A basic study on the development of metallic biomaterials

金属生物材料要求具有较高的耐腐蚀性、强度和生物相容性，腐蚀不仅与金属生物材料的生物相容性有关，而且还与断裂有关，因此我们必须了解生物材料在体内的腐蚀行为。但目前还很难阐明体内的腐蚀现象。本研究旨在探讨生物因素对金属种植体体外腐蚀性能的影响。本研究表明，在体内影响腐蚀的生物因素是巨噬细胞。在RPMI1640+FBS、RPMI-1640+FBS+U937电池、RPMI1640+FBS+MA噬菌体、每种含高密度聚乙烯颗粒的介质和林格液等7种条件下对316不锈钢盘片进行了腐蚀损伤试验。用交流电法测量了SUS316在各种条件下的腐蚀速率(Rp-1)。阻抗法，并比较它们的比率。我们观察了腐蚀过程。结果如下：1)在浸泡试验中，SUS316在培养的巨噬细胞表面出现了许多微小的不均匀突起。巨噬细胞培养液中的平均粗糙度(Ra)和Rp-1比无细胞培养、U937细胞培养和林格液培养时的平均粗糙度(Ra)和Rp-1增大。因此，巨噬细胞的存在必然会影响生物种植体的腐蚀行为。2)在含有巨噬细胞吞噬聚乙烯颗粒的介质中进行浸泡试验时，Ra和Rp-1的增加明显高于未吞噬巨噬细胞的介质。这说明激活的巨噬细胞吞噬了聚乙烯颗粒，加速了金属材料的腐蚀。3)本研究提出了体内腐蚀模型，并表明该模型可以解释一系列实验结果。

Metallic biomaterials are required to have high corrosion resisitan-ce, strength, and biocompatibility.The corrosion relates not only to the biocompatibility of the metallic biomaterials but also to the frac-ture.Therefor we must understand corrosion actions in vivo. But it difficult to elucidate the corrosion phenomenon in vivo. The purpose of this study is to investigate the effects of biological factor on corrosion properties in vitro of metallic implants.This study indecated that the biological factor on corrosion was macrophages in vivo. The corrosion damage of 316 stainless steel disk were performed on seven conditions of immersion test ; that are RPMI1640+FBS, RPMI-1640+FBS+U937 cells, RPMI1640+FBS+Ma-crophages, each medium with high-density polyethylene particles, and Ringer solution. We measured corrosion rate (Rp-1) of SUS316 in each condition by AC. Impedance method and compared their rate. We observed the corrosion process. The results are summarized as follows :1) The surface of SUS316 in medium culturing macrophages at immesion test was incidenced any number of minute protuberances of unevenness. And the average roughness (Ra) and Rp-1 in medium with culturing macrophages increased more than medium without cells, with culturing U937 cells and ringer solution. Therefor these indicated that the existence of macrophages must influence corrosion behavior of bioimplants.2) In case of performing immersion test in medium with macrophages phagocytosed polyethylene particles, the Ra and Rp-1 increased much higher than them in medium with macrophages without phagocytosing. This suggests that the activating macrophages phagocytosed polyethylene particles were sped up corrosion of metallic materials.3) This study suggested the corrosion model in vivo, and it shows that the model can explain a series of experimental results.