FIRST PRINCIPLES DESIGN OF DEGRADABLE MG ALLOYS FOR BONE REGENERATION

用于骨再生的可降解镁合金的第一性原理设计

• 批准号: 7723341
• 负责人: Min Gao
• 金额: $ 0.05万
• 依托单位: CARNEGIE-MELLON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7723341
• 关键词: Alloys; Biocompatible Materials; Bone Growth; Bone Regeneration; Bone Tissue; Chloride Ion; Chlorides; Computer Retrieval of Information on Scientific Projects Database; Corrosion; Development; Electronics; Elements; Environment; Fracture; Funding; Grant; Hand; Human; Indium; Inflammatory; Institution; Ions; Lead; Length; Magnesium; Mechanics; Metabolism; Numbers; Osteogenesis; Phase; Physiological; Process; Property; Rate; Reaction; Research; Research Personnel; Resources; Screening procedure; Solubility; Source; Stainless Steel; Structure; System; Thermodynamics; Tissues; Titanium; United States National Institutes of Health; base; bone; cold temperature; density; design; interest; particle; poly(lactic acid); scaffold; size; solid solution; theories; tool; vasodilator-stimulated phosphoprotein

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. For bone regeneration, a key issue is to build a degradable scaffold that has appropriate mechanical strength during bone regeneration and suitable degradation rate (i.e., degradation of scaffold matching bone formation in the scaffold). It also must have a large size (a length of 10-15cm) and are easy to be processed. At present, polymeric scaffolds, such as poly lactic acid, degrade simultaneously in the whole scaffold, and lead to the scaffold collapse before the accomplishment of bone regeneration. On the other hand, commonly used metallic biomaterials including stainless steels and titanium alloys can release toxic metallic ions and/or particles through corrosion or wear processes, which cause inflammatory cascades and tissue loss. Further, these metallic biomaterials have much higher elastic moduli than natural human bones, and consequently, they can cause reduced stimulation of new bone growth. The proposed project will concern Mg-based alloy for bone regeneration. Pure magnesium has low density and is exceptionally lightweight. It has high fracture toughness, and it is essential to human metabolism and is naturally found in bone tissue. But, pure magnesium corrodes too fast in the physiological pH (7.47.6) and high chloride environment of the physiological system, and is not appropriate for bone regeneration. Therefore, there is urgent need to develop Mg-based alloys that can degrade at a rate comparable to the rate of bone formation in the scaffold. Further, the as-sought Mg alloys must have elastic moduli that are as close as possible to that of human bones and sufficient strength. Lastly, the toxic elements in the Mg alloys must be strictly controlled. These will be served as the screening tools for alloy development. The VASP package that solves for the electronic band structure using electronic density functional theory will be used in this project to calculate electronic structure and accordingly the elastic and thermodynamic properties of various Mg-based alloys. A number of potential alloying elements such as Al, Li, Zn, Y, La, Ce, Ag etc. will be considered. The phase stability of Mg-based binary, ternary and higher-order systems including solubility prediction will all be calculated at the low temperature limit. The elastic properties (e.g. Youngs modulus, yield strength, Poisson ratio) of both solid solution of hcp (hcp=hexagonal close packed) Mg alloys and the very Mg-rich compounds of multi-component system will be one focus of this project. The other focus will concern the possible reactions when the alloy in interest is in the electrolytic physiological environment. To begin with, only H2O and Cl- ions will be considered at the low temperatures limit.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 对于骨再生，关键问题是构建可降解支架，其在骨再生期间具有适当的机械强度和合适的降解速率（即，与支架中骨形成匹配的支架降解）。它还必须具有大尺寸（10- 15 cm的长度）并且易于加工。目前，以聚乳酸为代表的高分子支架在整个支架中同时降解，导致支架在骨再生完成之前发生坍塌。另一方面，常用的金属生物材料，包括不锈钢和钛合金，可通过腐蚀或磨损过程释放有毒金属离子和/或颗粒，导致炎症级联反应和组织损失。此外，这些金属生物材料具有比天然人骨高得多的弹性模量，因此，它们可导致对新骨生长的刺激降低。该项目将涉及用于骨再生的镁基合金。纯镁具有低密度和非常轻的重量。它具有高断裂韧性，是人体新陈代谢所必需的，天然存在于骨组织中。但是，纯镁在生理系统的生理pH（7.47.6）和高氯化物环境中腐蚀太快，不适合骨再生。因此，迫切需要开发能够以与支架中骨形成速率相当的速率降解的镁基合金。此外，所寻求的镁合金必须具有尽可能接近人骨的弹性模量和足够的强度。最后，必须严格控制镁合金中的有毒元素。这些将作为合金开发的筛选工具。在本项目中，将使用使用电子密度泛函理论求解电子能带结构的VASP软件包来计算各种镁基合金的电子结构以及相应的弹性和热力学性质。将考虑许多潜在的合金元素，例如Al、Li、Zn、Y、La、Ce、Ag等。镁基二元、三元和高阶体系的相稳定性，包括溶解度预测，都将在低温极限下计算。hcp（hcp=六方密排）镁合金固溶体和富镁多元系化合物的弹性性能（如杨氏模量、屈服强度、泊松比）将是本项目的重点之一。另一个焦点将关注当感兴趣的合金在电解生理环境中时可能的反应。开始，在低温限值下仅考虑H2O和Cl-离子。