Novel dual type-II WO₃/g-C₃N₄/Cu₂O-Au heterojunction-based photoelectrochemical aptasensor for ultra-sensitive AFB1...

Given the extreme toxicity and carcinogenicity of aflatoxin B1 (AFB1) in foodstuffs and medicinal products, ultrasensitive detection for it is critically important. Herein, we engineered a type-II dual WO₃/g-C₃N₄/Cu₂O-Au heterojunction via hydrothermal synthesis and photoreduction, which synergistically integrates the structural stability of WO₃, the visible-light response of Cu₂O, the optimal band alignment of g-C₃N₄, and the plasmonic enhancement effect of Au nanoparticles. Leveraging the band structure differences among these constituent semiconductor components, this architecture enables efficient separation of photogenerated electron-hole pairs, resulting in a 6.7-fold enhancement in photocurrent compared to pristine WO₃. Integrating this optimized photoelectrochemical (PEC) sensor platform with aptamer-based specific recognition, the biosensor achieves ultrasensitive quantification of AFB1 across a 7-order-of-magnitude linear range (10⁻⁵ ng/mL to 100 ng/mL) and an ultra-low limit of detection (LOD) of 2.29 fg/mL. Validation through highly sensitive determination of AFB1 in real Astragalus samples (a widely used Traditional Chinese Medicine (TCM)) yielding recoveries ranging from 98.5% to 102.1% verifies its applicability for quality control of medicinal products. This work presents a high-performance PEC biosensor for AFB1 and establishes a generalized component integration strategy for designing heterostructured nanomaterials aimed at detecting ultra-trace mycotoxins in complex food and pharmaceutical matrices.