A fluorescent: τ -probe: Quantitative imaging of ultra-trace endogenous hydrogen polysulfide in cells and in vivo

Abstract

Hydrogen sulfide (H2S) has been recognized as an important endogenous gasotransmitter associated with biological signaling transduction. However, recent biological studies implied that the H2S-related cellular signaling might actually be mediated by hydrogen polysulfides (H2Sn, n > 1), not H2S itself. Unraveling such a mystery strongly demanded the quantification of endogenous H2Sn in living systems. However, endogenous H2Sn has been undetectable thus far, due to its extremely low concentration within cells. Herein, we demonstrated a strategy to detect ultra-trace endogenous H2Snvia a fluorescent τ-probe, through changes of fluorescence lifetime instead of fluorescence intensity. This τ-probe exhibited an ultrasensitive response to H2Sn, bringing about the lowest value of the detection limit (2 nM) and a lower limit of quantification (10 nM) to date. With such merits, we quantified and mapped endogenous H2Sn within cells and zebrafish. The quantitative information about endogenous H2Sn in cells and in vivo may have a significant implication for future research on the role of H2Sn in biology. The methodology of the τ-probe established here might provide a general insight into the design and application of any fluorescent probes, beyond the limit of utilizing fluorescence intensity.