Incorporating Cu(II) to Biodegradable Mg Surface via Schiff Base Covalently Grafted UiO-66-NH₂ Coating for...

Magnesium (Mg)-based implant materials exhibit unique biodegradable properties, but their excessively rapid corrosion leads to compromised mechanical performance, reduced biocompatibility, and insufficient capability to meet multifarious clinical demands. Herein, this work developed a multifunctional coating that both addresses corrosion protection and enables multifunctional applications. A facile Cu(II)-incorporated coating system through Schiff base covalently grafted UiO-66-NH₂ is constructed onto Mg surface for synergistic integration of corrosion control and biofunctionalization. The Cu(II) active sites contribute to biocatalytic reactions and antibacterial action, which can catalyze the decomposition of S-nitrosoglutathione (GSNO) to release NO (1.7 × 10^-7 mol cm^-2 min^-1) for vasodilation, effectively decompose H₂O₂, and scavenge reactive oxygen species (ROS) to alleviate oxidative stress (catalytic decomposition and removal efficiency exceed 60%), as well as demonstrate superior antibacterial efficacy against both E. coli and S. aureus (over 99.9% inhibition rates). Moreover, the coating remarkably retards Mg corrosion and significantly improves cytocompatibility and hemocompatibility of Mg surface. Simultaneous control of Cu²⁺ and Mg²⁺ ions release on the surface microenvironment facilitates biochemical effect on osteoblast differentiation ability (gene expression of RUNX2 + 356% and OCN + 223%). This work opens up a feasible route of developing a multipurpose surface modification strategy incorporating metal active sites to Mg surface for customized functions.