Ultrasensitive photoelectrochemical sensor enabled by target–induced signal quenchers release strategy
In this work, a target-induced signal quenchers release strategy was proposed to construct a sensitive photoelectrochemical (PEC) sensor. To achieve it, Cu nanoclusters (NCs) featuring with outstanding chemical performance were introduced and then be pickled with acid to generate Cu2+ signal quenchers to quench the photocurrent response. Moreover, three–dimension (3D) hierarchical seaweed-like TiO2 nanomaterial (HSTN) was firstly prepared and served as the electron transporting material, which could provide the highly pathways for the transfer of photoinduced electrons. Meanwhile, in order to extending the light response to visible range, the narrow band gap CdS quantum dots (QDs) were employed to form the HSTN/CdS heterojunction. In addition, the magnetic bead (MB) modified PSA aptamer (MB–Apt) was used as the auxiliary structure which could combine with DNA-Cu NCs through the specific recognition. When the target PSA was existed, the MB-Apt would bond with PSA due to the relatively large interaction force, triggering the release of Cu NCs. With the aid of acid, the Cu NCs could be converted to Cu2+ and then react with CdS to form CuxS, decreasing the photocurrent signal. Consequently, the concentration of PSA could be accurately detected through monitoring the change of photocurrent. This work provided an ingenious idea to fabrication of highly sensitive PEC sensors.