Polycarbonate-hydroxyapatite hybrid coatings enabling antibacterial and osteogenic regulation of magnesium implants

Magnesium-based implants hold great promise for orthopedic applications; however, their clinical translation is severely hindered by rapid corrosion and insufficient biological functionality. Herein, we report a multifunctional organic-inorganic hybrid coating constructed by integrating catechol-functionalized photo-crosslinkable polycarbonates with guanidine- and phenylboronic acid-modified hydroxyapatite nanoparticles on magnesium alloy substrates. The resulting hybrid coating forms a stable surface-eroding barrier, effectively suppressing rapid degradation while maintaining long-term interfacial integrity. Benefiting from the combined contribution of guanidyl functionalities and redox-active catechol/phenylboronic acid-containing structures, the coating exhibits potent antibacterial activity against Staphylococcus aureus and Escherichia coli and effectively reduces intracellular reactive oxygen species (ROS) levels. Meanwhile, the incorporation of bioactive hydroxyapatite promotes mineralized matrix deposition and osteogenic differentiation. This multifunctional coating establishes a favorable interfacial microenvironment integrating corrosion protection, antibacterial activity, oxidative stress regulation, and osteogenic stimulation, providing a versatile strategy for enhancing the biological performance of magnesium-based orthopedic implants.