In situ Ag₂S quantum dot-sensitized BiOI/Bi₂O₃ heterojunction: A label-free photoelectrochemical aptasensor for...

Patulin (PAT), a potent mycotoxin commonly found in fruit and vegetable products, represents a critical threat to food safety and public health. Its cytotoxicity arises from the disruption of intracellular signaling pathways and oxidative balance, leading to gastrointestinal impairment, immune suppression, and systemic toxicity. To mitigate these risks, we present a label-free photoelectrochemical (PEC) aptasensor for ultrasensitive PAT detection, employing an in situ-synthesized Ag₂S quantum dot (QD)-sensitized BiOI/Bi₂O₃ heterojunction. The BiOI/Bi₂O₃ heterostructure enhanced charge carrier separation, while the in situ-anchored Ag₂S QDs functioned as effective photosensitizers, significantly amplifying the PEC response. Integrated with a PAT-specific aptamer, the sensor demonstrated selective target recognition, achieving a linear detection range from 0.001 to 100 ng/mL and a remarkably low detection limit of 0.56 pg/mL. The aptasensor exhibited high selectivity against structurally similar mycotoxins, excellent stability (94.2% signal retention through 15 on/off light irradiation cycles). Successful PAT quantification in spiked apple juice samples confirmed its practicality for real-world applications. This study establishes a sensitive, cost-effective, and reliable analytical tool for monitoring mycotoxins in food safety protocols.