Novel Double Z-Scheme ZnS/Bi ₂ S ₃ /Bi ₂ Ti ₄ O ₁₁ Electrospun Heterojunction-Triggered Photocurrent-Polarity-Switching Cathodic Aptasensor for Fumonisin B1 Analysis

Agricultural products are usually susceptible to mycotoxin contamination; the rapid and reliable detection of mycotoxins at the early stage is crucial for food safety. Here, a photocurrent-polarity-switchable cathodic photoelectrochemical (PEC) aptasensing platform was established for fumonisin B1 (FB1) analysis based on a novel ZnS/Bi₂S₃/Bi₂Ti₄O₁₁ (BTO) electrospun nanoheterojunction. Introducing S/Zn sources on Bi₄Ti₃O₁₂ electrospun nanofibers induced the component transformation of Bi₄Ti₃O₁₂ into BTO to generate ZnS/Bi₂S₃/BTO with double Z-scheme heterojunctions, thereby switching from anodic to cathodic photocurrent. On the photocathodic aptasensing interfaces of ZnS/Bi₂S₃/BTO, the FB1 aptamer-modified Au NPs/NiCo₂O₄ as peroxidase-like mimics accelerate the oxidation of 4-chloro-1-naphthol in a H₂O₂ environment to produce insoluble precipitates, quenching the photocathodic current with a 77.6% quenching efficiency. After incubation with FB1, the specific binding between FB1 and the aptamer could effectively reduce the catalytic sites of Au NPs/NiCo₂O₄, resulting in the recovery of photocathodic current signals for the detection of FB1 with a linear range of 0.5 pg/mL-1000 ng/mL and a detection limit of 0.385 pg/mL. In a word, this work for the first time synthesized the novel ZnS/Bi₂S₃/BTO double Z-scheme electrospun heterojunctions as highly active photocathodic materials, offering a new perspective in the advancing polarity-switchable PEC bioanalysis.