BMP2@PDA-LDH Functionalized Coating on ZK60 Magnesium Alloy: Enhanced Corrosion Resistance and Promoted Bone Defect Regeneration

Magnesium alloys have significant advantages as biodegradable orthopedic implants. However, their rapid degradation in physiological environments and lack of efficient osteointegration severely limit clinical applications. To effectively regulate the degradation rate of ZK60 magnesium alloy and enhance its bone defect regeneration ability, this study employed micro-arc oxidation (MAO) and hydrothermal treatment to create a microporous coating, followed by a layered double hydroxide (LDH) coating to seal the micropores and enhance corrosion resistance. Meanwhile, polydopamine (PDA) modification and BMP2 loading were applied to construct a functional composite coating with both corrosion resistance and osteogenic activity. The corrosion resistance and bone defect regeneration performance were systematically evaluated in vitro and in vivo. Results showed that the LDH coating exhibited a typical layered structure and effectively sealed the MAO coating micropores, forming a dense protective layer. Electrochemical results showed that compared with pristine ZK60, the corrosion current density of BMP2@PDA-LDH/ZK60 decreased from 6.18 × 10 -5 A/cm² to 8.15 × 10 -6 A/cm², indicating the coating significantly retarded the corrosion rate. In vitro and in vivo biological assessments demonstrated that the coating effectively promoted rat bone marrow mesenchymal stem cells (BMSCs) adhesion and bone defect regeneration; specifically, the bone mineral density (BMD) value of the BMP2@PDA-LDH/ZK60 group was 454.25 ± 31.41 mg/cm³, which was 1.44 times higher than that of the LDH/ZK60 group.This study provides a novel strategy for biodegradable magnesium alloys with excellent corrosion resistance and osteogenic potential. • MAO-hydrothermal LDH coating enhances adhesion and corrosion resistance. • PDA stably loaded BMP2 and achieved sustained release. • The functionalized composite coating promoted bone defect regeneration.