Quantitatively\nElucidating the Trade-Off between Zwitterionic\nAntifouling Surfaces and Bioconjugation Performance

Zwitterionic materials, known for their high hydrophilicity,\nare\nwidely used to minimize the nonspecific adsorption of biomolecules\nin complex biological solutions. However, these materials can also\nreduce the capture efficiency between targets and peptide probes.\nTo demonstrate how antifouling surfaces affect capture efficiency,\nwe utilize a poly(3,4-ethylenedioxythiophene) (PEDOT)-based surface\nincorporating varying ratios of phosphorylcholine (PEDOT-PC) and maleimide\nfunctional groups to achieve both antifouling properties and peptide–protein\nbinding. As a model system, the peptide YWDKIKDFIGGSSSSC, attached\nvia maleimide groups, is used to capture the target protein, calmodulin\n(CaM). By systematically monitoring protein binding on both antifouling\nand peptide-immobilized PEDOT surfaces using a quartz crystal microbalance\nwith dissipation, the results reveal that PEDOT-PC reduces both the\nspecific binding between peptides and target proteins as well as the\nrate of protein fouling on the electrode surface. From these findings,\nwe propose an equation for quantitative analysis. Furthermore, electrochemical\nimpedance spectroscopy and differential pulse voltammetry are performed\nto measure the changes in the impedance in CaM solutions. The data\nindicate that impedance increases with protein adsorption, confirming\nthe practical utility of the designed electrode surface.