Bioactive Zn ingredients endow Ti-Zn composites with exceptional mechanical and osteogenic properties as biomedical...

Titanium-based (Ti-) alloys are promising materials as bioimplants with superior mechanical properties and excellent biocompatibility. However, their bioinertia and high elastic moduli are not comparable to natural bone tissue; thus, novel Ti alloys with good biomechanical adaptation and high bioactivity are desired. Zinc (Zn) is recognized for ideal biodegradability and its biological effects can be considered to endow pure Ti with rewarding bio functions. Herein, this study has employed a designed spark plasma sintering (SPS) procedure to effectively diffuse varying amounts of Zn into pure Ti as bioactive ingredients and generate novel TiZn composites as bone defect implants. The as-sintered TiZn samples feature a gradient core-shell structure, achieving a match of high strength and low elastic moduli to satisfy the load-bearing requirements while avoiding the stress-shielding effect. A moderate degradation of the Zn component allows TiZn materials to maintain stable mechanical support and exhibit satisfactory cytocompatibility. Ti20Zn, Ti30Zn, and Ti90Zn are confirmed to exert antibacterial and osteogenic abilities by in vitro experiments. Further analyses of in vivo implantation in the rat femur show they exhibit qualified biosafety and are superior to pure Ti in treating bone defects through bio-friendly Zn ions release. This study achieves a reasonable combination of the mechanical properties of pure Ti and the biological functions of pure Zn, providing a better choice for bone injury and fracture treatment.