A quinoline-based probe for the ratiometric fluorescent detection of sulfite in lysosomes of living cells.

[Display omitted] • A quinoline-based sensor for the ratiometric detection of HSO 3 − in an almost pure aqueous solution has been developed. • The sensor could be utilized to detect endogenous and exogenous HSO 3 − in the lysosomes of living C6 glioma cells. • The sensor could detect HSO 3 − in real water samples with good application value. A lysosome-targeting ratiometric fluorescent probe was synthesized for detecting sulfite based on sulfite-triggered nucleophilic addition reaction. Due to the specific reaction, the fluorescence intensity ratio (I 530 / I 390) of the probe in an almost aqueous solution (0.5% DMSO) changed significantly after the addition of HSO 3 −, corresponding to the change in the fluorescence color of the solution from green to blue. The recognition was conducted using high-resolution mass spectrometry, proton nuclear magnetic resonance, and density functional theory calculations. The fluorescent probe could be utilized to quantitatively monitor HSO 3 − in lysosomes of living C6 glioma cells and real-water samples. [ABSTRACT FROM AUTHOR]