Silver nanoparticles as redox reporters for the amplified electrochemical detection of the single base mismatches

In this manuscript, a strategy for the amplification of the responses of an electrochemical DNA hybridization biosensor using silver nanoparticles (Ag-NPs) as redox reporters and its capability for the detection of a single base mismatches (SBM) including thermodynamically stable ones, is described. In this assay, Ag-NPs are immobilized on the top of recognition layer and their oxidation signals are followed. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) are used to monitoring the electrode response. Only for complementary target sequence, electron can transfer between Electrode surface and nanoparticles via DNA and Ag-NPs can be oxidized. Therefore this DNA biosensor could differentiate between complementary target and one containing either SBM or thermodynamically stable G-A and G-T targets through oxidation signal of Ag-NPs. This biosensor is able to detect SBM by overcome the direct electron transfer of redox reporter with electrode surface and positioning of it before the mismatch position. (C) 2011 Elsevier B.V. All rights reserved.