Cyanazine herbicide monitoring as a hazardous substance by a DNA nanostructure biosensor

Cyanazine is a beneficial herbicide in the triazines group that inhibits photosynthesis in plants and monitoring of this herbicide is so important for study agriculture products. The present researches have been focused on monitoring of cyanazine by a straightforward and fast electrochemical strategy. Herein, to monitor the cyanazine level, Pt and Pd doped CdO nanoparticle decorated SWCNTs composite (Pt-Pd-CdO/SWCNTs) has been synthesized as a conductive mediator and characterized by EDS, SEM and TEM techniques. The Pt-Pd-CdO/SWCNTs and ds-DNA have been used for modification of the gold electrode (GE). Moreover, the oxidation signal of guanine relative to ds-DNA at the surface of Pt-Pd-CdO/SWCNTs/ds-DNA/GE has been considered as an bioelectroanalytical issue to monitoring cyanazine for the first time. Electrochemical impedance spectroscopic (EIS) signals have confirmed that the inclusion of Pt-Pd-CdO/SWCNTs at the surface of the GE has lowered charge-transfer resistance by ca.1.54 times and created a highly conductive state for monitoring of cyanazine in nanomolar concentration. On the other hand, differential pulse voltammograms (DPV) of Pt-Pd-CdO/SWCNTs/ds-DNA/GE have indicated a linear dynamic range of 4.0 nM-70 µM with a detection limit of 0.8 nM to the monitoring of cyanazine. In addition, the molecular docking study has emphasized that cyanazine herbicide is capable of binding to ds-DNA preferably at the guanine-cytosine rich sequences, and confirmed experimental results. In the final step, Pt-Pd-CdO/SWCNTs/ds-DNA/GE has been successfully utilized for the monitoring of cyanazine herbicide in food and water samples.