▎ 摘　　要

Electrochemistry offers sensitivity, selectivity and low cost for fabrication of sensors capable of detection of selected DNA targets or mutated genes associated with human disease. In this work, we have developed a novel label-free, indicator-free strategy of electrochemical DNA sensor based on Fe3O4 nanoparticles/reduced graphene oxide (Fe3O4/r-GO) nanocomposite modified electrode. By using Fe3O4/r-GO nanocomposite as a substrate to immobilize probe DNA and subsequent hybridization with target sequence to form dsDNA, a great signal amplification was achieved through measuring changes in DPV peak current of underlying Fe(II)/Fe(III) redox system. With the remarkable attomolar sensitivity and high specificity and at the same time, great simplicity, the proposed strategy may find great applications in different DNA assay fields.