Endogenous sulfur dioxide (SO2), as a gas signal molecule, has a certain physiological functions.Understanding the role of endogenous SO2 in human physiology and pathology is of great signi cance to the biological characteristics of SO2,which bring challenges to develop uorescent probes with excellent performance. Herein, we rationally designed and constructed a novel near-infrared bioprobe benzaldehyde-benzopyrylium (BBp) by employing the nucleophilic addition benzopyrylium perchlorate uorophore and benzaldehyde moiety by means of C=C/C=O group that serves as both uorescence reporting unit. Probe BBp exhibit excellent sensing performance with uorescent "On−Off"rapid response (100 s ) and long-wavelength emission (670 nm).With the treatment of HSO3−, the color of BBp solution obviously varies from purple to colorless, and the uorescent color varies from red to colorless. By the uorescence and colorimetric changes, probe BBp was capable of sensitive determination HSO3-with low limits of detection (LOD) of 0.43 μM, realizing visual quantitative monitoring SO2 derivative levels. Due to the low phototoxicity and good biocompatibility, it was successfully applied to monitor SO2 derivatives and uorescence imaging in HepG2 and HeLa living cells. Hopefully, this work supplies a new strategy for designing NIR uorescent probes for quantitative determination SO2 derivatives in biological samples.

Endogenous sulfur dioxide (SO2), as a gas signal molecule, has a certain physiological functions. Understanding the role of endogenous SO2 in human physiology and pathology is of great significance to the biological characteristics of SO2,which bring challenges to develop fluorescent probes with excellent performance. Herein, we rationally designed and constructed a novel near-infrared bioprobe benzaldehyde-benzopyrylium (BBp) by employing the nucleophilic addition benzopyrylium perchlorate fluorophore and benzaldehyde moiety by means of C=C/C=O group that serves as both fluorescence reporting unit. Probe BBp exhibit excellent sensing performance with fluorescent “On−Off”rapid response (100 s ) and long-wavelength emission (670 nm). With the treatment of HSO3−, the color of BBp solution obviously varies from purple to colorless, and the fluorescent color varies from red to colorless. By the fluorescence and colorimetric changes, probe BBp was capable of sensitive determination HSO3-with low limits of detection (LOD) of 0.43 μM, realizing visual quantitative monitoring SO2 derivative levels. Due to the low phototoxicity and good biocompatibility, it was successfully applied to monitor SO2 derivatives and fluorescence imaging in HepG2 and HeLa living cells. Hopefully, this work supplies a new strategy for designing NIR fluorescent probes for quantitative determination SO2 derivatives in biological samples.