Preparation And Performance Study Of Partially Degradable Magnesium-titanium Composite Materials

Objective: Magnesium and magnesium alloys can be degraded in physiological environments and promote new bone formation.However,their application as bone repair materials is limited due to the rapid deterioration of mechanical properties during the degradation process.Although titanium and its alloys have excellent biocompatibility,they lack sufficient bioactivity.To address the issue of trade-off between mechanical and biological properties,these two materials can be prepared into a composite material,which is expected to combine magnesium’s osteogenic properties with titanium’s mechanical properties to better promote bone growth in vivo.In this study,we used a method of infiltrating pure magnesium melt into a 3D printed titanium scaffold without pressure to prepare magnesium-titanium composite materials and demonstrated their potential as a new type of partially degradable bioactive implant material.Methods: In this study,magnesium-titanium composite materials were prepared using a 3D printing and melt infiltration method.The elemental composition of the composite material was evaluated by X-ray diffraction(XRD),the surface morphology of the composite material was evaluated by scanning electron microscopy(SEM)and energydispersive X-ray(EDX)spectroscopy,and the volume of each component and internal structure of the composite material was evaluated by three-dimensional volume rendering using X-ray diffraction topography(XRT).The degradation behavior of the magnesium-titanium composite material was evaluated through electrochemical and immersion experiments.The mechanical properties of pure magnesium,magnesium alloys,and magnesium-titanium composite materials were evaluated by ambient temperature compression and three-point bending experiments,and SEM images were taken during dynamic compression at different strains to analyze the dynamic compression changes of the composite material.MC3T3-E1 cells were cultured in extracts of pure magnesium,magnesium alloys,and magnesium-titanium composite materials,and cell proliferation and toxicity were detected using CCK 8 assay.In vivo biological evaluation of pure magnesium and magnesium-titanium composite materials was performed through New Zealand white rabbit bone defect implantation experiments for 2 and 8 weeks.Results: In terms of material characterization,the study successfully prepared magnesium-titanium composite materials,with a phase composition of Mg and Ti,and no presence of oxygen elements.The composite material is topologically dualcontinuous and is dispersed in three-dimensional space.In terms of mechanical properties,the magnesium-titanium composite material exhibited higher strength than its components in compression and three-point bending experiments.The composite material’s Young’s modulus,calculated using the Nielsen method,was closer to that of bone.In terms of degradation performance,the degradation rate of the composite material was higher than that of pure magnesium and the compound,but did not exceed the required magnesium element content for the human body in electrochemical and immersion experiments.In terms of biocompatibility,in Cell Counting Kit 8(CCK 8)experiments,the magnesium-titanium composite material showed no cell toxicity to mouse embryonic preosteoblast cells(MC3T3-E1)during a 3-day degradation process.The composite material group showed better osteogenic performance in the animal experiment after 8 weeks.Conclusion: A locally degradable material,magnesium-titanium composite material,was successfully prepared.The degradation of the magnesium phase can induce the formation of new bone tissue and grow into the titanium scaffold,achieving mechanical interlocking between titanium and bone.During this process,the titanium scaffold provides stable and permanent support,and the Young’s modulus adapts to the direction of the bone and decreases.In vitro and in vivo experiments showed that the extract of the composite material was alkaline,showed the degradation trend of the composite material,and had no cell toxicity.Although the degradation rate of the composite material was higher than that of pure magnesium,no significant adverse reactions were observed during the implantation period,and the composite material showed good osteogenesis.This study provides new possibilities for the combination of mechanical durability and biological activity of medical materials and supports the processing of functional implants with precision structures according to personalized needs.