Biocompatibility and surface modification of metallic biomaterials in biochemical/ mechanical environment

在这项研究中，我发现溶解和再钝化行为强烈依赖于底物材料，即使有/没有细胞。在Ti6Al4V合金上，由于钝化膜的击穿，弹性区电流略有增加。然后在塑性变形开始后不久，电流迅速增加，表明由于滑移带的形成，新形成的表面面积急剧增加。在纯钛上也观察到类似的电流行为。另一方面，对于316L型不锈钢，电流在弹性区没有变化，在塑性变形开始时开始增大。延伸结束后，由于再钝化作用，电流迅速下降，接近应变前的水平。对于变形过程中的电荷密度，加/不加电池时差异不大。另一方面，对于变形后的电荷密度，在吸附蛋白质的样品上可以识别出较大的电荷密度，在有细胞的样品上观察到最大的电荷密度。这一结果表明蛋白质和细胞抑制再钝化。当蛋白质或细胞在样品表面积聚时，蛋白质或细胞与金属表面形成封闭空间。在这个空间中，溶质的扩散被阻断，H+离子达到高浓度。结果，pH变低，再钝化被抑制。目前在Ti6Al4V合金上的细胞停滞是再钝化抑制的显著例子。

In this study, I revealed that dissolution and repassivaiton behavior strongly depended on substrate material even with/ without cells. On Ti6Al4V alloy, a slight increase of current was observed in elastic region due to the breakdown of passive films. Then soon after the plastic deformation started, the current rapidly increased, indicating that the area of newly created surfaces drastically increased as a result of formation of slip band. The similar current behavior was observed on pure Ti. On the other hand, for type 316L stainless steel, the current did not change in elastic region and started to increase at the onset of plastic deformation. After the end of elongation, the current rapidly decreased approaching to the level before straining as a result of repassivation. For the charge density during deformation, there was little difference with/ without cells. On the other hand, for the charge density after deformation, the larger charge density was recognized on the sample adsorbed proteins and the maximum charge density was observed on the sample with cells. This result suggests that proteins and cells inhibit the repassivation. When proteins or cells accumulate on the sample surface, a closed space is made between proteins or cells and metal surface. In this space, the diffusion of solute is blocked and H+ ions reach a high concentration. As a result, the pH becomes low and repassivation is inhibited. The current stagnation on Ti6Al4V alloy with cells is the remarkable example of the repassivation inhibition.