新型骨诱导型降解涂层的研制及生物活性调控的研究

Biomedical titanium and titanium alloys hold great potentials for orthopedic/dental implants because of the excellent biocompatibility and strong mechanical properties. However, the initial instability after implantation and low bioactivity leading to the slow healing and poor osseointegration are current major issues for medical applications. Typically, micro-/nano-structured surfaces and immobilization of bioactive molecules have great effects on the bioactivity improvement of the metal surfaces. Therefore, the electrospraying technique in this study is used to construct biodegradable coatings loaded with bone morphogenetic proteins (rhBMP-2) on the hydrophilic SLA-treated implants with micro-/nano-pores. The major coating materials include biodegradable chitosan and hyaluronic acid. The mechanical and bioactive properties of the degradable coating are controlled via tuning the material components, the coating structure and the rhBMP-2 loading efficiency. By using protein analysis techniques and biological evaluation, a systematical research is done to study the effects of immobilization process and coating materials/structure on the BMP release, the 2D/3D micro-structure, and the biological activity. Moreover, in vivo studies are conducted to uncover the basic principles of the influences of rhBMP-2 bioactivities, surface characteristics, and coating properties on the osteogenetic process. On the basis of above research, Materials Studio is used to develop a theoretical model to investigate the interactions between the degradable coating and the metal surface, optimize the coating design, and predict the related characteristics. The integrated influences of rhBMP-2 bioactivity, coating properties, and micro-/nano-meter topography on bone-formation and osseointegration will make the guidance for designing the metal implant surface with high bioactivities experimentally and theoretically. The key technologies developed in this project will improve the osseointegration performance of dental implants and undoubtedly benefit the health care and implantodontics in China.

钛及钛合金种植体初期稳定性不佳、生物活性低是其在临床应用中的主要问题。微纳表面的构建和活性因子的负载对促进金属材料的生物活性有着显著影响。为此，本项目以具典型诱骨功能的重组人骨形态发生蛋白-2（rhBMP-2）为模型，采用静电喷涂法，在微纳亲水结构的种植体表面构建骨诱导型降解涂层。结合蛋白分析和生物学评价，系统地研究固载工艺、涂层材料/结构对rhBMP-2释放行为、微观结构、以及生物活性的影响规律。通过细胞和动物模型的成骨性能评价，揭示钛植入体表面的rhBMP-2、涂层材料、与微纳亲水结构的协同作用对成骨过程影响的基本规律。基于以上研究，应用Materials Studio软件，构建种植体表面与降解涂层相互作用的理论模型，优化并预测涂层设计及相关特性，为金属植入材料的高活性表面构建提供理论和技术支持。通过本项目的实施，将突破种植体表面活性修饰的技术关键，促进我国种植医学的发展。

针对种植体的生物活性不足、初期稳定性不佳的问题，基于涂层特性及微/纳结构和生长因子协同促进骨性整合的策略，采用静电喷涂技术和生物锚定技术，在植入材料表面构建骨诱导型降解涂层。系统地研究固载工艺、涂层材料/结构对rhBMP-2释放行为、微观结构以及生物活性的影响规律，揭示钛植入体表面的rhBMP-2、涂层材料、与微纳亲水结构的协同作用对成骨过程影响的基本规律。围绕上述研究内容取得了以下创新研究结果：.1.静电喷涂工艺构建的壳聚糖CHi涂层和透明质酸HA涂层明显减缓了蛋白因子的释放速率；相比较厚的Chi涂层，HA涂层较薄（～500 nm）、更加均匀，亲水特性适中。硫酸软骨素CS生物锚定涂层亲水、可控（<100 nm），具有缓释rhBMP-2的能力。.2. 静电喷涂工艺瞬时反应，其对rhBMP-2的微观结构略有影响。而Chi和HA均与rhBMP-2之间无化学键作用。因此，工艺过程和材料对蛋白的结构和成骨活性的影响可忽略。CS与rhBMP-2存在较强的静电作用，蛋白因子与基底之间通过长直链型分子连接，该结构近似模拟了细胞外基质作用，很好地维持了rhBMP-2的分子结构的生物活性。.3.相比酸碱喷少处理的SLA表面，几类涂层均表现出促进细胞的粘附、增殖和成骨分化的特性，尤其是生物锚定rhBMP-2的移植物在体内可诱导产生更多致密的新骨，呈现出良好的成骨性能，实现了移植物-宿主骨的骨性整合。而分子模拟的结果发现表面粗糙度大（RMS～20nm）的涂层有利于rhBMP-2的吸附，并维持了其较好的活性构象；沟脊比为1:1的纳米图案化拓扑结构最适合rhBMP-2的固载和活性维持。. 基于以上成果发现，生物锚定技术较静电喷涂工艺略难，但实现了移植物-宿主骨的良好骨性整合，更适于工程制备和实际应用，为设计构建新型活性植入材料及临床植入医学的发展提供了技术支持和指导。