【作者】 刘世敏；

【导师】 杨贤金；

【作者基本信息】 天津大学 ， 材料学， 2011， 博士

【摘要】 钛因具有优良的生物相容性、耐蚀性以及机械加工等综合性能在临床上被广泛用作种植体的基体材料。然而钛属于生物惰性材料,植入到生物体后与骨组织之间不能形成骨性结合。为赋予钛种植体良好的生物活性以及其它综合性能,利用微弧氧化技术对钛进行表面改性处理是一种十分有效的方法。本文利用微弧氧化技术在钛表面制备了多孔二氧化钛陶瓷层以及磷灰石（apatite）/二氧化钛（TiO₂）复合涂层。运用SEM、XRD、XPS及FTIR多种检测方法对膜层的形貌和相成分进行了分析;探讨了微弧氧化对陶瓷层硬度、粗糙度、耐蚀性以及膜层与基体之间结合力的影响;通过模拟体液浸泡实验研究了微弧氧化层对类骨磷灰石的诱导能力及诱导机理;最后通过体外细胞培养实验对微弧氧化层的生物学性能进行了评价。研究结果如下:电解液组分不同,微弧氧化后陶瓷层的表面形貌、元素组成也不同。在由醋酸钙和磷酸二氢钠配制的电解液中进行微弧氧化,当电压低于330 V时,生成的陶瓷层表面是多孔结构。随着施加电压的升高以及处理时间的延长,多孔陶瓷层的厚度、平均孔径逐渐增大,膜层的相成分由锐钛矿逐渐向金红石转变。当电压为330V时,试样表面有磷灰石出现,电压升高至390V时,得到花瓣状的apatite/TiO₂复合层。微弧氧化后试样的表面硬度、粗糙度及耐蚀性明显增加。在实验参数范围内,随着电压的升高,试样表面硬度及粗糙度逐渐升高。微弧氧化膜层与基体之间有着较高的结合力,随着电压的升高,结合力呈现先升高然后下降的趋势。复合中层的apatite以及多孔层中的锐钛矿在模拟体液中对磷灰石的生长有很好的诱导作用。在模拟体液中,复合层中的apatite层首先发生溶解,使溶液中钙、磷离子浓度增加,然后因新的钙磷层的生成而不断消耗溶液中的离子,溶液中钙、磷离子浓度逐渐降低。这一过程可由溶解-沉淀机制来解释。在磷灰石的形核与生长过程中,电荷之间的吸引力起着主要作用。微弧氧化后试样的毒性等级均为0级。小鼠成骨细胞在两种微弧氧化层表面的早期黏附性均得到提高。在种植的第7天观察细胞形态,细胞在多孔TiO₂层上大量增殖形成细胞层。复合层表面也有大量细胞附着,细胞伸出的伪足之间相连形成网状结构。而纯钛表面细胞的数量少,体积也较小。MTT测试进一步证实多孔的TiO₂层以及apatite/TiO₂复合层有利于细胞的增殖与分化,而复合层的功能尤其突出,这说明材料表面的结构及化学成分对细胞的生长有很重要的影响。更多还原

【Abstract】 Titanium has been widely used to manufacture clinical implants owing to its good biocompatibility, corrosion resistance, and mechanical processing performance. However, the interface integration between the implant and the bone is relatively weak due to the inertia of titanium. To endow the titanium implant with good bioactivity and other comprehensive performance, micro-arc oxidation （MAO） is usually adopted to modify the surface of titanium.Porous TiO₂ and apatite/TiO₂ composite coatings were prepared on the titanium surface by MAO, as discussed in this thesis. Scanning electron microscope （SEM）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and Fourier transformation infrared spectroscopy （FT-IR） were employed to investigate the surface morphology and phase composition of the coatings. The hardness, roughness, and corrosion resistance of the coatings as well as the bonding force between the substrate and coating were also studied. The growing mechanism of the apatite layer on different MAO coatings was studied by immersion the MAO samples in a simulated body fluid （SBF） for the biomimetic deposition. The biocompatibility and bioactivity of the MAO coatings were also investigated by in vitro cell culture. The results are listed as follows:The surface morphology and phase composition of the MAO coating were affected by the composition of the electrolyte during MAO process. When the MAO was conducted in an electrolyte containing calcium acetate monohydrate and sodium phosphate monobasic dehydrates, the coating was porous below the voltage of 330 V. The average pore diameter and coating thickness increased with the applied voltage and oxidation time. With the increase of applied voltage, some anatase TiO₂ transformed to rutile TiO₂. Some apatite appeared on the MAO coating at 330 V. When the voltage was increased to 390V, petal-like apatite/TiO₂ composite coating formed on the pure titanium.The hardness, roughness and corrosion resistance of the coatings significantly increased after the MAO treatment. The hardness and roughness of the MAO coatings increased also with the applied voltage within current experimental scale. The bonding force between the substrate and coating was high. The bonding force increased firstly and then decreased with the applied voltage. The apatite of the composite coating as well as the anatase TiO₂ in the porous layer exhibited good apatite-inducing ability in SBF. The apatite coating was firstly dissolved into the SBF, resulting in the increase of Ca and P concentrations in the SBF. Then the Ca and P concentrations in the SBF decreased continuously due to the formation of a new apatite layer on the MAO coating. The formation of the apatite layer in SBF was suggested to a dissolution-precipitation mechanism. The electrostatic interaction was the most important factor in inducing apatite nucleation. The level of cytotoxicity was grade 0 for all the MAO samples. At earlier stage, the number of the MC3T3-E1 cells attached on MAO coatings significantly increased. After culturing for 7days, a cell layer formed on the porous TiO₂ coating because of cell proliferation. Large amount of cells were attached on the apatite/TiO₂ composite coating. Cell pseudopods exhibited a network structure. Whereas the number and dimension of the cells attached on the titanium were small. MTT tests further showed that porous TiO₂ and apatite/TiO₂ coating were beneficial to the cell multiplication and differentiation. Additionally, the apatite/TiO₂ composite coating was more obvious than the porous TiO₂ in this aspect. This indicated that the surface structure and chemical constituents had a very important influence on cell growth.更多还原