A mitochondria-targetable far-red emissive fluorescence probe for highly selective detection of cysteine with a large Stokes shift

Abstract

Selective detection of cysteine (Cys) over homocysteine (Hcy) and glutathione (GSH) has attracted considerable attention. In this work, a benzothiazole-based fluorescent probe HBTMP has been developed for effective recognition of Cys in Tris-HCl buffered (10 mM, pH = 7.0, 1% DMSO) water solution. HBTMP displays highly selective and sensitive far-red fluorescence “turn on” response to Cys over Hcy, GSH, other amino acids, and human constant metal ions and anions. The Cys recognition event by HBTMP holds other distinct advantages such as a large Stokes shift and a low detection limit. The intramolecular electrostatic interaction in HBTMP-Hcy adduct is believed to play an auxiliary role that responsible to the high selectivity of HBTMP to Cys over Hcy. Cell imaging studies show that HBTMP is applicable to image Cys in living MCF-7 cells and targetable to mitochondria.