Electrophoretic separations of proteins in capillaries with hydrolytically stable surface structures

Area of Science:

• Analytical Chemistry
• Separation Science
• Materials Science

Background:

• Capillary electrophoresis (CE) is a powerful separation technique.
• Uncoated fused silica capillaries suffer from protein adsorption and variable electroosmotic flow (EOF).
• Existing capillary coating methods have limitations in stability and pH range.

Purpose of the Study:

• To develop a highly stable polyacrylamide-coated capillary for capillary electrophoresis.
• To improve protein separation by minimizing adsorption and eliminating EOF.
• To evaluate the performance of the new coating across a wide pH range.

Main Methods:

• Surface-chlorinated fused silica capillaries were reacted with vinyl magnesium bromide.
• The resulting vinyl groups were reacted with acrylamide to immobilize polyacrylamide.
• The coated capillaries were tested for protein separation performance compared to uncoated capillaries.

Main Results:

• The polyacrylamide coating is stable over a pH range of 2-10.5.
• Protein adsorption to capillary walls was significantly reduced.
• Electroosmotic flow was virtually eliminated, improving migration time reproducibility.
• Peak skew was reduced for model proteins compared to uncoated capillaries.

Conclusions:

• The vinyl-bound polyacrylamide coating provides a stable and effective surface for capillary electrophoresis.
• This method offers improved protein separation efficiency and reproducibility.
• The coating is suitable for CE applications across a broad pH spectrum.