Near-Infrared Chemiluminescence Probe for Superoxide Anion Imaging in Alzheimer's Disease

Alzheimer's disease (AD) has a complex pathogenesis in which superoxide anion (O₂^•-), a key reactive oxygen species (ROS), plays a critical role. Monitoring O₂^•- is essential for understanding AD mechanisms and improving early diagnosis. Chemiluminescence imaging provides high contrast without external excitation, making it ideal for in vivo O₂^•- detection. However, few probes can specifically image O₂^•- in the AD brain. To address this, we designed a chemiluminescence probe, DIP-O, for in vivo O₂^•- imaging in AD. In vitro tests showed that DIP-O emits in the near-infrared region (708 nm) with a tissue penetration depth over 2.0 cm, high sensitivity (LOD = 27.9 nM), and excellent specificity for O₂^•-. We validated its imaging performance in peripheral inflammation models (e.g., arthritis and peritonitis), where it enabled real-time, high-contrast tracking of O₂^•-. Furthermore, DIP-O successfully crossed the blood-brain barrier and distinguished O₂^•- levels in the brains of three-month-old AD mice versus wild-type mice, indicating early diagnostic potential. Finally, we applied DIP-O to monitor age-dependent O₂^•- changes in AD mice, demonstrating its capability for sensitive imaging throughout disease progression.