Abnormal accumulation of β-amyloid (Aβ) peptide aggregates in the brain is a major hallmark of Alzheimer's disease (AD). Aβ aggregates interfere with neuronal communications, ultimately causing neuronal damage and brain atrophy. Much effort has been made to develop AD treatments that suppress Aβ aggregate formation, thereby attenuating Aβ-induced neurotoxicity. Here, the design of Aβ nanodepletors consisting of ultralarge mesoporous silica nanostructures and anti-Aβ single-chain variable fragments, with the goal of targeting and eliminating aggregative Aβ monomers, is reported. The Aβ nanodepletors impart a notable decline in Aβ aggregate formation, resulting in significant mitigation of Aβ-induced neurotoxicity in vitro. Furthermore, stereotaxic injections of Aβ nanodepletors into the brain of an AD mouse model system successfully suppress Aβ plaque formation in vivo up to ≈30%, suggesting that Aβ nanodepletors can serve as a promising antiamylodoisis material.aged 65 and older are living with AD, [4] which accounts for an estimated 60-80% of dementia.Accumulation of extracellular β-amyloid (Aβ) plaques and intracellular tau proteinderived neurofibrillary tangles are major hallmarks of Alzheimer-associated brain damages in AD patients. These features are being explored from the perspective of pathological diagnosis and clinical treatment of AD. [5,6] Aβ monomers, which are derived from the cleavage of amyloid precursor protein by βand γ-secretase, [7] assemble into toxic Aβ oligomers and aggregates having cross β-sheet-rich secondary structures that induce neuronal damages. [8][9][10][11] Ultimately, the self-assembly process leads to the deposition of amyloid plaques, a strong and stable network that is difficult to break. Hence, removing monomeric Aβ at the early stage of dementia is thought to be a promising strategy for slowing the progression of AD. [12][13][14][15][16] Here, we report an Aβ-depleting nanostructure (denoted hereafter as Aβ nanodepletors) that can selectively capture and clear Aβ peptide monomers in brain (Scheme 1).