Nanowires array modified electrode for enhanced electrochemical detection of nucleic acid

Abstract

The gold nanowires array electrode (AuNWsA) was synthesized by two step electrodeposition, which provided well oriented vertically aligned nanowires. The dimensions of the nanowires were determined by scanning electron micrograph and found to be around 1.5μm in length with 200nm diameter. Each nanowire was separated by a distance of 2–3 times the diameter of the nanowire itself. The electrochemical performance of the AuNWsA electrode was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Using these analytical tools, this AuNWsA electrode was shown to have a high effective surface area and excellent electron transfer surfaces compared with flat bare Au electrode. The AuNWsA electrode was then used as an electrochemical biosensor electrode by immobilizing probe DNA and analyzed by CV, EIS and Fourier transform infrared measurements. The results of this analysis suggested that the AuNWsA electrode provides good surfaces for the immobilization and hybridization of DNA. The selectivity of the probe DNA immobilized AuNWsA electrode was tested using non-complementary and one base pair mismatching DNA. The detection limit of the AuNWsA electrode was determined to be 6.78×10−9M, which is two times smaller than the bare Au electrode.