Mitochondria-targeted redox-logic carbon dots for in vivo realtime visualization of peroxynitrite during...

Mitochondrial oxidative imbalance is closely associated with inflammation, tissue injury and disease progression, where endogenous thiols and peroxynitrite (ONOO^-) play a competitive dominant role in determining cellular redox status. However, this process is hindered by the fact that ONOO^- has an ultrashort half-life (10-20 ms), is spatially heterogeneous, and exhibits antagonistic interplay with glutathione (GSH). Existing fluorescent nanoprobes rely on irreversible mechanisms and are unable to capture the net redox balance. Herein, a novel approach for the in vivo visualization of ONOO^- is presented using near-infrared mitochondria-targeted silicon-doped carbon dots (Si-Mito CDs) as a redox-logic nanoprobe. Si-Mito CDs demonstrate excellent mitochondrial colocalization (Pearson coefficient: 0.92), exhibit a sensitive response to GSH (0-10 μM) and ONOO^- (0-100 μM), and successfully detects endogenous mitochondrial ONOO^- elevation (fluorescence intensity nearly doubled) in LPS/IFN-γ-stimulated HepG-2 cells, with signal suppression upon TEMPO treatment confirming specificity. Importantly, real-time zebrafish tail amputation imaging revealed fluorescence enhancement peaking at 5 min post-injury, followed by gradual decline, which directly reflected spatiotemporal ONOO^-/GSH fluctuation dynamics. This work establishes a novel reversible sensing platform for elucidating wound healing mechanisms and guiding therapeutic interventions.