A dual-emission fluorescence sensor based on MIL-53-OPH@S-S-AuNCs probe for synchronous hydrolysis and detection of organophosphorus pesticides

Residual organophosphorus pesticides (OPs) frequently contaminate farm products, such as vegetables, and consequently threaten food safety. Herein, we present an enzyme-regulated dual-emission probe, MIL-53-OPH@S-S-AuNCs, for synchronous OPs hydrolysis and fluorescence determination. The probe, containing NH 2 -MIL-53(Al), organophosphorus hydrolase (OPH), and disulfide-functionalized Au nanoclusters (S-S-AuNCs), thus provides two emissive outputs (F 427 and F 655 ). Specifically, an OPH-assisted hydrolysis route is designed, where OPs are converted into class-informative products, including p-nitrophenol (PNP) and thiol/thiolate species (R-SH/S - ). PNP induces pronounced quenching of the blue emission (F 427 ) via resonance energy transfer, while sulfur-containing products perturb the disulfide-crosslinked state of S-S-AuNCs and attenuate the red emission (F 655 ). Stepwise optimizations are performed to promote efficient catalytic conversion and stable dual-channel readout, where quenching time, pH, and temperature are tuned to achieve pleasurable sensing conditions. This method provides log-linear quantification for OPs in a wide range of 6.5 × 10 −6 ∼20 μg mL −1 , with an impressive limit of detection of 3.4 × 10 −6 μg mL −1 . The proposed method is further validated by natural sample analyses and recovery tests in real vegetables, giving relative errors of 4.2∼8.6% and recoveries of 96.2∼105.2%.