Rational design of cascade reaction-assisted trinal-site fluorescent probe for simultaneous discrimination of Cys, Hcy, GSH, and H2S in living cells and zebrafish

The reactive sulfur species (RSS), in particular Cys, Hcy , GSH, and H 2 S, play an essential role in lots of critical physiological and pathological processes. To elucidate their complex interrelationships in signaling and metabolic pathways, suitable molecular tools to simultaneously distinguish Cys, Hcy , GSH, and H 2 S are urgently needed. Herein, we developed a novel cascade reaction-assisted trinal-site fluorescent probe BCS by connecting three functional fragments for simultaneously distinguishing Cys, Hcy , GSH, and H 2 S. The probe BCS exhibited red fluorescence in the absence of the four biological RSS. However, with the attendance of Cys, Hcy , GSH, and H 2 S, the probe showed different fluorescence patterns, including blue, blue/red, green/red, and no fluorescence, respectively. More importantly, based on the different RSS-induced fluorescence patterns and multi-color fluorescence imaging, probe BCS was used to discriminate and visualize all four biological RSS in both HepG2 cells and zebrafish. It is expected that probe BCS will have applications in the diagnosis and research of RSS-related diseases in the future.