Protein Detection via Filtered Nanopore Pulse Waveform Analysis
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Solution Overview
Problem
Conventional protein detection and quantification methods, such as ELISA and pore electrical resistance, struggle with noise signals from contaminants, leading to inefficiencies in sensitivity, cost, and time requirements, especially in clinical settings.
Innovation Solution
A method using antibody-modified or antigen-modified particles, filtered through a specific size-blocking filter, is applied in a sensor with two chambers connected by a pore, measuring ionic current changes to selectively detect and quantify proteins by analyzing pulse waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ELISA or chemiluminescence methods are used, then protein detection sensitivity is improved, but measurement procedure complexity and time requirements increase
Solution Approach 1:
The measurement procedure is segmented into distinct functional modules: sample preparation module, antibody-antigen binding module, and detection module. Each module performs a specific function independently, allowing parallel processing and reducing overall procedure complexity while maintaining sensitivity.
Solution Approach 2:
Sample preparation and antibody-antigen complex formation are performed before the actual measurement step. This preliminary action allows the system to pre-process samples and pre-form complexes, reducing the complexity and time of the measurement procedure itself while maintaining detection sensitivity.
2Measurement precision
If repeated washing steps are performed to remove noise, then detection specificity is improved, but inspection time increases
Solution Approach 1:
Noise sources are extracted and removed from the measurement system through selective filtering of the sample and use of specific antibodies that bind only to target antigens. This extraction approach eliminates the need for repeated washing steps while maintaining detection specificity.
Solution Approach 2:
Specific antibodies serve as intermediaries that selectively bind to target antigens, facilitating the separation of target signals from background noise. This intermediary approach enables specific detection without requiring extensive washing procedures.
3Ease of manufacture
If pore electrical resistance method is used, then equipment cost is reduced, but noise separation from target signals becomes difficult
Solution Approach 1:
Antibodies serve as intermediaries that specifically bind to target antigens, enabling the differentiation of target signals from background noise in the pore electrical resistance method. This intermediary approach maintains equipment simplicity while improving noise separation capability.
Solution Approach 2:
The measurement parameters are optimized by adjusting pore size, applied voltage, and antibody concentration to enhance the signal-to-noise ratio. These parameter changes enable effective noise separation using cost-effective equipment.
4Object-affected harmful factors
If filtration is performed to remove contaminants, then noise reduction is achieved, but target protein recovery may be lost
Solution Approach 1:
The filtration system uses locally optimized filter properties with specific pore sizes and charge characteristics that selectively retain contaminants while allowing target proteins to pass through. This local quality approach reduces noise while minimizing target protein loss.
Solution Approach 2:
Filtration parameters such as pore size, flow rate, and buffer composition are optimized to maximize target protein recovery while effectively removing contaminants. These parameter changes achieve noise reduction without significant loss of target proteins.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables highly sensitive, inexpensive, and rapid protein detection and quantification in biological samples with reduced noise interference, even in the presence of contaminants.
Implementation Method 1
filtering the biological sample through a filter having a blocking size m
Implementation Method 2
antibody-modified particles having a particle diameter d and an antibody that binds to the antigen attached to its surface
Implementation Method 3
measuring a transient change in the ionic current that occurs each time the antibody-modified particle or the antigen-modified particle passes through the pore as a pulse waveform
Implementation Method 4
the so-called pore electrical resistance method (Patent Literature 2) is used, in which nano-sized particles in an electrolyte are driven by electrophoresis
Data Source
AI summary
A method for estimating presence or absence or a concentration of an antigen or an antibody to be detected in a biological sample collected from a living body, including the steps of:filtering the biological sample through a filter having a blocking size m to prepare a filtered sample;preparing a measurement target sample by mixing:antibody-modified particles having a particle diameter d and an antibody that binds to the antigen attached to its surface, or antigen-modified particles having a particle diameter d and an antigen that binds to the antibody attached to its surface,the filtered sample, anda first electrolyte solution;to a sensor having a structure in which two chambers separated by a partition wall having a pore with a pore diameter D communicate with each other through the pore, and an electrode is provided in each of the two chambers, filling one of the two chambers of the sensor with the measurement target sample;filling the other of the two chambers of the sensor with a second electrolyte solution to electrically connect the two chambers through the pores;applying a voltage between two electrodes in each of the two chambers to allow an ionic current to flow between the two electrodes via the pore, and measuring a transient change in the ionic current that occurs each time the antibody-modified particle or the antigen-modified particle passes through the pore as a pulse waveform group consisting of a plurality of pulse waveforms; andestimating the presence or absence or the concentration of the antigen or the antibody to be detected in the biological sample by analyzing the pulse waveform group;wherein the blocking size m is equal to or more than a lower limit determined according to a size of the antigen or the antibody to be detected and is equal to or less than ½ of the pore diameter D, andwherein the diameter d of the antibody-modified particle or the antigen-modified particle is ⅕ or more of the pore diameter D and less than the pore diameter D.