A novel lipid droplets-targeted ratiometric fluorescence probe for HSO3−/SO32− in living cells

A new ratiometric fluorescence probe (named CPC) with high selectivity and sensitivity toward bisulfite (HSO3−) based on a FRET platform was developed. Probe CPC was constituted by a coumarin-carbazole dyad with a large (pseudo) Stokes shift (197 nm). The limit of detection was measured to be as low as 18 nM and the signal-to-background ratio of fluorescence intensity was up to 73-folds, implying a high sensitivity of probe CPC toward HSO3−. What's more, probe CPC was successfully applied to the detection of endogenous HSO3− and specific imaging of lipid droplets in HepG2 cells.