A light-promoted activation fluorescein derivative with unexpected structure for sensing hydrogen sulfide

Hydrogen sulfide (H₂S) is involved in diverse physiological processes as a signaling molecule and serves in food safety monitoring as an indicator of spoilage, while its accurate detection remains challenging owing to the low concentrations and sample complexity in the real world. Here, we report a novel photoactivatable fluorescent probe, Fl-F-Me, for H₂S detection based on a nucleophilic reaction mechanism. Validated by single-crystal X-ray diffraction, this probe incorporates oxymethyl fluorescein, a fluorescein derivative with unconventional structure, as the fluorophore and pentafluorobenzenesulfonyl (PFBS), traditionally used for H₂O₂ detection, as the H₂S recognition unit. Upon activation with 365 nm ultraviolet (UV) irradiation, Fl-F-Me exhibits excellent selectivity for H₂S, anti-interference capability, rapid response in 7 min, and physiologically applicable sensitivity with a limit of detection (LOD) of 0.026 μM and a limit of quantitation (LOQ) of 0.086 μM over a pH range of 5 to 11. It has been successfully applied to quantify H₂S levels in food and water samples, reveal H₂S production in plant cells as a response to aluminum stress, and visualize endogenous and exogenous H₂S dynamics in larval and adult zebrafish. These findings highlight Fl-F-Me as a versatile H₂S sensor with promising applications in agricultural production, food industry, and biomedical research.