Fast response and highly selective detection of hydrogen sulfide with a ratiometric two-photon fluorescent probe and its application for bioimaging

H2S can be endogenously produced by enzymes and play critical roles in the functioning of living organisms. In order to better understanding its physiological and pathological functions, the development of efficient methods for monitoring H2S is desired. Herein, we reported a ratiometric two-photon fluorescent probe for detecting H2S. A typical ICT-based fluorescent dye, 4-hydroxy-1, 8-naphthalimide was considered as fluorophore of the probe on account of its two-photon absorption properties. We chemically masked it with a recognition motif for H2S, an electrophilic cyanate (ROs-CN), to construct a fluorescent probe. This novel structure has a fast response, highly sensitive and selective toward H2S over potentially competitive species. We could also observe ratiometric signal for H2S detection with a wide linear range of 1-10 μM and a detection limit of 0.24 μM. Moreover, the probe successfully demonstrated its utility for bioimaging in the living cells with low cytotoxicity. And probe 1 exhibited the capability of two-photon imaging of H2S in cells.