Dual-site lysosome-targeted fluorescent probe for separate detection of endogenous biothiols and SO₂ in living cells

Biothiols and SO₂ play crucial roles in many physiological and pathological processes. To unravel their complicated interrelationship and cellular cross-talk, it would be highly desirable to develop single-molecule fluorescent probes that can selectively detect biothiols and SO₂via different emission channels. Here, a novel chromenylium derivative, BPO-Py-diNO₂, based on the rational design of dual recognition sites for biothiols and SO₂ selectively and sensitively responded to biothiols with near-infrared fluorescence, and to SO₂ with green fluorescence. The emission shift for the two channels was 170 nm. BPO-Py-diNO₂ was selectively enriched in lysosomes. It could also be used to evaluate dual-channel imaging of endogenous biothiols and SO₂ in living HeLa cells, and it could be used for monitoring the mutual interconversion of biothiols and SO₂.