A coumarin-based fluorescent turn-on probe for detection of biothiols in vitro.

A novel fluorescent probe (CA-N) was designed and synthesized for detection of biothiols. CA-N displayed a strong fluorescence in the presence of biothiols with high sensitivity, and the mechanism for detection biothiols was based on the Michael addition reaction of a thiol group to α,β-unsaturated ketones. CA-N showed low detection limit for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), which were calculated as 3.16, 0.19 and 5.15 μM, respectively. At the same time, CA-N exhibited high selectivity toward biothiols compared with other biological amino acids. In vitro cell experiments proved that CA-N had no cytotoxicity, high cell permeability and could be employed in living cell imaging for biothiols.