Ratiometric fluorescence immunoassay based on silver nanoclusters and calcein-Ce³⁺ for detecting ochratoxin A

Ochratoxin A (OTA), a dangerous mycotoxin, is found in many crops. It is essential to create sensitive OTA detection techniques to ensure food safety. Based on the principle of p-nitrophenol (PNP) quenched the fluorescence of bovine serum albumin silver nanocluster (BSA-AgNCs) through an internal filtering effect, and phosphate activated fluorescence of calcein-Ce³⁺ system, a ratiometric fluorescence immunoassay for OTA detection was developed. In this strategy, the value of F₅₁₈/F₆₄₀ was used as a signal for response of OTA concentration. The detection range of this strategy was 0.625-25 ng/mL, the limit of detection (LOD) was 0.04 ng/mL. This new immunoassay offered a brand-new platform for detecting OTA.