Electrochemical sensing the DNA damage in situ induced by a cathodic process based on Fe@Fe2O3 core–shell nanonecklace and Au nanoparticles mimicking metal toxicity pathways in vivo

Sensitive electrochemical sensing for the DNA damage in situ based on a cathodic process of Fe@Fe2O3 core–shell nanonecklace and Au nanoparticles was performed by a novel biosensor, which was constructed via a glassy carbon electrode (GCE) modified with a multilayer film comprising of separate layers of poly(dimethyldiallylammonium chloride) (PDDA), the mixture of Fe@Fe2O3 core–shell nanonecklace and Au nanoparticles, PDDA and double strand DNA (ds-DNA). Iron ions and H2O2 (Fenton reagents) were generated continuously at a constant rate by the cathodic process. The two Fenton reagents reacted further to generate hydroxyl radicals in situ, which attacked ds-DNA in the film and caused severe damage of ds-DNA molecules. These courses of DNA damage were just like those happened in organism. It could be used to mimic metal toxicity pathways in vivo. Fe@Fe2O3 core–shell nanonecklace and Au nanoparticles played considerable synergistic effects for DNA damage. Differential pulse voltammetry and cyclic voltammetry were applied to monitor the DNA damage. Different from the previously reported metal-mediated DNA damage sensor, the process of the ds-DNA damage was not achieved in the solution of metal ions and H2O2, but merely in buffer solution, and the instable enzymes were not used in the whole course. The biosensor possesses the potential as a screening tool for rapid assessment of the genotoxicity of existing and new chemicals.