A Ruthenium(II) complex-based probe for colorimetric and luminescent detection and imaging of hydrogen sulfide in living cells and organisms

The development of reliable bioanalytical probes for sensitive and specific detection of hydrogen sulfide (H2S) plays important role for better understanding the roles of this biomolecule in living cells and organisms. Taking advantages of unique photophysical properties of ruthenium(II) (Ru(II)) complex, this work presents the development of a responsive Ru(II) complex probe, Ru-PNBD, for colorimetric and luminescent analysis of H2S in living cells and organisms. In aqueous solution, Ru-PNBD is yellow color and non-luminescent because of the photoinduced electron transfer (PET) process from Ru(II) complex luminophore to NBD moiety. The H2S-triggered specific nucleophilic substitution reaction with Ru-PNBD cleaves the NBD moiety to form pink NBD-SH and highly luminescent Ru-PH. The color of the solution thus changes from yellow to pink for colorimetric analysis and the emission intensity is about 65-fold increased for luminescent analysis. Ru-PNBD has high sensitivity and selectivity for H2S detection, low cytotoxicity and good permeability to cell membrane, which allow the application of this probe for H2S imaging in living cells, Daphnia magna, and larval zebrafish. Collectively, this work provides a useful tool for H2S analysis and expands the scope of transition metal complex probes.