in the signal between states (a), (b), and (c). In some embodiments, the signal comprises an ionic current, a change in ionic current, or derivations thereof. In some embodiments, the measuring comprises detecting a presence of the biopolymer, a concentration of the biopolymer, or any combination thereof. In some embodiments, the measuring comprises detecting one or more characteristics of the biopolymer. In some embodiments, the one or more characteristics of the biopolymer comprise a shape of the biopolymer, a structure of the biopolymer, one or more mutations of the biopolymer, a surface charge of the biopolymer, one or more post-translation modifications of the biopolymer, one or more ligands coupled to the biopolymer, or any combination thereof. In some embodiments, (b) comprises contacting the biopolymer with the first side of the fluidic chamber. In some embodiments, (b) comprises contacting the biopolymer with the second side of the fluidic chamber. In some embodiments, the nanopore system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a method comprising: (a) providing a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein a net charge of the second region of the channel is at least about 50% more neutral as compared to a respective region (e.g., constriction region) of a wild-type biological nanopore; and (b) contacting the engineered biological nanopore with a biopolymer. In some embodiments, the net charge of the second region of the channel is at least about 70% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 85% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 90% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is less cationic as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is less anionic as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the engineered biological nanopore generates an electro- osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the net charge of the second region of the channel generates the EOF. In some embodiments, the engineered biological nanopore has anion-selectivity P(- ) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positively-charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the method further comprises measuring a signal generated by translocating the biopolymer through the engineered biological nanopore. In some embodiments, the measuring the signal comprises measuring a signal for a state of (a) an open channel of the engineered biological nanopore; (b) capture of the biopolymer by a first opening of the engineered biological nanopore; or (c) exit of the biopolymer through a second opening of the engineered biological nanopore. In some embodiments, the measuring comprises detecting differences in the signal between states (a), (b), and (c). In some embodiments, the signal comprises an ionic current, a change in ionic current, or derivations thereof. In some embodiments, the measuring comprises detecting a presence of the biopolymer, a concentration of the biopolymer, or any combination thereof. In some embodiments, the measuring comprises detecting one or more characteristics of the biopolymer. In some embodiments, the one or more characteristics of the biopolymer comprise a shape of the biopolymer, a structure of the biopolymer, one or more mutations of the biopolymer, a surface charge of the biopolymer, one or more post-translation modifications of the biopolymer, one or more ligands coupled to the biopolymer, or any combination thereof. In some embodiments, (b) comprises contacting the biopolymer with the first side of the fluidic chamber. In some embodiments, (b) comprises contacting the biopolymer with the second side of the fluidic chamber. In some embodiments, the nanopore system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a system comprising: (a) a fluidic chamber; and a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 1.4 nm, wherein the engineered biological nanopore is configured to contact a biopolymer. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel is configured to generate the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in the system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a system comprising: (a) a fluidic chamber; and (b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 3 nm; wherein the engineered biological nanopore is not FraC, wherein the engineered biological nanopore is configured to contact a biopolymer. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel is configured to generate the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in the system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a system comprising: (a) a fluidic chamber; and (b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein the second region of the channel has a neutral charge; wherein the engineered biological nanopore is configured to contact a biopolymer. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of a wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the neutral charge of the second region of the channel is configured to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to another region adjacent to a constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, the shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides a system comprising: (a) a fluidic chamber; and (b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein a net charge of the second region of the channel is at least about 50% more neutral as compared to a respective region (e.g., constriction region) of a wild-type biological nanopore, wherein the engineered biological nanopore is configured to contact a biopolymer. In some embodiments, the net charge of the second region of the channel is at least about 70% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 85% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 90% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is less cationic as compared to the respective region (e.g., constriction region) of the wild- type biological nanopore. In some embodiments, the net charge of the second region of the channel is less anionic as compared to the respective region (e.g., constriction region) of the wild- type biological nanopore. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the net charge of the second region of the channel is configured to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to another region adjacent to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the biopolymer comprises a non-nucleic acid based polymer analyte. In some embodiments, the non-nucleic acid based polymer analyte comprises a protein, a polypeptide, a peptide, a saccharide, a lipid, a polymer, an inorganic material, or any combination thereof. In some embodiments, the non- nucleic acid based polymer analyte is the peptide, the protein, or the polypeptide. In some embodiments, the first side of the fluidic chamber comprises a first solution and the second side of the fluidic chamber comprises a second solution. In some embodiments, the first solution comprises a first concentration of a solute and the second solution comprises a second concentration of the solute. In some embodiments, the solute comprises an ion or an osmolyte. In some embodiments, a difference between the first concentration of the solute and the second concentration of the solute is configured to generate an electro-osmotic force. In some embodiments, the system further comprises a pair of electrodes. In some embodiments, the pair of electrodes is configured to provide an applied voltage to generate an electrophoretic force. In some embodiments, the applied voltage is a positive voltage on the first side of the fluidic chamber. In some embodiments, the applied voltage is the positive voltage on the second side of the fluidic chamber. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides an engineered biological nanopore comprising a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 1.4 nm. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel is configured to generate the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in a nanopore system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the respective region (e.g., another region adjacent to the constriction region) of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides an engineered biological nanopore comprising a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region (e.g., another region adjacent to a constriction region) of a wild-type biological nanopore, wherein a first ring of charges in the first region and a second ring of charges in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 3 nm; wherein the engineered biological nanopore is not FraC. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the first region of the channel and the second region of the channel is configured to generate the EOF. In some embodiments, the EOF acts in an opposite direction to an electrophoretic force in a nanopore system. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the respective region (e.g., another region adjacent to the constriction region) of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the second region comprises the width from about 0.4 nm to about 1.4 nm. In some embodiments, the constriction region has a neutral charge. In some embodiments, a net positive charge of the constriction region is increased. In some embodiments, a net neutral charge of the constriction region is increased. In some embodiments, the channel comprises a length of at least about 2 nm. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides an engineered biological nanopore comprising a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein the second region of the channel has a neutral charge. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of a wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the neutral charge of the second region of the channel is configured to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5 In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to another region adjacent to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the another region adjacent to the constriction region of the wild-type biological nanopore In some embodiments, the second region is more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the constriction region of the wild-type biological nanopore. In some embodiments, a shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. In another aspect, the present disclosure provides an engineered biological nanopore comprising a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein a net charge of the second region of the channel is at least about 50% more neutral as compared to a respective region (e.g., a constriction region) of a wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 70% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 85% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is at least about 90% more neutral as compared to the respective region (e.g., constriction region) of the wild-type biological nanopore. In some embodiments, the net charge of the second region of the channel is less cationic as compared to the respective region (e.g., constriction region) of the wild- type biological nanopore. In some embodiments, the net charge of the second region of the channel is less anionic as compared to the respective region (e.g., constriction region) of the wild- type biological nanopore. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore. In some embodiments, the positive charge of the first region of the channel and the net charge of the second region of the channel is configured to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the respective region (e.g., another region adjacent to the constriction region) of the wild-type biological nanopore. In some embodiments, a shortest distance between a first ring of charges in the first region and a second ring of charges in the second region is at most about 5 nm. In some embodiments, the first region of the channel comprises at least about 5 unitary positive charges. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the one or more monomers comprises a first portion and at least a second portion. In some embodiments, the first portion comprises one or more mutated amino acid residues. In some embodiments, the one or more mutated amino acid residues comprises one or more positive charged amino acid residue. In some embodiments, the second portion comprises another one or more mutated amino acid residues. In some embodiments, the another one or more mutated amino acid residues comprises one or more neutrally charged amino acid residue. In some embodiments, a mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 5 nm. In some embodiments, the mutated amino acid residue of the one or more mutated amino acid residues and another mutated amino acid residue of the another one or more mutated amino acid residues comprises a distance of at most about 3 nm. In some embodiments, the engineered biological nanopore comprises a conical geometry, a semi-conical geometry, a straight geometry, or a vestibule geometry. In some embodiments, the engineered biological nanopore comprises the conical geometry or the semi-conical geometry. In some embodiments, the engineered biological nanopore comprises an engineered T7 nanopore, an engineered SPP1 nanopore, an engineered Phi29 nanopore, an engineered Mycobacterium smegmatis porin A (MspA) nanopore, an engineered fragaceatoxin C (FraC) nanopore, an engineered cytolysin A (ClyA) nanopore, an engineered TMH4C4 nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the straight geometry. In some embodiments, the engineered biological nanopore comprises an engineered stable protein 1 (SP1) nanopore, an engineered pleurotolysin toxin (PlyAB) nanopore, an engineered outer membrane protein G (OmpG) nanopore, an engineered aerolysin nanopore, an engineered ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore comprises the vestibule geometry. In some embodiments, the engineered biological nanopore comprises an engineered alpha-hemolysin nanopore, an engineered curli specific gene G (CsgG) nanopore, or any combination thereof. In some embodiments, the engineered biological nanopore has a first opening and a second opening. In some embodiments, the first region of the channel comprises the first opening. In some embodiments, the second region of the channel comprises the second opening. In some embodiments, the first region of the channel comprises the second opening. In some embodiments, the second region of the channel comprises the first opening. In some embodiments, the second region of the channel is located between the first opening of the biological nanopore and the second opening of the engineered biological nanopore. In some embodiments, the engineered biological nanopore is an engineered MspA nanopore. In some embodiments, the engineered MspA nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position D90 or D91 of a wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the monomer comprises a mutation corresponding to position T83, L88, I105, N108, or any combination thereof of the wild-type amino acid sequence as set forth in SEQ ID NO: 1. In some embodiments, the engineered biological nanopore is an engineered CsgG nanopore. In some embodiments, the engineered CsgG nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 2. In some embodiments, the engineered biological nanopore is an engineered CsgG / F nanopore. In some embodiments, the engineered CsgG / F nanopore comprises a monomer with an amino acid sequence with at least about 70% sequence identity to an amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position Y51, N55, F56, or any combination thereof, of a wild-type amino acid sequence as set forth in SEQ ID NO: 3. In some embodiments, the monomer comprises a mutation corresponding to position F48, T58, N15, N17, A20, L23, N24, Q27, or any combination thereof, of the wild-type amino acid sequence as set forth in SEQ ID NO: 3. Another aspect of the present disclosure provides a non-transitory computer readable medium comprising machine executable code that, upon execution by one or more computer processors, implements any of the methods above or elsewhere herein. Another aspect of the present disclosure provides a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein. In some aspects, the present disclosure provides a method comprising: (a) providing a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein (i) the first region is modified to be more net positive than a respective region of a wild-type biological nanopore and / or (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore, wherein the first region of the channel is adjacent to the second region of the channel; and (b) contacting the engineered biological nanopore with a biopolymer. In some embodiments, (i) the first region is modified to be more net positive than the respective region of the wild-type biological nanopore and (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore. In some embodiments, the first region is modified to be more net positive than the respective region of a wild-type biological nanopore. In some embodiments, the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore. In some embodiments, the first region is more net positive than the second region. In some embodiments, one or more amino acids in the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids. In some embodiments, one or more amino acids in the first region is mutated to one or more positive amino acids. In some embodiments, when one or more amino acids in the second region is modified to one or more neutral amino acids or one or more positive amino acids, then one or more amino acids in the adjacent region is mutated to one or more positive amino acids. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first region comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective region of a wild-type biological nanopore. In some embodiments, the first region comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective region of the wild-type biological nanopore. In some embodiments, the mutated at least one amino acid in the first region is at most 10 nm away from the mutated at least one amino acid in the second region. In some embodiments, a ring of charge comprising the mutated at least one amino acid in the first region is at most 10 nm away from another ring of charge comprising the mutated at least one amino acid in the second region. In some embodiments, the engineered biological nanopore comprises one or more monomers. In some embodiments, a monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, a monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or an increased net positive as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to at least a neutral amino acid or at least a positive amino acid to exhibit the increased net neutral charge or the increased net positive, respectively, as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, the at least one mutated amino acid in the first portion of each of one or more monomers (or less than all monomers) forms one or more rings of charges. In some embodiments, the at least one mutated amino acid in the second portion of each of one or more monomer (or less than all monomers) forms an additional one or more rings of charges. In some embodiments, the one or more rings of charges is at most 10 nm away from the additional one or more rings of charges. In some embodiments, each monomer of the engineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region. In some embodiments, each monomer of the engineered biological nanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit an increased net positive charge. In some embodiments, the first portion comprises at least one amino acid that is mutated to exhibit the increased net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the first portion comprises at least one amino acid that is mutated to a positive amino acid to exhibit the increased net positive charge as compared to the respective portion of the monomer of the wild- type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge. In some embodiments, the second portion comprises at least one amino acid that is mutated to exhibit the increased net neutral charge or the increase net positive charge as compared to a respective portion of a monomer of a wild-type biological nanopore. In some embodiments, the second portion comprises at least one amino acid that is mutated to a neutral amino acid or a positive amino acid to exhibit the increased net neutral charge or the increased net positive charge, respectively, as compared to the respective portion of the monomer of the wild-type biological nanopore. In some embodiments, the at least one mutated amino acid in the first portion of each monomer forms one or more rings of charges along the engineered biological nanopore. In some embodiments, the at least one mutated amino acid in the second portion of each monomer forms another one or more rings of charges along the engineered biological nanopore. In some embodiments, the one or more rings of charges is at most 10 nm away from the another one or more rings of charges. In some embodiments, the at least one mutated amino acid in the first portion is at most 10 nm away from the at least one mutated amino acid in the second portion. In some embodiments, one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, one or more amino acids in the second portion is modified to one or more neutral amino acids or one or more positive amino acids. In some embodiments, when one or more amino acids in the second portion is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids, then one or more amino acids in the first portion is mutated to one or more positive amino acids. In some embodiments, the engineered biological nanopore generates an electro- osmotic force (EOF) greater than an EOF of a wild-type biological nanopore. In some embodiments, the first region modified to be more net positive and the second region modified to be more net neutral or more net positive to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, the positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the respective region of the wild- type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the respective region of the wild- type biological nanopore. In some embodiments, the second region is more neutral as compared to the respective region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the respective region of the wild-type biological nanopore. In some aspects, the present disclosure provides a system comprising: (a) a fluidic chamber; and (b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein (i) the first region is modified to be more net positive than a respective region of a wild-type biological nanopore and / or (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore, wherein the first region of the channel is adjacent to the second region of the channel; wherein the engineered biological nanopore is configured to contact a biopolymer. In another aspect, the present disclosure provides an engineered biological nanopore comprising a channel, wherein the channel comprises a first region and a second region, which second region has a constriction region, wherein (i) the first region is modified to be more net positive than a respective region of a wild-type biological nanopore and / or (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore, and wherein the first region of the channel is adjacent to the second region of the channel. In some embodiments, the engineered biological nanopore is configured to generate an electro-osmotic force (EOF) greater than an EOF of a wild-type biological nanopore. In some embodiments, the first region modified to be more net positive and the second region modified to be more net neutral or more net positive are configured to generate the EOF. In some embodiments, the engineered biological nanopore has an anion-selectivity P(-) / P(+) of at least about 1.5. In some embodiments, the second region of the channel comprises a first entrance and a second entrance. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel. In some embodiments, a positive charge of the first region of the channel is adjacent to the second entrance of the second region of the channel. In some embodiments, a positive charge of the first region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel. In some embodiments, the first region is more positive as compared to the respective region of the wild-type biological nanopore. In some embodiments, a net charge of the first region is at least about 50% more positive as compared to the respective region of the wild-type biological nanopore. In some embodiments, the second region is more neutral as compared to the respective region of the wild-type biological nanopore. In some embodiments, a net charge of the second region of the channel is at least about 50% more neutral as compared to the respective region of the wild-type biological nanopore. Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive Incorporation by Reference All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and / or take precedence over any such contradictory material. Detailed Description While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed. Where values can be described as ranges, it will be understood that such disclosure includes the disclosure of all possible sub-ranges within such ranges, as well as specific numerical values that fall within such ranges irrespective of whether a specific numerical value or specific sub-range is expressly stated. The terms “a,” “an,” and “the,” as used herein, generally refers to singular and plural references unless the context clearly dictates otherwise. Any reference to “or” herein can be intended to encompass “and / or” unless otherwise stated. Whenever the term “at least,” “greater than,” or “greater than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 can be equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3. Whenever the term “no more than,” “less than,” or “less than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 can be equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1. The term “about” when referring to a measurable value such as an amount, a temporal duration, and the like, can be meant to encompass variations of ±20% or in some instances ±10%, or in some instances ±5%, or in some instances ±1%, or in some instances ±0.1% from the specified value, as such variations can be appropriate to perform the disclosed methods. As used herein, “about” and “approximately” may mean an acceptable degree of error for the quantity measured given the nature or precision of the measurements. Exemplary degrees of error can be within 20 percent (%), typically, within 10%, and more typically, within 5% of a given range of values. The compositions and methods of the present invention encompass polypeptides and nucleic acids having the sequences specified, or sequences substantially identical or similar thereto, e.g., sequences at least 80%, 85%, 90%, 95% identical or higher to the sequence specified. In the context of an amino acid sequence, the term “substantially identical” can be used herein to refer to a first amino acid that contains a sufficient or minimum number of amino acid residues that can be i) identical to, or ii) conservative substitutions of aligned amino acid residues in a second amino acid sequence such that the first and second amino acid sequences can have a common structural domain and / or common functional activity. For example, amino acid sequences that contain a common structural domain having at least about 80%, 85%, 90%.91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% 99%, 99.5%, 99.9%, or 100% sequence identity to a reference sequence, e.g., a sequence provided herein. In the context of nucleotide sequence, the term “substantially identical” can be used herein to refer to a first nucleic acid sequence that contains a sufficient or minimum number of nucleotides that can be identical to aligned nucleotides in a second nucleic acid sequence such that the first and second nucleotide sequences encode a polypeptide having common functional activity, or encode a common structural polypeptide domain or a common functional polypeptide activity. For example, nucleotide sequences having at least about 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% 99%, 99.5%, 99.9%, or 100% sequence identity to a reference sequence, e.g., a sequence provided herein. The term “variant” can refer to a polypeptide that has a substantially identical amino acid sequence to a reference amino acid sequence, or can be encoded by a substantially identical nucleotide sequence. In some cases, the variant can be a functional variant. The term “functional variant” can refer to a polypeptide that has a substantially identical amino acid sequence to a reference amino acid sequence, or can be encoded by a substantially identical nucleotide sequence, and can be capable of having one or more activities of the reference amino acid sequence. Calculations of homology or sequence identity between sequences (the terms can be used interchangeably herein) can be performed as follows. To determine the percent identity of two amino acid sequences, or of two nucleic acid sequences, the sequences can be aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). In some cases, the length of a reference sequence aligned for comparison purposes can be at least 30%, preferably at least 40%, more preferably at least 50%, 60%, and even more preferably at least 70%, 80%, 90%, 100% of the length of the reference sequence. The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions can then be compared. When a position in the first sequence can be occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules can be identical at that position (as used herein amino acid or nucleic acid “identity” can be equivalent to amino acid or nucleic acid “homology”). A nanopore described herein may comprise one or more components. The one or more components may be of a family of binary toxin or a mutant, functional homolog, functional ortholog, or functional paralog thereof. “Homologs” can refer to proteins, peptides, oligopeptides, polypeptides having amino acid substitutions, deletions, insertions, or any combination thereof relative to an unmodified (e.g., wild-type) protein and having similar biological and / or functional activity as the unmodified protein from which they can be derived. “Ortholog” can refer to a gene or protein from different organisms (e.g., different species) that can be derived from a common ancestral gene. “Paralog” can refer to a gene or protein from the same organism (e.g., same species) that can be a product of gene duplication of a common ancestral gene. The percent identity between the two sequences may be a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. In some cases, the percent identity between two amino acid sequences can be determined using the Needleman and Wunsch ((1970) J. Mol. Biol. 48:444- 453 ) algorithm which has been incorporated into the GAP program in the GCG software package (available at http: / / www.gcg.com), using either a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6. In yet another preferred embodiment, the percent identity between two nucleotide sequences can be determined using the GAP program in the GCG software package (available at http: / / www.gcg.com), using a NWSgapdna.CMP matrix and a gap weight of 40, 50, 60, 70, or 80 and a length weight of 1, 2, 3, 4, 5, or 6. A particularly preferred set of parameters (and the one that should be used unless otherwise specified) can be a Blossum 62 scoring matrix with a gap penalty of 12, a gap extend penalty of 4, and a frameshift gap penalty of 5. The percent identity between two amino acid or nucleotide sequences can be determined using the algorithm of E. Meyers and W. Miller ((1989) CABIOS, 4:11- 17) which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4. The nucleic acid and protein sequences described herein can be used as a “query sequence” to perform a search against public databases to, for example, identify other family members or related sequences. Such searches can be performed using the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotide searches can be performed with the NBLAST program, score = 100, wordlength = 12 to obtain nucleotide sequences homologous to a nucleic acid molecule of the invention. BLAST protein searches can be performed with the XBLAST program, score = 50, wordlength = 3 to obtain amino acid sequences homologous to protein molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al., (1997) Nucleic Acids Res. 25:3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used. The term “amino acid” can embrace all molecules, whether natural or synthetic, which include both an amino functionality and an acid functionality and capable of being included in a polymer of naturally-occurring amino acids. Amino acids can include naturally-occurring amino acids; analogs, derivatives and congeners thereof; amino acid analogs having variant side chains; and all stereoisomers of any of any of the foregoing. As used herein the term “amino acid” can comprise both the D- or L- optical isomers and peptidomimetics. A “conservative amino acid substitution” can be one in which the amino acid residue can be replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains can include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine), aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine), or any combination thereof. As used herein, the term “mutation” can refer to an alteration in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA. In some cases, the mutation may be a large-scale mutation, such as amplifications (or gene duplications) or repetitions of a chromosomal segment, deletions of large chromosomal regions, chromosomal rearrangements (e.g., chromosomal translocations, chromosomal inversions, non-homologous chromosomal crossover, and interstitial deletions), and loss of heterozygosity. In some cases, the mutation may be a small-scale mutation, such as insertions, deletions, and substitution mutations. As used herein, the term “substitution mutation” can refer to the transition that exchange a single nucleotide for another. A mutation herein may comprise a chemical conjugation to a non-natural amino acid. In some aspects, the present disclosure provides nanopores, systems, methods, or any combination thereof for analysis of an analyte (e.g., a biopolymer or a non-nucleic acid-based polymer analyte). The nanopores, systems, methods, or any combination thereof described herein may be used to determine one or more characteristics of an analyte. A characteristic of an analyte can comprise a length of the analyte (e.g., a contour length, in the case of polymeric analyte), a volume of the analyte, a mass of the analyte, a shape of the analyte, a secondary structure of the analyte, a tertiary structure of the analyte, a charge distribution of the analyte, an identity of the analyte, a sequence of the analyte, any chemical modifications of the analyte, or any combination thereof. The invention relates to means and methods for analysis of target analytes using nanopore-based sensors. More in particular, it relates to methods, nanopore systems and devices for the single-molecule profiling of (bio)polymers, e.g. polynucleotides, polypeptides or polysaccharides, or nucleic acid-peptide conjugates. Nanopores selective for ions (e.g., anion-selective nanopores for negatively-charged ions) may generate strong EOFs that can facilitate the capture and / or translocation of heterogeneously charged biological molecules. The constriction region can also represent a sensing region of a nanopore described herein, wherein the sensing region may be where signal is generated (e.g., signal generated from capture and / or translocation of an analyte). A constriction region engineered with charged amino acid residues (e.g., positively-charged amino acid residues) may generate a strong EOF and be selective for anion species. However, without wishing to be bound by theory, an engineered nanopore with a charged constriction may also result in a small pool of available modifications (e.g., modifications to the nanopore) to tune a current signal. It can be advantageous to engineer a nanopore (e.g., a biological nanopore) and / or a monomer of a nanopore to generate strong EOF with modifications outside of the constriction region. For example, the present disclosure provides engineered nanopores (e.g., biological nanopore) with modifications to the constriction region to contain one or more neutral charges and / or positive charges. These engineered nanopores may then be modified to introduce one or more positively-charged amino acid residues to a region other than the constriction region (e.g., a region adjacent to the constriction region). This combination of charges can result in a strong EOF, and methods of generating a strong EOF that may not involve engineering a charged constriction region. Protein sequencing with nanopores can be accomplished by maintaining the protein intact (full-strand sequencing), or by digesting the proteins into smaller fragments. One strategy for sequencing these smaller peptide fragments relies on conjugating the peptide to a single-stranded DNA (ssDNA) strand. This construct can be then captured inside the nanopore through electrophoresis and subsequently moved outside the nanopore using DNA-processing enzymes, such as helicases1–3. Through this approach, peptides can be sequenced, and post-translational modifications (PTMs) such as phosphorylation can be identified4. A major limitation in this approach is the fact that neutral peptides could not be stretched3,4. To alleviate this problem, one option would be the generation of a force opposing the movement of the peptide outside the nanopore. This force could be the electro-osmotic flow (EOF). EOF holds promise for the detection and sequencing of biopolymers with nanopores. EOF was shown to be capable of mediating capture5–7and trapping8–10of molecules inside nanopores. Recently, EOF was demonstrated to facilitate even the translocation across nanopores of large molecules such as unfolded proteins, either with11,12or against the electrophoretic force13. EOF - the net flux of water generated by the movement of ions through the nanopores under an external applied potential - can be dependent on the surface charge of the nanopore lumen. EOF can be tuned by either changing the properties of the solution, such as pH14and ionic strength15, or by altering the charge on the nanopore lumen by means of mutagenesis. EOF directionality and magnitude was successfully manipulated in nanopores of various shapes and sizes6,7,13. Typically, when mutating a protein nanopore, the EOF can be tuned by altering the narrowest site of the lumen, namely the constriction area. Simultaneously, the constriction area of the nanopore contributes significantly to its electrical resistance, thereby primarily influencing the nanopore's ability to differentiate between various molecules. Consequently, modifying the constriction area to modulate EOF could potentially impact the sensing properties of the nanopore. For some nanopores, particularly those having or comprising a conical geometry, it can be advantageous to explore alternative ways of enhancing EOF. Accordingly, the present inventors set out to explore whether an EOF could be generated without affecting the sensing area of the pore. In particular, they aimed at generating an EOF in a nanopore comprising at least one narrow constriction area which quickly transitions at one or more sides to a much wider area, such as pores having a conical or hour-glass pore geometry, wherein the constriction area remains available for sensing. To gain a better understanding of how the ion selectivity changes in a conical pore during engineering, both the WT and the M2 mutant of the MspA nanopore were investigated. The MspA nanopore has a conical shape, meaning that the engineering guidelines identified for enhancing the EOF of cylindrical nanopores such as CytK and aerolysin do not apply. To that end, they took the MspA-M2 nanopore, which can be typically employed in the sequencing of ssDNA-peptide conjugates, as exemplary conical pore. The MspA channel can be ~10 nm long and has a funnel shape that can be ~5 nm wide on its extracellular side. A single narrow constriction at the opposite end has a diameter of only about 1 nm and quickly transitions to a much wider area. It was found that the anion-selectivity of a conical shaped nanopore can be increased by engineering the constriction area and / or regions close to the constriction area. As expected for conical pores, the constriction area dominated the selectivity of the nanopore. Unexpectedly, it was found that introducing one or multiple positive charges in a funnel region flanking the constriction area resulted in a nanopore having increased anion-selectively and a strong EOF. More in particular, introducing one or multiple positive lumen-facing amino acid residues outside of the constriction area in a funnel region having a diameter of up to about 3.5 nm (Cα-Cα), was found to alter the selectivity of the nanopore. The present finding that high EOF pores can be obtained by introducing positive charges in positions away from the narrowest site of the nanopore can be highly relevant since it allows to leave the (neutral) constriction area available for sensing. In an aspect, the present disclosure provides a method of improving the sensing properties of a protein nanopore having a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter. In some cases, the method comprising increasing the net positive charge at the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance. In some cases, the method may comprise increasing the net positive charge in the funnel region having a diameter of at least 2.2 nm, preferably at least 2.4 nm, more preferably in the range of about 2.4 to about 3.5 nm, expressed as the Cα-Cα distance. In some cases, the method comprises increasing the net positive charge at the constriction area and / or in the funnel region at a distance within up to about 3 nm from the constriction area along the longitudinal (central) pore axis. Suitably, increasing the net positive charge comprises substituting one or more negatively-charged amino acids, non-polar amino acids or aromatic amino acids at the constriction area and / or in the funnel region with one or more positively-charged amino acids. For example, the method can comprise increasing the net positive charge at the constriction area and / or in the funnel region by at least 5, preferably at least 8, more preferably at least 10 unitary charges. The increase in the net positive charge at the constriction area and / or in the funnel region may be per promoter (monomer). In an aspect, the present disclosure provides a method comprising: (a) providing:(i) a nanopore system, wherein the nanopore system comprises (1) a fluidic chamber and; (2) a membrane comprising a protein nanopore, wherein the membrane separates the fluidic chamber into a cis side and a trans side; and (ii) a polymer analyte; (b) translocating the polymer analyte from the cis side to the trans side of the fluidic chamber. In some cases, the nanopore has a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, wherein the lumen-facing residues in the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge, such that under an applied positive potential the nanopore system has a cis to trans electro-osmotic force resulting from a cis to trans net ionic current flow, wherein the cis to trans electro-osmotic force translocates the polymer analyte through the nanopore. In some cases, the polymer analyte can be of synthetic, semi-synthetic or biological origin, such as a biopolymer. In some cases, the polymer analyte comprises or consists of peptide units, saccharide units, nucleic acid units, water-soluble plastic monomers, or any combination thereof. In some cases, the polymer analyte is selected from the group of proteinaceous polymers, non-nucleic acid based polymers and nucleic acid-peptide conjugates. In an aspect, the present disclosure provides a modified nanopore having a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter. In some cases, the modified nanopore is an anion-selective nanopore. In some cases, the lumen-facing residues in the constriction area have a net positive charge. In some cases, the lumen-facing residues in the funnel region having a diameter up to about 3.5 nm (expressed as the Cα-Cα distance) have a net positive charge. In some cases, the lumen-facing residues in the constriction area and in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge. Another aspect of the present disclosure provides a nanopore system comprising (1) a fluidic chamber and; (2) a membrane comprising a protein nanopore disclosed herein, wherein the membrane separates the fluidic chamber into a first side (e.g., a cis side) and a second side (e.g., a trans side). In some cases, the system comprises a fluidic chamber; a membrane comprising a nanopore, wherein the membrane separates the fluidic chamber into a cis side comprising a first solution and a trans side comprising a second solution, wherein the first solution and the second solution can be configured to translocate a polymer analyte using an electro-osmotic flow; a pair of electrodes comprising a first electrode and a second electrode; and a controller operatively coupled to the fluidic chamber, said nanopore, and the pair of electrodes. In some cases, the controller: (a) uses the pair of electrodes to generate an electrophoretic force acting in an opposite direction to the electro-osmotic flow that translocates the polymer analyte through the nanopore, and (b) detects one or more signals associated with at least one characteristic of the polymer analyte during or subsequent to translocation of the polymer analyte through the nanopore. In some cases, the nanopore has a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter. In some cases, the lumen-facing residues in the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge; In some cases, the nanopore has a neutral constriction area. In some cases, the nanopore has an anion-selectivity P(-) / P(+) of greater than 1.3, preferably greater than 1.5, more preferably greater than 2.5, most preferably greater than 3. In some cases, the nanopore is a variant of Mycobacterium smegmatis porin A (MspA) or MspA paralog or homolog. A “paralog,” as defined herein, can be a gene from the same bacterial species that has similar structure and function. MspA paralogs include MspB, MspC, and MspD. A “homolog,” as defined herein, can be a gene from another bacterial species that has a similar structure and evolutionary origin. By way of an example, MspA homologs include MppA, PorM1, PorM2, PorM1, and Mmcs4296. In some cases, the Msp A variant nanopore comprises a mutant monomer of MspA / Msmeg0965, MspB / Msmeg0520, MspC / Msmeg5483, MspD / Msmeg6057, MppA, PorM1, PorM2, PorM1, Mmcs4296, Mmcs4297, Mmcs3857, Mmcs4382, Mmcs4383, Mjls3843, Mjls3857, Mjls3931 Mjls4674, Mjls4675, Mjls4677, Map3123c, Mav3943, Mvan1836, Mvan4117, Mvan4839, Mvan4840, Mvan5016, Mvan5017, Mvan5768, MUL —2391, Mflv1734, Mflv1735, Mflv2295, Mflv1891, MCH4691c, MCH4689c, MCH4690c, MAB1080, MAB1081, MAB2800, RHA1 ro08561, RHA1 ro04074, and RHA1 ro03127. In some cases, the funnel area up to a diameter of about 3.5, preferably about 3.0 nm, expressed as the Cα-Cα distance, can be more positively-charged when compared to funnel area of a wild-type MspA or MspA paralog or homolog porin. Any MspA pore described herein, such as a mutant MspA, may comprise 2-15 MspA monomers that can be the same or different. Optionally, a mutant MspA pore comprises 7-9 MspA monomers that can be the same or different. Optionally, at least a second monomer can be selected from the group consisting of a wild-type MspA monomer, a second mutant MspA monomer, a wild-type MspA paralog or homolog monomer, and a mutant MspA paralog or homolog monomer, wherein the second mutant MspA monomer may be the same or different than the first mutant MspA monomer. Optionally, the second monomer can be a wild-type MspA paralog or homolog monomer. A wild-type MspA paralog or homolog monomer may be a wild- type MspB monomer. In some cases, a nanopore described herein may be a monomeric nanopore (e.g., a nanopore comprising one monomer). In some cases, an engineered biological nanopore may be a monomeric MspA nanopore. A “mutant MspA monomer” refers to an Msp monomer that has at least or at most 70, 75, 80, 85, 90, 95, 98, or 99 percent or more identity, or any range derivable therein, but less than 100%, to a wild-type MspA monomer, and retains tunnel- forming capability when associated with one or more other Msp monomers. A mutant MspA monomer can be further defined as comprising one or more positively-charged mutation(s) in that portion of the sequence that contribute(s) to an increased net positive charge in the constriction area and / or in the flanking funnel region up to a diameter of about 3.5 nm of a fully-formed, tunnel-forming porin. The mutant Msp monomer may be a recombinant protein, for example. A mutant MspA monomer may comprise any mutation described herein. A “mutant MspA paralog or homolog monomer” refers to an MspA paralog or homolog monomer that has at least or at most 70, 75, 80, 85, 90, 95, 98, or 99 percent or more identity, or any range derivable therein, but less than 100%, to a wild-type MspA paralog or homolog monomer, and retains tunnel-forming capability. A mutant MspA paralog or homolog monomer comprises one or more positively- charged mutation(s) in that portion of the sequence that contribute(s) to an increased net positive charge in the constriction area and / or in the flanking funnel region up to a diameter of about 3.5 nm of a fully-formed, tunnel-forming porin. In some cases, the nanopore can be an anion-selective MspA, MspA paralog or homolog porin comprising a mutant MspA monomer, wherein the mutant MspA monomer comprises a variant of the sequence in SEQ ID NO: 1. In some cases, the variant comprises a positive charge at one or more lumen-facing amino acid positions in the stretch consisting of residues 82-89, residues 92-109 and / or in the stretch consisting of residues 103-111 in the sequence in SEQ ID NO:1, or a mutant MspA paralog or homolog comprising a positive charge at one or more of the corresponding amino acids. In some cases, the mutant MspA monomer comprises a variant of the sequence in SEQ ID NO: 1, said variant comprising a positive charge at one or more of the amino acid positions 90, 91, 93, 88, 103, 105 and 108. Suitably, the variant comprises one or more of the following substitutions: D90K / R, D91K / R, D93K / R, L88K / R, S103K / R, I105K / R and N108K / R. In some aspects, the mutant MspA monomer comprises an amino acid with a positive charge at one or more of amino acid positions 88, 103, 105 and 108, preferably at one or more of amino acid positions 88, 103 and 105, more preferably at positions 103 and / or 105. In some cases, the mutant MspA monomer comprises a positive charge at one or more of positions 90, 91 and 93, preferably positions 90 and / or 91. In some cases, the mutant MspA monomer comprises a neutral charge at one or more of positions 90, 91 and 93. In some cases, the mutant MspA monomer further comprises an amino acid with a positive charge at one or more of amino acid positions 118, 134 and 139, or a mutant MspA paralog or homolog comprising the corresponding amino acids. Useful mutant MspA monomers comprises amino acids with a neutral charge at positions 90, 91 and 93 and / or an amino acid with a positive charge at one or more of amino acid positions 118, 134, and 139, or a mutant MspA paralog or homolog comprising the corresponding amino acids. In some cases, the mutant MspA monomer comprises (i) amino acids with a neutral charge at positions 90, 91 and 93; (ii) an amino acid with a positive charge at one or more of amino acid positions 118, 134, and 139, and (iii) an amino acid with a positive charge at one or more of amino acid positions 88, 103, 105 and 108 or a mutant MspA paralog or homolog comprising the corresponding amino acids. Suitably, a nanopore comprises a mutant selected from the MspA mutants depicted in Table 1, 2 or 3. In some cases, the mutant can be selected from Table 1. In some cases, the mutant can be selected from Table 2. In some cases, the mutant can be selected from Table 3. A MspA monomer may comprise one or more mutations at any of the following amino acid positions: 88, 105, 108, 118, 134, or 139. A MspA monomer may comprise one or more of the following mutations: L88K, D90K / N / Q / R, D91K / N / Q, D93K / N / Q, S103K / R, I105K / R, N108K / R, D118R, D134R, or E139K. A MspA monomer may comprise the following mutations: S103K / I105K. A MspA monomer may comprise the following mutations: D90K / D91K. A MspA monomer may comprise the following mutations: D90N / D91N / D93N / D118R / D134R / E139K / S103K / I105K. A MspA monomer may comprise the following mutations: I105W / N108W. Moreover, an MspA monomer may comprise any other mutation described herein. Also provided are nucleic acid sequences encoding the mutant MspA monomers or MspA paralog or homolog porins described herein. For example, provided is a nucleic acid sequence encoding a mutant MspA porin or a mutant MspA paralog or homolog. Vectors comprising nucleic acid sequences described herein are also contemplated, such as a vector comprising a nucleic acid sequence encoding a mutant MspA porin or a mutant MspA paralog or homolog. Any vector described herein may further comprise a promoter sequence. Any vector described herein may further comprise a constitutive promoter. A constitutive promoter may comprise a promoter. A promoter may comprise an inducible promoter. An inducible promoter may comprise an acetamide-inducible promoter. Also provided are cultured cells transfected with any vector described herein, or progeny thereof wherein the cell can be capable of expressing a modified MspA pore, such as a mutant MspA porin or mutant MspA paralog or homolog. In other embodiments, the nanopore can be a modified CsgG pore or CsgG paralog or homolog, or a modified CsgG-CsgF mutant (PDB ID 6SI7). In another aspect, the present disclosure provides a device comprising an array of a system comprising any of the systems disclosed herein. In another aspect, the present disclosure provides the use of a method, nanopore system, or device disclosed herein for characterizing at least one feature of a target polymer, preferably for detection and analysis of one or more target polymer(s) at the single molecule level, more preferably for detection and analysis of one or more a target polypeptide(s) and / or nucleic acid-peptide conjugate(s). In another aspect, the present disclosure provides a use of any of the methods, kits, or devices disclosed herein for characterizing at least one feature of a polymer analyte. In another aspect, the present disclosure provides a use of any of the systems disclosed herein for characterizing at least one feature of a polymer analyte. In another aspect, the present disclosure provides a use of any of the methods, kits, or devices disclosed herein for detection and analysis of one or more polymer analytes at a single molecule level. In another aspect, the present disclosure provides a use of any of the systems disclosed herein for detection and analysis of one or more polymer analytes at a single molecule level. In another aspect, the present disclosure provides a use of any of the methods, kits, or devices disclosed herein for detection and analysis of one or more polypeptides or nucleic-acid peptide hybrids. In another aspect, the present disclosure provides a use of any of the systems disclosed herein for detection and analysis of one or more polypeptides or nucleic- acid peptide hybrids. Another aspect of the present disclosure provides a non-transitory computer readable medium comprising machine executable code that, upon execution by one or more computer processors, implements any of the methods above or elsewhere herein. Another aspect of the present disclosure provides a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein. In some aspects, the present disclosure provides pores for detecting and / or characterizing an analyte (e.g., a biopolymer). A pore may be a wild-type pore and / or a pore may be an engineered pore. In some cases, the pore (e.g., nanopore) comprises a transmembrane region. In some cases, the pore comprises a hydrophilic portion. In some cases, the pore comprises a hydrophobic portion. In some cases, the pore comprises a hydrophilic and a hydrophobic portion. In some cases, a pore comprises an opening (e.g., an entrance). In some cases, a pore comprises at least one opening. In some cases, a pore can comprise one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) openings. An entrance to a nanopore may be defined by a widest dimension (e.g., a measure from a first edge of an entrance to a second edge of the entrance). A pore may be measured by a diameter, a circumference, or any combination thereof. In some aspects, the present disclosure provides an engineered biological nanopore. The engineered biological nanopore may comprise a channel. The channel may comprise a first region. The channel may comprise a second region. The second region may have a constriction region. The first region of the channel may be adjacent to a second region of the channel. The first region of the engineered biological nanopore may be modified. The first region may be modified to be more net positive as compared to a respective region of a wild-type biological nanopore. The engineered biological nanopore may have one or more rings of charge. The first region may have a first ring of charge. The second region may have a second ring of charge. The first ring of charge in the first region and a second ring of charge in the second region may be separated by a distance of at most about 3 nm. The second region of the engineered biological nanopore may comprise a width of at most about 1.4 nm. The engineered biological nanopore may not be FraC. In some aspects, the present disclosure provides an engineered biological nanopore comprising a channel. The channel may comprise a first region. The channel may comprise a second region. The second region may have a constriction region. The first region of the engineered biological nanopore may be modified. The first region may be modified to be more net positive than a respective region of a wild-type biological nanopore. The second region of the engineered biological nanopore may be modified. The second region may be modified to be more net neutral than a respective region of a wild-type biological nanopore. The second region may be modified to be more net positive than a respective region of a wild-type biological nanopore. The first region of the channel may be adjacent to the second region of the channel. In some aspects, the present disclosure provides an engineered biological nanopore comprising a channel. The channel may comprise a first region. The channel may comprise a second region. The second region may have a constriction region. The first region of the channel may have a positive charge. The second region of the channel may have a neutral charge. The first region of the channel may be adjacent to the second region of the channel. In some aspects, the present disclosure provides an engineered biological nanopore comprising a channel. The channel may comprise a first region. The channel may comprise a second region. The second region may have a constriction region. The first region of the channel may be adjacent to the second region of the channel. The first region of the channel may have a positive charge. The second region of the channel may have a net charge. The net charge of the second region of the channel may be at least about 50% more neutral as compared to a respective region of a wild-type biological nanopore (e.g., a constriction region of a wild-type biological nanopore). A pore can comprise a channel through which an analyte may enter. Herein the terms “channel”, “lumen” and / or “vestibule” may be used interchangeably. The channel may be of the wild-type biological nanopore or the engineered biological nanopore. In some cases, an analyte may be trapped in the channel of the nanopore. In some cases, an analyte may translocate through the channel of the nanopore. In some cases, an analyte may partially translocate through the channel of the nanopore. The channel may be a same width through the entire channel or a channel may have two or more different widths through the entire channel. The channel may comprise at least one region. For example, the channel of the pore (e.g., the biological nanopore) may comprise a first region, a second region, a third region, or any combination thereof. In some cases, the channel of the nanopore comprises one or more constrictions (e.g., one or more constriction regions). The constriction region may be a region of the channel different in size (e.g., width, length, diameter, circumference, a widest dimension, or any combination thereof) than one or more other regions of the channel. The second region of the channel may have the constriction region. The first region and / or third region of the channel and the second region of the channel (e.g., comprising the constriction region) may be adjacent (e.g., immediately adjacent) to one another. In other cases, the first region and / or third region may be separated from the second region of the channel by a distance of at most about 4.0 nm, at most about 3.0 nm, at most about 2.0 nm, at most about 1.5 nm, at most about 1.0 nm, at most about 0.9 nm, at most about 0.8 nm, at most about 0.7 nm, at most about 0.6 nm, at most about 0.5 nm, at most about 0.4 nm, at most about 0.3 nm, at most about 0.2 nm, at most about 0.1 nm, or less than about 0.1 nm. In some cases, a first region and / or third region may be separated from a second region of the channel (e.g., comprising the constriction region) by a distance of at least about 0.001 nm, at least about 0.01 nm, at least about 0.05 nm, at least about 0.1 nm, at least about 0.5 nm, at least about 1 nm, at least about 2 nm, at least about 3 nm, at least about 4 nm, at least about 5 nm, at least about 10 nm, at least about 15 nm, or greater than about 15 nm. In some cases, a first region and / or third region may be separated from a second region of the channel (e.g., comprising the constriction region) by a distance of at most about 15 nm, at most about 10 nm, at most about 5 nm, at most about 4 nm, at most about 3 nm, at most about 2 nm, at most about 1 nm, at most about 0.5 nm, at most about 0.1 nm, at most about 0.05 nm, at most about 0.01 nm, at most about 0.001 nm, or less than about 0.001 nm. In some cases, a first region and / or third region may be separated from a second region of the channel (e.g., comprising the constriction region) by a distance from about 0.001 nm to about 15 nm. In some cases, a first region and / or third region may be separated from a second region of the channel (e.g., comprising the constriction region) by a distance from at least about 0.001 nm. In some cases, a first region and / or third region may be separated from a second region of the channel (e.g., comprising the constriction region) by a distance from about 0.001 nm to about 0.01 nm, about 0.001 nm to about 0.05 nm, about 0.001 nm to about 0.1 nm, about 0.001 nm to about 0.5 nm, about 0.001 nm to about 1 nm, about 0.001 nm to about 2 nm, about 0.001 nm to about 3 nm, about 0.001 nm to about 4 nm, about 0.001 nm to about 5 nm, about 0.001 nm to about 10 nm, about 0.001 nm to about 15 nm, about 0.01 nm to about 0.05 nm, about 0.01 nm to about 0.1 nm, about 0.01 nm to about 0.5 nm, about 0.01 nm to about 1 nm, about 0.01 nm to about 2 nm, about 0.01 nm to about 3 nm, about 0.01 nm to about 4 nm, about 0.01 nm to about 5 nm, about 0.01 nm to about 10 nm, about 0.01 nm to about 15 nm, about 0.05 nm to about 0.1 nm, about 0.05 nm to about 0.5 nm, about 0.05 nm to about 1 nm, about 0.05 nm to about 2 nm, about 0.05 nm to about 3 nm, about 0.05 nm to about 4 nm, about 0.05 nm to about 5 nm, about 0.05 nm to about 10 nm, about 0.05 nm to about 15 nm, about 0.1 nm to about 0.5 nm, about 0.1 nm to about 1 nm, about 0.1 nm to about 2 nm, about 0.1 nm to about 3 nm, about 0.1 nm to about 4 nm, about 0.1 nm to about 5 nm, about 0.1 nm to about 10 nm, about 0.1 nm to about 15 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 2 nm, about 0.5 nm to about 3 nm, about 0.5 nm to about 4 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 15 nm, about 1 nm to about 2 nm, about 1 nm to about 3 nm, about 1 nm to about 4 nm, about 1 nm to about 5 nm, about 1 nm to about 10 nm, about 1 nm to about 15 nm, about 2 nm to about 3 nm, about 2 nm to about 4 nm, about 2 nm to about 5 nm, about 2 nm to about 10 nm, about 2 nm to about 15 nm, about 3 nm to about 4 nm, about 3 nm to about 5 nm, about 3 nm to about 10 nm, about 3 nm to about 15 nm, about 4 nm to about 5 nm, about 4 nm to about 10 nm, about 4 nm to about 15 nm, about 5 nm to about 10 nm, about 5 nm to about 15 nm, or about 10 nm to about 15 nm. The at least one constriction area can be flanked on one or both sides by a wider funnel region. In some cases, the nanopore can have a conical shape. In some cases, the nanopore can have an hourglass shape. The flanking wider funnel region(s) can have a diameter of at least about 2 times the constriction diameter. Unless specifically indicated otherwise, when referring to “diameter” herein, one may determine a diameter by measuring center-to-center distances or atomic surface-to- surface distances. The constriction region of the nanopore may be a narrower region of the channel than another region of the channel. In some cases, the constriction region of the nanopore can contribute to the electrical resistance of the nanopore. A modulation of electrical resistance may allow the nanopore to differentiate between analytes in a complex sample. Therefore, modifying a constriction region of a nanopore to shift an electrical resistance may modulate the electro-osmotic force and / or may improve the ability of the nanopore to characterize an analyte. Characterization of an analyte may occur at the constriction region. In the constriction region, the current flow may be modulated most by the composition (e.g., local composition, e.g., amino acid composition) of the analyte within. The electro-osmotic flow (EOF) may be maximally created at a narrow region (e.g., a constriction region). The EOF may be maximally created at a constriction region due to a maximal electrostatic effect on cation or anion flux in the constrained dimensions of the constriction. In some cases, the nanopore comprises a shape (e.g., a geometry). For example, a nanopore may be cylindrical. In some cases, the nanopore can be conical shape. In some cases, the nanopore can be globular shape. In some cases, the nanopore can be hourglass shape. In some cases, the nanopore can be a toroidal shape, comprising a ring and a channel. In some cases, a nanopore comprises a biological nanopore or a solid state nanopore. The toroidal shape may comprise a toroidal polyhedral shape comprising a ring and a channel. The ring may comprise the protein or proteins that form the nanopore. The ring may comprise a cross sectional geometry similar to the protein or proteins that form the nanopore. The ring may be wider at a first side (e.g., a cis side) than a second side (e.g., a trans side), or wider at the second side (e.g., the trans side) than the first side (e.g., the cis side). The ring can comprise a portion comprising a conical geometry, a cylindrical geometry, an amorphous geometry, or combinations thereof. The channel can comprise the central portion of the nanopore geometry that does not comprise the proteins or peptides of the nanopore. The channel may allow molecules to translocate through the nanopore (i.e. through the channel). In case the nanopore can have two flanking funnel regions, e.g. in an hour-glass geometry, the funnel regions can have the same or distinct diameters. The funnel region can have a diameter of at least about 2.2, about 2.4, about 2.6, about 2.8, about 3.0, about 3.2, about 3.4, about 3.6, about 3.8, about 4.0, about 4.2, about 4.4, about 4.6, about 4.8, about 5.0, about 5.2, about 5.4, about 5.6, about 5.8, about 6.0, about 6.2, about 6.4, about 6.6, about 6.8, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5 or about 10 times the constriction diameter. The regions (e.g., funnel regions) may be the first region and the third region described herein. For example, the first region and third region may flank a second region of the nanopore. The second region may be a constriction region of the nanopore. The first and third regions (e.g., funnel regions) can have the same diameter or different (e.g., distinct) diameters. The first and third regions can each have a diameter of at least about 2.2, at least about 2.4, at least about 2.6, at least about 2.8, at least about 3.0, at least about 3.2, at least about 3.4, at least about 3.6, at least about 3.8, at least about 4.0, at least about 4.2, at least about 4.4, at least about 4.6, at least about 4.8, at least about 5.0, at least about 5.2, at least about 5.4, at least about 5.6, at least about 5.8, at least about 6.0, at least about 6.2, at least about 6.4, at least about 6.6, at least about 6.8, at least about 7.0, at least about 7.5, at least about 8.0, at least about 8.5, at least about 9.0, at least about 9.5, at least about 10, or greater than about 10 times the diameter of the second region (e.g., constriction region). A channel may restrict molecules from translocating through the nanopore. The restriction may be based on a width of the channel or a charge of the channel. The channel can comprise a channel length. The channel length can be the length of the channel as measured along a longitudinal axis of the channel. This longitudinal axis may run perpendicular to a membrane (e.g., run substantially perpendicular to a membrane). The length may be measured perpendicular to the ring of the shape (e.g., the toroidal shape) of the geometry of the nanopore. The channel length can be measured as the distance along the longitudinal axis of the channel between the most distant points of the nanopore along the longitudinal axis of the channel. In some embodiment, a channel may have a start point on a first side (e.g., a cis side) of a nanopore, and an end point on a second side (e.g., a trans side) of a nanopore, or a start point on a second side (e.g., a trans side) of a nanopore, and an end point on a first side (e.g., a cis side) of a nanopore. In some embodiments a channel length can be less than a linear length or a contour length of an analyte. In some embodiments a channel length can be greater than a linear length or a contour length of an analyte. In some cases, methods are provided relating to improving the sensing properties of a protein nanopore. In some cases, nanopores having improved sensing properties are provided. The nanopore can have at least one narrowest constriction area as its sensing region. The diameter of the narrowest constriction area can be preferably in a range having a lower limit selected from about 0.5 nm, about 0.6 nm, about 0.7 nm, about 0.8 nm and an upper limit independently selected from about 1.5 nm, about 1.4 nm, about 1.3 nm, about 1.2 nm, about 1.1 nm, about 1.0 nm, about 0.9 nm. The length of the constriction area can be up to about 2 nm, about 1.9 nm, about 1.8 nm, about 1.7 nm, about 1.6 nm, about 1.5 nm, about 1.4 nm, about 1.3 nm, about 1.2 nm, about 1.1 nm, about 1.0 nm, about 0.9 nm in length. In some cases, a channel comprises a channel length from about 0.5 nm to about 40 nm. In some cases, the channel can comprise a channel length of at least about 0.5 nm, at least about 1 nm, at least about 1.5 nm, at least about 2 nm, at least about 5 nm, at least about 10, at least about 15 nm, at least about 20 nm, at least about 25 nm, at least about 30 nm, at least about 35 nm, at least about 40 nm, or more than 40 nm. In some cases, the channel can comprise a channel length of at most about 40 nm, at most about 35 nm, at most about 30 nm, at most about 25 nm, at most about 20 nm, at most about 15 nm, at most about 10 nm, at most about 5 nm, at most about 2 nm, at most about 1.5 nm, at most about 1 nm, at most about 0.5nm, or less than 0.5 nm. In some cases, the channel can comprise a channel length of about about 0.5 nm, about 1 nm, about 1.5 nm, about 2 nm, about 5 nm, about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, about 35 nm, or about 40 nm. A first region and / or third region of the channel of the engineered biological nanopore described herein may comprise a dimension (e.g., width, length, diameter, circumference, or widest dimension) measured along a plane from a first alpha carbon of a first amino acid to a second alpha carbon of a second amino acid (e.g., between a first alpha carbon to a second alpha carbon that is opposite to the first alpha carbon). The dimension may be a diameter of the nanopore (e.g., the engineered biological nanopore). The diameter may be expressed as a Cα-Cα distance (e.g., the alpha-carbon to alpha-carbon distance). The diameter can be of a widest region of the first region and / or third region. In some cases, the diameter may be of a narrowest region of the first region and / or third region. In some cases, the dimension (e.g., width, length, diameter, circumference, or widest dimension) may be at least about 1 nanometer (nm), at least about 2 nm, at least about 2.5 nm, at least about 3 nm, at least about 3.5 nm, at least about 4 nm, at least about 4.5 nm, at least about 5 nm, at least about 5.5 nm, at least about 6 nm, at least about 7 nm, at least about 8 nm, at least about 9 nm, at least about 10 nm, or greater than about 10 nm, wherein the dimension (e.g., diameter) is expressed as the Cα-Cα distance (e.g., the alpha-carbon to alpha-carbon distance). In some cases, the first region and / or third region of the channel of the engineered biological nanopore described herein may comprise a diameter of at most about 10 nm, at most about 9 nm, at most about 8 nm, at most about 7 nm, at most about 6 nm, at most about 5.5 nm, at most about 5 nm, at most about 4.5 nm, at most about 4 nm, at most about 3.5 nm, at most about 3 nm, at most about 2.5 nm, at most about 2 nm, at most about 1 nm, or less than about 1 nm, wherein the diameter may be expressed as the Cα-Cα distance (e.g., the alpha-carbon to alpha-carbon distance). In some cases, the first region and / or third region of the channel of the engineered biological nanopore described herein may comprise a diameter of about 1 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm. A first region and / or third region of the channel (e.g., a region adjacent to a nanopore) may be a wider than a second region of the nanopore (e.g., comprising the constriction region). In some cases, the first region and / or third region may have one or more mutations (e.g., a plurality of mutations). The one or more mutations may be at an area of the first region and / or third region with a diameter (e.g., narrowest diameter) wider than a second region (e.g., a narrowest region). For example, the one or more mutations may be in a first region and / or third region comprising a diameter (e.g., narrowest diameter) of at least about 1 nanometer (nm), at least about 2 nm, at least about 2.5 nm, at least about 3 nm, at least about 3.5 nm, at least about 4 nm, at least about 4.5 nm, at least about 5 nm, at least about 5.5 nm, at least about 6 nm, at least about 7 nm, at least about 8 nm, or greater than about 8 nm, wherein the diameter is expressed as the Cα-Cα distance (e.g., the alpha-carbon to alpha-carbon distance). As another example, In some cases, the one or more mutations may be in a first region and / or third region comprising a diameter (e.g., narrowest diameter) of at most about 8 nm, at most about 7 nm, at most about 6 nm, at most about 5.5 nm, at most about 5 nm, at most about 4.5 nm, at most about 4 nm, at most about 3.5 nm, at most about 3 nm, at most about 2.5 nm, at most about 2 nm, at most about 1 nm, or less than about 1 nm, wherein the diameter may be expressed as the Cα-Cα distance (e.g., the alpha- carbon to alpha-carbon distance). In some cases, the one or more mutations may be in a first region and / or third region comprising a diameter (e.g., narrowest diameter) of about 1 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 7 nm, or 8 nm. A first region and / or third region of the channel (e.g., a region adjacent to a nanopore) may be a wider than a second region of the nanopore (e.g., comprising the constriction region). In some cases, a first region and / or third region of the channel of the engineered biological nanopore described herein may comprise a diameter of at least about, at most about, or about 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 7 nm, 8 nm, or a range between any of these two values, wherein the diameter can be expressed as the Cα-Cα distance (e.g., the alpha-carbon to alpha-carbon distance). For example, as shown in FIG. 7, a nanopore 700 may comprise a first region 710 and a second region (e.g., constriction region) 720. The first region can be adjacent to the second region. The first region can have a diameter 730. This diameter 730 can be expressed as a dimension from a first alpha carbon of a first amino acid to a second alpha carbon of a second amino acid (e.g., between a first alpha carbon to a second alpha carbon that is opposite to the first alpha carbon). A mutation 740 can be introduced at the area of the first region 710 where there is a diameter (e.g., narrowest diameter) 730. A nanopore can comprise at least one opening (e.g., entrance). The opening can be a first opening. The nanopore may comprise two or more opening (e.g., entrances). For example, a nanopore described herein may comprise a first opening and a second opening. An opening of a nanopore can face a side (e.g., compartment) of a nanopore system described herein. For example, a first opening of a nanopore may face a first side (e.g., cis side) of a membrane. A second opening of a nanopore may face a second side (e.g., trans side) of a membrane. In some cases, a first region and / or third region of a nanopore may comprise a larger dimension (e.g., width, length, diameter, circumference, or widest dimension) compared to a second region (e.g., comprising a constriction region) of the channel of the nanopore. For example, the first region and / or third region of the channel of the nanopore may comprise a dimension (e.g., width, length, diameter, circumference, or widest dimension) that may be at least about 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or greater than about 90% larger than that of a second region (e.g., comprising a constriction region) of the channel of the nanopore. For example, the first region and / or third region of the channel of the nanopore may comprise a dimension (e.g., width, length, diameter, circumference, or widest dimension) that may be at most about 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 5%, or less than about 5% larger than that of a second region (e.g., comprising a constriction region) of the channel of the nanopore. In some cases, an engineered biological nanopore described herein may comprise a first region and / or third region of a channel (e.g., adjacent to a constriction region) that can be at least about 1.5x, 2x, 3x, 4x, 5x, 10x, 50x, or greater than about 50x wider than a second region of a channel (e.g., comprising a constriction region). In some cases, an engineered biological nanopore described herein may comprise a first region and / or third region of a channel (e.g., adjacent to a constriction region) that can be at most about 50x, 10x, 5x, 4x, 3x, 2x, 1.5x, or less than about 1.5x wider than a second region of a channel (e.g., comprising a constriction region). In some cases, an engineered biological nanopore described herein may comprise a first region and / or third region of a channel (e.g., adjacent to a constriction region) that can be from about 2x to about 50x wider than a second region of a channel (e.g., comprising a constriction region). In some cases, an engineered biological nanopore described herein may comprise a first region and / or third region of a channel (e.g., adjacent to a constriction region) that can be from about 2x to about 3x, about 2x to about 4x, about 2x to about 5x, about 2x to about 6x, about 2x to about 7x, about 2x to about 8x, about 2x to about 9x, about 2x to about 10x, about 2x to about 20x, about 2x to about 25x, about 2x to about 50x, about 3x to about 4x, about 3x to about 5x, about 3x to about 6x, about 3x to about 7x, about 3x to about 8x, about 3x to about 9x, about 3x to about 10x, about 3x to about 20x, about 3x to about 25x, about 3x to about 50x, about 4x to about 5x, about 4x to about 6x, about 4x to about 7x, about 4x to about 8x, about 4x to about 9x, about 4x to about 10x, about 4x to about 20x, about 4x to about 25x, about 4x to about 50x, about 5x to about 6x, about 5x to about 7x, about 5x to about 8x, about 5x to about 9x, about 5x to about 10x, about 5x to about 20x, about 5x to about 25x, about 5x to about 50x, about 6x to about 7x, about 6x to about 8x, about 6x to about 9x, about 6x to about 10x, about 6x to about 20x, about 6x to about 25x, about 6x to about 50x, about 7x to about 8x, about 7x to about 9x, about 7x to about 10x, about 7x to about 20x, about 7x to about 25x, about 7x to about 50x, about 8x to about 9x, about 8x to about 10x, about 8x to about 20x, about 8x to about 25x, about 8x to about 50x, about 9x to about 10x, about 9x to about 20x, about 9x to about 25x, about 9x to about 50x, about 10x to about 20x, about 10x to about 25x, about 10x to about 50x, about 20x to about 25x, about 20x to about 50x, or about 25x to about 50x wider than a second region of a channel (e.g., comprising a constriction region). In some cases, a first opening of a nanopore may be the same dimension (e.g., diameter, circumference, and / or widest dimension) as a second opening. In some cases, a first opening of a nanopore may be a different dimension (e.g., diameter, circumference, and / or widest dimension) as a second opening. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a first opening of at least about 0.1 nm, at least about 0.5 nm, at least about 1 nm, at least about 2 nm, at least about 3 nm, at least about 4 nm, at least about 5 nm, at least about 6 nm, at least about 7 nm, at least about 8 nm, at least about 9 nm, at least about 10 nm, at least about 11 nm, at least about 12 nm, at least about 13 nm, at least about 14 nm, at least about 15 nm, at least about 16 nm, at least about 17 nm, at least about 18 nm, at least about 19 nm, at least about 20 nm, at least about 25 nm, at least about 30 nm, or greater than about 30 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a first opening of at most about 30 nm, at most about 25 nm, at most about 20 nm, at most about 19 nm, at most about 18 nm, at most about 17 nm, at most about 16 nm, at most about 15 nm, at most about 14 nm, at most about 13 nm, at most about 12 nm, at most about 11 nm, at most about 10 nm, at most about 9 nm, at most about 8 nm, at most about 7 nm, at most about 6 nm, at most about 5 nm, at most about 4 nm, at most about 3 nm, at most about 2 nm, at most about 1 nm, at most about 0.5 nm, at most about 0.1 nm, or less than about 0.1 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a first opening (e.g., cis opening) from about 1 nm to about 8 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a first opening (e.g., cis opening) from about 1 nm to about 1.5 nm, about 1 nm to about 2 nm, about 1 nm to about 2.5 nm, about 1 nm to about 3 nm, about 1 nm to about 3.5 nm, about 1 nm to about 4 nm, about 1 nm to about 4.5 nm, about 1 nm to about 5 nm, about 1 nm to about 6 nm, about 1 nm to about 7 nm, about 1 nm to about 8 nm, about 1.5 nm to about 2 nm, about 1.5 nm to about 2.5 nm, about 1.5 nm to about 3 nm, about 1.5 nm to about 3.5 nm, about 1.5 nm to about 4 nm, about 1.5 nm to about 4.5 nm, about 1.5 nm to about 5 nm, about 1.5 nm to about 6 nm, about 1.5 nm to about 7 nm, about 1.5 nm to about 8 nm, about 2 nm to about 2.5 nm, about 2 nm to about 3 nm, about 2 nm to about 3.5 nm, about 2 nm to about 4 nm, about 2 nm to about 4.5 nm, about 2 nm to about 5 nm, about 2 nm to about 6 nm, about 2 nm to about 7 nm, about 2 nm to about 8 nm, about 2.5 nm to about 3 nm, about 2.5 nm to about 3.5 nm, about 2.5 nm to about 4 nm, about 2.5 nm to about 4.5 nm, about 2.5 nm to about 5 nm, about 2.5 nm to about 6 nm, about 2.5 nm to about 7 nm, about 2.5 nm to about 8 nm, about 3 nm to about 3.5 nm, about 3 nm to about 4 nm, about 3 nm to about 4.5 nm, about 3 nm to about 5 nm, about 3 nm to about 6 nm, about 3 nm to about 7 nm, about 3 nm to about 8 nm, about 3.5 nm to about 4 nm, about 3.5 nm to about 4.5 nm, about 3.5 nm to about 5 nm, about 3.5 nm to about 6 nm, about 3.5 nm to about 7 nm, about 3.5 nm to about 8 nm, about 4 nm to about 4.5 nm, about 4 nm to about 5 nm, about 4 nm to about 6 nm, about 4 nm to about 7 nm, about 4 nm to about 8 nm, about 4.5 nm to about 5 nm, about 4.5 nm to about 6 nm, about 4.5 nm to about 7 nm, about 4.5 nm to about 8 nm, about 5 nm to about 6 nm, about 5 nm to about 7 nm, about 5 nm to about 8 nm, about 6 nm to about 7 nm, about 6 nm to about 8 nm, or about 7 nm to about 8 nm. In some cases, a nanopore provided herein may comprise a dimension of a first opening (e.g., cis opening) (e.g., diameter, circumference, and / or widest dimension) from about 8 nm to about 30 nm. In some cases, a nanopore provided herein may comprise a dimension of a first opening (e.g., cis opening) (e.g., diameter, circumference, and / or widest dimension) from at most about 30 nm. In some cases, a nanopore provided herein may comprise a dimension of a first opening (e.g., cis opening) (e.g., diameter, circumference, and / or widest dimension) from about 8 nm to about 9 nm, about 8 nm to about 10 nm, about 8 nm to about 11 nm, about 8 nm to about 12 nm, about 8 nm to about 13 nm, about 8 nm to about 14 nm, about 8 nm to about 15 nm, about 8 nm to about 20 nm, about 8 nm to about 25 nm, about 8 nm to about 30 nm, about 9 nm to about 10 nm, about 9 nm to about 11 nm, about 9 nm to about 12 nm, about 9 nm to about 13 nm, about 9 nm to about 14 nm, about 9 nm to about 15 nm, about 9 nm to about 20 nm, about 9 nm to about 25 nm, about 9 nm to about 30 nm, about 10 nm to about 11 nm, about 10 nm to about 12 nm, about 10 nm to about 13 nm, about 10 nm to about 14 nm, about 10 nm to about 15 nm, about 10 nm to about 20 nm, about 10 nm to about 25 nm, about 10 nm to about 30 nm, about 11 nm to about 12 nm, about 11 nm to about 13 nm, about 11 nm to about 14 nm, about 11 nm to about 15 nm, about 11 nm to about 20 nm, about 11 nm to about 25 nm, about 11 nm to about 30 nm, about 12 nm to about 13 nm, about 12 nm to about 14 nm, about 12 nm to about 15 nm, about 12 nm to about 20 nm, about 12 nm to about 25 nm, about 12 nm to about 30 nm, about 13 nm to about 14 nm, about 13 nm to about 15 nm, about 13 nm to about 20 nm, about 13 nm to about 25 nm, about 13 nm to about 30 nm, about 14 nm to about 15 nm, about 14 nm to about 20 nm, about 14 nm to about 25 nm, about 14 nm to about 30 nm, about 15 nm to about 20 nm, about 15 nm to about 25 nm, about 15 nm to about 30 nm, about 20 nm to about 25 nm, about 20 nm to about 30 nm, or about 25 nm to about 30 nm. In some cases, a nanopore provided herein may comprise a dimension of a first opening of about 1 nm, about 2 nm, about 3 nm, about 4 nm, or about 5 nm. In some cases, a nanopore provided herein may comprise a dimension of a second opening of about 1 nm, about 2 nm, about 3 nm, about 4 nm or about 5 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) of at least about 1 nm, at least about 1.5 nm, at least about 2 nm, at least about 2.5 nm, at least about 3 nm, at least about 3.5 nm, at least about 4 nm, at least about 4.5 nm, at least about 5 nm, at least about 5.5 nm, at least about 6 nm, at least about 7 nm, at least about 8 nm, at least about 9 nm, at least about 10 nm, at least about 11 nm, at least about 12 nm, at least about 13 nm, at least about 14 nm, at least about 15 nm, or greater than about 15 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) of at most about 15 nm, at most about 14 nm, at most about 13 nm, at most about 12 nm, at most about 11 nm, at most about 10 nm, at most about 9 nm, at most about 8 nm, at most about 7 nm, at most about 6 nm, at most about 5.5 nm, at most about 5 nm, at most about 4.5 nm, at most about 4 nm, at most about 3.5 nm, at most about 3 nm, at most about 2.5 nm, at most about 2 nm, at most about 1.5 nm, at most about 1 nm, or less than about 1 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) from about 0.5 nm to about 6 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) from about 0.5 nm to about 1 nm, about 0.5 nm to about 1.5 nm, about 0.5 nm to about 2 nm, about 0.5 nm to about 2.5 nm, about 0.5 nm to about 3 nm, about 0.5 nm to about 3.5 nm, about 0.5 nm to about 4 nm, about 0.5 nm to about 4.5 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 5.5 nm, about 0.5 nm to about 6 nm, about 1 nm to about 1.5 nm, about 1 nm to about 2 nm, about 1 nm to about 2.5 nm, about 1 nm to about 3 nm, about 1 nm to about 3.5 nm, about 1 nm to about 4 nm, about 1 nm to about 4.5 nm, about 1 nm to about 5 nm, about 1 nm to about 5.5 nm, about 1 nm to about 6 nm, about 1.5 nm to about 2 nm, about 1.5 nm to about 2.5 nm, about 1.5 nm to about 3 nm, about 1.5 nm to about 3.5 nm, about 1.5 nm to about 4 nm, about 1.5 nm to about 4.5 nm, about 1.5 nm to about 5 nm, about 1.5 nm to about 5.5 nm, about 1.5 nm to about 6 nm, about 2 nm to about 2.5 nm, about 2 nm to about 3 nm, about 2 nm to about 3.5 nm, about 2 nm to about 4 nm, about 2 nm to about 4.5 nm, about 2 nm to about 5 nm, about 2 nm to about 5.5 nm, about 2 nm to about 6 nm, about 2.5 nm to about 3 nm, about 2.5 nm to about 3.5 nm, about 2.5 nm to about 4 nm, about 2.5 nm to about 4.5 nm, about 2.5 nm to about 5 nm, about 2.5 nm to about 5.5 nm, about 2.5 nm to about 6 nm, about 3 nm to about 3.5 nm, about 3 nm to about 4 nm, about 3 nm to about 4.5 nm, about 3 nm to about 5 nm, about 3 nm to about 5.5 nm, about 3 nm to about 6 nm, about 3.5 nm to about 4 nm, about 3.5 nm to about 4.5 nm, about 3.5 nm to about 5 nm, about 3.5 nm to about 5.5 nm, about 3.5 nm to about 6 nm, about 4 nm to about 4.5 nm, about 4 nm to about 5 nm, about 4 nm to about 5.5 nm, about 4 nm to about 6 nm, about 4.5 nm to about 5 nm, about 4.5 nm to about 5.5 nm, about 4.5 nm to about 6 nm, about 5 nm to about 5.5 nm, about 5 nm to about 6 nm, or about 5.5 nm to about 6 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) from about 6 nm to about 15 nm. In some cases, a nanopore provided herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) of a second opening (e.g., trans opening) from about 6 nm to about 7 nm, about 6 nm to about 8 nm, about 6 nm to about 9 nm, about 6 nm to about 10 nm, about 6 nm to about 11 nm, about 6 nm to about 12 nm, about 6 nm to about 13 nm, about 6 nm to about 14 nm, about 6 nm to about 15 nm, about 7 nm to about 8 nm, about 7 nm to about 9 nm, about 7 nm to about 10 nm, about 7 nm to about 11 nm, about 7 nm to about 12 nm, about 7 nm to about 13 nm, about 7 nm to about 14 nm, about 7 nm to about 15 nm, about 8 nm to about 9 nm, about 8 nm to about 10 nm, about 8 nm to about 11 nm, about 8 nm to about 12 nm, about 8 nm to about 13 nm, about 8 nm to about 14 nm, about 8 nm to about 15 nm, about 9 nm to about 10 nm, about 9 nm to about 11 nm, about 9 nm to about 12 nm, about 9 nm to about 13 nm, about 9 nm to about 14 nm, about 9 nm to about 15 nm, about 10 nm to about 11 nm, about 10 nm to about 12 nm, about 10 nm to about 13 nm, about 10 nm to about 14 nm, about 10 nm to about 15 nm, about 11 nm to about 12 nm, about 11 nm to about 13 nm, about 11 nm to about 14 nm, about 11 nm to about 15 nm, about 12 nm to about 13 nm, about 12 nm to about 14 nm, about 12 nm to about 15 nm, about 13 nm to about 14 nm, about 13 nm to about 15 nm, or about 14 nm to about 15 nm. The constriction region of the nanopore may also have a dimension (e.g., diameter, circumference, and / or widest dimension). The constriction region may comprise a length, where the length can be a length along a longitudinal axis of a channel region of a nanopore. In some cases, the length of the constriction region of the nanopore (e.g., biological nanopore) can be at least about 0.1 nm, at least about 0.2 nm, at least about 0.3 nm, at least about 0.4 nm, at least about 0.5 nm, at least about 0.6 nm, at least about 0.7 nm, at least about 0.8 nm, at least about 0.9 nm, at least about 1.0 nm, at least about 2.0 nm, at least about 3.0 nm, at least about 4.0 nm, at least about 5.0 nm, or greater than about 5.0 nm. In some cases, the length of the constriction region of the nanopore (e.g., biological nanopore) can be at most about 5.0 nm, at most about 4.0 nm, at most about 3.0 nm, at most about 2.0 nm, at most about 1.0 nm, at most about 0.9 nm, at most about 0.8 nm, at most about 0.7 nm, at most about 0.6 nm, at most about 0.5 nm, at most about 0.4 nm, at most about 0.3 nm, at most about 0.2 nm, at most about 0.1 nm, or less than about 0.1 nm. In some cases, the length of the constriction region of the nanopore (e.g., biological nanopore) can be from about 0.1 nm to about 1.2 nm. In some cases, the length of the constriction region of the nanopore (e.g., biological nanopore) can be from about 0.1 nm to about 0.2 nm, about 0.1 nm to about 0.3 nm, about 0.1 nm to about 0.4 nm, about 0.1 nm to about 0.5 nm, about 0.1 nm to about 0.6 nm, about 0.1 nm to about 0.7 nm, about 0.1 nm to about 0.8 nm, about 0.1 nm to about 0.9 nm, about 0.1 nm to about 1 nm, about 0.1 nm to about 1.1 nm, about 0.1 nm to about 1.2 nm, about 0.2 nm to about 0.3 nm, about 0.2 nm to about 0.4 nm, about 0.2 nm to about 0.5 nm, about 0.2 nm to about 0.6 nm, about 0.2 nm to about 0.7 nm, about 0.2 nm to about 0.8 nm, about 0.2 nm to about 0.9 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 1.1 nm, about 0.2 nm to about 1.2 nm, about 0.3 nm to about 0.4 nm, about 0.3 nm to about 0.5 nm, about 0.3 nm to about 0.6 nm, about 0.3 nm to about 0.7 nm, about 0.3 nm to about 0.8 nm, about 0.3 nm to about 0.9 nm, about 0.3 nm to about 1 nm, about 0.3 nm to about 1.1 nm, about 0.3 nm to about 1.2 nm, about 0.4 nm to about 0.5 nm, about 0.4 nm to about 0.6 nm, about 0.4 nm to about 0.7 nm, about 0.4 nm to about 0.8 nm, about 0.4 nm to about 0.9 nm, about 0.4 nm to about 1 nm, about 0.4 nm to about 1.1 nm, about 0.4 nm to about 1.2 nm, about 0.5 nm to about 0.6 nm, about 0.5 nm to about 0.7 nm, about 0.5 nm to about 0.8 nm, about 0.5 nm to about 0.9 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 1.1 nm, about 0.5 nm to about 1.2 nm, about 0.6 nm to about 0.7 nm, about 0.6 nm to about 0.8 nm, about 0.6 nm to about 0.9 nm, about 0.6 nm to about 1 nm, about 0.6 nm to about 1.1 nm, about 0.6 nm to about 1.2 nm, about 0.7 nm to about 0.8 nm, about 0.7 nm to about 0.9 nm, about 0.7 nm to about 1 nm, about 0.7 nm to about 1.1 nm, about 0.7 nm to about 1.2 nm, about 0.8 nm to about 0.9 nm, about 0.8 nm to about 1 nm, about 0.8 nm to about 1.1 nm, about 0.8 nm to about 1.2 nm, about 0.9 nm to about 1 nm, about 0.9 nm to about 1.1 nm, about 0.9 nm to about 1.2 nm, about 1 nm to about 1.1 nm, about 1 nm to about 1.2 nm, or about 1.1 nm to about 1.2 nm. In some cases, a first region and / or third region can comprise a length. The length of the first region and / or third region can be a length as measured along a longitudinal axis of the channel. This longitudinal axis may run perpendicular to a membrane (e.g., run substantially perpendicular to a membrane). The length of the first region and / or third region can be measured as the distance along the longitudinal axis of the first region and / or third region between the most distant points of the first region and / or third region along the longitudinal axis of the channel. In some cases, a length of a first region and / or third region of the nanopore may be at least about 0.5 nm, at least about 1 nm, at least about 2 nm, at least about 3 nm, at least about 4 nm, at least about 5 nm, at least about 10 nm, at least about 15 nm, at least about 20 nm, or greater than about 20 nm. In some cases, a length of a first region and / or third region of the nanopore may be at most about 20 nm, at most about 15 nm, at most about 10 nm, at most about 5 nm, at most about 4 nm, at most about 3 nm, at most about 2 nm, at most about 1 nm, at most about 0.5 nm, or less than about 0.5 nm. In some cases, a length of a first region and / or third region of the nanopore may be about 0.5 nm, about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 10 nm, about 15 nm, or about 20 nm. In some cases, a length of the first region and / or third region may be from about 3 nm to 10 nm. In some cases, a second region (e.g., constriction region) can comprise a length. The length of the second region (e.g., constriction region) can be a length as measured along a longitudinal axis of the channel. This longitudinal axis may run perpendicular to a membrane (e.g., run substantially perpendicular to a membrane). The length of the second region (e.g., constriction region) can be measured as the distance along the longitudinal axis of the second region (e.g., constriction region) between the most distant points of the second region (e.g., constriction region) along the longitudinal axis of the channel. In some cases, a length of a second region (e.g., constriction region) of the nanopore may be at least about 0.1 nm, at least about 0.5 nm, at least about 1 nm, at least about 1.5 nm, at least about 2 nm, at least about 2.5 nm, at least about 3 nm, at least about 3.5 nm, at least about 4 nm, at least about 4.5 nm, at least about 5 nm, at least about 10 nm, or greater than about 10 nm. In some cases, a length of a second region (e.g., constriction region) of the nanopore may be at most about 10 nm, at most about 5 nm, at most about 4.5 nm, at most about 4 nm, at most about 3.5 nm, at most about 3 nm, at most about 2.5 nm, at most about 2 nm, at most about 1.5 nm, at most about 1 nm, at most about 0.5 nm, at most about 0.1 nm, or less than about 0.1 nm. In some cases, a length of a second region (e.g., constriction region) of the nanopore may be about 0.5 nm, about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 10 nm, about 15 nm, or about 20 nm. In some cases, a length of the second region (e.g., constriction region) may be from about 0.1 nm to 5 nm. The method can comprise increasing the net positive charge at the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance. The funnel region for adding one or more positive charges or having a net positive charge preferably has a diameter in a range having a lower limit selected from about 2.0 nm, about 2.1 nm, about 2.2 nm, about 2.3 nm, about 2.4 nm, about 2.5 nm and an upper limit independently selected from about 2.6 nm, about 2.7 nm, about 2.8 nm, about 2.9 nm, about 3.0 nm, about 3.1 nm, about 3.2 nm, about 3.3 nm, about 3.4 nm, about 3.5 nm. In some cases, one or more amino acid mutations may be present in a region of the nanopore comprising a constriction region (e.g., a narrowest region). The one or more amino acid mutations may be present in a region (e.g., constriction region) comprising a dimension (e.g., diameter, circumference, and / or widest dimension) measured from an alpha-carbon position of an amino acid backbone. The dimension of the constriction region may be measured from a first alpha-carbon position to a second alpha-carbon position. For example, the one or more amino acid mutations may be present in a region (e.g., constriction region) comprising a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha- carbon position to a second alpha-carbon position In some cases, a constriction region of a nanopore described herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) measured from an alpha-carbon position of an amino acid backbone. The dimension of the constriction region may be measured from a first alpha-carbon position to a second alpha-carbon position. In some cases, a constriction region of a nanopore described herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha-carbon position to a second alpha-carbon position of at least about 0.2 nm, at least about 0.3 nm, at least about 0.4 nm, at least about 0.5 nm, at least about 0.6 nm, at least about 0.7 nm, at least about 0.8 nm, at least about 0.9 nm, at least about 1.0 nm, at least about 1.1 nm, at least about 1.2 nm, at least about 1.3 nm, at least about 1.4 nm, at least about 1.5 nm, at least about 1.6 nm, at least about 1.7 nm, at least about 1.8 nm, at least about 1.9 nm, at least about 2.0 nm, at least about 2.1 nm, at least about 2.2 nm, at least about 2.3 nm, at least about 2.4 nm, at least about 2.5 nm, at least about 2.6 nm, at least about 2.7 nm, at least about 2.8 nm, at least about 2.9 nm, at least about 3.0 nm, at least about 3.1 nm, at least about 3.2 nm, at least about 3.3 nm, at least about 3.4 nm, at least about 3.5 nm, at least about 3.6 nm, at least about 3.7 nm, at least about 3.8 nm, at least about 3.9 nm, at least about 4.0 nm, or greater than about 4.0 nm. As another example, the one or more amino acid mutations may be present in a region (e.g., constriction region) comprising a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha-carbon position to a second alpha- carbon position In some cases, a constriction region of a nanopore described herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha-carbon position to a second alpha-carbon position of at most about 4.0 nm, at most about 3.9 nm, at most about 3.8 nm, at most about 3.7 nm, at most about 3.6 nm, at most about 3.5 nm, at most about 3.4 nm, at most about 3.3 nm, at most about 3.2 nm, at most about 3.1 nm, at most about 3.0 nm, at most about 2.9 nm, at most about 2.8 nm, at most about 2.7 nm, at most about 2.6 nm, at most about 2.5 nm, at most about 2.4 nm, at most about 2.3 nm, at most about 2.2 nm, at most about 2.1 nm, at most about 2.0 nm, at most about 1.9 nm, at most about 1.8 nm, at most about 1.7 nm, at most about 1.6 nm, at most about 1.5 nm, at most about 1.4 nm, at most about 1.3 nm, at most about 1.2 nm, at most about 1.1 nm, at most about 1.0 nm, at most about 0.9 nm, at most about 0.8 nm, at most about 0.7 nm, at most about 0.6 nm, at most about 0.5 nm, at most about 0.4 nm, at most about 0.3 nm, at most about 0.2 nm, or less than about 0.2 nm. In some cases, a constriction region of a nanopore described herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha-carbon position to a second alpha-carbon position from about 0.2 nm to about 4 nm. As another example, the one or more amino acid mutations may be present in a region (e.g., constriction region) comprising a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha- carbon position In some cases, a constriction region of a nanopore described herein may comprise a dimension (e.g., diameter, circumference, and / or widest dimension) measured from a first alpha-carbon position to a second alpha-carbon position from about 0.2 nm to about 0.3 nm, about 0.2 nm to about 0.4 nm, about 0.2 nm to about 0.5 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 1.5 nm, about 0.2 nm to about 2 nm, about 0.2 nm to about 2.5 nm, about 0.2 nm to about 3 nm, about 0.2 nm to about 3.5 nm, about 0.2 nm to about 4 nm, about 0.3 nm to about 0.4 nm, about 0.3 nm to about 0.5 nm, about 0.3 nm to about 1 nm, about 0.3 nm to about 1.5 nm, about 0.3 nm to about 2 nm, about 0.3 nm to about 2.5 nm, about 0.3 nm to about 3 nm, about 0.3 nm to about 3.5 nm, about 0.3 nm to about 4 nm, about 0.4 nm to about 0.5 nm, about 0.4 nm to about 1 nm, about 0.4 nm to about 1.5 nm, about 0.4 nm to about 2 nm, about 0.4 nm to about 2.5 nm, about 0.4 nm to about 3 nm, about 0.4 nm to about 3.5 nm, about 0.4 nm to about 4 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 1.5 nm, about 0.5 nm to about 2 nm, about 0.5 nm to about 2.5 nm, about 0.5 nm to about 3 nm, about 0.5 nm to about 3.5 nm, about 0.5 nm to about 4 nm, about 1 nm to about 1.5 nm, about 1 nm to about 2 nm, about 1 nm to about 2.5 nm, about 1 nm to about 3 nm, about 1 nm to about 3.5 nm, about 1 nm to about 4 nm, about 1.5 nm to about 2 nm, about 1.5 nm to about 2.5 nm, about 1.5 nm to about 3 nm, about 1.5 nm to about 3.5 nm, about 1.5 nm to about 4 nm, about 2 nm to about 2.5 nm, about 2 nm to about 3 nm, about 2 nm to about 3.5 nm, about 2 nm to about 4 nm, about 2.5 nm to about 3 nm, about 2.5 nm to about 3.5 nm, about 2.5 nm to about 4 nm, about 3 nm to about 3.5 nm, about 3 nm to about 4 nm, or about 3.5 nm to about 4 nm. In some cases, a distance or dimension (e.g., diameter) may be measured from an atom to a nearest atom of the side chain of the amino acid residue. The side chain (e.g., atom of the side chain) may protrude into the constriction region of the channel and / or constriction-forming portion of the monomer. In some cases, a distance or dimension (e.g., diameter) of an atom to a nearest atom of an amino acid residue of an engineered monomer and / or engineered biological nanopore described herein may be at least about 0.0001 nm, at least about 0.0005 nm, at least about 0.001 nm, at least about 0.005 nm, at least about 0.01 nm, at least about 0.02nm, at least about 0.03 nm, at least about 0.04 nm, at least about 0.05 nm, at least about 0.06 nm, at least about 0.07 nm, at least about 0.08 nm, at least about 0.09 nm, at least about 0.1 nm, at least about 0.2 nm, at least about 0.3 nm, at least about 0.4 nm, at least about 0.5 nm, at least about 0.6 nm, at least about 0.7 nm, at least about 0.8 nm, at least about 0.9 nm, at least about 1.0 nm, at least about 1.1 nm, at least about 1.2 nm, at least about 1.3 nm, at least about 1.4 nm, at least about 1.5 nm, at least about 1.6 nm, at least about 1.7 nm, at least about 1.8 nm, at least about 1.9 nm, at least about 2.0 nm or greater than about 2.0 nm. In some cases, a distance or dimension (e.g., diameter) of an atom to a nearest atom of an amino acid residue of an engineered monomer and / or engineered biological nanopore described herein may be at most about 2.0 nm, at most about 1.9 nm, at most about 1.8 nm, at most about 1.7 nm, at most about 1.6 nm, at most about 1.5 nm, at most about 1.4 nm, at most about 1.3 nm, at most about 1.2 nm, at most about 1.1 nm, at most about 1.0 nm, at most about 0.9 nm, at most about 0.8 nm, at most about 0.7 nm, at most about 0.6 nm, at most about 0.5 nm, at most about 0.4 nm, at most about 0.3 nm, at most about 0.2 nm, at most about 0.1 nm, at most about 0.09 nm, at most about 0.08 nm, at most about 0.07 nm, at most about 0.06 nm, at most about 0.05 nm, at most about 0.04 nm, at most about 0.03 nm, at most about 0.02 nm, at most about 0.01 nm, at most about 0.005 nm, at most about 0.001 nm, at most about 0.0005 nm, at most about 0.0001 nm, or less than about 0.0001 nm. In some cases, a distance or dimension (e.g., diameter) of an atom to a nearest atom of an amino acid residue of an engineered monomer and / or engineered biological nanopore described herein may be from about 0.0001 nm to about 2 nm. In some cases, a distance or dimension (e.g., diameter) of an atom to a nearest atom of an amino acid residue of an engineered monomer and / or engineered biological nanopore described herein may be from about 0.0001 nm to about 0.001 nm, about 0.0001 nm to about 0.005 nm, about 0.0001 nm to about 0.01 nm, about 0.0001 nm to about 0.05 nm, about 0.0001 nm to about 0.1 nm, about 0.0001 nm to about 0.2 nm, about 0.0001 nm to about 0.3 nm, about 0.0001 nm to about 0.4 nm, about 0.0001 nm to about 0.5 nm, about 0.0001 nm to about 1 nm, about 0.0001 nm to about 2 nm, about 0.001 nm to about 0.005 nm, about 0.001 nm to about 0.01 nm, about 0.001 nm to about 0.05 nm, about 0.001 nm to about 0.1 nm, about 0.001 nm to about 0.2 nm, about 0.001 nm to about 0.3 nm, about 0.001 nm to about 0.4 nm, about 0.001 nm to about 0.5 nm, about 0.001 nm to about 1 nm, about 0.001 nm to about 2 nm, about 0.005 nm to about 0.01 nm, about 0.005 nm to about 0.05 nm, about 0.005 nm to about 0.1 nm, about 0.005 nm to about 0.2 nm, about 0.005 nm to about 0.3 nm, about 0.005 nm to about 0.4 nm, about 0.005 nm to about 0.5 nm, about 0.005 nm to about 1 nm, about 0.005 nm to about 2 nm, about 0.01 nm to about 0.05 nm, about 0.01 nm to about 0.1 nm, about 0.01 nm to about 0.2 nm, about 0.01 nm to about 0.3 nm, about 0.01 nm to about 0.4 nm, about 0.01 nm to about 0.5 nm, about 0.01 nm to about 1 nm, about 0.01 nm to about 2 nm, about 0.05 nm to about 0.1 nm, about 0.05 nm to about 0.2 nm, about 0.05 nm to about 0.3 nm, about 0.05 nm to about 0.4 nm, about 0.05 nm to about 0.5 nm, about 0.05 nm to about 1 nm, about 0.05 nm to about 2 nm, about 0.1 nm to about 0.2 nm, about 0.1 nm to about 0.3 nm, about 0.1 nm to about 0.4 nm, about 0.1 nm to about 0.5 nm, about 0.1 nm to about 1 nm, about 0.1 nm to about 2 nm, about 0.2 nm to about 0.3 nm, about 0.2 nm to about 0.4 nm, about 0.2 nm to about 0.5 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 2 nm, about 0.3 nm to about 0.4 nm, about 0.3 nm to about 0.5 nm, about 0.3 nm to about 1 nm, about 0.3 nm to about 2 nm, about 0.4 nm to about 0.5 nm, about 0.4 nm to about 1 nm, about 0.4 nm to about 2 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 2 nm, or about 1 nm to about 2 nm. A constriction region may be located at any region of a nanopore (e.g., a region of the channel of the biological nanopore). In some cases, the constriction region can be located at the first entrance of the nanopore (e.g., the biological nanopore). For example, the constriction region can be adjacent to a first entrance of the nanopore. A constriction region may be located at least about 0.0001 nm (nanometers), 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 15 nm, 20 nm, or greater than about 20 nm from a first entrance of a nanopore. A constriction region may be located at most about 20 nm, 15 nm, 10 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, 0.5 nm, 0.1 nm, 0.05 nm, 0.01 nm, 0.001 nm, 0.0001 nm, or less than about 0.0001 nm from a first entrance of a nanopore. In some cases, a constriction region may be located from about 0.0001 nm to about 10 nm from a first entrance of a nanopore. In some cases, a constriction region may be located from about 0.0001 nm to about 0.0005 nm, about 0.0001 nm to about 0.001 nm, about 0.0001 nm to about 0.005 nm, about 0.0001 nm to about 0.01 nm, about 0.0001 nm to about 0.05 nm, about 0.0001 nm to about 1 nm, about 0.0001 nm to about 2 nm, about 0.0001 nm to about 3 nm, about 0.0001 nm to about 4 nm, about 0.0001 nm to about 5 nm, about 0.0001 nm to about 10 nm, about 0.0005 nm to about 0.001 nm, about 0.0005 nm to about 0.005 nm, about 0.0005 nm to about 0.01 nm, about 0.0005 nm to about 0.05 nm, about 0.0005 nm to about 1 nm, about 0.0005 nm to about 2 nm, about 0.0005 nm to about 3 nm, about 0.0005 nm to about 4 nm, about 0.0005 nm to about 5 nm, about 0.0005 nm to about 10 nm, about 0.001 nm to about 0.005 nm, about 0.001 nm to about 0.01 nm, about 0.001 nm to about 0.05 nm, about 0.001 nm to about 1 nm, about 0.001 nm to about 2 nm, about 0.001 nm to about 3 nm, about 0.001 nm to about 4 nm, about 0.001 nm to about 5 nm, about 0.001 nm to about 10 nm, about 0.005 nm to about 0.01 nm, about 0.005 nm to about 0.05 nm, about 0.005 nm to about 1 nm, about 0.005 nm to about 2 nm, about 0.005 nm to about 3 nm, about 0.005 nm to about 4 nm, about 0.005 nm to about 5 nm, about 0.005 nm to about 10 nm, about 0.01 nm to about 0.05 nm, about 0.01 nm to about 1 nm, about 0.01 nm to about 2 nm, about 0.01 nm to about 3 nm, about 0.01 nm to about 4 nm, about 0.01 nm to about 5 nm, about 0.01 nm to about 10 nm, about 0.05 nm to about 1 nm, about 0.05 nm to about 2 nm, about 0.05 nm to about 3 nm, about 0.05 nm to about 4 nm, about 0.05 nm to about 5 nm, about 0.05 nm to about 10 nm, about 1 nm to about 2 nm, about 1 nm to about 3 nm, about 1 nm to about 4 nm, about 1 nm to about 5 nm, about 1 nm to about 10 nm, about 2 nm to about 3 nm, about 2 nm to about 4 nm, about 2 nm to about 5 nm, about 2 nm to about 10 nm, about 3 nm to about 4 nm, about 3 nm to about 5 nm, about 3 nm to about 10 nm, about 4 nm to about 5 nm, about 4 nm to about 10 nm, or about 5 nm to about 10 nm from a first entrance of a nanopore. In some cases, the constriction region can be located at the second entrance of the nanopore (e.g., the biological nanopore). For example, the constriction region can be located adjacent to the second entrance of the nanopore. A constriction region may be located at least about 0.0001 nm, 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 15 nm, 20 nm, or greater than about 20 nm from a second entrance of a nanopore. A constriction region may be located at most about 20 nm, 15 nm, 10 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, 0.5 nm, 0.1 nm, 0.05 nm, 0.01 nm, 0.001 nm, 0.0001 nm, or less than about 0.0001 nm from a second entrance of a nanopore. In some cases, a constriction region may be located from about 0.0001 nm to about 10 nm from a second entrance of a nanopore. In some cases, a constriction region may be located from about 0.0001 nm to about 0.0005 nm, about 0.0001 nm to about 0.001 nm, about 0.0001 nm to about 0.005 nm, about 0.0001 nm to about 0.01 nm, about 0.0001 nm to about 0.05 nm, about 0.0001 nm to about 1 nm, about 0.0001 nm to about 2 nm, about 0.0001 nm to about 3 nm, about 0.0001 nm to about 4 nm, about 0.0001 nm to about 5 nm, about 0.0001 nm to about 10 nm, about 0.0005 nm to about 0.001 nm, about 0.0005 nm to about 0.005 nm, about 0.0005 nm to about 0.01 nm, about 0.0005 nm to about 0.05 nm, about 0.0005 nm to about 1 nm, about 0.0005 nm to about 2 nm, about 0.0005 nm to about 3 nm, about 0.0005 nm to about 4 nm, about 0.0005 nm to about 5 nm, about 0.0005 nm to about 10 nm, about 0.001 nm to about 0.005 nm, about 0.001 nm to about 0.01 nm, about 0.001 nm to about 0.05 nm, about 0.001 nm to about 1 nm, about 0.001 nm to about 2 nm, about 0.001 nm to about 3 nm, about 0.001 nm to about 4 nm, about 0.001 nm to about 5 nm, about 0.001 nm to about 10 nm, about 0.005 nm to about 0.01 nm, about 0.005 nm to about 0.05 nm, about 0.005 nm to about 1 nm, about 0.005 nm to about 2 nm, about 0.005 nm to about 3 nm, about 0.005 nm to about 4 nm, about 0.005 nm to about 5 nm, about 0.005 nm to about 10 nm, about 0.01 nm to about 0.05 nm, about 0.01 nm to about 1 nm, about 0.01 nm to about 2 nm, about 0.01 nm to about 3 nm, about 0.01 nm to about 4 nm, about 0.01 nm to about 5 nm, about 0.01 nm to about 10 nm, about 0.05 nm to about 1 nm, about 0.05 nm to about 2 nm, about 0.05 nm to about 3 nm, about 0.05 nm to about 4 nm, about 0.05 nm to about 5 nm, about 0.05 nm to about 10 nm, about 1 nm to about 2 nm, about 1 nm to about 3 nm, about 1 nm to about 4 nm, about 1 nm to about 5 nm, about 1 nm to about 10 nm, about 2 nm to about 3 nm, about 2 nm to about 4 nm, about 2 nm to about 5 nm, about 2 nm to about 10 nm, about 3 nm to about 4 nm, about 3 nm to about 5 nm, about 3 nm to about 10 nm, about 4 nm to about 5 nm, about 4 nm to about 10 nm, or about 5 nm to about 10 nm from a second entrance of a nanopore. A constriction region can be located between the first and second entrance of a nanopore (e.g., the biological nanopore). For example, a constriction region may reside in a channel of a nanopore described herein at any distance between a first entrance and a second entrance of the nanopore. A nanopore may comprise a constriction region with an adjacent channel region. An adjacent channel region can comprise a region of the nanopore channel that may be at least about 0.0001 nm, 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, or greater than about 10 nm from a constriction region. An adjacent channel region can comprise a region of the nanopore channel that may be at most about 10 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, 0.5 nm, 0.1 nm, 0.05 nm, 0.01 nm, 0.001 nm, 0.0001 nm, or less than about 0.0001 nm from a constriction region. The method can comprise increasing the net positive charge at the constriction area and / or in the funnel region just outside of the at least one constriction area. The distance can be a length between a first region (e.g., a funnel region) and a second region (e.g., a constriction region). The distance (e.g., length) of the funnel region to the constriction area (measured along the central pore axis) can be preferably in a range having a lower limit selected from about 0.2 nm, about 0.3 nm, about 0.4 nm, about 0.5 nm, about 0.6 nm, about 0.7 nm, about 0.8 nm, about 0.9 nm, about 1.0 nm, about 1.2 nm, about 1.5 nm, about 2.0 and an upper limit independently selected from about 3 nm, about 2.9 nm, about 2.8 nm, about 2.7 nm, about 2.6 nm, about 2.5 nm, about 2.4 nm, about 2.3 nm, about 2.2 nm, or about 2.1 nm. An "applied potential" can refer to an electrical potential (e.g., voltage) that is introduced to a system. The terms "applied potential" and "applied voltage" may be used interchangeably herein. The applied potential may be a force driving charge (e.g., ions) to move through the system. For example, the nanopore system described herein may have a solution (e.g., an electrolyte solution) and the membrane may be immersed in the solution. The solution can contain a concentration of one or more ions that conduct electricity. A potential (e.g., voltage difference) can be applied across the membrane, creating an electric field that drives ionic current through a nanopore. In the nanopore system, a positive potential may be applied to a first side (e.g., a cis side) or a second side (e.g., a trans side). In some cases, a negative potential may be applied to a first side (e.g., a cis side) or a second side (e.g., a trans side). An applied voltage may refer to a first applied voltage and / or a second applied voltage. As an example, a first applied voltage, or a second applied voltage, or any combination thereof can be applied to any side of a nanopore system described herein. In some cases, an applied voltage may be at least about 10 mV, 20 mV, 30 mV, 40 mV, 50 mV, 60 mV, 70 mV, 80 mV, 90 mV, 100 mV, 150 mV, 200 mV, 250 mV, 300 mV, 350 mV, 400 mV, 450 mV, 500 mV, 600 mV, 700 mV, 800 mV, 900 mV, 1000 mV, or greater than about 1000 mV in magnitude. A potential difference (e.g., voltage difference) can be established between a first side and second side of the nanopore system. For example, a positive electrical voltage may be introduced on one side of the system (e.g., a trans side), relative to another side of the system (e.g., a "cis" side), where the voltage may be negative. The electrical field may then drive charged molecules (e.g., negatively-charged molecules) through a nanopore from one side of the system to the other. In some cases, a potential difference of the nanopore system may be less than about -10 mV or greater than about +10 mV. For example, a potential difference of the system may be less than about -300 mV, about -300 mV, about -200 mV, about -180 mV, about -160 mV, about -140 mV, about -120 mV, about -100 mV, about -80 mV, about -60 mV, about -40 mV, about -20 mV, about -10 mV, about 0 mV, about +10 mV, about +20 mV, about +40 mV, about +60 mV, about +80 mV, about +100 mV, about +120 mV, about +140 mV, about +160 mV, about +180 mV, about +200 mV, about +300 mV, or greater than about +300 mV. In some cases, an electro-osmotic flow can act across the membrane in a first side (e.g., cis side) to a second side (e.g., trans side) direction. In some cases, an electro- osmotic flow can act across the membrane in a second side (e.g., trans side) to a first side (e.g., cis side) direction. An electro-osmotic flow can be the flow that results from a net flow of a mobile layer of ions along a surface as induced by an applied potential (e.g., applied voltage potential). For example, a charged surface may form a static layer of oppositely charged mobile ions. Under an applied potential the charged mobile ions may be induced to move in the direction of higher potential if negative, or in the direction of lower potential if positive. The flow of charged ions can create a drag on the surrounding solvent (e.g., water) molecules, which in turn can result in a net flow that exerts a force acting on the surrounding molecules, both charged and neutral. For example, in a positively-charged nanopore channel, an electro-osmotic flow can result from a net flow of negative ions (e.g., anions) in a cis to trans direction (e.g., due to a lower potential on the trans side) causing the surrounding water to flow cis to trans and exert a force on surrounding molecules. The amount of ion flow and the corresponding magnitude of the electro-osmotic flow can be influenced by parameters such as an ion concentration difference across the membrane, a difference in potential, a net charge of a nanopore channel, a geometry of a nanopore channel, or any combinations thereof. The net charge of the channel, the geometry of the channel, or any combination thereof, can influence a flow of molecules through the channel. The flowing molecules can be analytes, ions, water, other molecules, or any combination thereof on a first side (e.g., cis side) or a second side (e.g., trans side) of a nanopore. The flowing molecules can generate an ionic current from a flow of ions. Without wishing to be bound by thereof, as an analyte translocates through a pore, other molecules (such as ions) can be obstructed from translocating through the pore. This obstruction in translocation of other molecules (e.g., ions) can change the ionic current by changing the rate of flow of ions. This change in current can be measured, for example, by a pair of electrodes configured to measure a current from a first side (e.g., cis side) to a second side (e.g., trans side) across the nanopore. A nanopore of a nanopore system described herein may employ alternative means of measuring the voltage-current properties of the nanopore system, such as those that employ fluorescence probes of ionic flux or field effect transistor systems than measure changes in voltage. However, there can also be other suitable detection methods, such as tunneling, surface enhanced raman, plasmonics, and other spectroscopic methods that do not measure the ionic current and instead measure the properties of the target analyte in the nanopore directly. In some cases, the change in current can be measured by a pair of electrodes configured to measure a current from a first side (e.g., cis side) to a second side (e.g., trans side) across a membrane of which the nanopore may be disposed. In some cases, a narrow geometry of the channel can slow a progression of an analyte through a pore. A change to a net charge or a geometry of a channel of a nanopore can change the flow of molecules through the pore. For example, changing a channel to have a more positive net charge can reduce a flow of a positively- charged molecule (e.g., a potassium ion). In some cases, changing a channel to have a wider geometry can increase a flow of a larger molecule (e.g., a glucose molecule or a peptide analyte). In some cases, changing a channel to have a more positive net charge and a narrower geometry can reduce a flow of a large, positively- charged molecule. The net charge of the channel can influence the flow of charged molecules through the nanopore. As another example, changing a first portion and / or third portion of one or more monomers (e.g., contributing to a first region of a channel and / or third region of a channel of an engineered biological nanopore) to have a more positive net charge can reduce a flow of a positively-charged molecule (e.g., a potassium ion). In some cases, changing a first portion and / or third portion of one or more monomers (e.g., contributing to a first region and / or third region of an engineered biological nanopore) to have a wider geometry can increase a flow of a larger molecule (e.g., a glucose molecule or a peptide analyte). In some cases, changing a first portion and / or third portion of one or more monomers (e.g., contributing to a first region of a channel and / or third region of a channel of an engineered biological nanopore) to have a more positive net charge and a narrower geometry can reduce a flow of a large, positively-charged molecule. The net charge of the channel can influence the flow of charged molecules through the nanopore. In some cases, a shift in the net charge can make some charged molecules translocate more easily through the pore. In some cases, a shift in the net charge can make some charged molecules translocate with more difficulty through the pore. One or more mutations may be introduced to modify a charge of a first region, second region, third region, or any combination thereof. In some cases, a region (e.g., a first region or a third region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore. A respective region can be an identical region of a wild-type nanopore as compared to the region of a nanopore described herein (e.g., an engineered biological nanopore). A region (e.g., a first region or a third region) may have an amino acid composition comprising a plurality of amino acids. The plurality of amino acids may comprise one or more positively-charged amino acids, one or more neutral amino acids, one or more negatively-charged amino acids, or any combination thereof. A region (e.g., a first region or a third region) may be modified by introducing one or more amino acid mutations to the region (e.g., a first region or a third region). In some cases, a region (e.g., a first region or a third region) may be modified by introducing one or more amino acid mutations to a monomer comprising a portion that corresponds to that region. As an example, a region (e.g., a first region or a third region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore by substituting one or more negatively-charged amino acids and / or one or more neutral charged amino acids with one or more positively-charged amino acids. As another example, a region (e.g., a first region or a third region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore by deleting one or more negatively-charged amino acids and / or one or more neutral charged amino acids. As another example, a region (e.g., a first region or a third region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore by adding one or more positively-charged amino acids to the region. As another example, if a region (e.g., a first region or a third region) has a net negative charge, the region may be modified to be more net positive as compared to a respective region of a wild-type nanopore by substituting one or more negatively-charged amino acids with one or more neutral charged amino acids and / or one or more positively-charged amino acids. As another example, if the region (e.g., a first region or a third region) has a greater number of positively- charged amino acid residues compared to a number of negatively-charged amino acids and one or more neutral charged amino acids, the region may still be modified to be more net positive as compared to a respective region of a wild-type nanopore by (i) substituting one or more negatively-charged amino acids and / or one or more neutral charged amino acids with one or more positively-charged amino acids; (ii) deleting one or more negatively-charged amino acids and / or one or more neutral charged amino acids; (iii) adding one or more positively-charged amino acids; (iv) or any combination thereof. One or more natural amino acids and / or non- natural amino acids may be introduced to modify the region to be more net positive as compared to a respective region of a wild-type nanopore. One or more natural amino acids and / or non-natural amino acids may be deleted to modify the region to be more net positive as compared to a respective region of a wild-type nanopore. The natural amino acids (e.g., positively-charged natural amino acids) and / or non- natural amino acids (e.g., positively-charged non-natural amino acids) may be any described herein. In some cases, an electro-osmotic flow can be the flow that results from one or more constriction regions present in a nanopore channel. For example, constriction regions in a nanopore can affect the flow of some ions (e.g. larger hydrated ions) more than other ions (e.g. smaller hydrated ions). In some cases, an electro-osmotic flow can be the flow that results from a net flow of mobile ions along a surface as induced by an applied potential and one or more constriction regions present in a nanopore channel. In some cases, an electro-osmotic flow can be created or modified by a difference between a solution on a first side (e.g., cis side) of a membrane and a solution on a second side (e.g., trans side) of a membrane. In some cases, the solution on the first side (e.g., cis side) of the membrane can be a first solution. In some cases, the solution on the second side (e.g., trans side) of the membrane can be a second solution. The difference can be a difference in concentration of a molecule, including an ion, an electrolyte, an osmolyte, or any combination thereof. In some cases, the engineered biological nanopore may generate an EOF that can be greater than an EOF of a wild-type biological nanopore. The EOF of the engineered biological nanopore may be greater than an EOF of the wild-type biological nanopore due to a first region of a channel comprising a different charge as compared to that of the wild-type biological nanopore, and / or, a second region of the channel comprising a different charge as compared to that of the wild-type biological nanopore, a third region of a channel comprising a different charge as compared to that of the wild-type biological nanopore, or any combination thereof. In some cases, the engineered biological nanopore may comprise a first region and / or third region with an increase in net positive charge compared to a first region and / or third region of a wild-type biological nanopore. In some cases, the engineered biological nanopore may comprise a first region and / or third region with a greater number of positively-charged amino acid residues than that of a first region and / or third region of a wild-type biological nanopore. In some cases, the engineered biological nanopore may comprise a first region and / or third region with a greater number of neutral charged amino acid residues than a first region and / or third region of a wild-type biological nanopore. In some cases, the engineered biological nanopore described herein may comprise a first region and / or third region of the channel comprising a positive charge. In some cases, the first and / or third region of the engineered biological nanopore may be more positive as compared to a respective region of a wild-type nanopore. In some cases, a net charge of a first and / or third region may be at least about 50% more positive as compared to a respective region of the wild-type biological nanopore. For example, a net charge of the first and / or third region may be at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, or greater than about 95% more positive as compared to a respective region of the wild-type biological nanopore. As another example, a net charge of the first and / or third region may be at most about 95%, 90%, 85%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or less than about 20% more positive as compared to a respective region of the wild-type biological nanopore (e.g., another region adjacent to the constriction region of the wild-type biological nanopore). In some cases, the engineered biological nanopore may comprise a second region with an increase in net neutral charge compared to a second region of a wild-type biological nanopore. In some cases, the engineered biological nanopore may comprise a second region with a greater number of positively- charged amino acid residues than that of a second region of a wild-type biological nanopore. In some cases, the engineered biological nanopore may comprise a second region with a greater number of neutral charged amino acid residues than a second region of a wild-type biological nanopore. In some cases, the engineered biological nanopore described herein may comprise a second region of the channel comprising a neutral charge. In some cases, a second region may be more neutral as compared to a respective region of a wild-type biological nanopore. For example, a net charge of a second region may be at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, or greater than about 95% more neutral as compared to a respective region of a wild-type biological nanopore. As another example, a net charge of the second region may be at most about 95%, 90%, 85%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or less than about 20% more neutral as compared to a respective region of the wild-type biological nanopore (e.g., a constriction region of the wild-type biological nanopore). In some cases, the positive charge of the first region and / or third region of the channel and the neutral charge of the second region of the channel may generate the EOF. The increase in positive charge of the first region and / or third region of the channel (e.g., adjacent to the constriction region) and / or an increase in positive charge of the second region may generate the EOF. In some cases, a first region may be modified. The first region may be modified to be more net positive than a respective region of a wild-type nanopore (e.g., a wild- type biological nanopore). In some cases, the second region of the engineered biological nanopore may be modified. The second region may be modified to be more net neutral or more net positive than a respective region of a wild-type nanopore (e.g., a wild-type biological nanopore). For example, a pore (e.g., an engineered biological nanopore) described herein may comprise a first region modified be more net positive and a second region modified to be more net neutral or more net positive than a respective region of a wild-type nanopore (e.g., a wild- type biological nanopore). A region (e.g., a second region) may have an amino acid composition comprising a plurality of amino acids. The plurality of amino acids may comprise one or more positively-charged amino acids, one or more neutral amino acids, one or more negatively-charged amino acids, or any combination thereof. A region (e.g., a second region) may be modified by introducing one or more amino acid mutations to the region (e.g., a second region). As an example, a region (e.g., a second region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore by substituting one or more negatively- charged amino acids and / or one or more neutral charged amino acids with one or more positively-charged amino acids. As an example, a region (e.g., a second region) may be modified to be more net neutral as compared to a respective region of a wild-type nanopore by substituting one or more negatively-charged amino acids and / or one or more positively-charged amino acids with one or more neutral- charged amino acids. As another example, a region (e.g., a second region) may be modified to be more net positive as compared to a respective region of a wild-type nanopore by deleting one or more negatively-charged amino acids and / or one or more neutral charged amino acids. As another example, a region (e.g., a second region) may be modified to be more net neutral as compared to a respective region of a wild-type nanopore by deleting a same number of negatively-charged amino acids and positively-charged amino acids. For example, if the region (e.g., a second region) has 10 amino acids with 4 negatively-charged amino acids and 6 positively- charged amino acids, the region may be modified to be more neutral by (i) deleting one or more positively-charged amino acids; (ii) substituting one or more negatively-charged amino acids and / or one or more positively-charged amino acids with one or more neutral-charged amino acids; (iii) adding one or more negatively- charged amino acids; or (iv) any combination thereof). One or more natural amino acids and / or non-natural amino acids may be introduced to modify the region to be more net positive as compared to a respective region of a wild-type nanopore. One or more natural amino acids and / or non-natural amino acids may be deleted to modify the region to be more net positive as compared to a respective region of a wild-type nanopore. The first region modified to be more net positive and / or the second region modified to be more net neutral or more net positive may generate an EOF. In some cases, a monomer of the nanopore can comprise a first portion, a second portion, a third portion, or any combinations thereof. A first portion of the monomer may correspond to a first region of the nanopore. A second portion of the monomer may correspond to a second region of the nanopore. A third portion of the monomer may correspond to a third region of the nanopore. In some cases, the engineered monomer may comprise a first portion and / or third portion with an increase in net positive charge compared to a first portion and / or third portion of a wild-type biological monomer. In some cases, the engineered monomer may comprise a first portion and / or third portion with a greater number of positively-charged amino acid residues than that of a first portion and / or third portion of a wild-type monomer. In some cases, the engineered monomer may comprise a first portion and / or third portion with a greater number of neutral charged amino acid residues than a first portion and / or third portion of a wild-type monomer. In some cases, the engineered monomer described herein may comprise a first portion and / or third portion of the channel comprising a positive charge. In some cases, the engineered monomer may comprise a second portion with an increase in net neutral charge compared to a second portion of a wild-type monomer. In some cases, the engineered monomer may comprise a second portion with a greater number of positively-charged amino acid residues than that of a second portion of a wild-type monomer. In some cases, the engineered monomer may comprise a second portion with a greater number of neutral charged amino acid residues than a second portion of a wild-type monomer. In some cases, the engineered monomer described herein may comprise a second portion of the channel comprising a neutral charge. In some cases, the positive charge of the first portion and / or third portion of the channel and the neutral charge of the second portion of the channel may generate the EOF. The neutral charge of (i) the second region of the channel or (ii) the second portion (e.g., constriction-forming portion) of the engineered monomer may comprise a range of neutrality. For example, a second portion of a monomer may comprise two negatively-charged amino acid residues and mutating one amino acid residue to a neutral amino acid residue can result in a 50% increase in neutrality (e.g., neutral charge). In some cases, there may be a 100% increase in neutral charge if all non- neutral amino acid residues can be mutated to neutral amino acid residues. In some cases, the positively-charged first region and / or third region of the channel adjacent to the neutral charged second region (e.g., comprising the constriction region) of the nanopore can generate an EOF greater than an EOF generated by a wild-type pore (e.g., a pore that may not comprise the positively-charged first region of the channel adjacent to the neutral charged constriction region). An EOF may be generated between a difference of net ionic current flow between cations and anions. A cation can comprise a positively-charged ion, for example potassium (K+). An anion can comprise a negatively-charged ion, for example chlorine (Cl-). The engineered biological nanopore described herein may increase an anion selectivity (also referred to as P(-) / P(+)). In some cases, an EOF of the nanopore described herein comprising a positively- charged first region and / or third region of the channel adjacent to an increased neutrally-charged second region (e.g., constriction region) may comprise an EOF of at least about 1.1-fold, at least about 1.2-fold, at least about 1.3-fold, at least about 1.4-fold, at least about 1.5-fold, at least about 2.0-fold, at least about 2.5-fold, at least about 3.0-fold, at least about 3.5-fold, at least about 4.0-fold, at least about 4.5-fold, at least about 5.0-fold, at least about 6.0-fold, at least about 7.0-fold, at least about 8.0-fold, at least about 9.0-fold, or at least about 10.0-fold greater than an EOF generated by a wild-type nanopore or a nanopore that does not comprise a positively-charged first region and / or third region of the channel adjacent to the increased neutrally-charged second portion (e.g., constriction region). In some cases, an EOF of the nanopore described herein comprising a positively-charged first region and / or third region of the channel adjacent to an increased neutrally- charged second region (e.g., constriction region) may comprise an EOF of at most about 10.0-fold, at most about 9.0-fold, at most about 8.0-fold, at most about 7.0- fold, at most about 6.0-fold, at most about 5.0-fold, at most about 4.5-fold, at most about 3.5-fold, at most about 3.0-fold, at most about 2.5-fold, at most about 2.0-fold, at most about 1.5-fold, at most about 1.4-fold, at most about 1.3-fold, at most about 1.2-fold, or at most about 1.1-fold greater than an EOF generated by a wild-type nanopore or a nanopore that does not comprise a positively-charged first region and / or third region of the channel adjacent to the increased neutrally-charged second portion (e.g., constriction region). In some cases, an EOF of the nanopore described herein comprising a positively- charged first region and / or third region of the channel adjacent to an increased neutrally-charged second region (e.g., constriction region) may comprise an EOF from about 1.1-fold to about 10-fold greater than an EOF generated by a wild-type nanopore or a nanopore that does not comprise a positively-charged first region and / or third region of the channel adjacent to the increased neutrally-charged second portion (e.g., constriction region). In some cases, an EOF of the nanopore described herein comprising a positively-charged first region and / or third region of the channel adjacent to an increased neutrally-charged second region (e.g., constriction region) may comprise an EOF from about 1.1-fold to about 1.2-fold, about 1.1-fold to about 1.3-fold, about 1.1-fold to about 1.4-fold, about 1.1-fold to about 1.5-fold, about 1.1-fold to about 2-fold, about 1.1-fold to about 3-fold, about 1.1-fold to about 4-fold, about 1.1-fold to about 5-fold, about 1.1-fold to about 8-fold, about 1.1-fold to about 10-fold, about 1.2-fold to about 1.3-fold, about 1.2-fold to about 1.4-fold, about 1.2-fold to about 1.5-fold, about 1.2-fold to about 2-fold, about 1.2-fold to about 3-fold, about 1.2-fold to about 4-fold, about 1.2-fold to about 5-fold, about 1.2-fold to about 8-fold, about 1.2-fold to about 10-fold, about 1.3-fold to about 1.4-fold, about 1.3-fold to about 1.5-fold, about 1.3-fold to about 2-fold, about 1.3- fold to about 3-fold, about 1.3-fold to about 4-fold, about 1.3-fold to about 5-fold, about 1.3-fold to about 8-fold, about 1.3-fold to about 10-fold, about 1.4-fold to about 1.5-fold, about 1.4-fold to about 2-fold, about 1.4-fold to about 3-fold, about 1.4-fold to about 4-fold, about 1.4-fold to about 5-fold, about 1.4-fold to about 8-fold, about 1.4-fold to about 10-fold, about 1.5-fold to about 2-fold, about 1.5-fold to about 3- fold, about 1.5-fold to about 4-fold, about 1.5-fold to about 5-fold, about 1.5-fold to about 8-fold, about 1.5-fold to about 10-fold, about 2-fold to about 3-fold, about 2- fold to about 4-fold, about 2-fold to about 5-fold, about 2-fold to about 8-fold, about 2-fold to about 10-fold, about 3-fold to about 4-fold, about 3-fold to about 5-fold, about 3-fold to about 8-fold, about 3-fold to about 10-fold, about 4-fold to about 5- fold, about 4-fold to about 8-fold, about 4-fold to about 10-fold, about 5-fold to about 8-fold, about 5-fold to about 10-fold, or about 8-fold to about 10-fold greater than an EOF generated by a wild-type nanopore or a nanopore that does not comprise a positively-charged first region and / or third region of the channel adjacent to the increased neutrally-charged second portion (e.g., constriction region). Improving sensing properties may comprise increasing the anion-selectivity and / or increasing EOF of the nanopore. The increase may be at least 10%, at least 15%, at least 18%, at least 20%, at least 23%, at least 25%, at least 30%, at least 40%, at least 50%, at least 70%, at least 80%, at least 90%, at least 100%, at least 125%, at least 140%, at least 150%, at least 170%, at least 180%, at least 200%, at least 250%, at least 300%, at least 350%, at least 400%, at least 450%, at least 500%, at least 600%, at least 700% as compared to the nanopore without having an increased net charge of the lumen-facing residues in the constriction area and / or in the funnel region as defined above. In some cases, modified nanopore can be an anion-selective nanopore. In some cases, the anion-selectivity P(-) / P(+) of the nanopore can be at least 1.25, at least 1.3, at least 1.4, at least 1.5, at least 1.6, at least 1.7, at least 1.8, at least 1.9, at least 2.0, at least 2.1, at least 2.2, at least 2.4, at least 2.6, at least 2.8, at least 3.0, at least 3.2, at least 3.4, at least 3.6, at least 3.8, at least 4.0, at least 4.2, at least 4.4, at least 4.6, at least 4.8, at least 5.0, at least 5.5, at least 6.0, at least 6.5, at least 6.8, at least 7.0, at least 7.3, at least 7.5, at least 7.7, at least 8.0, at least 8.5, at least 9.0. The net positive charge may be increased by at least 1, 2, 3, 4 or 5 unitary charges. In some cases, the net positive charge can be increased by > 5 unitary charges, > 7, > 10, > 15 charges. In some cases, the net positive charge may be increased by at least 1, 2, 3, 4, 5, or more unitary charges per promoter (monomer). In some cases, the nanopore can have a net positive charge at the pore exit, in a region just below the constriction area. In some cases, the nanopore can have a positively-charged constriction area. A “positively-charged constriction area” refers to a constriction area comprising amino acid side chains that cumulatively exhibit a net positive electrical charge when immersed in an aqueous solution. The pH of the liquid medium (e.g., a buffered aqueous solution) in contact with the constriction area may affect whether the constriction area can be characterized as positively-charged or not. In some cases, the nanopore can have a neutral constriction area. A “neutral constriction area” refers to a constriction area comprising amino acid side chains that cumulatively exhibit no net electrical charge when immersed in an aqueous solution. The pH of the liquid medium (e.g., a buffered aqueous solution) in contact with the constriction area may affect whether the constriction zone can be characterized as neutral or not. In some cases, the nanopore can have a net positive charge in the funnel region combined with a neutral constriction area. The second region of the channel (e.g., comprising the constriction region) may comprise a first entrance, a second entrance, or any combination thereof. In some cases, the positive charge of the first region and / or third region may be adjacent to a first entrance of the second region of the channel. The positive charge may be a positively-charged amino acid residue of the engineered biological nanopore (e.g., of a monomer of the engineered biological nanopore). The positive charge may be a ring of charge of the engineered biological nanopore. In some cases, the positive charge of the first region and / or third region of the channel may be at least about, at most about, or about 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1.0 nm, 2.0 nm, 3.0 nm, 4.0 nm, 5.0 nm, or 10 nm from the first entrance of the second region of the channel. In some cases, the positive charge of the first region and / or third region of the channel may be at least about, at most about, or about 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1.0 nm, 2.0 nm, 3.0 nm, 4.0 nm, 5.0 nm, or 10 nm from the second entrance of the second region of the channel. The positive charge of the first region and / or third region of the channel may be adjacent to the first entrance of the second region and the second entrance to the second region. For example, the positive charge may be on both sides of the second region of the channel. In some cases, the positive charge of the first region and / or third region of the channel may be at least about, at most about, or about 0.001 nm, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1.0 nm, 2.0 nm, 3.0 nm, 4.0 nm, 5.0 nm, or 10 nm from the first entrance of the second region and the second entrance to the second region. In some cases, the nanopore can have a net positive charge in a region just below the constriction area combined with a neutral constriction area. In some cases, the nanopore can be a transmembrane protein pore derived from beta- barrel pores or alpha-helix bundle pores, beta-barrel pores comprising a barrel or channel that can be formed from beta-strands. Examples of beta-barrel pores can include, but are not limited to, beta-toxins, such as alpha-hemolysin, anthrax toxin and leukocidins, and outer membrane proteins / porins of bacteria, such as Mycobacterium smegmatis porin (Msp), for example MspA, MspB, MspC or MspD, CsgG from the E. coli curli secretion system, outer membrane porin F (OmpF), outer membrane porin G (OmpG), outer membrane phospholipase A, outer membrane protein FhuA, outer membrane protein A (OmpA) and Neisseria autotransporter lipoprotein (NalP) and other pores, such as lysenin, bacterial nucleoside transporter Tsx. The nanopore (e.g., engineered biological nanopore) can comprise one or more monomeric units. The one or more monomeric units may be from a beta-barrel pore or alpha-helix pore. The terms “monomer” and “monomeric unit” may be used interchangeably herein. The monomeric unit can be the individual subunit protein of a pore described herein. One or more monomeric units can assemble to form a functional porin channel. As an example, a nanopore (e.g., engineered biological nanopore) described herein may comprise one or more monomeric units of a MspA pore, CsgG pore, CsgF pore, OmpF pore, OmpG pore, outer membrane phospholipase A pore, outer membrane protein FhuA pore, OmpA pore, NalP pore, aHL pore, FraC pore, lysenin pore, bacterial nucleoside transporter Tsx pore, or any combinations thereof, or any functional homologs thereof, or any functional paralogs thereof, or any functional orthologs thereof. In some cases, alpha-helix bundle pores comprise a barrel or channel that can be formed from alpha-helices. Examples of alpha-helix bundle pores can include, but are not limited to, inner membrane proteins and outer membrane proteins, such as WZA polysaccharide transporter and FraC. In a specific embodiment, the nanopore can be selected from the group consisting of Aerolysin (Aer), Cytolysin K (CytK), Mycobacterium smegmatis porin A (MspA), alpha-hemolysin (aHL), E. coli curli secretion system component CsgG, Fragaceatoxin C (FraC) or an engineered mutant thereof. In one embodiment the nanopore can be a transmembrane pore derived from or based on Msp, e.g. MspA, a-hemolysin (a-HL), lysenin, CsgG, ClyA, Spl or haemolytic protein fragaceatoxin C (FraC). In some cases, the nanopore (e.g., the biological nanopore) can comprise a conical geometry or a semi-conical geometry. A conical geometry can comprise a shape in which a nanopore tapers over a longitudinal axis, wherein a first entrance of a nanopore can be larger (e.g., comprises a wider dimension) than a second entrance. The nanopore may comprise a T7 nanopore, a SPP1 nanopore, a Phi29 nanopore, a Mycobacterium smegmatis porin A (MspA) nanopore, a fragaceatoxin C (FraC) nanopore, a cytolysin A (ClyA) nanopore, a TMH4C4 nanopore, or any combination thereof. In some cases, the nanopore (e.g., the biological nanopore) can comprise a straight geometry (e.g., a cylindrical geometry). A straight geometry may comprise a shape in which a channel of a nanopore can be the same width (e.g., diameter) over its longitudinal axis. The nanopore may comprise a stable protein 1 (SP1) nanopore, a pleurotolysin toxin (PlyAB) nanopore, an outer membrane protein G (OmpG) nanopore, an aerolysin nanopore, a ferric hydroxamate uptake component A (FhuA) nanopore, or any combination thereof. In some cases, the nanopore (e.g., the biological nanopore) can comprise a vestibule geometry (e.g., a globular geometry or goblet geometry). The nanopore may comprise an alpha-hemolysin nanopore, a curli specific gene G (CsgG) nanopore, or any combination thereof. In some cases, the nanopore comprises a pore-forming toxin. The nanopore can comprise an α-pore-forming toxin, a β-pore-forming toxin, or any combination thereof. The nanopore can comprise a pore-forming toxin derived from a bacterium. The bacterium can be of a genus of bacteria including, but not limited to, Xenorhabdus, Yersinia, Providencia, Pseudomonas, Proteus, Morganella, or Photorhabdus. In some cases, the nanopore comprises a pore-forming toxin derived from a bacterial species selected from the group consisting of Escherichia coli, Mycobacterium smegmatis, Staphylococcus aureus, Salmonella typhi, P. aeruginosa, A. baumanii, Klebsiella oxytoca, Bacillus cereus, A. hydrophila, S. marcescens, V. cholerae, P. entomophila, C. perfringens, and Y. enterocolitica. In some cases, the nanopore can be a T7 pore, a PN pore, a SP1 pore, a Phi29 pore, a PlyAB pore, an alpha-hemolysin (α-HL) pore, a SPP1 pore, a FraC pore, a MspA pore, a CsgG pore, an OmpG pore, an aerolysin pore, a ClyA pore, a FhuA pore, a PFO pore, or a TMH4C4 pore. In some cases, the nanopore described herein may comprise one or more monomers from T7, PN, SP1, Phi29, PlyAB, α-HL, SPP1, FraC, MspA, CsgG, OmpG, aerolysin, ClyA, FhuA, PFO, TMH4C4, or any combination thereof. In some cases, an engineered biological nanopore described herein may comprise one or monomers from a T7 pore, a PN pore, a SP1 pore, a Phi29 pore, a PlyAB pore, an alpha-hemolysin (α-HL) pore, a SPP1 pore, a FraC pore, a MspA pore, a CsgG pore, an OmpG pore, an aerolysin pore, a ClyA pore, a FhuA pore, a PFO pore, or a TMH4C4 pore. In some cases, the nanopore described herein may comprise one or more monomers from T7, PN, SP1, Phi29, PlyAB, α-HL, SPP1, FraC, MspA, CsgG, OmpG, aerolysin, ClyA, FhuA, PFO, TMH4C4, or any combination thereof. Exemplary modified nanopores can be based on a Mycobacterium smegmatis porin A (MspA), MspA nanopore, a MspA paralog or MspA homolog, a CsgG nanopore, a CsgG nanopore, a CsgG nanopore or on a nanopore having a similar advantageous geometry for sensing. MspA can be a conical shaped octameric biological nanopore. The MspA channel can be ~10 nm long and has a funnel shape that can be ~5 nm wide on its extracellular side. It contains a rigid 16-stranded β-barrel structure. MspA contains a single narrow constriction zone at the opposite end that measures just ~1.2 nm in diameter and 0.6 nm in length. The constriction zone quickly transitions to a much wider area. In one embodiment, the invention provides a modified MspA-type nanopore having improved sensing properties obtained by introducing one or more positive charges at position(s) in the funnel region and / or near the constriction area. In some cases, the funnel region and / or the constriction area can be more positively- charged when compared to the funnel area and / or the constriction area of a wild- type MspA or MspA paralog or homolog porin. For example, the nanopore can be an anion-selective variant of Mycobacterium smegmatis porin A (MspA) or MspA paralog or homolog. In some cases, the anion-selective Msp A variant nanopore comprises (a monomer of) modified MspA / Msmeg0965, MspB / Msmeg0520, MspC / Msmeg5483, MspD / Msmeg6057, MppA, PorM1, PorM2, PorM1, Mmcs4296, Mmcs4297, Mmcs3857, Mmcs4382, Mmcs4383, Mjls3843, Mjls3857, Mjls3931 Mjls4674, Mjls4675, Mjls4677, Map3123c, Mav3943, Mvan1836, Mvan4117, Mvan4839, Mvan4840, Mvan5016, Mvan5017, Mvan5768, MUL —2391, Mflv1734, Mflv1735, Mflv2295, Mflv1891, MCH4691c, MCH4689c, MCH4690c, MAB1080, MAB1081, MAB2800, RHA1 ro08561, RHA1 ro04074, and RHA1 ro03127. The nanopore may comprise a number of monomers. The nanopore may comprise a plurality of monomers. A monomer can be a pore-forming protein. A monomer can comprise any pore-forming protein described herein. Monomers may be arranged vertically, horizontally, and / or layered as rings to form a nanopore described herein. In some cases, a nanopore (e.g., biological nanopore) comprises at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 40, 50, or greater than 50 monomers. In some cases, a nanopore (e.g., biological nanopore) comprises at most about 50, 40, 30, 25, 20, 18, 16, 14, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, or less than 2 monomers. In some cases, a nanopore may comprise 1 monomer. For example, the nanopore may be an OmpG nanopore. In some cases, a nanopore (e.g., biological nanopore) comprises from about 3 monomers to about 40 monomers. In some cases, a nanopore (e.g., biological nanopore) comprises from about 3 monomers to about 4 monomers, about 3 monomers to about 5 monomers, about 3 monomers to about 6 monomers, about 3 monomers to about 7 monomers, about 3 monomers to about 8 monomers, about 3 monomers to about 9 monomers, about 3 monomers to about 10 monomers, about 3 monomers to about 15 monomers, about 3 monomers to about 20 monomers, about 3 monomers to about 30 monomers, about 3 monomers to about 40 monomers, about 4 monomers to about 5 monomers, about 4 monomers to about 6 monomers, about 4 monomers to about 7 monomers, about 4 monomers to about 8 monomers, about 4 monomers to about 9 monomers, about 4 monomers to about 10 monomers, about 4 monomers to about 15 monomers, about 4 monomers to about 20 monomers, about 4 monomers to about 30 monomers, about 4 monomers to about 40 monomers, about 5 monomers to about 6 monomers, about 5 monomers to about 7 monomers, about 5 monomers to about 8 monomers, about 5 monomers to about 9 monomers, about 5 monomers to about 10 monomers, about 5 monomers to about 15 monomers, about 5 monomers to about 20 monomers, about 5 monomers to about 30 monomers, about 5 monomers to about 40 monomers, about 6 monomers to about 7 monomers, about 6 monomers to about 8 monomers, about 6 monomers to about 9 monomers, about 6 monomers to about 10 monomers, about 6 monomers to about 15 monomers, about 6 monomers to about 20 monomers, about 6 monomers to about 30 monomers, about 6 monomers to about 40 monomers, about 7 monomers to about 8 monomers, about 7 monomers to about 9 monomers, about 7 monomers to about 10 monomers, about 7 monomers to about 15 monomers, about 7 monomers to about 20 monomers, about 7 monomers to about 30 monomers, about 7 monomers to about 40 monomers, about 8 monomers to about 9 monomers, about 8 monomers to about 10 monomers, about 8 monomers to about 15 monomers, about 8 monomers to about 20 monomers, about 8 monomers to about 30 monomers, about 8 monomers to about 40 monomers, about 9 monomers to about 10 monomers, about 9 monomers to about 15 monomers, about 9 monomers to about 20 monomers, about 9 monomers to about 30 monomers, about 9 monomers to about 40 monomers, about 10 monomers to about 15 monomers, about 10 monomers to about 20 monomers, about 10 monomers to about 30 monomers, about 10 monomers to about 40 monomers, about 15 monomers to about 20 monomers, about 15 monomers to about 30 monomers, about 15 monomers to about 40 monomers, about 20 monomers to about 30 monomers, about 20 monomers to about 40 monomers, or about 30 monomers to about 40 monomers. A monomer can comprise one or more portions. For example, a monomer may comprise a first portion, a second portion, a third portion, or any combination thereof. In some cases, a monomer may comprise more than three portions. A first portion of a monomer can correspond to a first region of a nanopore described herein (e.g., an engineered biological nanopore). A second portion of a monomer can correspond to a second region of a nanopore described herein (e.g., an engineered biological nanopore). The second portion of the monomer may be a constriction region-forming portion. A third portion of a monomer can correspond to a third region of a nanopore described herein (e.g., an engineered biological nanopore). In some cases, a nanopore described herein may comprise a homogeneous monomeric composition. A homogeneous monomeric composition can comprise, any of the monomers disclosed herein, with the same amino acid composition. For example, a nanopore may be comprised of 8 monomers. Each monomer may comprise at least one portion. For example, each monomer may comprise a first portion, a second portion, a third portion, or any combination thereof. In some cases, the first portions of monomers of the nanopore may be the same amino acid composition. In some cases, the second portions of monomers of the nanopore may be the same amino acid composition. The same amino acid composition can refer to two or more portions of monomers (e.g., first portions of the monomers) with the same amino acid sequence. In some cases, the third portions of monomers of the nanopore may be the same amino acid composition. In some cases, the first, second, and third portions between each monomer of the nanopore may be the same amino acid composition (e.g., comprise the same charge). One or more of the monomers of the nanopore may be arranged vertically, horizontally, and / or layered, the amino acid residues (e.g., positively-charged amino acid residues, neutral amino acid residues, or any combination thereof) may form one or more rings of charges. In some cases, a pore may be engineered to contain regions of separate rings of charges along the longitudinal length of the channel. For example, a nanopore may be engineered to contain regions of at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 11, at least about 12, at least about 13, at least about 14, at least about 15, at least about 16, at least about 17, at least about 18, at least about 19, at least about 20, or greater than about 20 separate rings of charges along the longitudinal length of the channel. A nanopore may be engineered to contain regions of at most about 20, at most about 19, at most about 18, at most about 17, at most about 16, at most about 15, at most about 14, at most about 13, at most about 12, at most about 11, at most about 10, at most about 9, at most about 8, at most about 7, at most about 6, at most about 5, at most about 4, at most about 3, at most about 2, or less than about 2 separate rings of charges along the longitudinal length of the channel. A nanopore may be engineered to contain regions from about 2 to about 20 separate rings of charges along the longitudinal length of the channel. A nanopore may be engineered to contain regions from about 2 to about 3, about 2 to about 4, about 2 to about 5, about 2 to about 6, about 2 to about 7, about 2 to about 8, about 2 to about 9, about 2 to about 10, about 2 to about 15, about 2 to about 20, about 3 to about 4, about 3 to about 5, about 3 to about 6, about 3 to about 7, about 3 to about 8, about 3 to about 9, about 3 to about 10, about 3 to about 15, about 3 to about 20, about 4 to about 5, about 4 to about 6, about 4 to about 7, about 4 to about 8, about 4 to about 9, about 4 to about 10, about 4 to about 15, about 4 to about 20, about 5 to about 6, about 5 to about 7, about 5 to about 8, about 5 to about 9, about 5 to about 10, about 5 to about 15, about 5 to about 20, about 6 to about 7, about 6 to about 8, about 6 to about 9, about 6 to about 10, about 6 to about 15, about 6 to about 20, about 7 to about 8, about 7 to about 9, about 7 to about 10, about 7 to about 15, about 7 to about 20, about 8 to about 9, about 8 to about 10, about 8 to about 15, about 8 to about 20, about 9 to about 10, about 9 to about 15, about 9 to about 20, about 10 to about 15, about 10 to about 20, or about 15 to about 20 separate rings of charges along the longitudinal length of the channel. A region of a channel of a nanopore described herein may comprise one or more rings of charges. In some cases, a first region and / or third region of the channel may comprise at least about 1, at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, or greater than about 20 rings of charges. In some cases, a first region and / or third region of the channel may comprise at most about 20, at most about 15, at most about 10, at most about 9, at most about 8, at most about 7, at most about 6, at most about 5, at most about 4, at most about 3, at most about 2, at most about 1, or less than about 1 ring of charges. In some cases, a first region and / or third region of the channel may comprise from about 1 ring of charges to about 20 rings of charges. In some cases, a first region and / or third region of the channel may comprise from about 1 ring of charges to about 2 rings of charges, about 1 ring of charges to about 3 rings of charges, about 1 ring of charges to about 4 rings of charges, about 1 ring of charges to about 5 rings of charges, about 1 ring of charges to about 6 rings of charges, about 1 ring of charges to about 7 rings of charges, about 1 ring of charges to about 8 rings of charges, about 1 ring of charges to about 9 rings of charges, about 1 ring of charges to about 10 rings of charges, about 1 ring of charges to about 15 rings of charges, about 1 ring of charges to about 20 rings of charges, about 2 rings of charges to about 3 rings of charges, about 2 rings of charges to about 4 rings of charges, about 2 rings of charges to about 5 rings of charges, about 2 rings of charges to about 6 rings of charges, about 2 rings of charges to about 7 rings of charges, about 2 rings of charges to about 8 rings of charges, about 2 rings of charges to about 9 rings of charges, about 2 rings of charges to about 10 rings of charges, about 2 rings of charges to about 15 rings of charges, about 2 rings of charges to about 20 rings of charges, about 3 rings of charges to about 4 rings of charges, about 3 rings of charges to about 5 rings of charges, about 3 rings of charges to about 6 rings of charges, about 3 rings of charges to about 7 rings of charges, about 3 rings of charges to about 8 rings of charges, about 3 rings of charges to about 9 rings of charges, about 3 rings of charges to about 10 rings of charges, about 3 rings of charges to about 15 rings of charges, about 3 rings of charges to about 20 rings of charges, about 4 rings of charges to about 5 rings of charges, about 4 rings of charges to about 6 rings of charges, about 4 rings of charges to about 7 rings of charges, about 4 rings of charges to about 8 rings of charges, about 4 rings of charges to about 9 rings of charges, about 4 rings of charges to about 10 rings of charges, about 4 rings of charges to about 15 rings of charges, about 4 rings of charges to about 20 rings of charges, about 5 rings of charges to about 6 rings of charges, about 5 rings of charges to about 7 rings of charges, about 5 rings of charges to about 8 rings of charges, about 5 rings of charges to about 9 rings of charges, about 5 rings of charges to about 10 rings of charges, about 5 rings of charges to about 15 rings of charges, about 5 rings of charges to about 20 rings of charges, about 6 rings of charges to about 7 rings of charges, about 6 rings of charges to about 8 rings of charges, about 6 rings of charges to about 9 rings of charges, about 6 rings of charges to about 10 rings of charges, about 6 rings of charges to about 15 rings of charges, about 6 rings of charges to about 20 rings of charges, about 7 rings of charges to about 8 rings of charges, about 7 rings of charges to about 9 rings of charges, about 7 rings of charges to about 10 rings of charges, about 7 rings of charges to about 15 rings of charges, about 7 rings of charges to about 20 rings of charges, about 8 rings of charges to about 9 rings of charges, about 8 rings of charges to about 10 rings of charges, about 8 rings of charges to about 15 rings of charges, about 8 rings of charges to about 20 rings of charges, about 9 rings of charges to about 10 rings of charges, about 9 rings of charges to about 15 rings of charges, about 9 rings of charges to about 20 rings of charges, about 10 rings of charges to about 15 rings of charges, about 10 rings of charges to about 20 rings of charges, or about 15 rings of charges to about 20 rings of charges. In some cases, a second region of the channel may comprise at least about 1, at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, or greater than about 20 rings of charges. In some cases, a second region of the channel may comprise at most about 20, at most about 15, at most about 10, at most about 9, at most about 8, at most about 7, at most about 6, at most about 5, at most about 4, at most about 3, at most about 2, at most about 1, or less than about 1 ring of charges. In some cases, a second region of the channel may comprise from about 1 ring of charges to about 20 rings of charges. In some cases, a second region of the channel may comprise from about 1 ring of charges to about 2 rings of charges, about 1 ring of charges to about 3 rings of charges, about 1 ring of charges to about 4 rings of charges, about 1 ring of charges to about 5 rings of charges, about 1 ring of charges to about 6 rings of charges, about 1 ring of charges to about 7 rings of charges, about 1 ring of charges to about 8 rings of charges, about 1 ring of charges to about 9 rings of charges, about 1 ring of charges to about 10 rings of charges, about 1 ring of charges to about 15 rings of charges, about 1 ring of charges to about 20 rings of charges, about 2 rings of charges to about 3 rings of charges, about 2 rings of charges to about 4 rings of charges, about 2 rings of charges to about 5 rings of charges, about 2 rings of charges to about 6 rings of charges, about 2 rings of charges to about 7 rings of charges, about 2 rings of charges to about 8 rings of charges, about 2 rings of charges to about 9 rings of charges, about 2 rings of charges to about 10 rings of charges, about 2 rings of charges to about 15 rings of charges, about 2 rings of charges to about 20 rings of charges, about 3 rings of charges to about 4 rings of charges, about 3 rings of charges to about 5 rings of charges, about 3 rings of charges to about 6 rings of charges, about 3 rings of charges to about 7 rings of charges, about 3 rings of charges to about 8 rings of charges, about 3 rings of charges to about 9 rings of charges, about 3 rings of charges to about 10 rings of charges, about 3 rings of charges to about 15 rings of charges, about 3 rings of charges to about 20 rings of charges, about 4 rings of charges to about 5 rings of charges, about 4 rings of charges to about 6 rings of charges, about 4 rings of ch...

Claims

Claims WHAT IS CLAIMED IS:

1. A method comprising:(a) providing a nanopore system, wherein the nanopore systemcomprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region of a wild-type biological nanopore, wherein a first ring of charge in the first region and a second ring of charge in the second region comprises a distance of at most about 3 nanometers (nm), wherein the second region comprises a width of at most about 1.4 nm; and (b) contacting the engineered biological nanopore with a biopolymer.

2. A method comprising:(a) providing a nanopore system, wherein the nanopore systemcomprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more net positive as compared to a respective region of a wild-type biological nanopore, wherein a first ring of charge in the first region and a second ring of charge in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 3 nm; wherein the engineered biological nanopore is not FraC; and(b) contacting the engineered biological nanopore with a biopolymer.

3. The method of claim 1 or 2, wherein the first region is more net positivethan the second region.

4. The method of any one of claims 1-3, wherein one or more amino acids inthe second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids.

5. The method of any one of claims 1-3, wherein one or more amino acids inthe first region is mutated to one or more positive amino acids.

6. The method of any one of claims 1-5, wherein when one or more amino acidsin the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids, then one or more amino acids in the adjacent region is mutated to one or more positive amino acids.

7. The method of any one of claims 1-6, wherein the first region comprises atleast one amino acid that is mutated to exhibit an increased net positive charge.

8. The method of claim 7, wherein the mutated at least one amino acid in thefirst region is at most 10 nm away from a mutated at least one amino acid in the second region.

9. The method of claim 7 or 8, wherein the first ring of charge comprising themutated at least one amino acid in the first region is at most 10 nm away from the second ring of charge comprising the mutated at least one amino acid in the second region.

10. The method of any one of claims 1-9, wherein the engineered biologicalnanopore comprises one or more monomers.

11. The method of any one of claims 1-10, wherein a monomer of the engineeredbiological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region.

12. The method of claim 11, wherein a monomer of the engineered biologicalnanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion.

13. The method of claim 11 or 12, wherein the first portion comprises at leastone amino acid that is mutated to exhibit an increased net positive charge.

14. The method of claim 13, wherein the second portion comprises at least oneamino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge.

15. The method of claim 14, wherein the at least one mutated amino acid in thefirst portion is at most 10 nm away from the at least one mutated amino acid in the second portion.

16. The method of any one of claims 1-15, wherein the engineered biologicalnanopore generates an electro-osmotic force (EOF) greater than an EOF of the wild-type biological nanopore.

17. The method of claim 16, wherein the first region of the channel and thesecond region of the channel generates the EOF.

18. The method of claim 16 or 17, wherein the EOF acts in an opposite directionto an electrophoretic force in the nanopore system.

19. The method of any one of claims 1-18, wherein the engineered biologicalnanopore has an anion-selectivity P(-) / P(+) of at least about 1.5.

20. The method of any one of claims 1-19, wherein the second region of thechannel comprises a first entrance and a second entrance.

21. The method of claim 20, wherein the first region of the channel is adjacentto the first entrance of the second region of the channel.

22. The method of claim 20 or 21, wherein the first region of the channel isadjacent to the second entrance of the second region of the channel.

23. The method of any one of claims 1-22, wherein one or more amino acidmutations in the second region of the engineered biological nanopore increase an anion selectivity p(Cl- / K+) relative to the wild-type biological nanopore.

24. The method of any one of claims 1-23, wherein one or more amino acidmutations in the first region of the engineered biological nanopore increase an anion selectivity p(Cl- / K+) relative to the wild-type biological nanopore.

25. The method of any one of claims 1-24, wherein one or more amino acidmutations in the first region and the second region of the engineered biological nanopore increase an anion selectivity p(Cl- / K+) relative to the wild-type biological nanopore.

26. The method of claim 24 or 25, wherein the first region comprises one ormore amino acid mutations that increase a positive charge in the residuesthat contribute to a region of the engineered biological nanopore comprising a diameter of at most 5 nm.

27. The method of any one of claims 1-26, wherein the first region comprisesone or more amino acid mutations that increase a positive charge in the residues that contribute to a region of the engineered biological nanopore comprising a diameter of at most 2 nm.

28. The method of any one of claims 1-27, wherein a net charge of the firstregion is at least about 50% more positive as compared to the respective region of the wild-type biological nanopore.

29. The method of any one of claims 1-28, wherein the second region is moreneutral as compared to the respective region of the wild-type biological nanopore.

30. The method of any one of claims 1-29, wherein a net charge of the secondregion of the channel is at least about 50% more neutral as compared to the respective region of the wild-type biological nanopore.

31. The method of any one of claims 1-30, wherein the second region comprisesa width from about 0.5 nm to about 2.0 nm.

32. The method of any one of claims 1-31, wherein the constriction region has aneutral charge.

33. The method of any one of claims 1-32, wherein the second region comprisesone or more amino acid mutations that increase a neutral charge in the residues that contribute to a narrowest region of the engineered biological nanopore comprising a diameter of at most 1.0 nm.

34. The method of any one of claims 1-33, wherein the engineered biologicalnanopore comprises an anion selectivity (p(Cl- / K+)) of at least about 2.0.

35. The method of any one of claims 1-34, wherein the engineered biologicalnanopore comprises a cation selectivity (p(K+ / Cl-)) of at most about 1.0.

36. A method comprising:(a) providing a nanopore system, wherein the nanopore systemcomprises (1) a fluidic chamber and (2) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein thesecond region has a constriction region, wherein (i) the first region is modified to be more net positive than a respective region of a wild- type biological nanopore and / or (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore, wherein the first region of the channel is adjacent to the second region of the channel; and (b) contacting the engineered biological nanopore with a biopolymer.

37. The method of claim 36, wherein the engineered biological nanoporegenerates an electro-osmotic force (EOF) greater than an EOF of a wild-type biological nanopore.

38. The method of claim 37, wherein the first region modified to be more netpositive and the second region modified to be more net neutral or more net positive to generate the EOF.

39. The method of any one of claims 36-38, wherein the engineered biologicalnanopore has an anion-selectivity P(-) / P(+) of at least about 1.5.

40. The method of any one of claims 36-39, wherein the second region of thechannel comprises a first entrance and a second entrance.

41. The method of claim 40, wherein the positive charge of the first region of thechannel is adjacent to the first entrance of the second region of the channel.

42. The method of claim 40 or 41, wherein the positive charge of the first regionof the channel is adjacent to the second entrance of the second region of the channel.

43. The method of any one of claims 40-42, wherein the positive charge of thefirst region of the channel is adjacent to the first entrance of the second region of the channel and the second entrance of the second region of the channel.

44. The method of any one of claims 36-43, wherein the first region is morepositive as compared to the respective region of the wild-type biological nanopore.

45. The method of any one of claims 36-44, wherein a net charge of the firstregion is at least about 50% more positive as compared to the respective region of the wild-type biological nanopore.

46. The method of any one of claims 36-45, wherein the second region is moreneutral as compared to the respective region of the wild-type biological nanopore.

47. The method of any one of claims 36-46, wherein a net charge of the secondregion of the channel is at least about 50% more neutral as compared to the respective region of the wild-type biological nanopore.

48. A system comprising:(a) a fluidic chamber; and(b) a membrane comprising an engineered biological nanopore, wherein themembrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more positive as compared to a respective region of a wild-type biological nanopore, wherein a first ring of charge in the first region and a second ring of charge in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 1.4 nm, wherein the engineered biological nanopore is configured to contact a biopolymer.

49. A system comprising:(a) a fluidic chamber; and(b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region is modified to be more positive as compared to a respective region of a wild-type biological nanopore, wherein a first ring of charge in the first region and a second ring of charge in the second region comprises a distance of at most about 3 nm, wherein the second region comprises a width of at most about 3 nm; wherein the engineered biological nanopore is not FraC, wherein the engineered biological nanopore is configured to contact a biopolymer.

50. A system comprising:(a) a fluidic chamber; and (b) a membrane comprising an engineered biological nanopore, wherein the membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein (i) the first region is modified to be more net positive than a respective region of a wild- type biological nanopore and / or (ii) the second region is modified to be more net neutral or more net positive than a respective region of the wild-type biological nanopore, wherein the first region of the channel is adjacent to the second region of the channel; wherein the engineered biological nanopore is configured to contact a biopolymer.

51. A system comprising:(a) a fluidic chamber; and(b) a membrane comprising an engineered biological nanopore, whereinthe membrane separates the fluidic chamber into (1) a first side and (2) a second side, wherein the engineered biological nanopore comprises a channel, wherein the channel comprises a first region and a second region, wherein the second region has a constriction region, wherein the first region of the channel is adjacent to the second region of the channel, wherein the first region of the channel has a positive charge, wherein a net charge of the second region of the channel is at least about 50% more neutral as compared to a respective region of a wild-type biological nanopore, wherein the engineered biological nanopore is configured to contact a biopolymer.

52. A method of improving the sensing properties of a protein nanopore havinga narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, the method comprising increasing the net positive charge at the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance.

53. The method of claim 52, comprising increasing the net positive charge in thefunnel region having a diameter of at least 2.2 nm, preferably at least 2.4 nm, more preferably in the range of about 2.4 to about 3.5 nm, expressed as the Cα-Cα distance.

54. The method of claim 52 or 53, comprising increasing the net positive chargeat the constriction area and / or in the funnel region at a distance within up to about 3 nm from the constriction area along the longitudinal (central) pore axis.

55. The method of any one of claims 52-54, wherein increasing the net positivecharge comprises substituting one or more negatively-charged amino acids, non-polar amino acids or aromatic amino acids at the constriction area and / or in the funnel region with one or more positively-charged amino acids.

56. The method of any one of claims 52-55, comprising increasing the netpositive charge at the constriction area and / or in the funnel region by at least 5, preferably at least 8, more preferably at least 10 unitary charges.

57. A method comprising:(a) providing:(i) a nanopore system, wherein the nanopore system comprises(1) a fluidic chamber and; (2) a membrane comprising a protein nanopore, wherein the membrane separates the fluidic chamber into a cis side and a trans side; and (ii) a polymer analyte;(b) translocating the polymer analyte from the cis side to the trans sideof the fluidic chamber, wherein the nanopore has a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, wherein the lumen-facing residues in the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge, such that under an applied positive potential the nanopore system has a cis to trans electro-osmotic force resulting from a cis to trans net ionic current flow, wherein the cis to trans electro-osmotic force translocates the polymer analyte through the nanopore.

58. The method of claim 57, wherein the polymer analyte is of synthetic, semi-synthetic or biological origin, such as a biopolymer, preferably comprising or consisting of peptide units, saccharide units, nucleic acid units, water- soluble plastic monomers, or any combination, more preferably wherein the polymer analyte is selected from the group of proteinaceous polymers, non- nucleic acid based polymers and nucleic acid-peptide conjugates.

59. A modified nanopore having a narrowest constriction area from about 0.5 toabout 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, wherein the lumen-facing residues in the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge.

60. A nanopore system comprising (1) a fluidic chamber and; (2) a membranecomprising a protein nanopore, wherein the membrane separates the fluidic chamber into a cis side and a trans side; and wherein the protein nanopore has a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, wherein the lumen-facing residues in the constriction area and / or in the funnel region having a diameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge.

61. A system comprising:(a) a fluidic chamber;(b) a membrane comprising a nanopore, wherein the membraneseparates the fluidic chamber into a cis side comprising a first solution and a trans side comprising a second solution, wherein the first solution and the second solution are configured to translocate a polymer analyte using an electro-osmotic flow, and wherein the nanopore has a narrowest constriction area from about 0.5 to about 1.5 nm in diameter and up to 2 nm in length as its sensing region flanked by a wider funnel region having a diameter of at least two times the constriction diameter, wherein the lumen-facing residues in the constriction area and / or in the funnel region having adiameter up to about 3.5 nm expressed as the Cα-Cα distance have a net positive charge; (c) a pair of electrodes comprising a first electrode and a secondelectrode; and (d) a controller operatively coupled to the fluidic chamber, saidnanopore, and the pair of electrodes, wherein the controller: (i) uses the pair of electrodes to generate an electrophoreticforce acting in an opposite direction to the electro-osmotic flow that translocates the polymer analyte through the nanopore, and (ii) detects one or more signals associated with at least onecharacteristic of the polymer analyte during or subsequent to translocation of the polymer analyte through the nanopore.

62. A device comprising an array of a system comprising the system accordingto claim 61.

63. A method, modified nanopore, system or device according to any one ofclaims 52-62, wherein the nanopore has a neutral constriction area.

64. A method, modified nanopore, system or device according to any one ofclaims 52-63, wherein the nanopore has an anion-selectivity P(-) / P(+) of greater than 1.3, preferably greater than 1.5, more preferably greater than 2.5, most preferably greater than 3.

65. A method, modified nanopore, system or device according to any one ofclaims 52-64, wherein the nanopore is an anion-selective variant of Mycobacterium smegmatis porin A (MspA) or MspA paralog or homolog, preferably wherein the anion-selective Msp A variant nanopore comprises a mutant monomer of MspA / Msmeg0965, MspB / Msmeg0520, MspC / Msmeg5483, MspD / Msmeg6057, MppA, PorM1, PorM2, PorM1, Mmcs4296, Mmcs4297, Mmcs3857, Mmcs4382, Mmcs4383, Mjls3843, Mjls3857, Mjls3931 Mjls4674, Mjls4675, Mjls4677, Map3123c, Mav3943, Mvan1836, Mvan4117, Mvan4839, Mvan4840, Mvan5016, Mvan5017, Mvan5768, MUL —2391, Mflv1734, Mflv1735, Mflv2295, Mflv1891, MCH4691c, MCH4689c, MCH4690c, MAB1080, MAB1081, MAB2800, RHA1 ro08561, RHA1 ro04074, and RHA1 ro03127.

66. A method, modified nanopore, system or device according to claim 65,wherein the funnel area up to a diameter of about 3.5, preferably about 3.0 nm, expressed as the Cα-Cα distance, is more positively-charged when compared to funnel area of a wild-type MspA or MspA paralog or homolog porin.

67. A method, modified nanopore, system or device according to claim 65 or 66,wherein the nanopore is an anion-selective MspA, MspA paralog or homolog porin comprising a mutant MspA monomer, wherein the mutant MspA monomer comprises a variant of the sequence in SEQ ID NO: 1, and wherein the variant comprises a positive charge at one or more lumen- facing amino acid positions in the stretch consisting of residues 82-89, residues 92-109 and / or in the stretch consisting of residues 103-111 in the sequence in SEQ ID NO:1, or a mutant MspA paralog or homolog comprising a positive charge at one or more of the corresponding amino acids.

68. A method, modified nanopore, system or device according to any one ofclaims 65-67, wherein the mutant MspA monomer comprises a variant of the sequence in SEQ ID NO: 1, said variant comprising a positive charge at one or more of the amino acid positions 90, 91, 93, 88, 103, 105 and 108, preferably wherein the variant comprises one or more of the following substitutions: D90K / R, D91K / R, D93K / R, L88K / R, S103K / R, I105K / R and N108K / R.

69. A method, modified nanopore, system or device according to claim 68,wherein the mutant MspA monomer comprises an amino acid with a positive charge at one or more of amino acid positions 88, 103, 105 and 108, preferably at one or more of amino acid positions 88, 103 and 105, more preferably at positions 103 and / or 105.

70. A method, modified nanopore, system or device according to any one ofclaims 65-69, wherein the mutant MspA monomer comprises a positive charge at one or more of positions 90, 91 and 93, preferably positions 90 and / or 91.

71. A method, modified nanopore, system or device according to any one ofclaims 65-70, wherein the mutant MspA monomer comprises a neutral charge at one or more of positions 90, 91 and 93.

72. A method, modified nanopore, system or device according to any one ofclaims 65-71, wherein the mutant MspA monomer further comprises an amino acid with a positive charge at one or more of amino acid positions 118, 134 and 139, or a mutant MspA paralog or homolog comprising the corresponding amino acids.

73. A method, modified nanopore, system or device according to claim 71 or 72,wherein the mutant MspA monomer comprises amino acids with a neutral charge at positions 90, 91 and 93 and / or an amino acid with a positive charge at one or more of amino acid positions 118, 134, and 139, or a mutant MspA paralog or homolog comprising the corresponding amino acids.

74. A method, modified nanopore, system or device according to claim 73,wherein the mutant MspA monomer comprises (i) amino acids with a neutral charge at positions 90, 91 and 93; (ii) an amino acid with a positive charge at one or more of amino acid positions 118, 134, and 139, and (iii) an amino acid with a positive charge at one or more of amino acid positions 88, 103, 105 and 108 or a mutant MspA paralog or homolog comprising the corresponding amino acids.

75. A method, modified nanopore, system or device according to any one of thepreceding claims, comprising a nanopore selected from the MspA mutants depicted in Table 1, 2 or 3.

76. A method, modified nanopore, system or device according to any one ofclaims 52-75, wherein the nanopore is a modified CsgG pore or CsgG paralog or homolog, or a modified CsgG-CsgF mutant (PDB ID 6SI7).

77. A method, modified nanopore, system or device according to claim 76,wherein the modified CsgG pore comprises at least one CsgG monomer which is a variant of SEQ ID NO: 2, preferably wherein the modified CsgG pore or CsgG paralog or homolog, or a modified CsgG-CsgF mutant is selected from the mutants depicted in Table 6 or 7.

78. The use of a method, nanopore system, or device according to any one of thepreceding claims for characterizing at least one feature of a target polymer, preferably for detection and analysis of one or more target polymer(s) at the single molecule level, more preferably for detection and analysis of one or more a target polypeptide(s) and / or nucleic acid-peptide conjugate(s).

79. The method of claim 36, wherein the first region is more net positive thanthe second region.

80. The method of claim 36 or 79, wherein one or more amino acids in thesecond region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids.

81. The method of any one of claims 36, 79, and 80, wherein one or more aminoacids in the first region is mutated to one or more positive amino acids.

82. The method of any one of claims 36 and 79-81, wherein when one or moreamino acids in the second region is modified to (1) one or more neutral amino acids or (2) one or more positive amino acids, then one or more amino acids in the adjacent region is mutated to one or more positive amino acids.

83. The method of any one of claims 36 and 79-82, wherein the first regioncomprises at least one amino acid that is mutated to exhibit an increased net positive charge.

84. The method of claim 83, wherein the mutated at least one amino acid in thefirst region is at most 10 nm away from a mutated at least one amino acid in the second region.

85. The method of claim 83 or 84, wherein the first ring of charge comprisingthe mutated at least one amino acid in the first region is at most 10 nm away from the second ring of charge comprising the mutated at least one amino acid in the second region86. The method of any one of claims 36 and 79-85, wherein the engineeredbiological nanopore comprises one or more monomers.

87. The method of any one of claims 36 and 79-86, wherein a monomer of theengineered biological nanopore comprises a first portion corresponding to the first region and a second portion corresponding to the second region.

88. The method of claim 87, wherein a monomer of the engineered biologicalnanopore comprises a net charge in the first portion that is more positive as compared to a net charge in the second portion.

89. The method of claim 87 or 88, wherein the first portion comprises at leastone amino acid that is mutated to exhibit an increased net positive charge.

90. The method of any one of claims 87-89, wherein the second portioncomprises at least one amino acid that is mutated to exhibit an increased net neutral charge or an increased net positive charge.

91. The method of claim 90, wherein the at least one mutated amino acid in thefirst portion is at most 10 nm away from the at least one mutated amino acid in the second portion.

92. The method of any one of claims 1-35, wherein the engineered biologicalnanopore comprises a narrowest constriction area from about 0.5 nm to about 2.0 nm in diameter.

93. The method of any one of claims 1-35, wherein the engineered biologicalnanopore comprises a narrowest constriction area of at most 3 nm in length.

94. The method of any one of claims 1-35, wherein the engineered biologicalnanopore comprises a first region having a diameter of at most about 5 nm as the Cα-Cα distance.

95. The method of any one of claims 1-35, wherein the engineered biologicalnanopore comprises a first region at a distance within up to about 5 nm from the second region along a longitudinal (central) pore axis.

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