AZ31B镁合金表面改性及医用基础研究

IMR OpenIR

	AZ31B镁合金表面改性及医用基础研究
	王强
学位类型	博士
导师	杨柯 ; 谭丽丽
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	镁合金表面改性生物降解生物学性能 Magnesium Alloys Surface Modification Biodegradation Biological Property
摘要	"镁及镁合金因其优异的生物相容性、综合力学性能及可降解性，吸引了研究者的广泛关注与研究。但是由于镁及镁合金在体液环境中的降解速度过快，会导致植入部位的局部碱化和氢气释放，影响到其在临床上的应用。采用表面改性处理技术，控制镁及镁合金的降解速度，成为其在生物材料领域应用的关键。本文选择AZ31B镁合金作为基体材料，基于骨充填和骨固定应用背景，分别在其表面成功制备出Ca-P涂层和含硅涂层，并对涂层形成机理、相组成、微观组织、电化学性能、力学性能等进行了系统研究。在此基础上，以含硅涂层为重点研究对象，采用体外和体内实验相结合的方法对表面改性后镁合金的生物学性能进行了评价。论文得到如下主要研究结果：（1）采用化学转化的方法在AZ31B镁合金表面制备了片状或花絮状形貌特征的由Ca3(PO4)2、Mg3(PO4)2及少量的Ca(H2PO4)2、Mg(H2PO4)2组成的钙磷涂层，涂层均匀、致密。（2）Ca-P涂层有效改善了AZ31B镁合金在模拟体液中的耐腐蚀性能，降低了模拟体液的pH 值。Ca-P涂层并非完全保护镁合金基体不被腐蚀，而是减缓基体合金的腐蚀速率。（3）体内植入实验证明，未处理AZ31B镁合金在植入早期会导致炎症产生，降解过程中刺激成骨作用明显，但同时局部有溶骨现象。Ca-P涂层能够控制镁合金的降解，减少因过快降解而引起的不良组织反应，表现出良好的生物相容性和生物活性。（4）采用化学转化方法在AZ31B镁合金表面制备出含硅涂层，涂层的主要成分为Mg2SiO4、MgO和SiO2。浸泡实验表明，含硅涂层有效降低了AZ31B镁合金基体的降解速度，尤其在浸泡初期效果更为明显，涂层在Hank’s溶液中会逐步转化为溶解度更低的Ca3(PO4)2。（5）溶血实验表明，未表面改性处理AZ31B镁合金在降解初期的溶血现象非常严重。随着样品在模拟体液中浸泡时间的延长，表面改性前后样品的溶血率总体上都呈上升趋势，但在所有时间点，含硅涂层样品始终满足溶血率的要求，表明硅涂层具有良好的抗溶血性能。（6）细胞相容性实验证实，含硅涂层表面改性后AZ31B镁合金表现出更低的细胞毒性。采用浸提液所培养细胞的生长情况表明，含硅涂层表面改性AZ31B镁合金浸提液培养的细胞在数量、生长状态，以及粘附、增殖及分泌基质等方面均明显优于未改性AZ31B镁合金。含硅涂层AZ31B镁合金显示出更好的细胞相容性。（7）动物植入实验表明，含硅涂层AZ31B镁合金显示了比未涂层合金、钛合金及PLA更强的骨整合能力，较可降解PLA骨钉具有更高的抗弯曲能力和抗力学衰减性能。"
其他摘要	"Magnesium and its alloys have attracted much attention as medical materials owing to their good biocompatibility, better mechanical properties combination and biodegradability. The key obstacle of the biodegradable Mg implants in biomedical application is their rapid degradation resulting in serious local alkalization and hydrogen evolution. Surface modification is one of the effective methods to solve the above problem. Ca-P coating and Si-containing coating were respectively prepared on the surface of AZ31B magnesium alloy for the application in bone filling and bone fixation. Formation mechanism, phase composition, microstructure, electrochemical properties and mechanical properties of the coatings were studied in detail. Especially, in vitro and in vivo experiments were carried out to evaluate the biological properties of the Si-containing coating. The main results are summarized as followings: (1) Ca-P coating composed of Ca3(PO4)2, Mg3(PO4)2, Ca(H2PO4)2 and Mg(H2PO4)2 was prepared on AZ31B alloy by chemical deposition method. The coating was homogeneous and dense. (2) The corrosion resistance of AZ31B alloy was improved by Ca-P coating with lower pH value in simulated body fluids. The substrate was temporarily, not completely, protected by the coating. (3) The in vivo implantation test showed, as for the uncoated AZ31B alloy, inflammation occurred during the early implantation. Obvious stimulated osteogenesis was found during the degradation of uncoated AZ31B alloy while osteolysis was also found. The Ca-P coating reduced the harmful tissue reaction around the implants owing to the reduced degradation rate of the implants, and showed excellent biocompatibility and bioactivity. (4) Si-containing, composed of Mg2SiO4, MgO and SiO2, was prepared on AZ31B alloy by chemical conversion method. Immersion test showed that the degradation of AZ31B alloy was delayed by the coating especially during the early stage of immersion. Si-containing coating was transferred to Ca3(PO4)2 with lower solubility in Hank’s solution. (5) Hemolysis test indicated that the hemolysis of uncoated AZ31B alloy occurred seriously during the early stage of degradation. The hemolysis ratio increased with the increase of immersion time of both the coated and uncoated AZ31B samples in simulated body fluid. However, the hemolysis results of AZ31B samples with Si-containing coating at any immersion duration satisfied the need of hemolysis. (6) Cytocompatibility test showed that the AZ31B alloy with Si-containing coating displayed lower cell toxicity. The amount, growth state of the cell cultured in the leaching liquor of the samples with Si-containing coating, and the attachment, proliferation and matrix secretion of the cell on the surface of the coated samples are obviously better than those cultured in the leaching liquor of the uncoated samples and those on the surface of the uncoated samples. (7) Implantation test showed that the AZ31B alloy with the Si-containing coating displayed better osseointegration than the uncoated alloy, titanium alloy and PLA, and higher anti-bending ability and anti-degradation of mechanical property."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64491
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	王强. AZ31B镁合金表面改性及医用基础研究[D]. 北京. 中国科学院金属研究所,2012.