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

A Comparison of Differently Synthesized Gold-coated Magnetic Nanoparticles as 'Dispersible Electrodes'

Gold-coated magnetic nanoparticles (Au@MNPs) have attracted significant interest in electrochemistry in recent years. This is especially the case with their application as dispersible electrodes where modified Au@MNPs are dispersed into a solution, selectively bind to the analyte of interest and are then brought to an electrode via application of a magnetic field for measurement. This paper characterizes four types of Au@MNPs with different sizes, shapes, and method of synthesis as dispersible electrodes. The Au@MNPs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy and scanning electron microscopy. In addition, the electrochemical behaviour of Au@MNPs was investigated using cyclic voltammetry. The four sorts of Au@MNPs were evaluated with regards to the three main features required in the dispersible electrodes approach, well-defined morphology, well-defined electrochemistry and fast response to a magnetic field. The Cubic-Au@MNPs, which presents the simplest synthetic route, showed the best electrochemical stability and performance, responding quickly to a magnet and had a well defined shape