A simple preparation method for large-area, wavy graphene oxide nanowalls and their application to freely switchable impedimetric DNA detection

Abstract

In this paper, we report a simple and low-cost method to prepare large-area, wavy graphene oxide (GNO) nanowalls intercalated by sulfonated polyaniline (SPAN). Through ultrasonication of a mixed dispersion of graphite oxide (GO) and SPAN, the negatively charged SPAN continuously diffused and was adsorbed and intercalated into the simultaneously resulting GNO layers to form a homogenous and three-dimensional interconnected nanowall structure. This unique morphology has a large specific surface area and improves the electrochemical response of [Fe(CN)₆]^3−/4−, which has been widely adopted to monitor the immobilization and hybridization of DNA. The accessible space, large specific surface area and richly conjugated structures were beneficial to efficiently immobilize a probe DNA via π–π* interactions between the conjugated interface and the DNA bases, which also ensured a highly sensitive and freely switchable impedimetric DNA detection due to a hybridization that induces the dsDNA to be released from the conjugated surface.