微量元素掺杂改性医用镁合金氧化膜的制备及性能研究

Magnesium has been suggested as a revolutionary biodegradable metal for use as an orthopaedic material. However, the too fast degradation rate in vivo restricts its clinical applications. As an effective surface treatment method, micro-arc oxidation (MAO) can improve the corrosion resistance and the biocompatibility of magnesium alloys. Iron, zinc and copper are essential trace elements for bone growth. In addition, zinc and copper possess antibacterial ability. In order to promote and accelerate the formation of osseointegration, based on the principle of bionics, medical functional ceramic coatings doped with iron, zinc and copper elemens are fabricated on magnesium alloys in the project by adding iron, zinc and copper salts into a nertural solution composed of calcium salts and phosphorus-containing compounds. The influences of iron, zinc and copper salts concentration and electric parameters on coating properties such as chemical compositions, corrosion resistance, biocompatibility, antibacterial ability and bioactivity are investigated. The influencing regularity of trace elements on the performance of anodic coatings with each other is also clarified. The coating structure with excellent corrosion reistance and biocompatibilty and the preparation technology are obtained by using an orthogonal experiment. In vivo degradable regularity of MAO treated samples and the mechanism of new bone formation induced by trace elements are discussed by the animal implantion test. The research achievements will reveal the mechanism of trace elements jointly taking part in the coating formation, clarify the regularity about the structure change and corrosion degradation of anodic coatings in vitro and in vivo, establish the model of new bone development in vivo induced by trace elements. These results will provide the important theoretical foundation and experimental data for the development of anodic coaitngs with excellent corroson resistance, good antibacterial and bioactive property on medical magnesium alloys.

镁被认为是一种革命性的可降解金属骨科植入材料，但其在体内降解速度过快。微弧氧化能有效改善镁合金的耐蚀性和生物相容性。铁、锌、铜是骨生长必不可少的微量元素，且锌和铜还具有抗菌性。为促进和加速骨结合，本项目根据仿生学原理，在以钙盐和含磷物为主要组分的中性溶液中，添加铁、锌和铜盐，在镁合金表面制备铁、锌和铜掺杂改性的生物医学功能涂层。拟研究铁、锌、铜盐浓度和电参数对氧化膜成分、耐蚀性、生物相容性、抗菌性和生物活性影响，清晰微量元素之间共同影响涂层性能的规律。使用正交实验，获得具有高耐蚀性和生物相容性抗菌涂层的结构与制备工艺。采用动物体内植入实验，探讨氧化样品体内降解规律和微量元素诱导新骨形成机制。研究成果有望揭示微量元素共同参与氧化膜形成的机制，清晰氧化膜体内外组织演化与腐蚀降解规律，建立微量元素体内诱导新骨生长模型，为在医用镁合金表面制备高耐蚀性抗菌性生物活性涂层提供重要的理论基础和实验数据。

铁、锌、铜是骨生长必不可少的微量元素。本项目根据仿生学原理，采用微弧氧化在镁合金表面制备铁、锌和铜掺杂改性的生物医学功能涂层。.与磷酸相比，植酸能增加涂层厚度和涂层与镁合金基体之间的结合力，因而更有效地提高膜层耐蚀性。氧化膜中氟含量与其生物相容性密切相关。在仅含植酸或磷酸溶液中制备的微弧氧化涂层F含量高于19.00 at％，因而显示出高毒性。.在近中性溶液中，研究了0, 6, 12和18 g/L EDTAFeNa浓度对WE43镁合金氧化膜性能影响。结果表明，在镁合金表面制备的含铁氧化膜能显著提高镁合金的耐蚀性和体外生物相容性。随着EDTAFeNa浓度增加，氧化膜中铁含量增加，但涂层耐蚀性下降。.使用一步微弧氧化，能在WE43镁合金表面成功制备含锌量最高为4.12 wt.%的涂层。影响氧化膜中Zn元素含量的大小顺序为：EDTA-ZnNa2 > NH4HF2 > H3PO4 > 植酸。制备的含锌氧化膜具有很好的耐蚀性，其腐蚀电流密度比基体低两个数量级。.EDTA离子和铜离子对镁合金均具有腐蚀作用。随着EDTA-CuNa2浓度增加，Mg与溶液中的Cu离子发生了氧化还原反应，在镁合金表面析出更多的铜。但由于溶液中含有更多的EDTA腐蚀离子，最终使镁合金的耐蚀性变差。.植酸钠能增加氧化膜中磷和钙含量、厚度和结合力。微弧氧化尤其是在基本溶液中添加4 g/L植酸钠能显著提高AZ31B镁合金耐蚀性和体外生物相容性。微弧氧化过程中，植酸裂解成磷酸根和低级磷酸肌醇；96小时急性毒性试验表明，50%微弧氧化溶液对彭泽鲫没有毒性。.在镁合金表面制备含锆0 at%, 12.80 at% (MAO-Zr10)和20.34 at% (MAO-Zr20)的微弧氧化样品。体外实验表明MAO-Zr10和MAO-Zr20不仅具有很好耐蚀性和生物相容性，而且能抑制锯齿细胞的炎症反应。体内实验表明MAO-Zr10和MAO-Zr20具有很好的骨免疫调节特性。