Functionalized GaN nanowire-based electrode for direct label-free voltammetric detection of DNA hybridization

Abstract

This study demonstrates the utility of functionalized GaN nanowires (GaNNWs) for electrochemical detection of nucleic acids, in aqueous solution, using cyclic voltammetry. In order to link probe DNA to the NW surface, we employed an organosulfur compound, 3-mercaptopropyl trimethoxysilane (MPTS), to functionalize the GaNNW surface. Interestingly, the MPTS-modified GaNNWs exhibited a potential window of 4.5 V, the widest reported to date, with very low background current, which provides an advantage for sensing DNA immobilization/hybridization, down to sub-pM concentration, via monitoring adenine and guanine oxidation. The oxidation of guanine was characterized by its peak potential and peak current, where the former serves as a fingerprint for DNA hybridization and the latter as a parameter for the extent of hybridization. Moreover, the GaNNW-based sensor exhibited excellent consistency in hybridization-dehybridization-rehybridization cycles.