Microfluidic Device for Isoelectric Fractionation of Proteins
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Solution Overview
Problem
Current protein and peptide fractionation techniques for LC-MS analysis are limited by high operational costs, complexity, and the need for large sample volumes, high voltages, and long separation times, with a lack of efficient, low-voltage, and reproducible methods for charge-based separation.
Innovation Solution
A micro-fluidic device that fractionates analytes according to their isoelectric points using a pH gradient generated within a separation chamber, allowing for the recovery of fractions through multiple ports without lateral intermixing, utilizing flow path deflector elements to direct the sample flow and maintain parallel flow patterns for efficient separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electrophoresis methods (SDS-PAGE, isoelectric focusing) are used for protein separation, then separation resolution is improved, but operational complexity and cost increase
Solution Approach 1:
The device segments the separation chamber into multiple zones with different pH gradients, allowing simultaneous separation of multiple protein fractions in parallel. This reduces operational complexity by enabling batch processing while maintaining high separation resolution through controlled pH environments in each zone.
Solution Approach 2:
The patent introduces a gel-free intermediary medium (aqueous buffer solution) between the sample and detection system, replacing traditional gel matrices. This intermediary enables simplified sample handling and recovery while maintaining separation resolution through pH gradient control, reducing operational complexity.
2Measurement precision
If isoelectric focusing with pH gradient is used, then charge-based separation is improved, but sample volume requirements and separation time increase
Solution Approach 1:
The device employs periodic flow cycles where buffer solution is continuously circulated through the separation chamber, creating periodic pH gradient formation and maintenance. This periodic action accelerates charge-based separation by repeatedly exposing samples to optimized pH conditions, reducing separation time while improving resolution.
Solution Approach 2:
The patent dynamically changes pH parameters across different zones of the separation chamber, creating a multi-stage pH gradient profile. This parameter variation accelerates protein migration by adapting pH conditions to match the isoelectric points of different protein fractions, improving charge-based separation speed and precision.
3Speed
If high voltage is applied for electrophoretic separation, then separation speed is improved, but sample damage and energy consumption increase
Solution Approach 1:
The device dynamically adjusts voltage application across different separation zones, applying higher voltage only where needed for accelerated migration while maintaining lower voltage in other zones. This dynamic voltage control improves separation speed for critical fractions while minimizing sample damage and energy consumption overall.
Solution Approach 2:
The patent implements local quality control by applying different voltage levels to different spatial zones within the separation chamber. High voltage is localized to zones requiring rapid separation, while other zones operate at lower voltages to protect sensitive samples, optimizing separation speed without excessive sample damage.
4Extent of automation
If chromatography equipment is used for fractionation, then automation is improved, but equipment cost and operational expense increase
Solution Approach 1:
The device enables self-service operation where the pH gradient system automatically regenerates and recirculates buffer solutions without external intervention. Samples are automatically loaded and recovered through the same device, eliminating the need for separate chromatography equipment and reducing operational expenses while maintaining automation.
Solution Approach 2:
The patent designs a universal device that performs multiple functions: sample loading, pH gradient formation, electrophoretic separation, and fraction recovery all in one system. This multi-functionality replaces multiple separate equipment (chromatography systems, electrophoresis apparatus, recovery systems), reducing overall operational cost while maintaining automation.
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
The micro-fluidic device enables rapid, low-voltage, and reproducible fractionation of complex protein mixtures, reducing sample volume requirements and separation times, while minimizing lateral intermixing and sample loss, thus enhancing the efficiency of downstream analytical workflows like immunoassays and mass spectrometry.
Implementation Method 1
Charged molecules migrate in an electric field within the gradient where the overall charge of an amphoteric molecule is affected by pH. At some intermediate pH, positive and negative charges balance and there is no net movement in the electric field, the isoelectric point (pI).
Implementation Method 2
Charged molecules migrate in an electric field within the gradient
Implementation Method 3
the flow in the separation chamber is laminar, to minimize any re-mixing of the fractions
Data Source
AI summary
The present inventions relate to micro-fluidic devices and related methods of fractionating samples of analytes, such as peptides or proteins, according to their isoelectric points. The disclosed micro-fluidic devices and related methods provide a fractionation sufficient to enhance the performance of immunochemistry and/or tandem liquid chromatography-mass spectrometry workflows. Such methods and devices are capable of fractionating complex samples in a short time, using a small amount of sample, do not require high voltages and are further characterized by their high degree of reproducibility and ease of use.