An ESIPT Fluorescent Probe for Detection of Biothiols and H 2 S: Application in Water Samples, Food Spoilage, and Cell Imaging

ABSTRACT Hydrogen sulfide (H 2 S), cysteine (Cys) and glutathione (GSH) are essential for maintaining physiological homeostasis and serve as key biomarkers for disease diagnosis. In this work, six fluorescent probes relying on the ESIPT mechanism were developed for the detection of biothiols and H 2 S. Specifically, probe AHB‐2A demonstrated high sensitivity (LOD: 79 nM), a large Stokes shift (113 nm), and a 66‐fold increase in fluorescence at 493 nm. The high sensitivity of AHB‐2A enables effective real‐time detection of biothiols and H 2 S in biological applications. In addition, AHB‐2A was used to measure H 2 S in water samples and to monitor the spoilage of food. Furthermore, AHB‐2A was capable of imaging both endogenous and exogenous Cys, GSH, and H 2 S in living cells and exhibited low toxicity in cells treated with high concentrations of the probe. The design strategy highlights both the compound's intrinsic properties and its adaptability to reactive conditions across different application contexts.