A water-soluble copper(II) complex fluorescent probe for high-sensitive and selective detection of endogenous H2S

H2S has been identified as a third gasotransmitter involved in bio-modulation pathways. However, the low concentration of endogenous H2S makes it difficult to trace and detect. In this study, a net charged and watersoluble copper(II) complex, Cu-L, is reported as an endogenous H2S detector by utilizing a fluorescence on-off-on strategy. The luminescence of ligand L (a DNS-modified DO2A derivant), which is quenched due to Cu2+ coordination, can be effectively and selectively relumed within seconds in the presence of H2S. Meanwhile, Cu-L has been successfully employed for exogenous and endogenous H2S imaging and neither Cu-L nor L shows toxicity at concentrations up to 50 mu M. Moreover, Cu-L can trace endogenous H2S concentration fluctuation by treating cells with different concentrations of S-propargyl-cysteine (SPRC), an endogenous H2S modulator. Therefore, Cu-L holds the potential for H2S detection both in vitro and in cell.