A multi-route chemiluminescent probe for real-time imaging of β-amyloid pathology in Alzheimer's disease.

Chemiluminescence imaging has emerged as a promising approach for β-amyloid (Aβ) detection, offering unique advantages such as excitation-free operation, high signal-to-noise ratio, deep tissue penetration, and cost-effectiveness. Here, we designed a series of chemiluminescent probes (BH-4, C-4, DJ-4, and EYA-4) based on the imidazo[1,2-α]pyrazin-3-(7H)-one scaffold. Through systematic in vitro characterization-including spectroscopic analysis, log P determination, and quantum yield evaluation-probe DJ-4 was identified as the optimal candidate. This probe exhibited exceptional selectivity toward Aβ1-42 aggregates, demonstrating a 125-fold signal enhancement in phosphate-buffered saline (PBS) and 10.5-fold in brain homogenate. In Alzheimer's disease (AD) mouse brain sections, DJ-4 effectively labeled Aβ plaques with strong colocalization to 6E10 antibody staining (Pearson's r = 0.89). Crucially, DJ-4 enabled real-time monitoring of cerebral Aβ dynamics via multiple administration routes (intravenous, intraperitoneal, and intranasal), achieving a greater than 1.8-fold contrast between APP transgenic and wild-type mice. These findings highlight its potential for early AD diagnosis and longitudinal disease progression tracking.