S-scheme Bi2S3/FeIn2S4 heterojunction for ultrasensitive photoelectrochemical detection of flutamide.

Flutamide (FLU), a nonsteroidal antiandrogen drug for prostate cancer therapy, requires sensitive monitoring due to its narrow therapeutic window. Herein, we constructed a novel photoelectrochemical sensor based on an S-scheme Bi2S3/FeIn2S4 heterojunction for ultrasensitive FLU detection. This charge transfer mechanism was confirmed through density functional theory calculations and electron paramagnetic resonance tests. FLU can act as a hole scavenger by transforming its nitro group into a nitroso derivative via a 2e-/2H+ transfer process, thereby amplifying the photocurrent signal. The sensor outperformed traditional techniques, exhibiting a wide dual-range linear detection capability (0.02 - 20 μM and 20 - 110 μM) with an ultralow detection limit of 10 nM. The designed sensor exhibits good repeatability and long-term storage stability (>92.8%). Moreover, this sensor was successfully applied in human serum and urine, with recovery rates ranging from 96.9% to 100.2%.