A Golgi-targeting NIR fluorescence-based probe for the detection of cysteine in living cells and mice

Cysteine (Cys) plays a vital role in the biological processes within cells and is closely associated with the proper function of the Golgi apparatus (GA). At present, highly selective and sensitive fluorescent probes, especially near-infrared (NIR) fluorescent probes for the specific detection of Cys in the Golgi apparatus have not been reported. Within this research, we developed a Golgi-targeting NIR fluorescence probe ( LGB-Cys ) for the detection of Cys based on an intermolecular charge transfer (ICT) mechanism, with a hemicyanine skeleton as the fluorophore, an acrylate as the response unit, and a p -aminobenzene sulfonamide as the GA-targeting group. In the absence of Cys, the acrylate group inhibits the ICT effect and quenches the fluorescence of the probe. However, upon the addition of Cys, the ICT process was recovered accompanied by a significant NIR emission enhancement at 705 nm due to the cleavage of acrylate. LGB-Cys exhibits the advantages of high selectivity, strong anti-interference ability, and high sensitivity (LOD = 0.134 μM) for Cys detection. Significantly, LGB-Cys was successfully used to image endogenous and exogenous Cys in living cells and to evaluate the oxidative stress of GA. Moreover, LGB-Cys could be applied for monitoring of Cys fluctuations in normal and HepG-2 xenograft tumor mice.