Crystal Violet-Sensitized Direct Z-Scheme Heterojunction Coupled with a G-Wire Superstructure for Photoelectrochemical Sensing of Uracil-DNA Glycosylase.

Dye sensitization achieving photoelectrochemical (PEC) signal amplification for ultrasensitive bioanalysis has undergone a major breakthrough. In this proposal, an innovative PEC sensing platform is developed by combining Z-scheme WO@SnS photoactive materials and a G-wire superstructure as well as a dye sensitization enhancement strategy. The newly synthesized WO@SnS heterojunction with outstanding PEC performance is employed as a photoelectrode matrix. Due to the formation of the Z-scheme heterojunction between WO and SnS, the migration dynamics of the photogenerated carrier is evidently augmented. To improve sensitivity, the target excision-driven dual-cycle signal amplification strategy is introduced to output exponential c-myc fragments. Crystal violet is then conjugated into the G-quadruplex to amplify the PEC signal, where crystal violet generates excited electrons by capturing visible light and rapidly injects electrons into the conduction band of SnS, suppressing the recombination of the photo-induced carrier. Moreover, the G-wire superstructure acts as a universal amplification pathway, ensuring adequate crystal violet loads. Specifically, the biosensor for uracil-DNA glycosylase quantification displays a wide detection range (0.0005-1.0 U/mL) and a lower detection limit (0.00025 U/mL). Furthermore, the Z-scheme electron migration mechanism and the crystal violet sensitization effect are discussed in detail. The construction of the PEC sensor provides a new consideration for signal amplification and material design.