A dicyanoisophorone-quinolinium-based near-infrared-emission fluorescent probe for ratiometric sensing of bisulfite/sulfite in living cells

Sulfur dioxide (SO2), as a known important sulfur oxide in RSS, has an essential role in achieving the homeostasis of organisms. The development of a highly sensitive and selective fluorescent probe for monitoring SO2 is of great interest in understanding its pathophysiology. Herein, we developed a new near-infrared FRET-based fluorescent probe QD, in which quinolinium fluorophore was selected as the donor and the dicyanoisophorone fluorophore was selected as the acceptor. Probe QD had dual colorimetric and ratiometric fluorescence, larger Stokes shift (277 nm) and longer emission wavelength (677 nm). The fluorescence spectrum showed that QD was highly selective and sensitive with excellent linear response concentration range of 2.5–80 μM. Importantly, probe QD allowed detection of SO2 derivatives and bioimaging of lysosome-targeted in live cells.