MOF-based ratiometric fluorescent biosensors for selective and sensitive detection of hydrogen sulfide in food products.

Hydrogen a metal-organic framework (MOF)-based ratiometric fluorescent biosensor (Uio-66-N3@Cy3) was developed for the determination of hydrogen sulfide (H2S). The sensor combines the high specificity of the H2S-azide reaction with the inherent self-calibration capability of MOF-based dual-emission signals for efficient detection. The biosensor operates via H2S-selective azide-to-amine conversion, which suppresses photoinduced electron transfer to simultaneously restore the MOF's intrinsic fluorescence while maintaining Cy3's stable fluorescence, enabling ratiometric detection. The biosensor exhibits a dual-linear response across 0.5-100 nM and 0.5-4.0 μM, with detection limits as low as 36 pM and 27 nM, respectively. Furthermore, the biosensor shows exceptional selectivity against 18 potential interferents and long-term stability (RSD < 3.5% over 14 days). Importantly, the ratiometric mechanism enables robust performance in complex food samples (beer and milk), yielding 99.74-103.00% recoveries with minimal variance. Unlike intensity-based probes, this system provides intrinsic calibration through simultaneous dual-channel detection, making it ideal for real-world applications. Our work not only delivers a superior H2S sensor but also establishes a generalizable platform for ratiometric detection of diverse contaminants in food systems.