Cellulose nanofiber (CNF) stabilized membrane and its manufacturing method

Abstract

The present invention includes membranes comprising one or more cellulose materials and wetting agent(s), and methods of making such membranes. In particular, in some embodiments, the present invention provides compositions and membranes comprising one or more cellulose materials (e.g., wood pulp and / or cellulose nanofibrils (CNF)) in combination with one or more inorganic minerals. The materials are combined and formed into membranes such that the resulting materials exhibit rapid and controlled water uptake properties, including, but not limited to, internal and surface wetting phenomena, internal pore volume, surface uniformity, and other improved physical properties.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 229,872, filed August 5, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Membranes made of cellulose materials (e.g., nitrocellulose) have been utilized in lateral flow devices, for example, for diagnostic and other point-of-care devices (Mansfield 2005) Drugs of abuse. Ch. 4. pp. 71-85). However, such devices are limited in their wicking capacity, and how to improve the dispersion of certain additives and optimize the wicking capacity in cellulose membranes remains a challenge. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Mansfield 2005)Drugs of abuse. Ch. 4. pp. 71-85 Summary of the Invention [Means for solving the problem]

[0004] In particular, in some embodiments, the present invention provides compositions and membranes that include one or more cellulosic materials (e.g., wood pulp and / or cellulose nanofibrils (CNF)) in combination with one or more inorganic minerals. The materials are combined and formed into membranes such that the resulting materials exhibit rapid and controlled water wicking properties, including, but not limited to, internal and surface wetting phenomena, internal pore volume, surface uniformity, and other improved physical properties. In some embodiments, the invention provides membranes that are well suited for use in, for example, lateral flow devices, diagnostic and other point-of-care devices (e.g., ELISA tests), automated sampling devices (e.g., environmental test strips), devices for concentrating biological or environmental samples, devices for separating and immobilizing analytes, and as universal horizontal and vertical wicking substrates.

[0005] The present invention also provides a method of making a membrane that exhibits the unique properties. One aspect of the present disclosure provides a membrane comprising a porous matrix material, the porous matrix material comprising (i) wood pulp, (ii) cellulose nanofilbril (CNF), and (iii) one or more wet minerals. In some embodiments, the one or more wet minerals comprise calcium carbonate (CaCO3), TiO2, alumina, fiberglass, or a combination thereof. In some embodiments, the CNF is present at a concentration in the range of 0.1-1.5% by weight on a dry weight basis. In some embodiments, the one or more wet minerals are present at a concentration in the range of 0.1-20% by weight of the porous matrix material. In some embodiments, the CNF comprises CNF obtained by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation.

[0006] In some embodiments, upon contact with a fluid containing an analyte, the analyte solution migrates across the membrane by capillary action. In some embodiments, the analyte is immobilized at a specific site on the membrane. In some embodiments, the analyte migrates across the membrane at a speed greater than about 0.5 mm / sec. In some embodiments, the analyte is or comprises a biological material.

[0007] In some embodiments, the porous matrix material is substantially homogeneous. In some embodiments, the porous matrix material comprises at least 60-90% porosity. In some embodiments, the porous matrix material comprises one or more additives. In some embodiments, the one or more additives comprise a foaming agent, a blowing agent, a templating agent, a plasticizer, or a combination thereof. In some embodiments, the one or more additives are present at a concentration in the range of 0.1-10% by weight on a dry weight basis. In some embodiments, the foaming agent comprises a surfactant. In some embodiments, the surfactant comprises a glucoside and / or myristic acid. In some embodiments, the surfactant comprises a biosurfactant, such as a fungus, a bacteria, a yeast, a glycolipid, a phospholipid, a glycopeptide, a saponin, a fatty acid, a protein, a polysaccharide, or a combination thereof. In some embodiments, the foaming agent comprises sodium bicarbonate. In some embodiments, the templating agent comprises salt, ice, dry ice, or a combination thereof. In some embodiments, the plasticizer comprises an acetylated monoglyceride, an alkyl citrate, an epoxidized soybean oil, a protein, a polyethylene glycol, a fatty acid, or a combination thereof.

[0008] In another aspect, the disclosure features a method that includes: (i) providing a slurry that includes wood pulp and water; (ii) mixing cellulose nanofilbril (CNF) and one or more wet minerals into the slurry; and (iii) drying the slurry to form a porous matrix material. In some embodiments, the one or more wet minerals include calcium carbonate (CaCO3), TiO2, alumina, fiberglass, or a combination thereof. In some embodiments, drying the slurry includes capillary dehydration, infrared drying, freeze drying, and / or microwave irradiation.

[0009] In some embodiments, the concentration of CNF is 0.1-1.5% by weight of the porous matrix material. In some embodiments, the one or more wet minerals are present at a concentration in the range of 0.1-20% by weight of the porous matrix material.

[0010] In another aspect, the disclosure features a method of separating an analyte from a fluid that includes: (i) providing a membrane that includes a porous matrix material; and (ii) contacting the membrane with a fluid that includes the analyte such that the fluid enters the membrane through capillary action, thereby separating the analyte, where the porous matrix material is a composite material that includes wood pulp, CNF, and one or more wettable minerals.

[0011] In some embodiments, the one or more wet minerals include calcium carbonate (CaCO3), TiO2, alumina, fiberglass, or a combination thereof.

[0012] In some embodiments, the contacting step is or includes contacting the membrane with a fluid contained in an adjacent space or material.

[0013] In some embodiments, the fluid moves across the membrane. In some embodiments, the fluid moves passively across the membrane. In some embodiments, the fluid moves across the membrane using a vacuum or positive pressure on the fluid. In some embodiments, the analyte is immobilized on the membrane. In some embodiments, the immobilized analyte is or comprises a biological material.

[0014] The drawings are for illustration purposes only and not for limitation. [Brief description of the drawings]

[0015] [Figure 1] Shown are SEM images of a pulp membrane with 1 wt% CNF (panel a), a pulp membrane with 5 wt% CNF (panel b), and a CNF membrane (panel c).

[0016] [Diagram 2] Figure 1 shows the results of vertical wicking tests conducted on various materials including pulp membrane, CNF membrane, pulp+CNF membrane, CNF+CaCO3, and pulp+CNF+CaCO3. The wicking results are expressed as vertical wicking time (sec) (y-axis) versus wicking height (mm) (x-axis).

[0017] [Diagram 3] Figure 1 shows the wicking rate of various pulp-CNF-CaCO3 membranes with varying weight % of CNF. Results are expressed as weight % of CNF (x-axis) versus vertical wicking rate (mm / sec) (y-axis).

[0018] [Figure 4] FIG. 1 is a schematic diagram of an exemplary analyte-target interaction on a membrane. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] definition In order that the present invention may be more readily understood, certain terms are first defined below. Additional definitions of the following terms, and other terms, are set forth throughout the specification. Publications and other reference materials referred to herein to describe the background of the invention and to provide additional details regarding its practice are incorporated herein by reference.

[0020] Approximately or about: As used herein, the term "approximately" or "about" refers to a value similar to a stated reference value when applied to one or more values ​​of interest. In certain embodiments, the term "approximately" or "about" refers to a range of values ​​that is within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or less in either direction (above or below) of the stated reference value, unless otherwise stated or a different meaning is evident from the context (except when such number exceeds 100% of the possible values).

[0021] Biological sample: As used herein, the term "biological sample" typically refers to a sample obtained or derived from a biological source of interest (e.g., a tissue or organism or cell culture) as described herein. In some embodiments, the source of interest includes an organism, such as an animal or human. In some embodiments, the biological sample is or includes a cytological tissue or fluid. In some embodiments, the biological sample may be or include bone marrow, blood, blood cells, ascites, tissue or fine needle biopsy samples, cell-containing body fluids, suspended nucleic acids, sputum, saliva, urine, cerebrospinal fluid, peritoneal fluid, pleural fluid, feces, lymph, gynecological body fluids, skin swabs, vaginal swabs, oral swabs, nasal swabs, washings or lavages such as ductal lavage or bronchoalveolar lavage, aspirates, scrapings, bone marrow specimens, tissue biopsy specimens, surgical specimens, feces, other body fluids, secretions, and / or excretions, and / or cells therefrom, and the like. In some embodiments, the biological sample is or includes cells obtained from an individual. In some embodiments, the obtained cells are or include cells from the individual from whom the sample was obtained. In some embodiments, the sample is a "primary sample" obtained directly from the source of interest by any suitable means. For example, in some embodiments, the primary biological sample is obtained by a method selected from the group consisting of a biopsy (e.g., fine needle aspirate or tissue biopsy), surgery, collection of bodily fluids (e.g., blood, lymph, feces, etc.), oral or nasal swabs, etc. In some embodiments, as will be clear from the context, the term "sample" refers to a preparation obtained by processing (e.g., by removing one or more components and / or adding one or more agents) of a primary sample, e.g., filtration using a semi-permeable membrane. Such a "processed sample" may include, for example, nucleic acids or proteins extracted from the sample or obtained by subjecting the primary sample to techniques such as amplification or reverse transcription of mRNA, isolation and / or purification of certain components, etc.

[0022] Biomarker: The term "biomarker" is used herein, consistent with usage in the art, to mean an entity, event, or feature whose presence, level, extent, type, and / or form correlates with a particular biological event or condition of interest and thus is considered to be a "marker" for that event or condition. To give some examples, in some embodiments, a biomarker may be or include a marker for a particular disease state, or the likelihood that a particular disease, disorder, or condition may occur. In some embodiments, a biomarker may be or include a marker for a particular disease or treatment outcome, or the likelihood thereof. Thus, in some embodiments, a biomarker has predictive capabilities, in some embodiments, a biomarker has prognostic capabilities, and in some embodiments, a biomarker has diagnostic capabilities, of the associated biological event or condition of interest. A biomarker may be or include any chemical class of entity, or may be or include a combination of entities. For example, in some embodiments, a biomarker may be or include a nucleic acid, a polypeptide, a lipid, a carbohydrate, a small molecule, an inorganic agent (e.g., a metal or ion), or a combination thereof. In some embodiments, the biomarker is a cell surface marker. In some embodiments, the biomarker is intracellular. In some embodiments, the biomarker is detected outside the cell (e.g., secreted or otherwise produced or present outside the cell, e.g., in a bodily fluid such as blood, urine, tears, saliva, cerebrospinal fluid, etc.). In some embodiments, the biomarker may be or include a genetic or epigenetic signature. In some embodiments, the biomarker may be or include a gene expression signature.

[0023] Cellulose nanofibrils: As used herein, the term "cellulose nanofibrils" refers to a state of cellulose material in which at least 75% of the cellulose material is considered to be "fines." In some embodiments, the percentage of the cellulose material that may be considered fines may be much higher, such as 80%, 85%, 90%, 95%, 99% or more. In this disclosure, the terms "nanofibrils," "nanocellulose," "highly fibrillated cellulose," and "ultrafibrillated cellulose" are all considered to be synonymous with cellulose nanofibrils.

[0024] Detectable entity: The term "detectable entity," as used herein, refers to any element, molecule, functional group, compound, fragment, or moiety that is capable of being detected. In some embodiments, a detectable entity is provided or utilized alone. In some embodiments, a detectable entity is provided and / or utilized in association with (e.g., bound to) another agent. Detectable entities include a variety of ligands, radionuclides (e.g., 3 H, 14 C. 18 F, 19 F, 32 P, 35 S, 135 I, 125 I, 123 I, 64 Cu, 187 Re, 111 In, 90 Y, 99m Tc, 177 Lu, 89 Examples of suitable fluorescent labels include, but are not limited to, inorganic fluorescent semiconductor nanocrystals (i.e., quantum dots), fluorescent dyes, chemiluminescent agents (e.g., acridinium esters, stabilized dioxetanes, etc.), bioluminescent agents, spectrally resolvable inorganic fluorescent semiconductor nanocrystals (i.e., quantum dots), metal nanoparticles (e.g., gold, silver, copper, platinum, etc.) nanoclusters, paramagnetic metal ions, enzymes (see below for specific examples of enzymes), colorimetric labels (e.g., dyes, colloidal gold, etc.), biotin, dioxygenin, haptens, and proteins for which antisera or monoclonal antibodies are available.

[0025] Fines: As used herein, fines refers to cellulosic materials or portions of cellulosic fibers having a weighted fiber length of less than 0.2 mm. In some embodiments, "fines" may refer to cellulosic materials having diameters between 5 nm and 100 nm inclusive, and having high surface-to-volume ratios and high length / diameter (aspect) ratios.

[0026] "Improve," "Increase," or "Decrease": As used herein, "improve," "increase," or "decrease," or grammatical equivalents, refer to a value relative to a baseline measurement, such as a measurement in the same sample prior to the initiation of a treatment or process step described herein, or a measurement in a control sample (or control samples) in the absence of a treatment described herein.

[0027] Porosity: The term "porosity" as used herein refers to a measure of void space in a material and is the fraction of void volume over the total volume, as a percentage between 0 and 100%. The determination of porosity is known to those skilled in the art using standardized techniques, such as mercury porosimetry and gas adsorption (e.g., nitrogen adsorption).

[0028] Sample: In some embodiments, the source of interest is a biological or environmental source. In some embodiments, the source of interest may be or include a cell or organism, such as a microorganism, a plant, an animal (e.g., human). In some embodiments, the source of interest is or includes a biological tissue or fluid. In some embodiments, the biological tissue or fluid may include amniotic fluid, aqueous humor, peritoneal fluid, bile, bone marrow, blood, breast milk, cerebrospinal fluid, uterine cavity, chyle, chime, semen, intestinal lymph fluid, exudate, feces, gastric acid, gastric juice, lymph, mucus, pericardial fluid, extralymphatic fluid, peritoneal fluid, pleural fluid, pus, ocular discharge, saliva, sebum, sperm, serum, smear, sputum, synovial fluid, sweat, tears, urine, vaginal fluid, vitreous humor, vomit, and / or combinations or components thereof. In some embodiments, the biological fluid may be or include intracellular fluid, extracellular fluid, intravascular fluid (plasma), interstitial fluid, lymphatic fluid, and / or transcellular fluid. In some embodiments, the biological fluid may be or include a phytoexudate. In some embodiments, the biological tissue or sample may be obtained, for example, by aspiration, biopsy (e.g., fine needle or tissue biopsy), swab (e.g., oral, nasal, skin, or vaginal swab), scraping, surgery, lavage, or irrigation (e.g., follicular, ductal, nasal, ocular, oral, uterine, vaginal, or other lavage or irrigation). In some embodiments, the biological sample is or includes cells obtained from an individual. In some embodiments, the sample is a "primary sample" that is obtained directly from the source of interest by any suitable means. In some embodiments, as will be clear from the context, the term "sample" refers to a preparation obtained by processing (e.g., by removing one or more components and / or adding one or more agents) of a primary sample. For example, filtration using a semipermeable membrane. Such a "processed sample" may include, for example, nucleic acids or proteins extracted from a sample or obtained by subjecting the primary sample to one or more techniques, such as amplification or reverse transcription of nucleic acids, isolation and / or purification of certain components, etc.

[0029] Substantially: As used herein, the term "substantially" refers to the quantitative condition of exhibiting a total or near-total degree or degree of a desired characteristic or property. Those skilled in the chemical arts will understand that biological and chemical phenomena rarely, if ever, proceed to completion and / or perfection or achieve or avoid absolute results. Thus, the term "substantially" is used herein to capture the potential lack of completeness inherent in many biological and chemical phenomena.

[0030] The present invention relates generally to the field of products made from cellulosic materials (e.g., pulp, fibers, and nanofibers), such as membranes that exhibit rapid and controlled aqueous wicking properties, including, but not limited to, internal and surface wetting phenomena, surface uniformity, and improved physical properties.

[0031] Nanofibrillated cellulose has previously been shown to be useful as a reinforcing material in wood and polymer composites, as a barrier coating for paper, paperboard and other substrates, and as a papermaking additive to control porosity and bond-dependent properties. Many groups are investigating the incorporation of nanocellulose materials into paper or other products, while other research groups are investigating the use of this material at low concentrations for reinforcement in certain plastic composites.

[0032] Prior to the present disclosure, most wicking membranes were made from nitrocellulose or other cellulosic materials that were heavily chemically modified (i.e., by nitration, sulfation, etc.) In addition, these nitrocellulose membranes were typically made by freeze-drying, limiting their wicking capacity.

[0033] The present disclosure provides new membrane compositions and methods for producing membranes with improved wicking capacity and other improved physical properties using one or more cellulose components. These membranes can be tailored for different applications, including biomedical applications. Furthermore, these new membrane compositions can be formed by simple drying methods, such as oven or microwave drying, allowing for better control of the physical properties of the membrane.

[0034] The inventors have determined that certain properties of the membrane confer wicking capabilities. For example, materials that achieve superior wicking often contain higher porosity and / or form lamellar channels (see, for example, the porous pulp-based material shown in FIG. 1a). Furthermore, uniform distribution of components (including additives and wettable minerals) throughout the formed membrane is desirable for, for example, lateral flow assays and point-of-care / diagnostic devices.

[0035] The inventors have successfully identified compositions that include one or more cellulosic materials (e.g., wood pulp and CNF) and one or more wet minerals, and that, when formed into a membrane, exhibit excellent wicking capabilities. The inventors achieve a substantially homogeneous membrane material, with the wet mineral(s) being uniformly distributed throughout the membrane by the addition of a certain amount of CNF. The inventors have found that membranes with high CNF content (e.g., greater than about 1.5 wt.% CNF) contain web-like structures (similar to CNF-based materials) and disrupt the lamella-like channels formed by the pores of the pulp material. In contrast, the provided materials and membranes can achieve excellent wicking properties with lower concentrations of CNF.

[0036] Furthermore, the inventors have found that the addition of small amounts of CNFs to the membrane composition improves the retention of wet minerals in the membrane. In some embodiments, CNFs are added to a composition of wood pulp and wet minerals at a concentration in the range of 0.1-1.5% by weight in an aqueous suspension before the membrane is dried. Surprisingly, the inventors have found that a particular ratio of membrane components (pulp, CNFs, and wet minerals) allows for both 1) the ability to retain wet minerals uniformly throughout the membrane material, and 2) the ability to maintain a porous channel-like structure that can effectively wick liquid.

[0037] Cellulosic Materials According to various embodiments, any of a variety of cellulose materials can be used in the provided compositions and films. The cellulose material can be any material that contains cellulose. Cellulose is naturally found in the stems, leaves, husks, husks, and ears of plants, or the leaves, branches, and wood of trees. The cellulose material can also be herbaceous materials, agricultural residues, and forestry residues. In some embodiments, the cellulose material is or includes pulp fibers, microcrystalline cellulose, and cellulose fibril aggregates. In some embodiments, the cellulose material is or includes micron-scale cellulose. In some embodiments, the cellulose material is or includes nanoscale cellulose (i.e., nanocellulose). In some embodiments, the nanocellulose is or includes cellulose nanofibrils. In some embodiments, the cellulose nanofibrils are or include microfibrillated cellulose, nanocrystalline cellulose, and bacterial nanocellulose.

[0038] Lignocellulosic Materials According to various embodiments, the cellulosic material used in the provided compositions and membranes is or includes any of a variety of lignocellulosic materials. In some embodiments, the lignocellulosic material is a material that includes and / or is derived from natural polymers based on lignin, cellulose, and hemicellulose obtained from materials such as wood, wood waste, spent pulping / fractionation liquids, algal biomass, food waste, grass, straw, corn stover, corn fiber, agricultural products and residues, forest residues, saw dust, wood shavings, sludge and municipal solid waste, bacterial cellulose, and mixtures thereof. In some embodiments, the lignocellulosic material is or includes wood pulp, such as chemically bleached wood pulp (softwood or hardwood), and wood residues (wood flour).

[0039] In some embodiments, micron-scale cellulose or nano-scale cellulose is obtained from lignocellulosic materials prior to and / or during preparation of the provided membranes.

[0040] Cellulose nanofibril (CNF) According to various embodiments, any of a variety of application-appropriate cellulose nanofibrils may be used. Cellulose nanofibrils are also known in the literature as microfibrillated cellulose (MFC), cellulose microfibrils (CMF), nanofibrillated cellulose (NFC) and cellulose nanofibrils (CNF), which are distinct from nanocrystalline cellulose (NCC) or cellulose nanocrystals (CNC). In some embodiments, the CNF comprises 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidized CNF. In some embodiments, the CNF comprises lignin-containing CNF (L-CNF).

[0041] Regardless of variations in nomenclature, various embodiments are applicable to nanocellulose fibers regardless of their actual physical dimensions, provided that at least one dimension (typically fiber width) is in the nanometer range. CNFs are generally produced from wood pulp by refining, grinding, or homogenization processes described below, which govern the final length and length distribution. Fibers tend to have at least one dimension (e.g., diameter) in the nanometer range, but fiber length can vary from as little as 0.1 μm to about 4.0 mm, depending on the type of wood or plant used as the source and the degree of refining. In some embodiments, the "as refined" fiber length is about 0.2 mm to about 0.5 mm. Fiber length is measured using industry standard testing equipment, such as the TechPap Morii Fiber Length Analyzer. Within limits, as the fiber becomes more refined, the % fines increases and the fiber length decreases.

[0042] CNF or lignocellulosic material can be treated, for example, by oxidation and / or homogenization to produce specific forms of CNF material, such as 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidized CNF.

[0043] In some embodiments, the CNFs are obtained from wood-based materials or residues. In some embodiments, the wood-based residues include sawdust. In some embodiments, the wood-based residues include wood flour. In some embodiments, the wood-based residues include wood shavings. In some embodiments, the wood-based residues include wood chips. These types of CNF materials are commonly known as lignin-containing cellulose nanofibrils (LCNF).

[0044] Wetting Agent In some embodiments, the membranes of the present disclosure further comprise one or more wetting agents to improve wicking of samples onto the membranes described herein.

[0045] In some embodiments, the wetting agent is an inorganic mineral or a wetting mineral. The wetting mineral can be, for example, any metal oxide that is naturally hydrophilic. Adding the wetting mineral to the cellulose membrane imparts hydrophilicity to the membrane, which is normally hydrophobic. In some embodiments, one or more wetting agents are added to a slurry that includes one or more cellulose materials before the membrane is formed.

[0046] Exemplary wetting minerals include any metal oxide that is hydrophilic in nature, such as CaCO3, SiO2, alumina, hydroxyapatite, calcium phosphate, and TiO2.

[0047] In some embodiments, the one or more wetting agents may be present in the slurry or film at a concentration of about 0.01% to about 80% by weight (either on a total or dry weight basis). In some embodiments, the one or more wetting agents may be present in the slurry or film at a concentration of about 0.01% to about 20% by weight (either on a total or dry weight basis). In some embodiments, one or more wetting agents may be present in the slurry or film at a concentration ranging from about 0.01-75%, 0.01-70%, 0.01-65%, 0.01-60%, 0.01-55%, 0.01-50%, 0.01-45%, 0.01-40%, 0.01-35%, 0.01-30%, 0.01-25%, 0.01-20%, 0.01-15%, 0.01-10%, 0.01-5%, 0.01-1%, 0.01-0.5% by weight (on either a total or dry weight basis).

[0048] Additives In some embodiments, the membranes of the present disclosure include one or more additives, hi some embodiments, the additives are added to a slurry that includes one or more cellulosic materials, and the slurry is formed into a membrane.

[0049] In some embodiments, the one or more additives modify the physical, mechanical, or chemical properties of the membrane compared to the same membrane without the one or more additives. In some embodiments, the one or more additives include wood derivatives, metal particles, latex particles, bioceramics, glass materials, proteins, fluorescent dyes, minerals, natural fibers, polymeric materials, or any combination thereof. In some embodiments, the additive is or includes a wood derivative.

[0050] In some embodiments, the additive comprises one or more foaming agents, foaming agents, and / or templating agents. Foaming agents include, for example, synthetic surfactants (both ionic and non-ionic), biosurfactants such as fungi, bacteria, yeasts, glycolipids, phospholipids, glycopeptides, saponins, fatty acids, proteins, polysaccharides. Foaming agents include, for example, CO2, baking soda, and the like.

[0051] In some embodiments, the additive comprises one or more plasticizers, such as, for example, acetylated monoglycerides, alkyl citrates, epoxidized soybean oil, proteins, PEG, fatty acids, or surfactants, such as glucosides (coco, decyl, lauryl, etc.), and myristic acid.

[0052] In some embodiments, the additive comprises one or more flame retardants. Examples of flame retardants include, for example, carbon (graphite, graphene, nanotubes), brominated polymers, chlorinated anhydrides, acids and paraffins, minerals (clays, borates, hydroxides of aluminum and magnesium, zinc stannate), nitrogen (melamine), phosphorus (red phosphorus, organic phosphates, halogenated phosphates, ammonium polyphosphates, phosphine oxides), silicon-based additives, organic acids, and carbonates.

[0053] In some embodiments, the additive is or comprises a metal particle. In some embodiments, the additive is or comprises a metal oxide particle. In some embodiments, the metal particle is a silver particle. In some embodiments, the metal particle is a gold particle. In some embodiments, the metal oxide particle is a titanium oxide particle. In some embodiments, the metal particle is an iron oxide particle. In some embodiments, the metal particle is a silver dioxide particle. In some embodiments, the metal oxide particle is an aluminum oxide particle.

[0054] In some embodiments, the additive is or comprises a stabilizer. An example of a stabilizer is citric acid.

[0055] In some embodiments, the additive is or includes latex particles.

[0056] In some embodiments, the additive is or comprises one or more bioceramic materials, hi some embodiments, the bioceramic materials are or comprise one or more of tricalcium phosphate, tricalcium phosphate derivatives, dicalcium phosphate, dicalcium phosphate derivatives, or any combination thereof.

[0057] In some embodiments, the additive comprises one or more glass materials. In some embodiments, the glass materials are bioactive. In some embodiments, the glass materials comprise glass fibers, glass beads, glass particles, or any combination thereof.

[0058] In some embodiments, the additive is or comprises one or more proteins, hi some embodiments, the protein comprises a growth factor.

[0059] In some embodiments, the additive is or comprises one or more fluorescent dyes. In some embodiments, the fluorescent dyes comprise one or more fluorescent tags.

[0060] In some embodiments, the additive comprises one or more minerals, which in some embodiments can be or include hydroxyapatite, hydroxyapatite derivatives, cement, concrete, clay, or any combination thereof.

[0061] In some embodiments, the additive comprises one or more natural fibers, hi some embodiments, the additive comprises polymeric fibers.

[0062] Other additives are known to those skilled in the art and may be considered for addition to the structures of the present invention without departing from the scope of the present invention.

[0063] In some embodiments, the one or more additives may be present in a concentration ranging from about 0.01% to about 80% by weight. In some embodiments, the one or more additives may be present in a concentration ranging from about 0.01-75%, 0.01-70%, 0.01-65%, 0.01-60%, 0.01-55%, 0.01-50%, 0.01-45%, 0.01-40%, 0.01-35%, 0.01-30%, 0.01-25%, 0.01-20%, 0.01-15%, 0.01 It may be present in a concentration ranging from 0.01-10%, 0.01-5%, 0.01-1%, 0.01-0.5%, 0.01-0.1%, 0.01-0.09%, 0.01-0.08%, 0.01-0.07%, 0.01-0.06%, 0.01-0.05%, 0.01-0.04%, 0.01-0.03%, or 0.01-0.02% by weight. In some embodiments, one or more additives may be present in a concentration ranging from about 0.05-80%, 0.1-80%, 0.5-80%, 1-80%, 5-80%, 10-80%, 15-80%, 20-80%, 25-80%, 30-80%, 35-80%, 40-80%, 45-80%, 50-80%, 55-80%, 60-80%, 65-80%, 70-80%, 71-80%, 72-80%, 73-80%, 74-80%, 75-80%, 76-80%, 77-80%, 78-80%, or 79-80% by weight.

[0064] An exemplary additive that alters the chemical properties of the composition is the addition of a reagent to the cellulose structure. In diagnostic applications, the reagent may include an analyte capture reagent, such as an antibody or fragment thereof. In environmental applications, the reagent may include any chemical reagent known to react with and detect the presence of environmental pollutants or other analytes. By controlling the degradation properties and porosity, the reagent may be slowly released into the environment.

[0065] General pulping and CNF processes The pulp used in the manufacture of the provided membranes and compositions can be obtained by any known pulping process. Examples of chemical pulping processes include (a) the Kraft process, (b) the sulfite process, and (c) the soda process, which are fully described in the literature, for example, Smook, Giry A., Handbook for Pulp & Paper Technologies, Tappi Press, 1992 (e.g., Chapter 4), and the article "Overview of the Wood Pulp Industry," Market Pulp Association, 2007.

[0066] The CNFs used in the manufacture of the provided films and compositions can be obtained via any known process for producing nanocellulose or fibrillated cellulose, such as the process disclosed in U.S. Pat. No. 10,563,352, which is incorporated herein by reference in its entirety. In some embodiments, the process for obtaining CNFs includes mechanically grinding wood pulp in any type of mill or device that breaks down and separates fibers. Such mills are known in the art and include, but are not limited to, Valley beaters, single disc refiners, double disc refiners, conical refiners, including both wide and narrow angles, cylindrical refiners, homogenizers, microfluidizers, and other similar milling or grinding devices. Examples of mechanical grinding devices can be found, for example, in Smook, Giry A., Handbook for Pulp & Paper Technologists, Tappi Press, 1992 (e.g., Chapter 13). The process of mechanical disintegration or grinding, regardless of the type of equipment, is sometimes referred to in the pulp literature as "refining."

[0067] The degree of refinement may be monitored during the process by any of several means. Certain optical instruments can provide continuous data on fiber length distribution and percent fines, either of which can be used to define the end point of the grinding stage. Within limits, as the fibers become more refined, the % fines increases and the fiber length decreases. Fiber length is measured using an industry standard tester such as a TechPap Morii Fiber Length Analyzer, which reads a particular "average" fiber length. In some embodiments, the "as refined" fiber length is from about 0.1 mm to about 0.6 mm, or from about 0.2 mm to about 0.5 mm.

[0068] In some embodiments, the pulp can be chemically modified (eg, by sulfation or nitration) prior to refining (eg, by homogenization).

[0069] Refining of the pulp to produce highly fibrillated cellulose can be carried out using various mechanical processes, such as using a homogenizer and / or an ultrafine grinder. In some embodiments, CNF can be produced using a low consistency refiner, for example, as described in U.S. Patent No. 7,381,294 (Suzuki et al.). In some embodiments, microfibrillated cellulose or CNF can be produced by recirculating the fiber slurry through a refiner. In some embodiments, two refiners are used sequentially.

[0070] As a non-limiting example, U.S. Patent No. 9,988,762 describes a scouring process for preparing CNFs from wood products, and is incorporated herein in its entirety. In some embodiments, the process for obtaining CNFs includes treating a slurry of cellulose fibers, preferably wood fibers, liberated from a lignocellulosic matrix using a pulping process. The pulping process can be a chemical pulping process, such as a sulfate (e.g., Kraft) or sulfite process. The process can include first and second mechanical scouring machines that apply shear to the fibers. The scouring machine can be a low consistency scouring machine. In such an embodiment, the shear force helps to break down the cell walls of the fibers, exposing the fibrils and nanofibrils contained in the wall structure. The mechanical treatment can be continued until a desired amount of fibrils is liberated from the fibers.

[0071] In certain scouring processes, large amounts of water are used. As mentioned above, the slurry may contain 90-99% (by weight) water and only 1-10% fiber. If desired, complete water removal is routinely achieved via conventional means (evaporation, freeze drying, electrospray, oven heating, microwave, etc.) and / or combined with other materials to achieve a particular final form (e.g., membrane material).

[0072] Method for forming a membrane In particular, the present disclosure provides a method of making a membrane comprising one or more cellulose components, the one or more cellulose components comprising micron-scale cellulose or cellulose nanofibrils (CNF), wood pulp, and wetting agent(s), the method comprising: (i) creating a cellulose slurry by combining one or more of the cellulose components and the wetting agent(s) with a liquid component; (ii) mixing the components of the cellulose slurry; and (iii) exposing the cellulose slurry to drying conditions, thereby forming a membrane.

[0073] Cellulose Slurry According to various embodiments of the present invention, a cellulose slurry is used in a composition for producing a membrane. In some embodiments, the cellulose slurry comprises one or more cellulose materials suspended in a liquid component, such as water. In some embodiments, the slurry comprises a suspension, a colloid, a mixture, an emulsion, or a hydrogel. In some embodiments, the cellulose component comprises micron-scale cellulose. In some embodiments, the cellulose component comprises CNF (CNF). In some embodiments, the cellulose component comprises wood-based residues.

[0074] In some embodiments, the cellulosic slurry comprises wood and / or other lignocellulosic derivatives, in some embodiments, the wood derivatives may be or include wood flour, wood pulp, or combinations thereof.

[0075] In some embodiments, the cellulose slurry comprises from 0.01 wt% to about 10 wt% (e.g., 0.01-0.1 wt%, 0.1-1.5 wt%, 0.1-2 wt%, 0.1-5 wt%, 1-10 wt%) CNFs on a dry weight basis, where the wt% is calculated based on the total weight of all solid components present in the slurry (excluding the weight of liquid components).

[0076] In some embodiments, the cellulose slurry comprises from 0.01% to about 10% by weight (e.g., 0.01-0.1%, 0.1-1.5%, 0.1-2%, 0.1-5%, 1-10% by weight) of pulp (e.g., soft and / or hard wood pulp) on a dry weight basis, where the weight percentages are calculated based on the total weight of all solid components present in the slurry (excluding the weights of liquid components).

[0077] In some embodiments, the cellulose slurry includes CNFs and a wetting agent (e.g., a wetting mineral). In some embodiments, the ratio of CNFs:wetting minerals present in the cellulose slurry is in the range of about 1:0.0001 to about 1:1000. In some embodiments, the ratio of CNFs:wetting minerals present in the cellulose slurry is in the range of about 1:0.0001 to 0.001, 1:0.001 to 0.1, 1:0.1 to 1, 1:1 to 5, 1:5 to 10, 1:10 to 20, 1:20 to 50, 1:50 to 100, or about 1:100 to 1000. In some embodiments, the ratio of CNF:wet mineral present in the cellulose slurry is about 1:0.0001, 1:001, 1:0.01, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:10, 1:12, 1:14, 1:15, 1:20, 1:50, 1:100 or about 1:1000.

[0078] In some embodiments, a wetting agent is added to dry CNFs, which are subsequently mixed with water to form a suspension.

[0079] In some embodiments, the cellulose slurry comprises pulp and CNF. In some embodiments, the ratio of pulp:CNF present in the cellulose slurry is in the range of about 1:0.0001 to about 1:1000. In some embodiments, the ratio of pulp:CNF present in the cellulose slurry is in the range of about 1:0.0001 to 0.001, 1:0.001 to 0.1, 1:0.1 to 1, 1:1 to 5, 1:5 to 10, 1:10 to 20, 1:20 to 50, 1:50 to 100, or about 1:100 to 1000. In some embodiments, the ratio of pulp:CNF present in the cellulose slurry is about 1:0.0001, 1:001, 1:0.01, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:10, 1:12, 1:14, 1:15, 1:20, 1:50, 1:100 or about 1:1000.

[0080] In some embodiments, the cellulose slurry includes an additive. In some embodiments, the cellulose slurry includes 0.01-95 wt. % of additive(s), where wt. % is calculated based on dry mass and wt. % is calculated based on the total weight of all solid components present in the slurry (and excludes the weight of liquid components). For example, in some embodiments, the cellulose slurry may include 0.01-95% (e.g., 0.01-90%, 0.01-80%, 0.01-70%, 0.01-60%, 0.01-50%, 0.01-40%, 0.01-30%, 0.01-20%, 0.01-10%, or 0.01-5%) wt. % of additive(s). In some embodiments, the cellulose slurry comprises at least 0.01% by weight (e.g., at least 0.01%, 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20% by weight) of additive(s).

[0081] In some embodiments, the ratio of another solid component (e.g., cellulosic material such as pulp and / or CNF) present in the cellulosic slurry to the additive is in the range of about 1:0.0001 to about 1:1000. In some embodiments, the ratio of another solid component (e.g., cellulosic material such as pulp and / or CNF) present in the cellulosic slurry to the additive is in the range of about 1:0.001 to about 1:100. In some embodiments, the ratio of other solid components (e.g., cellulosic materials such as pulp and / or CNF) present in the cellulosic slurry to additive is about 1:0.0001, 1:0.001, 1:0.01, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4, 1:5, 1:10, 1:12, 1:14, 1:15, 1:20, 1:50, 1:100 or about 1:1000. In some embodiments, the ratio of other solid components (e.g., cellulosic materials such as pulp and / or CNF) present in the cellulosic slurry to additives is within the range of about 1:0.0001-0.001, 1:0.001-0.1, 1:0.1-1, 1:1-5, 1:5-10, 1:10-20, 1:20-50, 1:50-100, or about 1:100-1000.

[0082] In some embodiments, the total solids content of the cellulose slurry is in the range of 0.01-10 wt% (e.g., 0.01-0.1 wt%, 0.1-1.5 wt%, 0.1-2 wt%, 0.1-5 wt%, 1-10 wt%), where wt% is calculated based on dry weight, and dry weight is calculated based on the total weight of all solid components present in the slurry (excluding the weight of liquid components).

[0083] In some embodiments, the cellulose slurry comprises a liquid component, and the liquid component is water. In some embodiments, the cellulose slurry comprises a liquid component, and the liquid component is an alcohol. In some embodiments, the alcohol is ethanol. In some embodiments, the anti-solvent comprises a mixture of water and an alcohol. In some embodiments, the liquid component is acetone.

[0084] In some embodiments, the pulp is soaked in a liquid (e.g., DI water) for a period of time before being further processed. In some embodiments, the pulp is soaked in the liquid for a time ranging from 1 hour to 7 days, e.g., 24 hours. In some embodiments, the pulp is soaked in the liquid for at least, e.g., 1, 2, 3, 4, 8, 16, 24 hours, 48 ​​hours, 72 hours, or more.

[0085] mixture Membranes of the present disclosure can be formed, for example, by providing a slurry including one or more cellulosic materials, a wetting agent, and a liquid, and mixing the components of the slurry to distribute and combine the components.

[0086] In some embodiments, the slurry is prepared by mechanical mixing, hi some embodiments, the mixing is accomplished by automated mixing, for example, using equipment such as an automatic disperser, blender, automatic shaker, ultrasonic mixer, or planetary mixer.

[0087] In some embodiments, the pulp slurry and the slurry containing the CNF and wet mineral suspension are mixed using any method suitable for the application, such as mixing techniques, such as mechanical mixing, In some embodiments, mixing is accomplished by automated mixing, using equipment such as an automated disperser, blender, automated shaker, ultrasonic mixer, or planetary mixer.

[0088] In some embodiments, the mixing of the components of the cellulose slurry comprises one or more mixing sessions, in some embodiments, the one or more mixing sessions (e.g., three mixing sessions) are separated in time by intervals ranging from minutes to days (e.g., at least 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 1 hour, 2 hours, 24 hours, 40 hours, or more).

[0089] In some embodiments, a first mixing session is used to mix the CNFs with additives (e.g., wet minerals) to form a first mixture. In some embodiments, a second mixing session is used to mix the pulp with water to form a second mixture. In some embodiments, another mixing session is used to mix the first mixture with the second mixture. In some embodiments, each mixing session is about 30 minutes.

[0090] In some embodiments, one or more mixing sessions include identical mixing conditions, hi some embodiments, one or more mixing sessions include conditions that vary in one or more parameters (e.g., time, intensity, volume of material, type of mixing / equipment used for mixing) from at least one other mixing session.

[0091] In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 3 hours. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 2 hours. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 1 hour. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 55 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 50 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 45 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 40 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 35 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 30 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 25 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 20 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 15 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 10 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 9 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 8 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 7 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 6 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 5 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 4 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 3 minutes. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 2 minutes.In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 1 minute. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 55 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 50 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 45 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 40 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 35 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 30 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 25 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 20 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 19 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 18 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 17 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 16 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 15 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 14 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 13 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 12 seconds. In some embodiments, the cellulose slurry is mixed for a period of time including about 10 seconds to about 11 seconds.

[0092] Drying Membranes of the present disclosure can be formed, for example, by providing a slurry including one or more cellulosic materials, wetting agent(s), and a liquid, mixing the components of the slurry to distribute and combine the components, and drying the cellulosic slurry using techniques such as capillary dewatering, gravity and vacuum filtration, electric ovens, infrared heating, microwave heating, freeze drying, ambient heating, or combinations thereof.

[0093] In some embodiments, the drying conditions include one or more drying sessions, which in some embodiments are separated in time by intervals ranging from minutes to days (e.g., at least 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 1 hour, 2 hours, 24 hours, 40 hours, or more).

[0094] In some embodiments, one or more drying sessions include identical drying conditions, hi some embodiments, one or more drying sessions include conditions that vary in one or more parameters (e.g., time, intensity, volume of material) from at least one other drying session.

[0095] In some embodiments, the process of exposing the cellulose slurry to one or more drying conditions can achieve a membrane comprising at least 80% by weight cellulose solids (e.g., at least 85%, 90%, 95%, 99% by weight cellulose solids). In some embodiments, the process of exposing the cellulose slurry to one or more drying conditions can achieve a membrane comprising about 95% by weight cellulose solids.

[0096] In some embodiments, first drying conditions can be applied to the lignocellulosic slurry to achieve a hydrogel of about 1-60% solids (e.g., about 1-10%, 10-20%, 20-30%, 30-40%, 40-50%, or about 50-60% solids). In some embodiments, second drying conditions can be applied to the hydrogel for complete or near complete dehydration (e.g., a film of at least 90% solids).

[0097] In some embodiments, the first drying conditions include capillary dehydration, gravity and vacuum filtration, electric oven, infrared heating, microwave heating, freeze drying, and / or ambient heating.

[0098] In some embodiments, the second drying conditions include capillary dehydration, gravity and vacuum filtration, electric oven, infrared heating, microwave heating, freeze drying, and / or ambient heating.

[0099] capillary action According to various embodiments, the methods provided include using capillary action to dewater a slurry containing cellulosic material (e.g., CNFs and pulp) by contacting the slurry with a surface of a porous dewatering material, and removing at least a portion of the water in the aqueous suspension via capillary action, thereby forming a porous nanocellulose material. In some embodiments, the removing step continues for at least 8 hours.

[0100] In some embodiments, capillary dewatering of a cellulosic slurry can be accomplished, for example, by placing the suspension in a porous container and balancing the effects of capillary pressure, hydrostatic pressure, and enthalpy.

[0101] According to any of the various embodiments, a porous dewatering material suitable for any application may be used. In some embodiments, to be useful according to the methods provided, the porous dewatering material must be capable of facilitating the movement of water out of the aqueous suspension and across the porous dewatering material, for example, to an exterior surface (i.e., a surface that does not contact the aqueous suspension). In some embodiments, the porous dewatering material comprises a hydrophilic surface. In some embodiments, the porous dewatering material is selected from the group consisting of firebrick, kiln brick, cinder block, terracotta ceramic, and porous gypsum-based material (e.g., plaster of Paris). In some embodiments, the porous dewatering material is used in combination with a rigid material (e.g., a rigid material), such that the cellulosic material is simultaneously dried and molded against the surface of the rigid material.

[0102] In some embodiments, the capillary dehydration method further includes controlling at least one of the pressure and temperature to control the rate of water removal from the second surface of the porous dehydrating material to control the porosity of the formed membrane.

[0103] Without wishing to be bound by any particular theory, it is likely that the gentle and controlled nature of capillary forces allows for the production of the provided materials as opposed to harsher methods (e.g., hot press molding, etc.) that have been used previously in attempts to achieve a higher percentage of solids in solution, for example.

[0104] In some embodiments, the pressure and / or temperature are manipulated. In some embodiments, adjusting the temperature comprises increasing the temperature. In some embodiments, adjusting the temperature comprises decreasing the temperature. In some embodiments, adjusting the pressure comprises increasing the pressure. In some embodiments, adjusting the pressure comprises decreasing the pressure. In some embodiments, controlling the pressure comprises creating at least a partial vacuum.

[0105] In some embodiments, the slurry is partially dewatered by capillary action to form a partially dried film and then further dried using other methods, hi some embodiments, the remaining water is frozen in the partially dried film and then further dried by allowing the remaining frozen water to evaporate from the film.

[0106] In some embodiments, capillary dehydration is performed using a mold as described in U.S. Patent Application No. 16 / 086,988 (published as U.S. Patent Application Publication No. 2019 / 0093288A1), which is incorporated by reference in its entirety.

[0107] Microwave radiation In some embodiments, the drying conditions include microwave radiation. In some embodiments, the one or more drying sessions include identical mixing conditions. In some embodiments, the one or more drying sessions include microwave conditions that vary in one or more microwave parameters from at least one other drying session. In some embodiments, the one or more microwave parameters include microwave power, microwave wavelength, microwave frequency, microwave directivity, microwave flux, and microwave irradiation duration. In some embodiments, the one or more drying sessions include a drying session, during which the microwave radiation varies in one or more of power, wavelength, frequency, directivity, and flux.

[0108] In some embodiments, the microwave radiation has a power of about 5 W / kg of cellulose slurry to about 100 kW / kg of cellulose slurry. In some embodiments, the microwave radiation has a power of about 5-90,000, 5-80,000, 5-70,000, 5-60,000, 5-50,000, 5-40,000, 5-30,000, 5-20,000, 5-10,000, 5-9,000, 5-8,000, 5-7,000, 5-6,000, 5-5,000, 5-4,000, 5-3,000, 5-2,000, 5-1,000, 5-900, 5-800, 5-700, 5 ~600, 5~500, 5~400, 5~300, 5~200, 5~100, 5~95, 5~90, 5~85, 5~80, 5~75, 5~70, 5~65, 5~60, 5~55, 5~50, 5~45, 5~40, 5~35, 5~30, 5~25, 5~20, 5~19, 5~18, 5~17, 5~16, 5~15, 5~14, 5~13, 5~12, 5~11, 5~10, 5~9, 5~8, 5~7, or 5~6 W / kg.

[0109] In some embodiments, the microwave radiation has a wavelength of about 1 millimeter to about 1 meter. In some embodiments, the microwave radiation has a wavelength of about 1-900, 1-850, 1-800, 1-750, 1-700, 1-650, 1-600, 1-550, 1-500, 1-450, 1-400, 1-350, 1-300, 1-250, 1-200, 1-150, 1-100, 1-90, 1-85, 1-80, 1-75, 1-70 , 1-65, 1-60, 1-55, 1-50, 1-45, 1-40, 1-35, 1-30, 1-25, 1-20, 1-19, 1-18, 1-17, 1-16, 1-15, 1-14, 1-13, 1-12, 1-11, 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, or 1-2 millimeters. In some embodiments, the microwave radiation is about 0.005 to 1, 0.01 to 1, 0.015 to 1, 0.02 to 1, 0.025 to 1, 0.03 to 1, 0.035 to 1, 0.04 to 1, 0.045 to 1, 0.05 to 1, 0.055 to 1, 0.06 to 1, 0.065 to 1, 0.07 to 1, 0.075 to 1, 0.08 to 1 , 0.085~1, 0.09~1, 0.095~1, 0.1~1, 0.2~1, 0.25~1, 0.3~1, 0.35~1, 0.4~1, 0.45~1, 0.5~1, 0.55~1, 0.6~1, 0.65~1, 0.7~1, 0.75~1, 0.8~1, 0.85~1, or 0.9~1 meters.

[0110] In some embodiments, the microwave radiation may have a frequency of 500 MHz to 100 GHz, 500 MHz to 50 GHz, 500 MHz to 10 GHz, or 500 MHz to 5 GHz. In some embodiments, the microwave radiation may have a frequency of 915 MHz. In some embodiments, the microwave radiation may have a frequency of 2,450 MHz. In some embodiments, the microwave radiation may have a frequency of 915 MHz to 2,450 MHz.

[0111] In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 3 hours. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 2 hours. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 1 hour. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 55 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 50 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 45 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 40 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 35 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 30 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 25 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 20 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 15 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 10 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 9 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 8 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 7 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 6 minutes.In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 5 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 4 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 3 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 2 minutes. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 1 minute. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 55 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 50 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 45 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 40 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 35 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 30 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 25 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 20 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 19 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 18 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 17 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 16 seconds.In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 15 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 14 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 13 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 12 seconds. In some embodiments, the cellulose slurry is exposed to microwave radiation for a time period including about 10 seconds to about 11 seconds.

[0112] In some embodiments, the cellulose slurry is contained within the mold when exposed to microwave radiation for at least one drying session (e.g., microwave radiation session). In some embodiments, the cellulose slurry is not contained within the mold when exposed to microwave radiation for at least one drying session.

[0113] In some embodiments, the cellulose slurry is exposed to microwave radiation until the liquid component content is about 0.01% to about 20% by weight (e.g., 0.05% to 20% by weight, 0.05% to 10% by weight, 0.1% to 20% by weight, 0.1% to 10% by weight, 1% to 20% by weight, 1% to 15% by weight, 1% to 10% by weight, 1% to 5% by weight).

[0114] In some embodiments, the variation of microwave radiation results in a cellulose composition having a uniform internal void per volume. In some embodiments, the variation of microwave radiation results in a cellulose composition having a uniform porosity.

[0115] The cellulose slurry of the present disclosure can be dried according to any method known in the art and is not limited to the specific examples provided herein.

[0116] Mold Forming In some embodiments, the cellulose slurry is extruded after at least one drying session. In some embodiments, the mold is cylindrical. In some embodiments, the mold is a sphere, a cone, a cube, a sheet or a thin film. In some embodiments, the shape of the film may be modified or changed relative to the shape of the mold if the semi-solid composition is removed from the mold while it is still somewhat malleable (e.g., up to about 80% water by weight) between the first and second drying conditions. In some embodiments, the semi-solid composition may be molded into a non-mold shape before the composition is completely dried in the subsequent drying conditions. In some embodiments, the semi-solid composition may be molded into a form and then exposed to drying conditions to obtain a desired shape without a mold.

[0117] In some embodiments, the dried or partially dried membrane may be attached, bonded, and / or combined with another membrane (e.g., of the same or different material). In some embodiments, the membrane may be combined with another material selected based on the end use of the membrane. For example, the membrane may be combined with a flexible backing, for example, for use in a lateral flow assay.

[0118] Examples of materials used in combination with the provided membranes include polyethylene terephthalate (PET) fibers, such as Dacron® fibers, nitrocellulose, polyester, nylon, cellulose acetate, hydrogels, polypropylene, fiberglass, etc. In some embodiments, the membranes may be combined with one or more other materials and then molded to form the final membrane material.

[0119] In some embodiments, the membrane comprises one or more layers of the same membrane material (eg, a membrane made from equal amounts of cellulosic material and wet minerals).

[0120] In some embodiments, the membrane comprises a first layer of membrane material (e.g., a membrane made from one or more cellulosic materials and wet minerals) and one or more additional layers comprising different membrane materials.

[0121] physical properties The present disclosure provides a membrane that includes various physical properties. The present disclosure recognizes that the inclusion of a certain amount of CNF in the membrane improves the dispersibility of wood pulp in water. Furthermore, the CNF enhances the mechanical properties of the membrane and the retention of wet minerals in the membrane.

[0122] In some embodiments, the membrane has a density of about 0.01 g / cm 3 ~Approx. 2.5g / cm 3 , for example, about 0.01 g / cm 3 ~Approx. 1.0g / cm 3 In some embodiments, the membrane has a density of about 0.02-2.4, 0.02-2.3, 0.02-2.2, 0.02-2.1, 0.02-2.0, 0.02-1.9, 0.02-1.8, 0.02-1.7, 0.02-1.6, 0.02-1.5, 0.02-1.4, 0.02-1.3, 0.02-1.2, 0.02-1.1, 0.02-1.0, 0.0 2~0.9, 0.02~0.8, 0.02~0.7, 0.02~0.6, 0.02~0.5, 0.02~0.4, 0.02~0.3, 0.02~0.2, 0.02~0.1, 0.02~0.09, 0.02~0.08, 0.02~0.07, 0.02~0.06, 0.02~0.05, 0.02~0.04, or 0.02~0.03g / cm 3 In some embodiments, the membrane has a density of about 0.01-1.0, 0.02-1.0, 0.03-1.0, 0.04-1.0, 0.05-1.0, 0.06-1.0, 0.07-1.0, 0.08-1.0, 0.09-1.0, 0.1-1.0, 0.2-1.0, 0.3-1.0, 0.4-1.0, 0.5-1.0, 0.6-1.0, 0.7-1.0, 0.8-1.0, or 0.9-1.0 g / cm. 3 has a density of

[0123] In some embodiments, the final amount of pulp in the membrane is about 0.01% to about 10% by weight (e.g., 0.01-0.1%, 0.1-1.5%, 0.1-2%, 0.1-5%, 1-10% by weight) of pulp (e.g., soft and / or hard wood pulp) on a dry weight basis, where weight % is calculated based on dry weight and weight % is calculated based on the total weight of all solid components present in the slurry (excluding the weight of liquid components).

[0124] In some embodiments, the cellulose membrane comprises 0.01-95 wt % additive(s), where wt % is calculated based on dry weight and wt % is calculated based on the total weight of all solid components present in the slurry (and excluding the weight of liquid components). For example, in some embodiments, the cellulose membrane may comprise 0.01-95% (e.g., 0.01-90%, 0.01-80%, 0.01-70%, 0.01-60%, 0.01-50%, 0.01-40%, 0.01-30%, 0.01-20%, 0.01-10%, or 0.01-5%) wt % additive(s). In some embodiments, the cellulose membrane comprises at least 0.01 wt.% (e.g., at least 0.01 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) of additive(s).

[0125] In some embodiments, the cellulose membrane comprises CNFs and a wetting agent (e.g., a wet mineral). In some embodiments, the ratio of CNFs:wet minerals present in the cellulose membrane is in the range of about 1:0.0001 to about 1:1000. In some embodiments, the ratio of CNFs:wet minerals present in the cellulose membrane is in the range of about 1:0.0001 to 0.001, 1:0.001 to 0.1, 1:0.1 to 1, 1:1 to 5, 1:5 to 10, 1:10 to 20, 1:20 to 50, 1:50 to 100, or about 1:100 to 1000. In some embodiments, the ratio of CNF:wet mineral present in the cellulose membrane is about 1:0.0001, 1:001, 1:0.01, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:10, 1:12, 1:14, 1:15, 1:20, 1:50, 1:100 or about 1:1000.

[0126] In some embodiments, the final ratio of pulp:CNF present in the cellulose membrane is in the range of about 1:0.0001 to about 1:1000. In some embodiments, the ratio of pulp:CNF present in the cellulose membrane is in the range of about 1:0.0001 to 0.001, 1:0.001 to 0.1, 1:0.1 to 1, 1:1 to 5, 1:5 to 10, 1:10 to 20, 1:20 to 50, 1:50 to 100, or about 1:100 to 1000. In some embodiments, the ratio of pulp:CNF present in the cellulose membrane is about 1:0.0001, 1:001, 1:0.01, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:10, 1:12, 1:14, 1:15, 1:20, 1:50, 1:100 or about 1:1000.

[0127] In some embodiments, the membrane has a nanocellulose fiber solids content of about 0.01, 0.1, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95% by weight. In some embodiments, the membrane has a nanocellulose fiber solids content of about 0.01% to about 10% by weight (e.g., 0.01% to 0.1%, 0.1% to 1.5%, 0.1% to 2%, 0.1% to 5%, 1% to 10% by weight). In some embodiments, the membrane has a nanocellulose fiber solids content of about 1-90%, 1-85%, 1-80%, 1-75%, 1-70%, 1-65%, 1-60%, 1-55%, 1-50%, 1-45%, 1-40%, 1-35%, 1-30%, 1-25%, 1-20%, 1-15%, 1-10%, 1-9%, 1-8%, 1-7%, 1-6%, 1-5%, 1-4%, 1-3%, or 1-2% by weight. In some embodiments, the membrane has a nanocellulose fiber solids content of about 0.01-95%, 0.1-95%, 5-95%, 10-95%, 15-95%, 20-95%, 25-95%, 30-95%, 35-95%, 40-95%, 45-95%, 50-95%, 55-95%, 60-95%, 65-95%, 70-95%, 75-95%, 80-95%, 85-95%, 90-95%, 91-95%, 92-95%, 93-95%, or 94-95% by weight.

[0128] In some embodiments, the membrane of the present disclosure further comprises one or more additives. In some embodiments, the one or more additives modify the physical, mechanical or chemical properties of the membrane compared to the same membrane without the one or more additives. In some embodiments, the additives comprise one or more foaming agents, blowing agents, and / or templating agents.

[0129] porosity The membranes described herein are characterized by their improved wicking capacity. The porosity of the membrane contributes to the wicking capacity and can be controlled and adjusted by various methods, including the drying time and method used to dry the cellulose slurry. The amount of cellulose material in the membrane can affect the porosity (and also the pore morphology). Pores that form lamella-like channels have been shown to increase the wicking capacity.

[0130] In some embodiments, the membrane comprises a substantially uniform porosity and / or pore size, hi some embodiments, the membrane comprises a gradient of porosity and / or pore size.

[0131] In some embodiments, the porosity of the membrane is in the range of at least 60-90%. In some embodiments, the porosity of the membrane is in the range of at least 10-90%, 20-90%, 30-90%, 40-90%, 50-90%, 60-90%, 70-90%, or 80-90%. In some embodiments, the porosity of the membrane is at least 10, 20, 30, 40, 50, 60, 70, 80, or at least 90%. In some embodiments, the porosity of the membrane is determined by the bulk to absolute density of the membrane. In some embodiments, the porosity and pore size distribution are tested using mercury porosimetry, or BET and / or BJH analysis.

[0132] In some embodiments, the pores in the membrane have an average diameter of 1 nm to 1000 microns (e.g., 10 nm to 1000 microns, 100 nm to 100 microns, 1 to 10 microns). In some embodiments, the pores in the membrane have an average diameter of 1 nm to 1000 nm (e.g., 1 to 10 nm, 10 to 20 nm, 20 to 100 nm, 100 to 200 nm, 200 to 300 nm, 300 to 400 nm, 400 to 500 nm, 500 to 600 nm, 600 to 700 nm, 700 to 800 nm, 800 to 900 nm, 900 to 1000 nm). In some embodiments, the pores in the membrane have an average diameter of 1-1000 μm (e.g., 1-10 μm, 10-20 μm, 20-100 μm, 100-200 μm, 200-300 μm, 300-400 μm, 400-500 μm, 500-600 μm, 600-700 μm, 700-800 μm, 800-900 μm, 900-1000 μm). In some embodiments, the pore size / morphology can be examined using a scanning electron microscope (SEM).

[0133] Suction The present disclosure provides membranes comprising cellulosic materials that exhibit a variety of improved properties, including improved wicking capabilities, which can generally be understood as the ability of a liquid (e.g., a liquid sample containing an analyte) to be drawn through a material by capillary action.

[0134] Wicking can be measured, for example, by wicking distance versus time. In some embodiments, testing of wicking capacity includes a vertical wicking test, a lateral wicking test, or a bidirectional wicking test (measures the progression of a solvent, e.g., water, through a membrane by capillary action). In some embodiments, wicking is assisted using a vacuum. In some embodiments, a bidirectional wicking test includes the assistance of a vacuum to test wicking capacity in one or more directions.

[0135] In some embodiments, the rate is measured visually by observing the progress of the solvent front of the liquid moving through the membrane, hi some embodiments, a visual indicator may appear when the liquid reaches a particular point on the membrane.

[0136] In some embodiments, the visual indicator can be, for example, a colorimetric label (eg, dyes, colloidal gold, etc.), a fluorescent agent, a chemiluminescent agent (eg, acridinium esters, stabilized dioxetanes, etc.), and a bioluminescent agent.

[0137] In some embodiments, the membrane is characterized by having the ability to wick liquid through the membrane at a rate of at least 0.1 mm / s, hi some embodiments, the membrane is capable of wicking liquid through the membrane at a rate of at least 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, or 20 mm / s or more.

[0138] In some embodiments, the improved wicking ability is an increase in wicking rate (e.g., vertical wicking test). In some embodiments, the increase in wicking rate is at least 0.1 mm / s increase compared to a membrane without CNF. In some embodiments, the increase in wicking rate is at least 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, or 20 mm / s increase, or more.

[0139] In some embodiments, the wicking capacity of the membrane is improved relative to membranes that do not include one or more of CNF, pulp, and wet minerals. In some embodiments, the wicking capacity of membranes that include additives is improved relative to membranes that do not include additives.

[0140] Analyte immobilization In some embodiments, one or more analytes in a liquid sample can be immobilized (ie, detected) on the membrane.

[0141] In some embodiments, the immobilization of the analyte is based on an interaction between the analyte in the fluid and a detection agent. In some embodiments, the sensing agent comprises a detectable entity. In some embodiments, the sensing agent is a chemically reactive species such as an enzyme, an antigen, or an antibody.

[0142] Examples of enzymes include, for example, horseradish peroxidase (HRP), alkaline phosphatase, catalase, urease, and glucose oxidase.

[0143] Exemplary detectable entities include various ligands, radionuclides (e.g., 3 H, 14 C. 18 F, 19 F, 32 P, 35 S, 135 I, 125 I, 123 I, 64 Cu, 187 Re, 111 In, 90 Y, 99m Tc, 177 Lu, 89 Zr, etc.), fluorescent dyes, chemiluminescent agents (e.g., acridinium esters, stabilized dioxetanes, etc.), bioluminescent agents, spectrally resolvable inorganic fluorescent semiconductor nanocrystals (i.e., quantum dots), metal nanoparticles (e.g., gold, silver, copper, platinum, etc.) nanoclusters, paramagnetic metal ions, enzymes (see below for specific examples of enzymes), colorimetric labels (e.g., dyes, colloidal gold, etc.), biotin, dioxygenin, haptens, and proteins for which antisera or monoclonal antibodies are available. Methods for measuring detectable substances include, but are not limited to, visible detection, fluorescence, chemiluminescence, radioactivity, colorimetry, gravimetry, X-ray diffraction, X-ray absorption, magnetism, and enzyme activity.

[0144] Analyte types include, for example, pathogens, enzymes, immune mediators, nucleic acids, proteins, glycoproteins, lipopolysaccharides, protein adducts, tumor and cardiac markers, and / or low molecular weight compounds, including, but not limited to, haptens, viruses or microorganisms such as bacteria, fungi (e.g., yeast or mold) or parasites (e.g., amoebas or nematodes), immune mediators such as antibodies, growth factors, complement, cytokines, lymphokines, chemokines, interferons and interferon derivatives, C-reactive protein, calcitonin, amyloid, adhesion molecules, antibodies, and chemoattractant components, drug molecules such as heroin or methamphetamine, and allergens.

[0145] In some embodiments, the fluid containing the analyte is a biological sample, hi some embodiments, the biological sample is whole blood, serum, plasma, mucosal fluid (from the oral, nasal, vaginal, anal, inner ear, and ocular cavities), cerebrospinal fluid (CSF), tears, penile fluid, secretions or exudates from glands, or secretions or exudates from lesions or blisters, such as lesions or blisters on the skin.

[0146] In some embodiments, the analyte is immobilized on the membrane in the form of aqueous droplets. In some embodiments, the aqueous droplets can be stored at ambient and elevated temperatures (30-70 °C) for applications such as ELISA tests based on enzyme-antigen-antibody interactions. o C) and dried on the membrane.

[0147] In some embodiments, the analyte is glucose and the membrane is used to detect the presence / level of glucose in a biological sample.

[0148] In some embodiments, the membrane is used as a substrate in a lateral flow device / assay, hi some embodiments, the membrane is used as a substrate in a diagnostic instrument.

[0149] In some embodiments, the membrane is used on a universal horizontal wicking substrate (e.g., a substrate that is compatible with multiple types of testing). In some embodiments, the membrane is used on a universal horizontal wicking substrate.

[0150] In some embodiments, the membrane is used in an automated sampling device (e.g., an environmental test strip). The automated sampling device may be any type of sampling device that does not require an external power source, such as vacuum, electricity, or heat. In some embodiments, the membrane is used in a device for concentrating biological or environmental samples.

[0151] In some embodiments, the provided membranes may be useful for filtering / separating one or more contaminants from a solution (e.g., an aqueous solution). In some embodiments, the membrane has a contaminant removal capacity measured in milligrams of contaminant per gram of membrane. In some embodiments, the contaminant is or includes a physical, chemical, biological, or radiological contaminant.

[0152] Examples of physical contaminants include, for example, sediment or organic material as a result of soil erosion. Examples of chemical contaminants include, for example, nitrogen, bleach, salt, pesticides, metals, toxins produced by bacteria, and human or animal drugs. Examples of biological contaminants include, for example, bacteria, viruses, protozoa, and parasites. Examples of radiological contaminants include, for example, cesium, plutonium, and uranium.

[0153] In some embodiments, the membranes are used in water quality testing, for example testing one or more properties of a water sample, such as pH, alkalinity, chlorine content, and heavy metal ion content.

[0154] The present disclosure provides membranes comprising cellulose materials that exhibit various improved properties, including one or more mechanical properties. In some embodiments, the mechanical properties include flexural strength. In some embodiments, the mechanical properties include compressive modulus. In some embodiments, the mechanical properties include tensile strength. EXAMPLES

[0155] The following examples disclose exemplary cellulose membranes made from wood pulp, cellulose microfibers and / or nanofibers, and various additives, as well as methods for making and testing the cellulose membranes. The following examples are provided to illustrate to one of ordinary skill in the art how to make and use the membranes described herein, and are not intended to limit the scope of the disclosure.

[0156] Example 1 In this example, membranes containing one or more cellulose materials (wood pulp and CNF) and wetting agents were prepared and tested for various physical and mechanical properties. The membranes described in this example were formed by (i) combining a cellulose component and a wetting agent with a liquid component to produce a cellulose slurry; (ii) mixing the components of the cellulose slurry; and (iii) exposing the cellulose slurry to drying conditions. Among the properties tested, vertical and horizontal wicking tests were performed on the resulting membranes. The membranes of this example were shown to have excellent wicking and mechanical properties.

[0157] material

[0158] The cellulosic materials used in this example include nanofibrillated cellulose (CNF) (soft and hardwood) and chemically bleached wood pulp (soft and hardwood).

[0159] CaCO3 (ground CaCO3 (GCC) and precipitated CaCO3 (PCC)) was used as wetting agents.

[0160] Preparation of cellulose slurry

[0161] Suspensions of 0.1-5 wt% of chemically bleached wood pulp (soft and hardwood) were prepared by soaking the dry pulp in DI water for 24 h followed by mechanical mixing for 30 min.

[0162] In the separation system, a 0.01-3 wt% aqueous CNF suspension was mixed using mechanical mixing with wet mineral to give a CNF / wet mineral mass ratio of 1:1. The pulp and CNF / wet mineral suspensions were mixed using the mixing techniques described above to give pulp:CNF ratios of 1:0.05, CNF / mineral ratios of 1:1, and pulp:wet mineral ratios of 1:0.01-0.3, respectively. The total solids content of the suspensions was in the range of 0.5-1 wt% prior to the dewatering step.

[0163] Dehydration and drying

[0164] The aqueous suspension of pulp, CNF and wet minerals was then dewatered using gravity and vacuum filtration to produce hydrogels with approximately 5-40% solids content, which were then transferred to a drying unit for complete dewatering using an electric oven at 105 °C.

[0165] The membranes are tested for various properties including porosity, wicking capacity / analyte immobilization, and other physical properties including wettability mineral retention and tensile strength. Pulp, CNF, pulp + CNF, and CNF + CaCO3 membranes were similarly prepared as controls.

[0166] To prepare CNF-only membranes, the CNF suspension was dehydrated using the freeze-drying method, since ambient or oven drying would lead to the formation of dense CNF membranes that could not be used for filtration purposes.

[0167] Porosity and pore morphology

[0168] The porosity of the membranes was calculated from the bulk and absolute density of the membranes. Scanning electron microscopy (SEM) was used to investigate the pore morphology. The porosity and pore size distribution were examined via mercury porosimetry, BET and BJH analysis.

[0169] The dehydrated and fully dried membranes exhibited porosities ranging from 60 to 95%. The porous structure of the membranes is highly dependent on the CNF content. Membranes with low CNF content (approximately 0.1-2%) exhibit a lamellar type porous structure (see Figure 1a), whereas membranes with relatively high CNF content (approximately 10-20%) exhibit a web-like pore morphology (see Figure 1b). For comparison, freeze-dried CNF-only membranes were prepared. These membranes exhibited a web-like interconnected pore morphology (Figure 1c).

[0170] Wicking test

[0171] The wicking capacity of the membrane was compared with other materials including CNF only membrane, pulp only membrane, pulp + CNF membrane, and CaCO3 membrane.

[0172] Vertical and lateral wicking tests were performed on the membranes using aqueous solutions with pH ranging from 4 to 10. One end of the membrane cut to a length of 50 mm was placed in a DI water bath (25 °C) while the other end of the sample was fixed to the sample holder. o C) and a vertical wicking test was performed. The membrane was graduated every 5 mm to allow visualization of the solvent front and quantification of the rate of solvent advance.

[0173] To test the unidirectional horizontal wicking properties of the membrane, water was introduced to the top of the membrane and the progress of the solvent front over time was recorded and used to calculate the wicking rate.

[0174] For bidirectional wicking measurements, water was introduced to the top of the membrane and the progress of the solvent front was recorded. Once the solvent front had traveled a certain distance in one direction, additional solvent (water) was introduced from the other end of the membrane. A vacuum / absorbent pad was also applied to the initial starting point of the membrane to encourage the backflow of water. The progress of the solvent front was recorded to calculate the backflow wicking rate. A water-soluble dye was used to track the progress of the backflow.

[0175] The vertical wicking velocity of the freeze-dried CNF membrane was very low (approximately 0.05 mm / s), as shown in Figure 2. The addition of 50% (w / w) wet minerals (CNF+CaCO3 membrane) slightly improved the wicking performance (0.08 mm / s).

[0176] In contrast, when wood pulp was used as the main matrix component, a highly porous structure was obtained regardless of the drying method. These materials showed three times higher wicking rates compared to CNF membranes. When CNFs were incorporated into these pulp membranes, the wicking rates began to show a decreasing trend because the CNFs induce a web-like interconnected porous network instead of a lamellar pore morphology. Without wishing to be bound by theory, the decrease in wicking rate with the addition of CNFs may be due to a decrease in the total internal pore volume in the membrane.

[0177] Surprisingly, the addition of wet minerals to the pulp membrane did not improve the wicking performance of the membrane. A possible reason for this phenomenon could be the lack of retention of wet minerals in the membrane during the dewatering step in the membrane manufacturing process. In contrast, CNF showed high retention of CaCO3 during the dewatering process, possibly due to the high surface area and wettability of the CNF material. High retention was observed during the wicking test. Further analysis using an ash test will determine the amount of wet minerals retained in the membrane.

[0178] When CNF and CaCO3 are incorporated into the pulp suspension (obtained above "Pulp + CNF + CaCO3" as shown in Figure 2), a high retention of wet minerals is observed, which is confirmed by ash tests. The wicking rate of the membrane (pulp + CNF + CaCO3) is surprisingly increased (20 times greater compared to the membrane with only CNF and 7 times greater than the membrane with only pulp). This phenomenon suggests that CNF acts as a binding and immobilizing / dispersing / stabilizing agent for wet minerals in the pulp suspension.

[0179] The addition of significant amounts of wet minerals requires a large amount of CNF in the membrane matrix. However, maximum wicking rates were shown when CNF was present in the membrane in the range of 1-2 wt% (dry basis). Below this range, there is no significant effect on the wicking rate of pulp+CNF+CaCO3 membranes due to low wet mineral retention. Above this range of CNF fractions, the wicking rate decreases dramatically due to enhanced web-like pore network and reduced total porosity. Thus, 1-2 wt% (dry mass basis) is the optimal range of CNF fraction in these pulp membrane matrices for excellent wicking rates. When 1-2 wt% CNF was used, the maximum fraction of CaCO3 retained in the matrix was about 10-20 wt% (see Figure 3).

[0180] Analyte immobilization

[0181] The enzyme (sensing agent) was immobilized (in the form of aqueous droplets) on the CNF+pulp+CaCO3 film, followed by drying at ambient and elevated temperatures (30–70 o C).

[0182] A solution containing an antibody (analyte) and an indicator (3,3',5,5'-tetramethylbenzidine (TMB)) was tested by unidirectional flow over a membrane containing a sensing agent (HRP enzyme) and the antigen recognized by the antibody (see setup in Figure 4). The sensing procedure using a CNF+pulp+CaCO3 membrane to sense a specific analyte (antibody) was completed in approximately 3 minutes (i.e., from the time the analyte-containing solution was applied to the membrane to the time the indicator was observed). In a bidirectional procedure, the sensing step took approximately 7 minutes to complete.

[0183] Tensile Strength Test

[0184] In addition to improved wicking properties, the addition of CNFs to wood pulp membranes improved the tensile strength of the membranes. This was demonstrated when wet membranes were transferred from the dewatering unit (capillary dewatering) to the drying unit without any visible damage (breaking or shattering). For membranes without CNFs, cracks and tears were observed when the membranes were transferred from the dewatering unit to the drying unit.

[0185] Dynamic mechanical analysis (DMA) is performed on the dry membranes for tensile strength testing.

[0186] Wet Mineral Retention Ash Test

[0187] Ash tests and atomic absorption spectroscopy are performed to calculate the residual minerals in the membrane.

[0188] Leaching tests are also performed to test the loss of minerals under wet conditions.

[0189] Equivalent It should be understood that various changes, modifications, and improvements to the present disclosure will be readily apparent to those skilled in the art. Such changes, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the present invention. Accordingly, the foregoing description and drawings are by way of example only, and any inventions described in this disclosure are further described in detail by the following claims.

[0190] One of ordinary skill in the art will understand the typical standards of deviation or error attributable to values ​​obtained in the assays or other processes described herein. Publications, websites, and other reference materials referred to herein to describe the background of the invention and to provide additional details regarding its practice are hereby incorporated by reference in their entirety.

Claims

1. 1. A membrane comprising a porous matrix material, the porous matrix material comprising: (i) wood pulp; (ii) cellulose nanofibrils (CNFs); and (iii) one or more wet minerals.

2. The one or more wet minerals are calcium carbonate (CaCO ３ ), TiO2, alumina, fiberglass, or a combination thereof.

3. 10. The membrane of claim 1, wherein the CNFs are present at a concentration in the range of 0.1 to 1.5 wt % on a dry weight basis.

4. 10. The membrane of claim 1, wherein the one or more wetting minerals are present at a concentration in the range of 0.1 to 20% by weight of the porous matrix material.

5. 2. The membrane of claim 1, wherein the CNF comprises CNF obtained by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation.

6. 10. The membrane of claim 1, wherein when contacted with a fluid containing an analyte, the analyte solution migrates across the membrane by capillary action.

7. The membrane of claim 6 , wherein the analyte is immobilized on specific sites on the membrane.

8. 7. The membrane of claim 6, wherein the analyte migrates across the membrane at a velocity greater than about 0.5 mm per second.

9. The membrane of any one of claims 6 to 8, wherein the analyte is or comprises a biological material.

10. The membrane of any one of claims 1 to 8, wherein the porous matrix material is substantially homogeneous.

11. The membrane of any one of claims 1 to 8, wherein the porous matrix material comprises a porosity of at least 60-90%.

12. The membrane of any one of claims 1 to 8, wherein the porous matrix material comprises one or more additives.

13. 13. The membrane of claim 12, wherein the one or more additives comprise a foaming agent, a blowing agent, a templating agent, a plasticizer, or a combination thereof.

14. 13. The membrane of claim 12, wherein the one or more additives are present at a concentration in the range of 0.1 to 10 wt % on a dry weight basis.

15. The membrane of claim 13 , wherein the foaming agent comprises a surfactant.

16. 16. The membrane of claim 15, wherein the surfactant comprises a glucoside and / or myristic acid.

17. 16. The membrane of claim 15, wherein the surfactant comprises a biosurfactant such as a fungus, a bacteria, a yeast, a glycolipid, a phospholipid, a glycopeptide, a saponin, a fatty acid, a protein, a polysaccharide, or a combination thereof.

18. 14. The membrane of claim 13, wherein the effervescent agent comprises sodium bicarbonate.

19. The membrane of claim 13 , wherein the templating agent comprises salt, ice, dry ice, or a combination thereof.

20. 14. The membrane of claim 13, wherein the plasticizer comprises an acetylated monoglyceride, an alkyl citrate, an epoxidized soybean oil, a protein, a polyethylene glycol, a fatty acid, or a combination thereof.

21. (i) providing a slurry comprising wood pulp and water; (ii) mixing cellulose nanofibrils (CNF) and one or more wet minerals into the slurry; (iii) drying the slurry to form a porous matrix material.

22. The one or more wet minerals are calcium carbonate (CaCO ３ ), TiO2, alumina, fiberglass, or a combination thereof.

23. 22. The method of claim 21, wherein drying the slurry comprises capillary dehydration, infrared drying, freeze drying, and / or microwave irradiation.

24. 22. The method of claim 21, wherein the concentration of CNFs is 0.1 to 1.5 wt% of the porous matrix material.

25. 25. The method of any one of claims 21 to 24, wherein the one or more wet minerals are present at a concentration in the range of 0.1 to 20% by weight of the porous matrix material.

26. 1. A method for separating an analyte from a fluid, comprising: (i) providing a membrane comprising a porous matrix material; (ii) contacting the membrane with a fluid containing an analyte, wherein the fluid enters the membrane by capillary action, thereby separating the analytes; wherein the porous matrix material is a composite material comprising wood pulp, CNF, and one or more wet minerals.

27. The one or more wet minerals are calcium carbonate (CaCO ３ ), TiO2, alumina, fiberglass, or a combination thereof.

28. 27. The method of claim 26, wherein the contacting step is or includes contacting the membrane with a fluid contained in an adjacent space or material.

29. 27. The method of claim 26, wherein the fluid moves across the membrane.

30. 30. The method of claim 29, wherein the fluid passively moves across the membrane.

31. 30. The method of claim 29, wherein the fluid is moved across the membrane using a vacuum or a positive pressure on the fluid.

32. The method of any one of claims 26 to 31, wherein the analyte is immobilized on the membrane.

33. 33. The method of claim 32, wherein the immobilized analyte is or comprises a biological material.

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