Target-switchable DNA hydrogels coupled with a Bi2Sn2O7/Bi2S3 heterojunction based on in situ anion exchange for the “signal-on” photoelectrochemical detection of DNA

Abstract

In this paper, a novel photoelectrochemical (PEC) “signal-on” biosensor based on a Bi₂Sn₂O₇/Bi₂S₃ heterojunctioncoupled with target-switchable DNA hydrogels is reported for the ultrasensitive detection of P53 gene DNA. For the first time, sulfide ions are discovered to display an excellent PEC sensitization effect on Bi₂Sn₂O₇ material by forming the Bi₂Sn₂O₇/Bi₂S₃ heterojunction. The sensitization amplitude increased by 63 times, and the photocurrent polarity switched from cathodic to anodic. When the target DNA-induced-cycling amplification process produced a mass of product chains (PD), PD was introduced into the target-switchable DNA hydrogels to quantitatively release sulfide ions, which were further introduced to the Bi₂Sn₂O₇-modified PEC platform and resulted in an enormous enhancement of the PEC signal due to the significant sensitization effect of sulfide ions on Bi₂Sn₂O₇via an anion-exchange reaction. The corresponding PEC signal change of the Bi₂Sn₂O₇/Bi₂S₃ platform was used for the detection of target DNA. This biosensing strategy opens up a novel sulfide ion-sensitized PEC platform and exhibits excellent analytical performance with a wide linear range (100 fM–10 nM), which has broad application prospects in bioanalysis and clinical diagnosis.