Thiol-chromene click chemistry: A turn-on fluorescent probe for specific detection of cysteine and its application in bioimaging

A turn-on fluorescent probe for specific detection of cysteine (Cys) was developed based on the thiolchromene click chemistry. Because of the relatively strong nucleophilic reactivity of SH of Cys compared with Hcy and GSH, this chromene derivate displayed excellent selectivity for Cys. The chromene derivate (probe 1) displayed non-fluorescent emission in DMSO/HEPES (v/v, 1:1, pH 7.4) system. However, the nucleophilic attack of Cys to the a., p-unsaturated ketone in probe 1 induced a 10 fold fluorescent emission enhancement at 515 nm. With the excellent properties including rapid, high selectivity and sensitivity toward Cys in aqueous solution, probe 1 was promoted to detect Cys quantitatively. The detection limit of this probe for Cys was found to be 64 nmol/L. The further bioimaging experiment of intracellular Cys detection by this probe was successfully applied in living cells, indicating that this probe holds great potential for biological applications. (C) 2015 Elsevier B.V. All rights reserved.