Electrophoretic separations in poly(dimethylsiloxane) microchips using mixtures of ionic, nonionic and zwitterionic...

Area of Science:

• Analytical Chemistry
• Microfluidics
• Biotechnology

Background:

• Electrophoresis on polydimethylsiloxane (PDMS) substrates is crucial for microchip separations.
• Controlling electroosmotic flow (EOF) and selectivity is key for efficient separations.
• Capacitively coupled contactless conductivity detection (C4D) offers sensitive detection in microfluidic devices.

Purpose of the Study:

• To investigate the effect of mixed surfactant systems on EOF and separation selectivity in electrophoresis.
• To introduce C4D for EOF measurement on PDMS microchips.
• To demonstrate the application of optimized surfactant systems for analyzing biological samples.

Main Methods:

• Measurement of EOF using various nonionic, ionic/nonionic, and zwitterionic/nonionic surfactant mixtures.
• Separation of model catecholamines using optimized surfactant systems.
• Detection of catecholamine release from PC12 cells.

Main Results:

• Nonionic surfactant concentration inversely affected EOF; addition of SDS or TDAPS increased EOF.
• Mixed surfactant systems (Tween 20/TDAPS) improved analyte resolution and peak heights compared to single surfactants.
• Successful detection of catecholamines released from PC12 cells using the developed method.

Conclusions:

• Mixed surfactant systems significantly enhance EOF and separation selectivity in PDMS-based electrophoresis.
• The developed method using C4D and mixed surfactants is effective for analyzing complex biological samples.
• This approach provides a valuable tool for sensitive detection of biologically relevant molecules.