NIR sensitive ZnO QDs decorated MXene hydrogel promotes spinal cord repair via tunable controlled release of Zn2+ and regulating ROS microenvironment of mitochondrion

Spinal cord injury (SCI) is one of the most devastating acute diseases. Zn2+ has been verified plays a crucial role in SCI repair, however, how to continuously release zinc ions at the lesion site is still a cutting-edge challenge. Therefore, it is urgent to design a novel nanoplatform for promoting SCI repair with multifunction of controlled release of Zn2+ and regulating ROS microenvironment of mitochondrion. Herein, we propose a protocol of preparing NIR sensitive ZnO quantum dots (QDs) decorated MXene hydrogel for SCI repair. TEM and EDS mapping showed that the ZnO QDs were uniformly distributed on the Mxene nanosheets. Catalase (CAT) analysis showed that the ZnO-Ti3C2 nano enzymes could effectively scavenge ROS. Molecular biology studies showed that ZnO-Ti3C2@H repaired mitochondrial function by scavenging ROS with a clearance rate of up to 80 %. Neuronal apoptosis was subsequently reduced, and nerves and blood vessels were regenerated. NIR irradiation warmed the injury site to 42.9 °C, which enabled rapid enrichment of Zn2+ at the lesion site. Footprinting and pathology experiments have shown that it improves functional recovery after injury and results in near-normal BMS scores. These results suggest that this multifunctional type of material incorporating NIR controlled release of Zn2+ provides a promising strategy for promoting SCI repair.