A visual and “turn-on” fluorescent probe for rapid detection of cysteine over homocysteine and glutathione

A novel chemodosimetric fluorescent probe 1 for biothiols was designed and synthesized based on benzothiazolium-quinoline hemicyanine dye with an acrylate group as a functional trigger moiety. Prober 1 exhibited high sensitivity and high selectivity for rapid detection of cysteine (Cys) over homocysteine and glutathione in aqueous environments. The maximal fluorescent response was immediately achieved within 1 min in the presence of only 1 equiv. of Cys, and the color change of the sensing process was discerned visually at the nanomole level. The exceptional high reactivity and specific response of probe 1 for Cys were promoted by the stabilization of the sensing product phenolate anion and the differences in the kinetics of the sensing reaction. Moreover, probe 1 was employed successfully to detect the free Cys residues within protein and monitor Cys in living HeLa cells by fluorescence imaging.

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