A near-infrared fluorescent probe selectively recognizing cysteine to release H2S and its applications.

Cysteine, a pivotal biothiol vital for human health, exhibits strong associations with various diseases, yet its concentration assessment is often confounded by structurally and functionally similar biothiols. Hydrogen sulfide (H2S), an endogenous gasotransmitter with therapeutic potential, faces challenges in achieving pharmacological effects due to the unpredictable presence of inorganic H2S donors. To address these issues, we developed TMN-ONCS, a near-infrared fluorescent probe that integrates a p-tolyl isothiocyanate with a dicyanoisophorone fluorophore through a self-immolative spacer. TMN-ONCS demonstrates high selectivity and analytical performance for cysteine, avoids the generation of multiple fluorophores seen in conventional isothiocyanate probes, and functions as a cysteine-activated fluorescent H2S donor with concurrent visualization. Furthermore, it mitigates lipopolysaccharide-induced inflammation in RAW 264.7 cells, highlighting its potential for treating inflammation.