A selective fluorescent probe for cysteine and its imaging in live cells

Abstract

A probe for the detection of cysteine over homocysteine based on 2-(2′-hydroxyphenyl)benzothiazole (HBT) was prepared and used in confocal microscopy experiments. The probe was designed to block excited state intramolecular proton transfer (ESIPT). When bromopropionyl group protection is removed, HBT is recovered via nucleophilic substitution and intramolecular cyclization. The probe was found to have a detection limit of 2.8 μM and exhibits a ∼20-fold increase. The probe showed cell membrane permeability and efficacy in living Hep3B cells.