A NIR turn-on fluorescent probe for specific recognition of cysteine and its application in cells and zebrafish

A new turn-on fluorescent probe (DC-O-SBD) for cysteine (Cys) with a large Stokes shift was synthesized. Free DC-O-SBD had almost no fluorescence. After reacting with Cys, it released near-infrared (NIR) fluorescence at 655 nm. DC-O-SBD can respond to Cys quickly and had high specificity for Cys. Moreover, DC-O-SBD had a low detection limit (0.16 μM) and a large Stokes shift (155 nm). In addition, DC-O-SBD can efficiently detect Cys in HeLa cells and zebrafish.