Covalent Zwitterionic Peptide-Based Antifouling Coating of the Fused Silica Capillary Applied for CE Separation of Proteins.

Zwitterionic compounds exhibit strong hydrophilicity, act as hydrogen bond receptors and donors, and form robust hydration layers through ionic solvation, which effectively prevent unwanted protein adsorption. To reduce nonspecific interactions between analytes and the inner surface of the separation compartment and then improve detection sensitivity and separation efficiency, it is essential to modify fused silica capillaries with functional groups. In this study, we synthesized a zwitterionic antifouling peptide (Glu-Lys)3Glu using solid-phase peptide synthesis. Then, we bound the peptide to the inner surface of a fused silica capillary using diazo resin as a coupling agent, resulting in stable and excellent antifouling and separation abilities. To evaluate the properties of the coating, we conducted fluorescent protein adsorption and electrophoresis experiments. The obtained results demonstrated that the coating effectively prevented protein adsorption and made it possible to separate five standard proteins in 20 min. Moreover, three proteins of egg white were separated within 15 min. These findings confirmed the very good anti-protein adsorption performance of the peptide-coated capillary and its practical value for various applications.