A FRET-based ratiometric fluorescent probe for detection of intrinsically generated SO2 derivatives in mitochondria

Highlights: • A novel FRET platform constructed by pyrido[1,2-a]benzimidazole and hemicyanine fluorophores was designed. • The probe exhibits highly sensitivity and selectivity toward SO₂ in pure water. • The probe can be applied to determine the endogenous SO₂ levels in mitochondria. -- Abstract: A mitochondria-targeted ratiometric fluorescent probe based on hemicyanine and pyrido[1,2-a]benzimidazole was presented. It shows high sensitivity and selectivity toward SO₂ in pure water. The limit of detection (LOD) was as low as 26.7 nM, which is superior to most reported probes. Most importantly, the probe was successfully used for fluorescence imaging of endogenous bisulfite in mitochondria in Glioma cells.