可降解镁合金的关键基础科学问题

In comparison to the traditional bio-inert biomedical metallic materials, biodegradable magnesium alloy is easily bio-corroded by the body fluid, and it interact dynamically with the host throughout its implantation period until a complete degradation. Corresponding key scientific issues are the chemical, biological and mechanical interaction mechanisms between biodegradable Mg alloy and its host. The purpose of the present work is to develop new kinds of biodegradable Mg alloys with the elements of Zn, Ca, Cr and Si as alloying elements/ surface coating components, which exhibit the special stimulation effect on the formation of new bone. After controlling the microstructure/substructure and mechanical property of the resulting materials, we will investigate the biocorrosion/biodegradation behavior and the ion release procedure, and evaluate the in vitro and in vivo biocompatibility and biosafety of the experimental materials, and reveal the evolution of the mechanical property of the materials with the implantation time inside the host. Furthermore, the chemical and biological interactions between biocorrosion products of the materials and the host will be studied on the molecule, cell and animal levels, and the transport and metabolism mechanism of the biocorrosion products inside the host body will be investigated. Finally the outcome of the present work will give a guideline on the optimization of the chemical composition and surface modification technology of the experimental Mg alloys with the controllable biodegradation rate and uniform biodegradation mode and the realized biological effects of the metal elements, and the optimal Mg alloy materials would biodegrade gradually matching perfect with the reconstruction of the tissue and the organ in the time, space and biofunctions. The results of the present work will provide new idea for the future development of biodegradable metallic materials.

与传统惰性医用金属相比，医用镁合金易被体液腐蚀，在植入机体后将全周期地与机体发生动态相互作用，直到完全降解；相应的亟待研究的关键科学问题是材料与机体之间的化学、生物学和力学相互作用机制。项目选择对新骨形成过程各阶段具有特异刺激效应的锌、钙、锶、硅作为镁的合金化/涂层元素，设计新型医用镁合金及表面涂层结构，调控其组织结构与力学性能，研究其降解行为和离子溶出过程，对其生物相容性做体外和体内综合评价，揭示其力学性能随降解时间的退化规律，从分子、细胞和动物水平探明其降解产物与机体之间的化学与生物学作用机制，研究降解产物在体内的转运与代谢机制，建立起最佳镁合金成分和表面改性工艺参数与其体内降解行为之间的对应关系，实现可控降解速度和均匀降解模式，发挥降解所释放出元素的生理学功效，使得在机体完成组织修复的过程中镁合金植入物的降解过程在时间、空间和生物功能上完美匹配，为发展可降解医用金属材料提供新思路。

与传统惰性医用金属相比，医用镁合金易被体液腐蚀，在植入机体后将全周期地与机体发生动态相互作用，直到完全降解；相应的亟待研究的关键科学问题是材料与机体之间的化学、生物学和力学相互作用机制。项目选择了对新骨形成过程各阶段具有特异刺激效应的锌、钙、锶、硅作为镁的合金化/涂层元素，设计了新型医用镁合金及表面涂层结构，调控其组织结构与力学性能，建立了适合骨内植入要求的可降解镁合金其合金成分、加工及热处理工艺、显微组织、表面结构与相组成、力学性能、降解性能、生物医学特性之间的内在联系，研究了其降解行为和离子溶出过程，对其生物相容性进行了体外和体内综合评价，揭示其力学性能随降解时间的退化（应力腐蚀和腐蚀疲劳）规律，从分子、细胞和动物水平探明了其降解产物与机体之间的化学与生物学作用机制，研究了降解产物在体内的转运与代谢机制，建立了最佳镁合金成分和表面改性工艺参数与其体内降解行为之间的对应关系，实现可控降解速度和均匀降解模式，发挥降解所释放出元素的生理学功效，使得在机体完成组织修复的过程中镁合金植入物的降解过程在时间、空间和生物功能上完美匹配，为发展可降解医用金属材料及其表面功能涂层提供了新思路。基于对可降解金属的理解，提出了可降解金属的双重筛选标准：生物可降解能力和生物相容性，并根据该标准对适合作为可降解金属的合金元素进行选择，并提出未来可降解金属的发展方向。