Abstract
Cysteine (Cys) is a crucial biomarker and plays various significant roles in many physiological and pathological processes. Here is reported a fluorescent probe Mito-cys by incorporating o-chlorobenzoic acid ester onto a hemicyanine platform. The probe exhibited excellent specificity and rapid response for cysteine. The developed method quantitatively monitored cysteine from 5 μM to 30 μM with a detection limit of 135 nM. The probe was also employed to image trace endogenous cysteine in living HeLa cells.