Improvement of biocompatibility of NiTi alloy by a cathode corrosion protection technique

NiTi合金具有超弹性、形状存储特性、高耐磨性等独特优异的机械性能。我们设计了一种阴极防腐蚀技术来防止合金的Ni离子释放，并改善其生物相容性。研究了黏附细胞对种植体金属抗腐蚀性能的影响。L929个成纤维细胞粘附在金属表面，培养3 d。然后用ICP分析仪测定溶解到培养基中的Ni离子浓度。为达到上述目的，采用L929成纤维细胞和U937巨噬细胞对金属粉末和金属Ni的腐蚀性液体进行了Ni毒性试验。对于纯镍，镍离子浓度的增加与电池密度成正比。对于NiTi合金，Ni离子的溶解量比纯Ni轻，但Ni离子浓度与电池密度的相关性显著。另一方面，当细胞蛋白用10%福尔马林溶液固定时，溶解的Ni离子浓度与活细胞相比较少。结果表明，种植体金属的耐蚀性很大程度上取决于活体粘附细胞的存在。

The NiTi alloy shows a unique, excellent mechanical properties like super-elasticity, a shape storage characteristic, and high wear resistance, etc. We designed the prevention of Ni ion release of the alloy by a cathode corrosion proof technique, and the improvement of the biocompatibility. We studied on the affect of adhesive cells on the corrosion resistance of implant metal. L929 fibroblastic cells, which were adhered on the surface of the metals, were cultured for 3 days. Then, the concentration of the Ni ion, which dissolved to the cultured medium was measured with the ICP analyzer. The toxicity test on Ni was carried out by using the L929 fibroblast and the U937 macrophage for a metallic powder and the corrosive liquid of metal Ni to achieve the above-mentioned purpose.About pure Ni, the amount of Ni ion concentration was increased proportionally to the cell density. For NiTi alloy, the amount of dissolution of the Ni ion was slighter than that of pure Ni, but the correlation of the concentration of Ni ion and the cell density was significant. On the other hand, when the protein of the cell was fixed with 10% formaline solution, the dissolved Ni ion concentration was a small amount compered with that of the living cells.According to the results, it was suggested that the corrosion resistance of implant metal was strongly depended on the existence of the living adhesive cells.