Bi-MOF-based point-of-care testing paper for dual-mode detection of H₂S

Hydrogen sulfide (H₂S) is noxious gas and significantly threatens human health. Herein, a Bi-based metal-organic frameworks (Bi-MOFs) based paper analysis device (PAD) has been developed for rapid and effective dual-mode detection of H₂S. The dominant H₂S sensing mechanism is explored. The H₂S can react with Bi-MOF to form bismuth sulfide (Bi₂S₃) MOF (Bi₂S₃-MOF), changing the color of PAD from white to black. The distinguish color change makes it very convenience for visible detection. Meanwhile, the generated Bi₂S₃-MOF exhibits excellent photothermal property, endowing it possible for photothermal imaging detection. In this regard, the PAD boasts a wide linear detection range of 0-40 μM for H₂S with an impressively low limit of detection (LOD) (0.23 μM). The constructed sensing system is demonstrated with outstanding selectivity and storage stability. Satisfied recovery is reached for H₂S detection in diverse real samples. Interestingly, the PAD can be used as intelligent label for assessing meat freshness by monitor H₂S release from meat under different storage temperatures. With integration capabilities of smartphones, the portable and user-friendly PAD offers a simple and rapid solution for on-the-go detection of H₂S in food and environment. The investigation provides an instructive way for environment monitoring and food safety guarding.