Cu2+ -Chelatable and ROS-Scavenging MXenzyme As NIR-II-Triggered Blood-Brain Barrier-Crossing Nanocatalyst Against Alzheimer's Disease.

Transition-metal dyshomeostasis has been identified as a critical pathogenic factor for the aggregates of amyloid-beta (Aβ) peptide, which is associated with the onset and progression of Alzheimer's disease (AD). Excessive transition-metal ions, especially copper ion (Cu2+ ), catalyze the formation of reactive oxygen species (ROS), triggering neuroinflammation and neuronal cell apoptosis. Therefore, developing a robust chelating agent can not only efficiently bind toxic Cu2+ , but also simultaneously scavenge the over-generated ROS that is urgently needed for AD treatment. In this work, a 2D niobium carbide (Nb2 C) MXene-based nano-chelator is constructed and its performance in suppressing Cu2+ -induced accumulation of aggregated Aβ peptide and acting as a nanozyme (MXenzyme) with powerful antioxidant property to scavenge excess cellular ROS is explored, and the intrinsic mechanism is revealed by computational simulation. Importantly, the benign photothermal effect of Nb2 C MXenzyme demonstrates the facilitated permeability of the blood-brain barrier under near-infrared laser irradiation, conquering limitations of the most conventional anti-AD therapeutic agents. This work not only demonstrates a favorable strategy for combating AD by engineering Nb2 C MXenzyme-based neuroprotective nano-chelator, but also paves a distinct insight for extending the biomedical applications of MXenes in treating transition-metal dyshomeostasis-and ROS-mediated central nervous system diseases.