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.