A mitochondria-targetable fluorescent probe for detection of bisulfite in living cells

A new colorimetric semi-cyanine fluorescent probe ( 3 ) based on benzo[ g ]indolium was designed and prepared. Probe 3 exhibited a clear OFF-ON fluorescence response at 460 nm toward HSO 3 − (0-8.0 eq.) within a short response time (3 min). In addition, probe 3 had good selectivity and competitiveness, with excellent sensitivity and a low detection limit (4.4 nM). The detection mechanism relied on nucleophilic HSO 3 − attacking the C&z.dbd;C double bond in a 1,4-nucleophilic addition reaction. Importantly, the confocal fluorescence results indicated that probe 3 targeted mitochondria and could detect HSO 3 − in living cells. A colorimetric fluorescent probe based on benzo[ g ]indolium was prepared as a mitochondria-targeted probe for detecting bisulfite.