Indicator-free electrochemical genosensing originated from the self-signal of poly-xanthurenic acid enhanced by Fe_3O_4/reduced graphene oxide

摘要

In this paper, an indicator-free electrochemical genosensing platform based on the self-signal changes of poly-xanthurenic acid (PXa) enhanced by Fe_3O_4/reduced graphene oxide (Fe_3O_4/RGO) was constructed. The resulting nanocomposite (PXa-Fe_3O_4/RGO) was characterized by transmission electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The π-π* stacking and hydrogen bonding between the conjugated Fe_3O_4/GO and aromatic ring of xanthurenic acid monomer promoted the electropolymerization efficiency accompanied with an increased electrochemical response of PXa. The immobilization of the specific probe DNA was successfully realized via the noncovalent method due to the π-π* interaction between the conjugated nanostructure of PXa-Fe_3O_4/ RGO and DNA bases. The hybridization between the probe DNA and target DNA induced the resulted double-stranded (ds)DNA to be released from the conjugated nanocomposite, accompanied with the self-signal regeneration of nanocomposite ("signal-on"). The self-signal changes could serve as a powerful tool for indicator-free and freely switchable detection of different target genes, and the synergistic effect of the integrated graphene-based nanocomposite effectively improved the sensitivity for the target DNA detection via EIS.