Self-adaptive copper-enriched Prussian blue nanozymes for cascade ROS scavenging and neurofunctional recovery in cerebral ischemia-reperfusion injury.

Ischemic stroke (IS) and the subsequent reperfusion induce severe oxidative stress and mitochondrial dysfunction through the excessive generation of reactive oxygen species (ROS). However, most existing therapeutic strategies target only a single pathological pathway, thereby limiting their therapeutic efficacy. Herein, we developed a multifunctional mesoporous copper-enriched Prussian blue nanozyme (Meso-Cu-PBMc) by synergistically integrating Cu2+ active sites within a Prussian blue framework, exhibiting robust multi-enzymatic mimetic activities, including superoxide dismutase (SOD)-, catalase (CAT)-, and peroxidase (POD)-, facilitating efficient ROS scavenging and the restoration of intracellular redox homeostasis. In vitro studies demonstrated that Meso-Cu-PBMc effectively protects neuronal cells against CoCl2-induced oxidative injury and significantly reduces intracellular ROS accumulation. In a middle cerebral artery occlusion/reperfusion (MCAo/R) rat model, intranasal administration of Meso-Cu-PBMc (20 mg kg-1) at the onset of reperfusion markedly reduced infarct volume from 54.32% to 13.03%, significantly improved neurological function, and enhanced locomotor recovery in a dose-dependent manner. Mechanistically, the nanozyme exerted dual therapeutic effects through both direct ROS scavenging and activation of the Nrf2/xCT/GPX4 antioxidant signaling pathway, thereby maintaining glutathione homeostasis and cellular redox balance. Furthermore, treatment restored the expression of brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95), increased the levels of SIRT1 and PGC-1α, and reduced the expression of GFAP and iNOS, indicating the preservation of neuronal plasticity and mitochondrial homeostasis, together with the attenuation of reactive gliosis. Collectively, these findings highlight Meso-Cu-PBMc as a promising therapeutic platform for the treatment of ischemia-reperfusion injury and other oxidative stress-associated neurological disorders.