Ultra-sensitive dual-responsive Zn(II)-MOF fluorescent probe: Rapid recognition of cinoxacin and vitamin B₂ in artificial urine and saliva matrices.

This study successfully synthesized a new zinc-based metal-organic framework material {[Zn(qdda)(bpy)₀.₅]·3H₂O} (Zn-MOF) by the solvothermal method and systematically investigated its performance as a fluorescent material for the simultaneous sensing of the antibacterial drug Cinoxacin (CNX) and Vitamin B₂ (VB₂). The structure, morphology, and composition of the material were comprehensively characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR). Fluorescence experiments demonstrated that the Zn-MOF demonstrates significant selectivity and sensitivity toward both CNX and VB₂, with detection limits of 9.2 nM and 24 nM, separately, a rapid response (within 60 s), as well as excellent anti-interference ability and recyclability. The observed fluorescence quenching was attributed to a synergistic mechanism involving competitive absorption (CA), resonance energy transfer (RET), and photoinduced electron transfer (PET). In a simulated saliva and urine environment, the material showed satisfactory spike recovery rates for CNX and VB₂, confirming its reliability in practical sample detection. This work opens a new avenue for developing high-performance MOF-based fluorescent sensors. Such sensors show great potential for the simultaneous detection of two analytes within complex biological environments.