Fabrication of label-free electrochemical impedimetric DNA biosensor for detection of genetically modified soybean by recognizing CaMV 35S promoter

Abstract

We report a simple and label-free electrochemical impedimetric DNA biosensor for genetically modified (GM) soybean detection by recognizing the Cauliflower Mosaic Virus 35S (CaMV 35S). In the detection system, gold nanoparticles decorated multiwalled carbon nanotube-reduced graphene oxide nanoribbons were employed to anchor the probe single-stranded DNA. When the target DNA fixed on the modified electrode surface via hybridizing reaction, the impedimetric signal showed a growing tendency due to the formed double-stranded DNA restraining the electron transfer process. Under optimal conditions, the increased impedimetric signal of the proposed DNA biosensor was linear with the logarithm of the target DNA concentrations in the range of 1×10−16M–5×10−10M with a low detection limit of 3.3×10−17M. Moreover, the biosensor possessed excellent selectivity for discriminating complementary sequences from mismatched DNA as well as satisfactorily applied for practical detection of GM soybean samples.