A novel fluorescent probe, viz. PI-Cys, was developed on the basis of the excited state intramolecular proton transfer (ESIPT) mechanism for the detection of cysteine (Cys). It consists of an new ESIPT dye as the fluorophore, linked via a hydroxyl moiety to an acrylate group. The acrylate group acts as an ESIPT blocking agent as well as a functional recognition moiety. In the presence of Cys, the reaction of Cys with PI-Cys results in cleavage of the acrylate moiety from PI-Cys, thereby unleashing the ESIPT process and leading to about 20-fold enhancement of fluorescence. The probe exhibits hi...
