人体模拟环境静态和动态条件下医用钛金属的腐蚀及失效机理研究

Ti and its alloys are common materials for medical implants and widely used for biomedical devices, especially as bone fixation systems and orthopaedic devices. It has been recently reported that Ti corrosion induces failures of implants, and Ti corrosion in human body has received considerable attention internationally. However, the corrosion characteristics and degradation mechanism of Ti alloys still remain unclear. In this project, the corrosion properties of Ti in simulated human body fluid environments will be investigated under static and moving conditions, revealing the influence of a variety of environmental factors on the corrosion of Ti and its failure mechanism. Under static conditions, the effects of biological factors including neutrophils and macrophages on corrosion of Ti alloys will be fully investigated; under moving conditions, mechanically-assisted crevice corrosion（MACC）of Ti alloys will be investigated by developing and fabricating a new laboratory MACC device, and the effects of several chemical and biological factors in peri-implant environment will be clarified. The MACC properties of various contacts at the interface will be revealed, and the corrosion-resistance of new Ti alloys will also be evaluated. This project will enrich the corrosion research methodology and evaluation system of clinical application of Ti alloys and this will provide sufficient and solid theoretical basis for proper application of Ti implants and reduction of adverse outcomes on patients due to corrosion of implants.

钛金属是常见的医用植入物材料，广泛用于医学器件，尤其是骨固定系统和矫形器械。最新研究表明，钛金属腐蚀易引起植入物失效，人体内钛金属的腐蚀现象已引起国内外的高度关注。但是，目前其腐蚀特性和失效机理仍不十分清楚。本项目将开展人体模拟环境中的钛金属腐蚀实验研究，揭示钛金属在静态和动态条件下多种环境因素的影响及其失效机理。研究静态条件下的生物因素包括中性粒细胞、巨噬细胞对钛腐蚀的影响机制；通过开发新型实验装置，揭示动态条件下钛金属植入物的机械性因素辅助缝隙腐蚀（mechanically-assisted crevice corrosion（MACC））特性，阐明植入物周围环境多种化学因素和生物因素的影响，揭示多种配合界面下钛金属MACC规律，科学评价新型钛合金耐蚀性。研究成果将丰富完善钛金属的腐蚀研究方法和临床应用评价体系，为钛植入物的合理应用、减少因植入物腐蚀造成的不良影响提供理论指导依据。

自上世纪50年代起，钛及钛合金已经被广泛地应用于生物医学领域。但是，由钛金属腐蚀而引起的植入物失效及不良细胞反应等现象被越来越多地报道。钛金属的腐蚀逐渐引起人们的关注，而钛金属植入物的腐蚀特性和失效机理仍不十分清楚。本项目研究了人体模拟环境静态和动态条件下钛金属的腐蚀状况及特性。研究发现，静态条件下中性粒细胞的存在促进了钛金属离子的释放，加速了腐蚀。其次，有针对性地开发了人体典型服役环境中钛金属植入物的机械性辅助缝隙腐蚀（MACC）实验装置，并阐明装置机械参数的影响。在MACC实验中，磨损时的开路电位（OCP）随着转速的增大而减小，磨损电流随着转速的增大而增大；较大负载磨损时的OCP要低于较小负载载荷，较大负载磨损时的磨损电流要高于较小负载载荷。此外，白蛋白的存在降低了平均磨损电流和累积的总磨损电荷，而过氧化氢和脂多糖对磨损电流和电荷影响不明显。此外，评价新型钛合金的腐蚀性能，Ti30Nb3Cu在所制备的合金中最耐腐蚀。同时，拓展研究了其他常用临床金属材料的腐蚀特性，白蛋白和过氧化氢共存时对医用金属材料的腐蚀具有明显的协同促进作用。本项目的开展明确了复杂人体环境中多种因素对医用金属材料腐蚀的影响，丰富完善了医用金属材料的腐蚀研究方法和临床评价体系，为医用金属材料可靠性的评估提供有价值的理论指导依据。