Z-scheme WO₃/CdS heterojunction-synergized molecularly imprinted photoelectrochemical sensor for ultrasensitive and...

Gentamicin (GEN) residues in food pose notable health hazards, including nephrotoxicity and ototoxicity, so developing trace detection methods with high sensitivity and selectivity is urgently required in the field of food safety. Conventional GEN detection approaches such as chromatography and immunosensing have inherent limitations like high cost or complex operation, and single-semiconductor photoelectrochemical (PEC) sensors face insufficient charge separation issues. This work addresses the critical need for developing a high-performance PEC sensing platform that combines superior photoelectric conversion capability with specific molecular recognition.

A Z-scheme WO₃/CdS heterojunction with excellent PEC properties was utilized to develop a novel molecularly imprinted photoelectrochemical sensor (MIP-PECS) for ultrasensitive and highly selective detection of GEN. The bandgap-matched Z-scheme heterojunction serves as a crucial strategy for high-efficiency photoelectrodes. Its built-in electric field (BEF) effectively enhances directional charge separation and significantly suppresses photogenerated carrier recombination relative to single-semiconductor counterparts, while retaining strong redox activities that outperform conventional type-II heterojunctions. A polypyrrole-based molecularly imprinted polymer film (PPy-MIPF) with GEN as template molecule and pyrrole (Py) as functional monomer improves selectivity. The sensor exhibits a low detection limit of 48.4 pmol/L, a wide linear range of 0.0001-100 μmol/L, an imprinting factor (IF) of 9.96, strong anti-interference capability, superior stability and reproducibility, and satisfactory recoveries of 93.2-108.3% in milk and honey samples.

This study concludes that the developed MIP-PECS integrates the Z-scheme WO₃/CdS heterojunction and PPy-MIPF to achieve excellent balanced PEC performance and selectivity. Combining simple operation and low cost, it overcomes conventional detection method limitations, providing a practical and promising platform for reliable antibiotic detection in food quality monitoring, environmental control and related fields.