医用金属材料的生物功能化研究

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	医用金属材料的生物功能化研究
	任玲
学位类型	博士
导师	杨柯
	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	医用金属材料生物功能不锈钢钛合金镁合金 Metallic Biomaterials Bio-functions Stainless Steel Titanium Alloy Magnesium Alloy
摘要	" 医用金属材料以其高强韧性、耐疲劳、易加工成形等优良性能成为临床上用量最大和应用广泛的一类生物医用材料。然而，目前临床应用的医用金属材料一般在生物体中表现为生物惰性。本文利用铜元素在人体中的诸多有益生物功能作用，通过在现有医用不锈钢成分基础上添加适量的铜元素，设计和制备出含铜不锈钢新材料，提出通过其在人体生理环境中发生腐蚀而持续释放微量铜离子，从而赋予含铜不锈钢抗细菌感染、抑制心血管支架内再狭窄等生物医学功能。为此，本文对含铜不锈钢开展了系统而深入的研究，获得了许多有意义的研究结果。此外，本文还初步研究探索了含铜钛合金的抗菌功能，以及可降解镁基金属的抗菌与抗肿瘤等生物医学功能。本文开展的主要研究工作及得到的主要结论如下：（1）含铜不锈钢抗细菌感染的医学功能研究在广泛临床应用的317L、304不锈钢成分基础上，设计并制备出317L型、304型含铜不锈钢（317L-Cu、304-Cu）。通过体外和动物体内植入等抗细菌感染实验，系统研究了含铜不锈钢的抗感染功能。研究结果表明，317L-Cu不锈钢对金黄色葡萄球菌、大肠杆菌等骨科常见感染细菌，304-Cu不锈钢对导致牙周炎的牙龈卟啉单胞菌都具有强烈的杀灭作用，并能明显地抑制细菌在不锈钢表面上的粘附及细菌生物膜的形成。此外，317L-Cu 不锈钢满足对植入材料的生物安全性基本要求。（2）含铜不锈钢抑制冠状动脉支架内再狭窄的医学功能研究在冠状动脉支架用316L不锈钢成分基础上，设计并制备出316L型含铜不锈钢（316L-Cu）。通过细胞粘附观察、流式细胞检测、Transwell实验、细胞划痕实验、动态凝血时间、血小板粘附、CCK-8细胞毒性实验等实验系统研究了316L-Cu不锈钢抑制冠脉支架内再狭窄的功能作用以及其生物安全性能。与316L不锈钢相比，316L-Cu不锈钢具有明显抑制动脉平滑肌细胞增殖和降低动脉平滑肌细胞迁移等作用，并且明显地减少血小板在其表面上的粘附，延长凝血时间。此外，316L-Cu不锈钢还能够显著地促进血管内皮细胞的增殖与迁移，从而可加快支架植入受损血管的重建过程。316L-Cu的上述表现均有益于降低冠状动脉支架内再狭窄的发生倾向。316L-Cu不锈钢满足对植入材料的生物安全性基本要求。（3）含铜不锈钢中富铜相的析出行为研究通过显微硬度、电阻率、X射线衍射、电化学阻抗以及差式扫描量热分析等材料研究方法，对含铜不锈钢中富铜相的析出行为进行了深入研究。研究结果表明，富铜相在含铜不锈钢中的析出分为两个过程，第一阶段是富铜相原子团簇的形成，第二阶段是富铜相原子团簇的溶解/粗化。富铜相的析出扩散激活能为181 kJ/mol，与铜原子在钢中的扩散激活能相近。透射电镜观察结果表明，含铜不锈钢中的富铜相易在晶界析出，尺寸约为20-30nm。（4）含铜不锈钢表面的铜离子溶出行为研究通过X射线光电子分析、电化学测试、浸泡腐蚀等研究了含铜不锈钢表面铜离子溶出行为及其耐蚀性能。研究结果表明，富铜相的存在会有助于含铜不锈钢中微量铜离子的溶出。含铜不锈钢主要是通过其表面上的富铜相及含铜钝化膜发生的一系列电化学反应而溶出铜离子。含铜不锈钢的耐点蚀性能会略有下降，但其总体耐腐蚀能力并没有发生明显改变，与普通不锈钢相当。（5）其它医用金属材料的生物医学功能探索以目前临床应用的纯钛和Ti-6Al-4V钛合金为成分基础，设计和制备出含铜钛合金，Ti-6Al-4V-xCu（x=1，3，5）和Ti-xCu（x=10，20，30）。研究结果表明，两种含铜钛合金均具有强烈的抗菌能力，并且满足对外科植入材料的细胞毒性评价要求。对生物可降解镁基金属的抗菌功能研究表明，纯Mg和AZ31镁合金在生理环境中降解产生的高碱性具有强烈的杀菌作用，具有疏松和多孔结构的含Si涂层仍然使镁基金属保持一定的抗菌作用，而具有致密完整结构的含F涂层可使镁基金属丧失抗菌作用。对生物可降解镁基金属的抗肿瘤功能研究表明，纯镁降解产生的碱性微环境对骨肿瘤细胞U-2OS的增殖具有强烈的抑制作用，通过表面改性，同样具有降低纯镁的降解速度，减缓pH值升高，进而影响对肿瘤细胞的抑制作用。"
其他摘要	"Metallic biomaterials, possessing excellent combination of mechanical properties including high strength-toughness, fatigue resistance, etc., are one class of biomaterials which have got extensive applications in clinic. However, metallic biomaterials behave biologically inert and generally play the mechanical supporting roles in human bodies. Copper (Cu) has been proved to have many useful bio-functions in human bodies, and therefore appropriate amounts of Cu were added into the currently used medical stainless steels in order to develop a novel class of Cu-bearing stainless steels, which can continuously release Cu ions due to the corrosion happening in physiological environment and then offer the stainless steels the biomedical functions of anti-infection and reducing the occurrence of in-stent restenosis. For this reason, systematic and deep studies on the newly developed Cu-bearing stainless steels were carried out in this dissertation. In addition, the anti-infective function of Cu-bearing titanium alloys, and anti-infective function and anti-tumor function of biodegradable magnesium-based metals were also explored. All the results achieved in this dissertation have provided useful evidences for establishment a new concept of novel metallic biomaterials with structural/functional integrity. The main researches and conclusions have been made as follows: (1) Study on the anti-infective function of Cu-bearing stainless steel Based upon the compositions of types 317L and 304 stainless steels that are widely used in clinic, two Cu-bearing stainless steels, 317L-Cu and 304-Cu, were designed and prepared by additions of proper amounts of Cu. The anti-infective functions of these two Cu-bearing stainless steels were systematically and deeply studied by both in vitro and in vivo anti-bacterial tests. The results indicated that the 317L-Cu steel showed strong anti-infective function against the common bacteria, including Escherichia coli (E. coli) and Staphylococcus aureus (S.aureus), and the 304-Cu steel showed strong anti-infective function against Porphyromonas gingivalis which could lead to the periodontitis. The Cu-bearing stainless steel could greatly reduce the adhesion of those bacteria and thus inhibit the formation of the bacteria caused bio-film on the steel surface, which is the main reason for bacterial infection. It was preliminarily proved that the Cu-bearing stainless steel could satisfy the requirement on bio-safety as an implant material. (2) Study on the function of reducing in-stent restenosis (ISR) of Cu-bearing stainless steel Based upon the composition of type 316L stainless steel that is widely used as a cardiovascular stent material, a Cu-bearing stainless steel, 316L-Cu, was designed and prepared by a proper addition of Cu. Observations on adhesion of vascular smooth muscle cells (VSMC) on the surface of the steel, flow cytometry, transwell experiment, cells scratch，dynamic clotting time, platelet adhesion and cytotoxicity evaluation were carried out to investigate the function of reducing ISR of the 316L-Cu steel. It was found that, compared with 316L stainless steel, the 316L-Cu steel obviously inhibited the proliferation and migration of VSMC on its surface, and reduced the amount of platelets adhered on its surface with longer clotting time. On the other hand, the 316L-Cu steel promoted the proliferation and migration of human vascular endothelial cells (HUVEC), which would then accelerate the revascularization of the damaged vascular after stent implantation. All these results clearly indicated that the 316L-Cu steel is potential to be used as a new stent material with function of reducing the occurrence of ISR. (3) Study on the precipitation of Cu-rich phases in Cu-bearing stainless steel Micro-hardness, electrical resistivity, X-ray diffraction (XRD), electrochemical impedance spectrometry (EIS) and differential scanning calorimetry (DSC) were used to study the precipitation process of Cu-rich phases in the Cu-bearing stainless steel. It was found that there were two stages during the precipitation of Cu-rich phases in the Cu-bearing steel, (i) the first stage - clustering of Cu atoms; and (ii) the second stage - dissolution/coarsening of the Cu-rich precipitates formed at the first stage. The activation energy for the Cu precipitation in the Cu-bearing steel was determined to be 181kJ/mol, indicating that the formation of the Cu-rich phases should be mainly related to the diffusion of Cu atoms in the steel. The Cu-rich phases easily precipitated at grain boundaries with size of about 20-30nm. (4) Study on the release of Cu ions from the surface of Cu-bearing stainless steel XRD, electrochemical measurement and homogeneous corrosion test were used to study the releasing behavior and corrosion resistance of the Cu-bearing stainless steel. The experimental results proved that trace amount of Cu ions release from the surface of the Cu-bearing steel could be promoted by the Cu-rich phases in the steel. The Cu ions releasing was mainly by means of the electrochemical reaction from both the Cu-rich phases and the Cu-bearing passive film on the steel surface. The corrosion resistance of the Cu-bearing steel was not obviously deteriorated compared with the conventional stainless steel, with a little bit reduction of pitting resistance. (5) Exploration of biomedical functions of other metallic biomaterials Based upon the composition of pure titanium (Ti) and Ti-6Al-4V alloy, Ti-6Al-4V-xCu (x=1, 3, 5) and Ti-xCu (x=10, 20, 30) were designed and prepared in order to develop the antibacterial titanium alloy. The experimental results indicated that these two kinds of Cu-bearing titanium alloys showed strong antibacterial abilities and preliminarily met the bio-safety requirement for implant material. Study on the antibacterial function of biodegradable magnesium-based metals (pure Mg and AZ31 alloy) showed that both Mg and AZ31 alloy had strong antibacterial effect against E. coil and S. aureus owing to the rapid increase of pH value of the bacterial suspension during their degradations. Mg with the Si coating by micro-arc oxidation (MAO) also showed antibacterial ability with a mild increase of the pH value due to the porous structure of the coating. But Mg and AZ31 alloy with the F and Si coatings, respectively, by chemical conversion lost their antibacterial abilities due to the much dense coatings with nearly no change of the pH value. A preliminary study on the anti-tumor function of Mg indicated that Mg showed a strong cytotoxic effect to the osteosarcoma U-2OS cells during its degradation, and this cytotoxicity could be somewhat adjusted by a MAO coating on surface of Mg to reduce the degradation rate and then the increase of pH value."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64498
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	任玲. 医用金属材料的生物功能化研究[D]. 北京. 中国科学院金属研究所,2012.