医用镁合金表面梯度纳米复合涂层的界面强化、降解机制与生物相容性

镁基骨植入材料在服役过程中的降解速率过快是实现其临床应用的主要瓶颈。对镁基体成分及涂层结构进行优化设计是解决降解“析氢”问题，并兼顾涂层结合强度和生物相容性的关键。本项目针对非晶镁合金表面水热反应生成致密ZnO层的实验现象展开深入研究，利用SEM、AFM和三维重构技术对Mg-Zn-Ca合金表面Ca-P/聚合物双涂层的界面结构与形貌特征进行显微分析，结合反应热力学和动力学分析，阐明特定镁基成分与水热反应条件对Ca-P涂层结构的影响规律；同时，采用有限元方法研究涂层的力学行为，通过体外降解、细胞毒性、细胞贴壁和动物体内植入等实验方法评估涂层的降解行为和生物相容性，从而揭示预涂层梯度结构的界面强化机制、复合涂层多孔结构的降解调控机制和骨诱导作用机制。通过本研究，将有望提出基于镁基成分控制与涂层结构设计的梯度纳米复合涂层的制备新方法，为开发可降解医用镁合金及其表面改性技术提供科学依据。

Owing to the serious fast decomposing and releasing hydrogen problems in the application of magnesium alloy bone implant, It is very important to optimize the chemical composition of the magnesium matrix and the microstructure of its surface coating in order to improve the overall mechanical properties and biocompatibility and acheive the stable, controllable decomposition of medical magnesium alloy. .In this project, profound and systematic study on fabricating gradient nanocomposite coating on medical Mg-Zn-Ca alloy will be performed. The microstructure and three-dimensional morphology of the coating and the interfacial relationship between coating and matrix will be analyzed by using SEM (Scanning Electron Microscopy), AFM (Atomic force Microscopy) and reconstruction technique based on the serial-sections method. And thermodynamic and dynamic analysis methods will be employed to explore the effect of special matrix composition and hydrothermal reaction on the formation of gradient Ca-P compound coating. Meanwhile, the finite element calculation will be employed to evaluate the mechanical properties and reveal the interfacial strengthening mechanism of the composite coating. Subsequently, in vitro decomposition test will be performed to reveal the effect of porous structure on decomposing process of magnesium bone support. And the cytotoxicity test, cell adhesion test and in vivo animal experiment will be used to evalute the biocompatiblity and reveal the osteoinduction mechanism of nanocomposite coating with porous structure..This study would be expected to propose a novel method for fabricating gradient nanocomposite coating based on chemical composition control of matrix and the interfacial structure design, thus to provide scientific basis for developing medical magnesium alloy and its surface modification technique.