Cross-linked coatings for electrophoretic separations in poly(dimethylsiloxane) microchannels

Area of Science:

• Analytical Chemistry
• Materials Science
• Biochemistry

Background:

• Poly(dimethylsiloxane) (PDMS) microdevices are widely used in microfluidics.
• Surface modification of PDMS is crucial for optimizing separation performance.
• Existing surface chemistries may not be optimal for all electrophoretic applications.

Purpose of the Study:

• To develop a versatile surface modification strategy for PDMS microdevices using UV-initiated polymerization.
• To optimize electrophoretic separations by tailoring surface properties with mixed monomer solutions.
• To evaluate the impact of different monomer combinations on separation efficiency and peptide analysis.

Main Methods:

• UV-initiated polymerization of mixed monomer solutions onto PDMS surfaces.
• Grafting surfaces with single neutral, neutral/negative, or neutral/negative/cross-linking monomers.
• Assessing surface properties and separation performance using model peptides and kinase/phosphatase substrates.
• Electrophoretic separation in modified PDMS microchannels.

Main Results:

• Cross-linked coatings achieved the highest quality electrophoretic separations.
• Separation efficiency reached up to 18,600 theoretical plates for peptides in a 2.5 cm channel.
• Rapid separations (as little as 400 ms) were achieved for test peptides.
• Simultaneous separation of five kinase and phosphatase substrates was demonstrated.

Conclusions:

• UV-initiated polymerization of mixed monomers offers a tunable approach for PDMS surface modification.
• Cross-linked coatings provide superior performance for electrophoretic separations.
• This strategy enables tailored PDMS surfaces for diverse electrophoretic applications, including peptide analysis.