3D printed porous magnesium metal scaffolds with bioactive coating for bone defect repair: enhancing angiogenesis and osteogenesis

In orthopedics, the effective treatment of bone defects remains a major challenge. Magnesium (Mg) metals, with their excellent biocompatibility and favorable osteoconductivity, osteoinductivity, and osseointegration properties, hold great promise for addressing this issue. However, the rapid degradation rate of magnesium restricts its clinical application. In this study, a triply periodic minimal surface (TPMS)-structured porous magnesium alloy (Mg-Nd-Zn-Zr, JDBM) was fabricated using the laser powder bed fusion (LPBF) process. Strontium-doped octacalcium phosphate (SrOCP) and strontium hydrogen phosphate biphasic composite coatings were applied to the surface of the scaffolds. The results showed that the TPMS structure exhibited porous biomimetic characteristics that resemble cancellous bone, promoting vascular ingrowth and new bone formation. Additionally, the SrOCP coating significantly increased the surface roughness and hydrophilicity of the scaffold, which enhanced cell adhesion and osteogenic differentiation. The SrOCP coating also markedly reduced the degradation rate of the JDBM scaffolds while ensuring the sustained release of bioactive ions (Mg²⁺, Zn²⁺, Sr²⁺, and Ca²⁺), thus maintaining the scaffolds' biofunctional activity. Compared to JDBM scaffolds, JDBM/SrOCP scaffolds exhibited better biocompatibility and stronger vascularization and bone regeneration capabilities both in vitro and in vivo. Overall, this study presents a novel strategy for the repair of bone defects using magnesium-based biomaterials, providing new insights for future clinical applications.