A blood-brain barrier-penetrating NIR fluorescent probe enables cross-model optical imaging of H2O2 in three neuroinflammation-related experimental mice models of brain injury.

BACKGROUND: Hydrogen peroxide (H2O2) is a key mediator of oxidative stress in neuroinflammation-related brain injury, yet brain H2O2 imaging remains challenging because of the blood-brain barrier (BBB) and tissue autofluorescence. In addition, most reported probes have been evaluated in only one or a few disease models, limiting cross-model comparison. Here, we developed MH-1, an H2O2-responsive near-infrared (NIR) fluorescent probe for brain-section optical mapping after systemic administration.

RESULTS: MH-1 exhibited an approximately 60-fold fluorescence turn-on at 667 nm, enabled H2O2 detection over 0.107-1000 μmol/L, and reached a stable response within approximately 30 min, with high selectivity, interference resistance, pH stability, and low cytotoxicity. Its fluorescence quantum yield increased from 0.72% to 2.45% upon activation. CD31 co-staining confirmed MH-1-associated fluorescence in extravascular brain parenchyma after systemic administration. Ex vivo brain-section imaging further revealed model-dependent H2O2-associated fluorescence in LPS-induced neonatal neuroinflammation, hypoxic-ischemic encephalopathy (HIE), and Alzheimer's disease (AD), with an effective imaging window of approximately 12 h.

SIGNIFICANCE: Rather than relying on a single best-in-class analytical parameter, MH-1 integrates NIR emission, a large fluorescence turn-on, BBB access, and applicability across three mechanistically distinct brain-injury models. This combined performance enables region-resolved, cross-model comparison of H2O2-associated oxidative stress in preclinical brain tissue.