Shabalovskaya S, Anderegg J, Van Humbeeck J
Katholieke Universiteit Leuven, MTM Kasteelpark Arenberg 44, B-3001 Leuven, Belgium.
Acta Biomater. 2008 May;4(3):447-67. doi: 10.1016/j.actbio.2008.01.013. Epub 2008 Feb 6.
Nitinol, a group of nearly equiatomic shape memory and superelastic NiTi alloys, is being extensively explored for medical applications. Release of Ni in the human body, a potential problem with Nitinol implant devices, has stimulated a great deal of research on its surface modifications and coatings. In order to use any of the developed surfaces in implant designs, it is important to understand whether they really have advantages over bare Nitinol. This paper overviews the current situation, discusses the advantages and disadvantages of new surfaces as well as the limitations of the studies performed. It presents a comprehensive analysis of surface topography, chemistry, corrosion behavior, nickel release and biological responses to Nitinol surfaces modified mechanically or using such methods as etching in acids and alkaline solutions, electropolishing, heat and ion beam treatments, boiling in water and autoclaving, conventional and ion plasma implantations, laser melting and bioactive coating deposition. The analysis demonstrates that the presently developed surfaces vary in thickness from a few nanometers to micrometers, and that they can effectively prevent Ni release if the surface integrity is maintained under strain and if no Ni-enriched sub-layers are present. Whether it is appropriate to use various low temperature pre-treatment protocols (< or = 160 degrees C) developed originally for pure titanium for Nitinol surface modifications and coatings is also discussed. The importance of selection of original Nitinol surfaces with regard to the performance of coatings and comparative performance of controls in the studies is emphasized. Considering the obvious advantages of bare Nitinol surfaces for superelastic implants, details of their preparation are also outlined.
镍钛诺是一组近乎等原子的形状记忆和超弹性镍钛合金，正被广泛探索用于医学应用。镍钛诺植入装置存在一个潜在问题，即人体中镍的释放，这刺激了对其表面改性和涂层的大量研究。为了在植入物设计中使用任何已开发的表面，了解它们是否真的比裸露的镍钛诺具有优势很重要。本文概述了当前的情况，讨论了新表面的优缺点以及所进行研究的局限性。它对镍钛诺表面的形貌、化学性质、腐蚀行为、镍释放以及生物反应进行了全面分析，这些表面通过机械方法或诸如在酸和碱性溶液中蚀刻、电解抛光、热和离子束处理、水煮和高压灭菌、传统和离子等离子体植入、激光熔化以及生物活性涂层沉积等方法进行了改性。分析表明，目前开发的表面厚度从几纳米到微米不等，并且如果在应变下保持表面完整性且不存在富镍亚层，它们可以有效防止镍的释放。还讨论了最初为纯钛开发的各种低温预处理方案（≤160℃）是否适用于镍钛诺表面改性和涂层。强调了在研究中选择原始镍钛诺表面对于涂层性能和对照的比较性能的重要性。考虑到裸露的镍钛诺表面在超弹性植入物方面的明显优势，还概述了其制备细节。
