Quantitative Monitoring and Visualization of Hydrogen Sulfide In Vivo Using a Luminescent Probe Based on a Ruthenium(II) Complex

Development of novel bioanalytical methods for monitoring of H2S is key toward understanding the physiological and pathological functions of this gasotransmitter in live organisms. A ruthenium(II)-complex-based luminescence probe, Ru-MDB (MDB: 4'-methyl-[2,2'-bipyridine]-4-yl) methyl 2-((2,4-dinitrophenyl) thio) benzoate), was developed by introducing a new H2S responsive masking moiety to a red-emitting Ru-II luminophore. Cleavage of this masking group by a H2S-triggered reaction leads to a luminescence off-on response. The long-lived emissions of Ru-MDB and its reaction product with H2S allowed quantitative detection of H2S in autofluorescence-rich human sera and adult zebrafish organs using the time-gated luminescence mode. Ru-MDB exhibits red emission, a large Stokes shift, high specificity and sensitivity for H2S detection, and low cytotoxicity, which enables imaging and flow cytometry analysis of lysosomal H2S generation in live inflamed cells under drug stimulation. Monitoring of H2S in live Daphnia magna, zebrafish embryos, adult zebrafish, and mice, was conducted by in vivo imaging using Ru-MDB as a probe.