Magnetic separation assisted NiTiO/CdInSZ-scheme heterojunction photoelectrochemical aptasensor for zearalenone detection.

Zearalenone (ZEN) is a harmful mycotoxin with estrogen-like activity that can cause reproductive and immune system disorders. In this study, a sandwich-structured photoelectrochemical (PEC) sensor was developed for the ultrasensitive detection of ZEN. The sensor utilizes a Z-scheme NiTiO/CdInS heterojunction as the photoactive layer, which significantly enhances light absorption, charge separation efficiency, and photostability. NiFeO nanoparticles modified with ZEN-specific aptamers serve as recognition probes, with ZEN molecules acting as a bridge to connect the probes to the PEC substrate. Unbound NiFeO probes can be rapidly, simply, and efficiently removed using an external magnetic field, while the ZEN-bound probes remain anchored to the electrode surface, resulting in concentration-dependent quenching of the photocurrent. This magnetic-assisted separation strategy simplifies the experimental procedure and greatly reduces false positives and negatives caused by non-standard washing operations. The optimized sensor exhibits a linear detection range from 100 fg/mL to 1 μg/mL, with a low detection limit of 2.6 fg/mL, demonstrating excellent selectivity, stability, and reproducibility. Overall, this platform offers a reliable, simple, and highly sensitive method for the detection of trace levels of ZEN in complex food and environmental samples.