Gold Nanoparticles as a Probe for Amyloid-β Oligomer and Amyloid Formation

The process of amyloid-beta (A beta) amyloid formation is pathologically linked to Alzheimer's disease (AD). The identification of A beta amyloids and intermediates that are crucial players in the pathology of AD is critical for exploring the underlying mechanism of A beta aggregation and the diagnosis of the disease. Herein, we performed a gold nanoparticle (AuNP)-based study to detect the formation of A beta amyloid fibrils and oligomers. Our results demonstrate that the intensity of the surface plasmon resonance (SPR) absorption band of the AuNPs is sensitive to the quantity of A beta 40 amyloids. This allows the SPR assay to be used for detection and semiquantification of A beta 40 amyloids and characterization of the kinetics of A beta amyloid formation. Furthermore, our study demonstrates that the SPR band intensity of the AuNPs is sensitive to the presence of oligomers of A beta 40, and an A,840 mutant which forms more stable oligomers. The kinetics of the stable oligomer formation of the A beta 40 mutant can also be monitored following the SPR band intensity change of AuNPs. Our results indicate that this nanoparticle-based method can be used for mechanistic studies of early protein self-assembly and fibrillogenesis.