Acute traumatic brain injury (TBI) is often accompanied by excessive mitochondrial hypochlorite (ClO
?) production, which contributes to neuroinflammation and secondary damage. However, deep-red mitochondria-targeted probes validated for in vivo imaging in TBI models remain limited. In this study, we developed a mitochondria-targeted deep-red cyclometalated iridium(III) phosphorescent probe,
Mito-Ir-HClO, for ClO
? detection. The probe showed good photostability and long-lived luminescence, responded to ClO
? within 3?min, and achieved a detection limit of 0.45?μM with satisfactory selectivity. Theoretical calculations combined with spectroscopic studies elucidate the sensing mechanism: the selective oxidation of the imine bond (C
N) by ClO? activates phosphorescence.
Mito-Ir-HClO enabled imaging of mitochondrial ClO
? in microglia (BV-2 and HMC3).
Mito-Ir-HClO was further applied to in vivo imaging in a TBI mouse model, allowing dynamic visualization of mitochondrial ClO
? changes during neuroinflammation. These results provide a useful strategy for the design of ClO
? probes and support the application of this probe in visualizing ClO
?-related changes in TBI.
