Lysosome-Targeted Single Fluorescence Probe for Two-Channel Imaging Intracellular SO₂ and Biothiols

As the members of reactive sulfur species, SO₂ and biothiols play a significant role in physiological and pathological processes and directly influence numerous diseases. Furthermore, SO₂ and biothiols can provide a reductive environment for lysosomes to carry out their optimal functionality. To this end, the development of single fluorescent probes for imaging SO₂ and biothiols from different emission channels is highly desirable for understanding their physiological nature. Here, a lysosome-targeted fluorescent probe (BPO-DNSP) with a dual reaction site for SO₂ and biothiols was presented. BPO-DNSP can sensitively and selectively respond to SO₂ in the green channel with a large Stokes shift over 105 nm, and to biothiols in the near-infrared emission channel with a large Stokes shift over 109 nm. The emission shift for the two channels was as high as 170 nm. Colocalization experiments verified that BPO-DNSP can selectively enrich lysosomes. Notably, BPO-DNSP can not only be used to image intracellular SO₂ and biothiols from two different channels, but also to monitor the conversion of biothiols to SO₂ without adding exogenous enzymes in living HeLa cells.