A photostable luminescent iridium(III) complex probe for imaging endogenous mitochondrial sulfur dioxide in living cells.

Sulfur dioxide (SO2) is an important signaling gas molecule, but its aberration is highly associated with inflammatory diseases and cancers. Luminescence probes for SO2 have emerged as essential instruments for elucidating its biological roles and facilitating disease diagnosis, owing to their high sensitivity and capabilities for real-time detection. Nevertheless, the majority of current probes lack subcellular selectivity and suffer from limited photostability. In this work, we develop an Ir(III)-based luminescence probe (Ir3) for the rapid, real-time, and accurate detection of SO2 in aqueous solution. This probe exhibits low cytotoxicity and provides exceptional imaging of mitochondrial SO2 in living cells. We anticipate that this probe will serve as a foundational tool for the advancement of effective imaging technologies for SO2, thereby enhancing the clinical and biomedical applications of Ir(III) complex-based detection probes.