An Electrochemical DNA Biosensor Based on Au-reduced Graphene Oxide Nanocomposite for Transgenic Event Bt63 Detection

A simple and reliable electrochemical biosensor based on an in situ synthetic Au-reduced graphene oxide (Au-RGO) nanocomposite was constructed in this work, which is considered to be a potential sensing platform for sensitive and selective Bt63 rice detection. UV-vis spectroscopy, transmission electron microscopy (TEM), and cyclic voltammograms of the surface characterization indicated that RGO was prepared successfully and Au nanoparticles were well dispersed on its surface with an average size of 20 nm. The square-wave voltammetry (SWV) response of the electrochemical marker methylene blue (MB) was chosen to monitor the probe immobilization and target hybridization event. Under the optimum conditions, the peak values of MB were linear with the logarithm of the target DNA concentrations being from 1.0 × 10^-9 to 1.0 × 10^-14 M; the detection limit was 3.36 × 10^-15 M. Studies also demonstrated that the DNA biosensor had high reproducibility and stability. At last, we used this biosensor to detect several rice samples; it showed good sensitivity and selectivity. Thus the applicability of the method as an effective tool for genetically modified organism (GMO) quantification was confirmed by its accurate and sensitive results in Bt63 rice screening.