A label-free electrochemical impedimetric DNA biosensor for genetically modified soybean detection based on gold carbon dots

A label-free electrochemical impedimetric biosensor was constructed based on gold carbon dots (GCDs) modified screen-printed carbon electrode for the detection of genetic modified (GM) soybean. The structure and property of GCDs were investigated. The GCDs can directly bind to single-stranded DNA probes through Au-thiol interaction and boost electric conductivity for the DNA sensor construction. The quantification of target DNA was monitored by the change of electron-transfer resistance ( R et ) upon the DNA hybridization on sensor surface. Under the optimal conditions, the R et response (vs. Ag reference electrode) increased with the logarithm of target DNA concentrations in a wide linear range of 1.0 × 10 −7  − 1.0 × 10 −13  M with a detection limit of 3.1 × 10 −14  M ( S / N  = 3). It was also demonstrated that the proposed DNA sensor possessed high specificity for discriminating target DNA from mismatched sequences. Moreover, the developed biosensor was applied to detect SHZD32-1 in actual samples, and the results showed a good consistency with those obtained from the gel electrophoresis method. Compared with the previous reports for DNA detection, the label-free biosensor showed a comparatively simple platform due to elimination of complicated DNA labeling. Therefore, the proposed method showed great potential to be an alternative device for simple, sensitive, specific, and portable DNA sensor. Graphical abstract