Multi-functional copper-based nanoenzyme system with antioxidant, ferroptosis inhibition for traumatic brain injury

Traumatic brain injury (TBI) is a major global health issue, causing blood–brain barrier disruption, neuroinflammation, and neuronal damage. Current therapies are limited and failed to address key pathological mechanisms like ferroptosis, oxidative stress, and inflammation, highlighting the need for novel treatments. Recent advances in nanomedicine, particularly nanozymes, offer promising solutions. Copper-based ultrasmall nanozymes, with excellent catalytic activity and biocompatibility, have shown potential in mitigating ferroptosis and oxidative stress. In this study, we developed polyethylene glycol-modified Cu 5.4 O (Cu 5.4 O-PEG), a nanomaterial with superior blood–brain barrier penetration and biocompatibility. Cu 5.4 O-PEG demonstrated no cytotoxicity and significantly reduced oxidative stress and ferroptosis in both in vitro and in vivo models, improving motor and cognitive functions in murine TBI models. The therapeutic effects were mediated through multiple mechanisms, including inhibition of the Fenton reaction, scavenging of reactive oxygen species (ROS), and reducing iron deposition, effectively limiting tissue damage. Proteomic analysis revealed modulation of ferroptosis-related proteins and activation of protective pathways related to transferrin receptor 1 (TfR1). Furthermore, using AAV-mediated knockdown of TfR1 in mice, we observed significant reductions in lipid peroxidation markers such as ACSL4, COX2, and 4HNE, indicating a decrease in iron-induced damage. Histological analysis showed reduced iron deposition, and improved neuronal morphology in TfR1 knockdown mice underwent TBI, indicating knockdown of TfR1 could alleviate TBI-indued ferroptosis and iron-dependent neurodegeneration. Taken together, these data imply that Cu 5.4 O-PEG presents a neuroprotective strategy for improving cerebral recovery after TBI, at least partly by inhibiting TfR1-mediated ferroptosis.