A novel DCM-NBD conjugate fluorescent probe for discrimination of Cys/Hcy from GSH and its bioimaging applications in living cells and animals

Biothiol compounds, commonly involving cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) are of wide range in mammalian cells for maintaining the stability of their internal environments. Due to their special significance in physiology and pathology for human, development of fluorescence probes for selective and sensitive detection of thiols under physiological conditions has attracted great interest. Compared to conventional fluorescent probes, near-infrared (NIR) fluorescent probes possess unique advantages for tracing molecular processes in vitro and in vivo. In this report, we designed and synthesized a novel NIR fluorescent probe DCM-NBD, which employed dicyanomethylene-4H-pyran (DCM) derivatives as the NIR fluorophore and nitrobenzoxadiazole (NBD) as the response group via ether linkage. It exhibited satisfactory selectivity and sensitivity to differentiate between Cys/Hcy and GSH by dual fluorescence signals. Moreover, the probe DCM-NBD showed admirable imaging capability in living cells and animals with low cytotoxicity.