Dual Z-scheme In2S3/Bi2S3/ZnS heterojunction with broad-spectrum response as a photoactive material for ultrasensitive detection of environmental Pollutant tetracycline.

Herein, a novel dual Z-scheme heterojunction In2S3/Bi2S3/ZnS (IBZS) with core-shell structure was prepared to establish a photoelectrochemical (PEC) biosensor for ultrasensitive detection of tetracycline (TC) referred to environmental pollution. Compared with the traditional single Z-scheme heterojunction with low PEC response, the dual Z-scheme heterojunction exhibited a strong PEC response due to its broad-spectrum response and highly efficient carrier migration. Furthermore, a redesigned target-triggered entropy-driven DNA reaction (TEDR) was implemented to mitigate spontaneous transient strand dissociation (breathing effect) in DNA duplexes, thereby effectively suppressing nonspecific background noise and enhancing the detection sensitivity of the biosensor. Hence, the PEC biosensor achieved an ultrasensitive detection of TC from 1.0 fM to 10 nM with a detection limit of 0.54 fM, which was far beyond the current TC detection methods. This strategy provided a new avenue for designing high-performance PEC photoactive materials, which was expected to be used to analyze antibiotics in environmental pollution monitoring and food quality control.