A coumarin-based fluorescent probe for thiols and its application in cell imaging

A new coumarin-based fluorescent probe CAA containing an acrylamide group has been designed and synthesized for the detection of biothiols. The probe CAA shows high selectivity and sensitivity for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) over other amino acids. A fluorescence turn-on response is induced by a Michael-type reaction. It shows a highly sensitive fluorescence emission to Cys, Hcy, and GSH, with detection limits of 192 nM for Cys, 158 nM for Hcy, and 155 nM for GSH (S/N = 3). Furthermore, confocal fluorescence microscopy imaging using RAW264.7 macrophages demonstrates that CAA can be an effective fluorescent probe for thiols in living cells.