Alzheimer’s disease (AD) is the most common neurodegenerative disease in the world. The pathogenesis of AD is associated with β-amyloid (Aβ) fibrillation. Nanoparticles have large surface area and can access the brain. But no investigation has been made to study the relationship between nanoparticles and AD. In our study, we observed Aβ fibril formation in the presence of six kinds of nanoparticles and found that TiO 2 nanoparticles can promote Aβ fibrillation by shortening nucleation process, which is the key rate-determining step of fibrillation. Hereby the interaction between Aβ and nanoparticles may contribute to AD etiology.