Liu X M, Wu S L, Chan Y L, Chu Paul K, Chung C Y, Chu C L, Yeung K W K, Lu W W, Cheung K M C, Luk K D K
Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
J Biomed Mater Res A. 2007 Aug;82(2):469-78. doi: 10.1002/jbm.a.31157.
NiTi shape memory alloy is one of the promising orthopedic materials due to the unique shape memory effect and superelasticity. However, the large amount of Ni in the alloy may cause allergic reactions and toxic effects thereby limiting its applications. In this work, the surface of NiTi alloy was modified by nitrogen plasma immersion ion implantation (N-PIII) at various voltages. The materials were characterized by X-ray photoelectron spectroscopy (XPS). The topography and roughness before and after N-PIII were measured by atomic force microscope. The effects of the modified surfaces on nickel release and cytotoxicity were assessed by immersion tests and cell cultures. The XPS results reveal that near-surface Ni concentration is significantly reduced by PIII and the surface TiN layer suppresses nickel release and favors osteoblast proliferation, especially for samples implanted at higher voltages. The surfaces produced at higher voltages of 30 and 40 kV show better adhesion ability to osteoblasts compared to the unimplanted and 20 kV PIII samples. The effects of heating during PIII on the phase transformation behavior and cyclic deformation response of the materials were investigated by differential scanning calorimetry and three-point bending tests. Our results show that N-PIII conducted using the proper conditions improves the biocompatibility and mechanical properties of the NiTi alloy significantly.
由于具有独特的形状记忆效应和超弹性，镍钛形状记忆合金是一种很有前景的骨科材料。然而，合金中大量的镍可能会引起过敏反应和毒性作用，从而限制了其应用。在这项工作中，通过在不同电压下进行氮等离子体浸没离子注入（N-PIII）对镍钛合金表面进行改性。采用X射线光电子能谱（XPS）对材料进行表征。利用原子力显微镜测量了N-PIII前后的形貌和粗糙度。通过浸泡试验和细胞培养评估改性表面对镍释放和细胞毒性的影响。XPS结果表明，离子注入显著降低了近表面镍浓度，表面氮化钛层抑制了镍的释放，有利于成骨细胞增殖，特别是对于在较高电压下注入的样品。与未注入和20 kV离子注入的样品相比，在30和40 kV较高电压下产生的表面对成骨细胞具有更好的粘附能力。通过差示扫描量热法和三点弯曲试验研究了离子注入过程中的加热对材料相变行为和循环变形响应的影响。我们的结果表明，在适当条件下进行的N-PIII显著改善了镍钛合金的生物相容性和力学性能。
