Zwitterionic Phenyl Phosphorylcholine on Indium Tin Oxide: a Low-Impedance Protein-Resistant Platform for Biosensing

In this study we have modified indium tin oxide (ITO) by electrografting phenylphosphorylcholine (PPC) and evaluated its protein-resistance performance using electrochemical impedance spectroscopy. During electrografting, significant amounts of PPC gets physically adsorbed on the surface, which cannot be removed by simply rinsing with water or buffer, and as a consequence the electrochemical response of such electrode is quite unstable. We have developed a simple protocol to remove the physically adsorbed PPC such that a stable interface is produced. It was found that such a stable surface, with appropriate amount of PPC, can dramatically reduce nonspecific adsorption of protein, giving us a platform of performing both electrochemical and spectroscopic studies in biological fluids.