Evaluation of zwitterionic silica monolayer as new coating for the separation of intact proteins by capillary electrophoresis

Overview & Synopsis

Coatings with zwitterionic compounds have been developed as antifouling surface to reduce or eliminate nonspecific adsorption to the solid/liquid interface. In this work, zwitterionic silica (SBSi) coating was modified on fused silica capillary for the first time by silanization (covalent bonding). The self-assembled SBSi coating was characterized using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle. A comparative study of electroosmotic flow (EOF) with bare fused silica capillary showed that the SBSi coating could provide effective suppression of EOF at pH 5.5. CE separations of three intact proteins (lysozyme, ribonuclease A, and myoglobin) were performed at pH 3.5 using different voltages ranging between 10 kV and 30 kV. Accordingly, the coating performances were assessed by plotting the plate height H versus the analyte velocity u, leading to similar performances as compared with polyelectrolyte multilayers (SMIL) coatings in similar conditions.