Ultrasmall superparamagnetic iron oxide nanoparticles-bound NIR dyes: Novel theranostic agents for Alzheimer's disease

Aggregation of the beta-amyloid peptide between nerve cells (neurons) in the brain leading to memory loss and progressive cognitive disability is thought to initiate Alzheimer's disease. Evidences indicate that the onset and progression of AD is associated with beta-amyloid fibrillation and amyloid-related changes particularly the formation of neurotoxic oligomers may appear 10-20 years before the cognitive deficits become evident. In this study, ultrasmall superparamagnetic iron oxide nanoparticles coupled to a phenothiazine-based near-infrared (NIR) fluorescent dye have been developed and evaluated as novel theranostic agents for AD. They can simultaneously perform in vivo NIR fluorescence and magnetic resonance imaging of A beta plaques in the brain of double transgenic mice, prevent A beta aggregation, disaggregate preformed A beta fibrils and play a protective effect on the toxicity of human neuroblastoma cells induced by A beta(1-42).