原位生长碳纳米管增强含氟羟基磷灰石涂层研究

To solve the problems of bioinert and the release of carbon debris of biomedical carbon/carbon composite implants, in situ grown of carbon nanotube reinforced fluoridated hydroxyapatite coatings for carbon/carbon composites are proposed. The main procedures for preparing the coatings are composed of three steps: firstly, the diamond like carbon coatings are applied for carbon/carbon composites with an aim of decreasing the release of carbon debris and eliminating the microstructure difference among carbon fiber, carbon matrix and holes. A dense and uniform surface for the growth of carbon nanotubes is obtained after the coatings being prepared. Secondly, in situ grown carbon nanotubes are prepared on diamond like carbon coatings by chemical vapour deposition technique. Thirdly, the fluoridated hydroxyapatites are prepared by ultrasonic electrochemical deposition and ion exchange methods. The fluoridated hydroxyapatites will fill and cover the carbon nanotubes uniformly, forming carbon nanotube reinforced fluoridated hydroxyapatite coatings. The technique and microstructures of the bioactive coatings will be studies with the physical model and growth kinetic equation being proposed. The reinforcement mechanism of the in situ carbon nanotube will be discussed. The bioactivity of the coatings will be analyzed by both cell culture and animal model tests. The research will provide academic foundation for the further application of bioactive modified carbon/carbon composite implants.

本项目针对炭/炭复合材料骨植入体的生物惰性及释放碳微粒的问题，提出并开发一种原位生长碳纳米管增强含氟羟基磷灰石涂层，涂层制备包括三个主要步骤：首先在炭/炭复合材料表面预沉积类金刚石碳层，用于消除炭/炭复合材料的碳纤维、碳基体和孔洞的微观结构差异，为后续碳纳米管的生长提供均匀致密的表面状态，同时也用于阻挡碳微粒的释放；其次采用化学气相沉积工艺在预沉积类金刚石碳层的表面原位生长碳纳米管；然后采用超声电沉积及离子交换复合工艺制备含氟羟基磷灰石，使之逐步填充入碳纳米管之间的孔隙并均匀覆盖材料表面，最终形成原位生长碳纳米管增强含氟羟基磷灰石涂层。明确该涂层的制备工艺和微观结构之间的关系，构建涂层的形成过程物理模型及生长动力学方程，阐明原位生长碳纳米管在涂层中的增强机理，揭示涂层的细胞学行为及动物体内的骨组织响应行为，从而为表面活化改性炭/炭复合材料骨植入体的广泛临床应用奠定理论基础。

炭/炭复合材料是一种极具潜力的骨修复用生物材料，但其表面呈生物惰性并容易释放炭微粒。本项目提出一种原位生长碳纳米管增强含氟羟基磷灰石涂层用于解决上述问题，项目主要研究了炭/炭复合材料表面预沉积类金刚石碳层的形貌、微观结构和表面状态；原位生长碳纳米管的尺寸，分布和微观结构；含氟羟基磷灰石涂层的形成过程、微观结构及其与碳纳米管之间的结合状态。并在此基础上制备了碳泡沫/羟基磷灰石复合涂层，测试了涂层与基体的界面结合强度，揭示了涂层的体外模拟体液诱导行为和细胞学行为。研究发现：采用等离子体增强化学气相沉积工艺在炭/炭复合材料表面制备的类金刚石涂层与炭/炭复合材料基体有较高的结合力，结合力数值达到了40.3 N。原位生长碳纳米管呈现弯曲状形貌并呈现无方向性生长，其可以在生物活性涂层内部保持其三维网络状结构。含氟羟基磷灰石涂层呈现带状形貌，其长度为几十微米，厚度为5-40 nm。碳泡沫可以为羟基磷灰石的沉积提供大量的孔隙结构，羟基磷灰石可以渗透入碳泡沫的孔隙中并形成均匀致密的涂层。该涂层与炭/炭复合材料基体的界面结合力为8.14±0.30 MPa，其数值是羟基磷灰石与炭/炭复合材料基体的界面结合力 (3.04±0.20 MPa)的2.7倍。细胞实验发现MG63细胞在碳泡沫/羟基磷灰石涂层的表面呈现良好的附着和增殖行为，该涂层无细胞毒性并改善了炭/炭复合材料的生物相容性。本项目的研究为促进为表面活化改性炭/炭复合材料骨植入体的广泛临床应用奠定理论基础，对于促进我国生物医用新材料的发展具有重要的现实意义。