Electrochemical nanostructuring of surfaces of bulk metallic glasses on Ti-Cu basis for improvement of their biocompatibility

Ti-Cu基块体非晶合金（BMG）由于具有良好的力学性能和生物功能性，被认为是牙科和创伤外科骨植入材料的新材料。然而，与目前临床使用的材料相比，其生物相容性仍然不足。一个关键的方面是它们的高Cu含量，这可能导致局部腐蚀现象，并因此导致有毒物质的释放和机械材料失效。此外，对于那些BMG，迄今为止还没有可靠的概念来产生永久性植入物所必需的生物活性表面状态。在应用项目中，将开发用于多组分Ti-Cu基BMG表面的电化学纳米结构化的方法，其目的是有效地改善生物相容性和腐蚀稳定性。该方法的目标是从近表面区域显著降低合金元素的浓度，所述合金元素是获得高玻璃形成能力所必需的，但对于生物相容性是关键的。同时，将产生纳米多孔的主要是氧化的表面结构，以提高耐腐蚀性并刺激骨细胞的活性。BMG的机械性能不得受到显著影响。在该项目中，两种有前途的大块玻璃形成Ti-Cu合金是研究的主题，其铸造工艺已经在IFW Dresden建立。对于纳米结构化，主要采用无卤化物酸溶液中的玻璃样品的阳极处理。从根本上研究了处理参数对表面态的影响，并描述了表面反应机理。一个关键方面是分析这些表面状态对合成生理溶液中BMG腐蚀行为的影响。特别是点蚀敏感性将通过生成定制的氧化态来降低。通过细胞生物学研究，将从根本上评估所选表面状态对人间充质基质细胞（hBMSC）和牙周膜成纤维细胞行为的影响。例如，对于一个选定的BMG的表面纳米结构化的压缩和拉伸载荷下的机械性能的影响将进行评估。在这些研究的结果中，将描述Ti-Cu基BMG的结构和化学特性之间的基本关系，电化学表面纳米结构化的衍生路线以及由此产生的腐蚀性、机械和细胞生物学性质。

Owing to their high mechanical biofunctionality bulk metallic glasses (BMG) on Ti-Cu base are considered as prospective new materials for bone implants in the fields of dentistry and trauma surgery. However, in comparison to materials in current clinical use their biocompatibility is still insufficient. A critical aspect is their high Cu content, which can cause local corrosion phenomena and in consequence, the release of toxic species and mechanical material failure. Moreover, for those BMGs there are so far no reliable concepts for the generation of bioactive surface states which are mandatory for permanent implants. In the applied project a method for an electrochemical nanostructuring of surfaces of multicomponent Ti-Cu-based BMGs will be developed with the objective of effectively improving the biocompatibility and corrosion stability. The method is targeted on significantly reducing the concentration of alloying elements which are necessary for obtaining high glass-forming ability but which are critical with respect to biocompatibility, from near-surface regions. At the same time nanoporous, predominantly oxidic surface structures will be generated in order to improve the corrosion resistance and to stimulate the activity of bone cells. The mechanical performance of the BMGs must not be significantly affected. In the project two promising bulk glass-forming Ti-Cu alloys are subject of investigation for which the casting processes are already established at the IFW Dresden. For the nanostructuring, anodic treatments of glassy samples in halogenide-free acid solutions are primarily employed. The effects of treatment parameters on the developing surface states are fundamentally investigated and the underlying surface reaction mechanisms are described. A key aspect is the analysis of the impact of those surface states on the corrosion behaviour of the BMGs in synthetic physiological solutions. In particular the pitting corrosion susceptibility is to be reduced by the generation of tailored oxidic states. By means of cell biological studies the effect of selected surface states on the behaviour of human mesenchymal stroma cells (hBMSC) and of periodontal ligament fibroblasts will be fundamentally evaluated. Exemplarily, for one selected BMG the impact of surface nanostructuring on the mechanical properties under compression and tensile load will be assessed. In result of these studies, fundamental relations between structural and chemical particularities of the Ti-Cu-based BMGs, derivable routes for electrochemical surface nanostructuring and resulting corrosive, mechanical and cell biological properties will be described.