A simple but effective fluorescent probe with large stokes shift for specific detection of cysteine in living cells

A novel 4'-hydroxybiphenyl-4-carbonitrile-based fluorescent probe, 1, for selective detection of cystein (Cys) over homocystein (Hcy) and glutathione (GSH) was developed. This probe had simple structure and could be easily synthesized with good yield from commercially available materials. Moreover, probe 1 showed a remarkable large Stokes shift (180 nm) and displayed a rapid (5 min) and highly sensitive response (the detection limit was 0.15 mu M) for Cys with fluorescence turn-on signal changes (142-fold fluorescence enhancement). Importantly, probe 1 could be used to detect and image both exogenous and endogenous Cys in living A549 cells.