Development of a mitochondria-targeted fluorescent probe for the ratiometric visualization of sulfur dioxide in living cells and zebrafish

Herein, a mitochondria-targeted ratiometric fluorescent probe for SO2 was proposed based on the FRET coumarin-phenylchromenylium dyad. The probe showed two distinct emission bands centered at 485 and 650 nm. Upon exposure to SO2, the acceptor emission was inhibited, and a significant enhancement in donor fluorescence was simultaneously induced; this resulted in a satisfactory ratiometric fluorescence signal. Importantly, the probe was biocompatible and successfully applied to monitor SO2 in live HeLa cells and zebrafish.