聚合物/玻璃纤维血管支架的脉冲激光烧蚀机理、界面强化及其生物矿化过程

Vascular scaffold is an effective approach to realize the repair and replacement of vascular. And polymer/fiberglass composite and pulse laser rapid sintering technique are an ideal material and an effective way, respectively to fabricate vascular scaffold. The mechanism of pulse laser ablation is generally studied based on the ideal Gaussian pulse distribution, and do not take into account the effects of the key laser energy factors, such as the actual pulse energy density distribution and spot diameter, pulse width, repetition frequency, and etc.. The researches about interfacial strengthening and biological mineralization process are insufficient. The aim of this project is to prepare the polymer/fiberglass composites vascular scaffold via pulse laser rapid sintering. Transient temperature field model with the laser energy density distribution is established according to laser energy factors. The related rules of the temperature field, stress field distribution and the laser energy field and its influence on surface quality and microstructure of the scaffold are found out. The mechanism of pulse laser sintering is revealed. The physical model of microcracks is established by the action of the composite interface. The extension process and fracture mode of microcracks are ascertained. The toughening mechanism and the correlation with mechanical properties are revealed. The biomineralization properties of the biodegradability, blood and cell compatibility are found out, and the biomineralization process and reaction mechanism is revealed. The project will promote the basic theory research of the preparation of vascular scaffold, and further provide theoretical foundation and guidance for the development application of the vascular tissue engineering.

血管支架是实现血管修复和替代的有效方法，聚合物/玻璃纤维和脉冲激光快速烧结技术是制备血管支架的理想材料和有效途径。目前脉冲激光烧蚀机理大都基于理想的高斯脉冲分布，对脉冲激光能量密度分布模式、光斑直径、脉宽和重复频率等关键激光能场因素的研究较少，且对聚合物和玻璃纤维间的界面强化和生物矿化过程研究不充分。本研究以脉冲激光快速烧结制备聚合物/玻璃纤维复合血管支架为目的，拟综合激光能场因素，建立脉冲激光能量密度分布模式的瞬态温度场模型，查明温度场、应力场和激光能场的关联规律及其对血管支架微观结构的影响，揭示其脉冲激光烧蚀机理；建立复合界面作用微裂纹的物理模型，查明微裂纹的扩展过程和断裂方式，揭示其增韧机制及其与机械性能的关联规律；查明支架的生物降解性、血液和细胞相容性等生物矿化性能，揭示其矿化过程和反应机制。本项目将推动血管支架制备基础理论的进步，并为血管组织工程发展应用提供理论指导和依据。

生物活性玻璃是一种具有良好生物相容性、生物活性、骨引导性和骨键合作用的理想的骨修复材料，但其脆性大，硬度低限制了其应用。本项目以生物活性玻璃为原料，利用高斯脉冲激光选择性烧结制备了人工骨支架，发现在某功率条件下，支架的致密度和表面形貌较好，且能有效抑制其它玻璃相的转变，而直接得到有利于生物性能的结晶相；分析了其与机械和生物性能的关联规律，获得了优化的激光工艺烧结参数。提出了利用纳米碳材料强韧化生物活性玻璃支架的方法，研究了碳纳米管含量对支架的微观结构、机械和生物学性能的影响，查明了纳米碳材料与生物活性玻璃基体的界面结合特性，并揭示了其增韧机理。发现通过碳纳米管的桥联、拔出和裂纹偏转等作用能有效提高支架的机械性能。提出了利用纳米氧化物增韧生物玻璃复合支架，研究了纳米氧化锆的含量对支架的微观结构、物相组成和机械性能的影响。查明了其相变的转变过程，分析了增韧条件下支架的断裂模式，揭示了其强化增韧机理，发现通过纳米氧化锆的相变作用、裂纹偏转、裂纹分叉以及穿晶断裂作用能有效提高支架的机械性能，且随着纳米氧化锆含量的增加，机械性能不断提高。提出了利用生物活性玻璃改善磷酸三钙的生物活性和生物相容性。研究了纳米生物玻璃对磷酸三钙骨支架机械性能和生物学性能的，分析了不同激光能量下不同含量下复合支架的微观形貌、物相成分和力学特性，并获得了最佳的含量比。发现通过纳米生物玻璃的弥散强化作用能有效改善支架的机械性能；并进一步获得了生物活性玻璃提高生物活性和细胞相容性的矿化过程和机制。提出了利用磷酸三钙和纳米氧化锌复合综合改善生物活性玻璃的生物活性和降解性。发现在生物培养早期纳米氧化锌能降低生物活性玻璃的降解速率，同时，磷酸三钙能维持后期的降解速率，由此改善了复合支架的生物活性。