A bright two-photon fluorescence probe with large stokes shift for deep tissue imaging of H2S during metabolism

Tissular H2S plays important role in neuroprotection, cardioprotection and angiogenesis. Herein, we develop a new fluorescent probe (Z)-4-(2-(6-(2,4-dinitrophenoxy)naphthalen-2-yl)vinyl)-1-methylpyridinium (EMII-H2S) for tissular imaging of H2S. EMH-H2S allows for sensitive response toward H2S under the excitation of both onephoton (410 nm) and two-photon (750 nm). Asymmetric electron structure contributes to the large stokes shift of 160 nm. With the better absorbance (39000 M-1 cm(-1)), quantum yield (0.201) as well as the two-photon absorption cross-section (119 GM), EMIT-H2S provides the higher brightness in response to H2S under either onephoton (epsilon Phi = 7638) or two-photon modes (delta Phi = 23.8), which compare favorably with many other highly bright fluorescent probes. EMII-H2S is applied in imaging of cellular endogenous H2S and tissue imaging at depths of 160 mu m-200 mu m in mouse liver. With the satisfactory properties, EMII-H2S is used to estimate the dynamic H2S release during metabolism of two type of H2S donors, demonstrating that the thiovaline provided the longlasting H2S production contrary to the rapid burst caused by NaHS. EMII-H2S proves to be an effective tool for imaging tissular H2S, which is of great significance for the visual analysis of gasotransmitters in tissue.