Polarity-Switching Photoelectrochemical Detection of Ochratoxin A Based on Target-Responsive Dendritic Mesoporous Silica Nanoparticle and Z-Scheme Hemin/HOF-101 Heterostructure

A novel polarity-switching photoelectrochemical (PEC) sensing method was proposed for quantifying ochratoxin A (OTA). Aminated dendritic mesoporous silica nanoparticle (DMSN) with well-defined pores was synthesized to encapsulate hemin, and its pore channels were sealed by OTA-specific aptamers as gatekeepers. Specific binding of OTA to the aptamer induced conformational changes and aptamer dissociation, triggering the release of entrapped hemin. The released hemin was captured by a hydrogen-bonded organic framework (HOF-101) modified electrode, which switched the photocurrent polarity from cathodic to anodic, with the anodic signal linearly increasing with OTA concentration. Under optimized conditions, the method exhibited a linear range of 10 pg mL^-1-10 μg mL^-1 and a limit of detection (LOD) of 3.5 pg mL^-1. Validated with camellia oil samples, its results were comparable to high-performance liquid chromatography (HPLC), verifying reliability for OTA detection in complex food matrices.