A sodium phytate–ethyl cellulose coating with sustained oleoyl serine release enables spatiotemporal osteoimmune regulation of magnesium implants

promotes osteoblast differentiation and mineralization, inhibits osteoclast activation, and induces macrophage polarization toward the M2 phenotype, achieving immune regulation-driven bone regeneration. In vivo validation of the femoral defect model in rats has shown that Mg-SP-EC-OS implants induce macrophage polarization toward the M2 phenotype through immune regulation, significantly promote new bone formation, reduce bone-implant interface cavities, and maintain excellent systemic biosafety. This multifunctional coating combines corrosion resistance, immunomodulation, and spatiotemporal osteogenic effects, achieving spatiotemporally controlled degradation aligned with the bone healing process. It provides a viable strategy for developing a new generation of degradable magnesium-based orthopedic implants.