Novel cascade reaction-based fluorescent cyanine chemosensor for cysteine detection and bioimaging in living system.

Precise detection of intracellular Cys will be helpful to accurately assess the physiological functions in the physiological and pathological processes. Herein, a new probe Meoeth-Cy-OBz-oCl capable of Cys sensing with high selectivity over other mercaptoamino-acid molecules including Hcy and GSH was developed. The studies on sensing mechanism supported thiols-induced SNAr substitution-rearrangement cascade reaction which allowed discriminating Cys from Hcy/GSH. And its preferential fluorescence response of Meoeth-Cy-OBz-oCl to intracellular Cys was also achieved by means of fluorescence imaging in HeLa cells. Besides, Meoeth-Cy-OBz-oCl was confirmed possessing mitochondria-targeting ability in living cells. In addition, fluorescence imaging in BALB/c mice revealed that Meoeth-Cy-OBz-oCl could visually monitor the variation of Cys in vivo.