Peroxidase-like NH2-MIL-101(Cr)-enabled fluorescence sensing of ofloxacin in honey through charge transfer modulation.

A critical need exists for advanced methods to monitor fluoroquinolones in food products. This work presents a sensitive fluorescence strategy for ofloxacin (OFL) detection in honey utilizing NH2-MIL-101(Cr), a chromium-based metal-organic framework synthesized hydrothermally. The framework exhibits intrinsic peroxidase (POD)-like activity, catalyzing H2O2-mediated oxidation of o-phenylenediamine (OPD) to yield the fluorescent product 2,3-diaminophenazine (DAP). The catalytic activity was notably quenched by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), which scavenges essential reactive oxygen species. Introduction of OFL, however, restores the fluorescence signal via the n → π* charge-transfer (CT) interaction with DDQ, decreasing its effective concentration. This recovery demonstrates a positive correlation with OFL levels. The assay shows a linear response from 25 to 600 μg/kg, a detection limit of 7.36 μg/kg, and recoveries of 81.5%-105.3% in spiked honey samples, with high selectivity against potential interferents. This study provides a novel approach for antibiotic residue analysis and underscores the utility of MOF-based nanozymes in food safety monitoring.