Sensitive detection of HIV gene by coupling exonuclease III-assisted target recycling and guanine nanowire amplification

In this work, a simple, label-free electrochemical biosensor was constructed with the combination of exonuclease III (Exo III)-assisted target recycling and guanine nanowire amplification for the detection of HIV gene. The presence of target DNA leads to target recycling process, which could obtain a digestion product named as help DNA with the assistance of Exo III. The released help DNA can hybridize with the G-quadruplex sequence-locked hairpin probe. Then, the active G-quadruplex sequence could form G-quadruplex structure in the presence of IC, which could trigger the formation of guanine nanowire with the help of Mg2+. The hemin/G-quadruplex repeat units could effectively catalyze the H2O2-mediated oxidation of 3,3',5,5'-tetramethyl benzidine dihydrochloride (TMB 2HCl) accompanied by a change in color of the reaction solution and an increased electrochemical current signal in the presence of hemin. The developed amplification strategy provides a sensitive and selective approach for the detection of target DNA with a detection limit of 3.6 pM. Furthermore, the proposed DNA sensor has a promising potential for biosensing in real settings. (C) 2016 Elsevier B.V. All rights reserved.