Polypyrrole nanowire modified with Gly-Gly-His tripeptide for electrochemical detection of copper ion.

We developed a novel biosensor comprising a transducer of carboxyl end-capped overoxidized polypyrrole nanowire electrode and a probe of tripeptide (Gly-Gly-His) selectively cognitive of Cu2+. The developed sensor was demonstrated to specifically detect Cu2+ in the nanomolar range. The diameter of the polypyrrole nanowires, prepared by one step template-free polymerization, was approximately 60-90 nm. For functionalization of the electrode, the carboxyl group was introduced by the addition of pyrrole-α-carboxylic acid which was covalently coupled with the amine group of the tripeptide. The structural features of the peptide functionalized nanowire electrode were confirmed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) spectroscopy. Using cyclic and square wave voltammetry, the nanowire biosensor proved to be highly sensitive to Cu2+ in the range of 20-300 nM.