Electrochemical Fabrication Of Au, Pt/self-doped Polyaniline Nanohybrids And Their Applications In Electrochemical Sensors

Nanohybrids of metal micro or nanostructures and conducting polymers have attracted steadily growing attention due to their interesting electrochemical properties and good biocompatibility. The nanohybrids have potential applications in constructing electrochemical sensing and biosensing platforms.In this paper, two nanohybrids of Pt/nanoSPAN and Au/nanoSPAN were fabricated on the nanoSPAN-modified electrodes. Based on the two modified electrodes, a series of investigations were performed. The two parts of the work can be summarized as follows:(1) Pt/nanoSPAN nanohybrid has been synthesized successfully through a multi-potential step electrodeposition method. The morphologies and electrochemical properties of the constructed film were characterized by using scanning electron microscopy, cyclic voltammetry, amperometry and electrochemical impedance spectroscopy, respectively. Based on the Pt/nanoSPAN nanohybrid-modified electrode, an electrochemical sensing and biosensing platform was constructed, and three kinds of probe molecules (CH3OH, H2O2, and DNA) have been investigated on the nanohybrid-modified electrochemical interface with high sensitivity.(2) Four electrochemical methods, namely cyclic voltammetric deposition, potentiostatic electrodeposition, multi-potential step electrodeposition and three-step electrodeposition, were adopted to fabricate Au micro-nanostructures on self-doped polyaniline nanofibers-coated glassy carbon electrodes (Au/nanoSPAN/GCEs). The morphologies and electrochemical properties of the constructed films, the characteristics of the immobilization of DNA were studied by scanning electron microscopy , cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. Thereinto, the optimization method of the four electrodeposition methods was three-step electrodeposition method, which was investigated in detailed in the following segments. The effect of deposition conditions, such as HAuCl4 concentration and deposition steps, on the morphologies and electrochemical properties of the Au micro-nanosructures were studied thoroughly, and the nucleation and growing mechanism were also expounded. Using the Au/nanoSPAN-modified electrode as a biocompatible platform, a high performance DNA biosensor was constructed. The gene fragment related to one of the screening genes for the genetically modified plants, cauliflower mosaic virus 35 S gene, was satisfactorily detected.