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-N 3 @Cy3) was developed for the determination of hydrogen sulfide (H 2 S). The sensor combines the high specificity of the H 2 S-azide reaction with the inherent self-calibration capability of MOF-based dual-emission signals for efficient detection. The biosensor operates via H 2 S-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 H 2 S sensor but also establishes a generalizable platform for ratiometric detection of diverse contaminants in food systems. Graphical