Immobilizing magnesium ions on 3D printed porous tantalum scaffolds with polydopamine for improved vascularization and osteogenesis.

Large bone defects remain a worldwide healthy problem needing to be solved. 3D printed tantalum (Ta) scaffolds have enormous potential to repair bone defects and have applied in clinic in recent years. Although the porous structure of 3D printed Ta scaffolds could allow bone ingrowth, the surface property that reactive with surrounding tissue is still unfavorable and thus the early osteointegration is impeded. Magnesium (Mg), a necessary element during bone development, has been reported with effectively osteogenesis and angiogenesis capacity. Hence, in this study, three concentrations of Mg were doped on the surface of 3D printed tantalum scaffolds utilizing the surface adhesion ability of polydopamine (Ta-PDA-Mg) to improve its surface bioactivity. The physiochemical property of resultant Ta-PDA-Mg scaffold was characterized and their osteogenic and angiogenic effects were tested through a serial of experiments both in vitro and in vivo. Results show that Ta-PDA-Mg2 possessed the highest ion release, and all scaffolds showed excellent biocompatibility. The adhesion, angiogenesis and osteogenesis were all improved in Mg doping groups in vitro, while the Ta-PDA-Mg2 exhibited the best performances. Then the in vivo performance was examined through rat femur condyles bone defect model. Results demonstrate that the Ta-PDA-Mg2 significantly enhanced the vascularized bone formation and the osteointegration, which was further confirmed through pull out test. Therefore, Mg doped 3D printed Ta scaffold could improve surface bioactivity and lead to better osteogenesis and angiogenesis, which may provide novel strategy to develop bioactive customized implants in orthopedic applications.