Flow-through sampling for electrophoresis-based microchips and their applications for protein analysis

Area of Science:

• Biotechnology
• Analytical Chemistry
• Microfluidics

Background:

• Microfluidic devices offer precise control over biological samples.
• Electrophoresis and hydrodynamic flow are key techniques in microchip-based separations.
• Integrated sample preparation and analysis enhance efficiency in biomolecular studies.

Purpose of the Study:

• To develop and model a flow-through sampling microchip for immunoseparation and protein analysis.
• To integrate on-chip wash/elution capabilities for protein purification and concentration.
• To demonstrate the device's application in studying affinity interactions and quantitative detection.

Main Methods:

• Utilized hydrodynamic pressure for sample flow and gating voltage for controlled sample loading.
• Developed a model to predict critical gating voltage based on flow rate, microchannel configuration, and electroosmosis.
• Integrated a C18 microcartridge for on-line wash/elution with electrophoretic separation and detection.

Main Results:

• The microchip demonstrated precise sample control, free of injection bias due to varying sample properties.
• Successfully estimated the binding constant of bovine serum albumin (BSA) and anti-BSA to be 3.3 x 10(7) M(-1).
• Achieved high linearity (R2 > 0.99) and low limit of quantitation (~10 ng) for Cy5-BSA detection in the integrated system.

Conclusions:

• The developed microchip provides a robust platform for immunoseparation, protein purification, and affinity analysis.
• On-chip integration of sample preparation steps enhances analytical throughput and sensitivity.
• The model accurately predicts critical operating parameters, facilitating device optimization and application.