【作者】 王细建；

【导师】 杨庆；

【作者基本信息】 东华大学 ， 材料学， 2008， 硕士

【摘要】 支架材料作为细胞粘附生长的模板,对工程化组织的构建起重要作用。材料本体组成和结构、表面拓扑结构、降解行为等对组织的生物特征产生重要影响。聚羟基丁酸戊酸酯(PHBV)和聚ε-己内酯(PCL)都是具有良好生物相容性、生物降解性和无毒性的生物医用材料。PHBV结晶度较高、球晶大,导致其脆性大、加工温度范围窄,此外还有疏水性强等缺点。PCL在生物医学等领域有许多潜在的应用价值,但其热变形温度比较低,作为骨科修复材料和组织工程支架材料使用时,其硬度和强度方面都达不到要求。因此,本研究采用熔融共混和溶液共混两种共混方法制备了PHBV/PCL共混材料,在保留原有生物性能的同时,共混材料的综合力学性能得到了提高,材料的生物体结合能力也有望同时得到提高。文章研究了共混材料的结构、力学和降解等特性,运用溶剂浇铸/粒子沥滤法和纤维粘结法制备了组织工程用三维多孔支架材料。研究结果表明:无论采用溶液共混法还是熔融共混法,PHBV与PCL都是不相容的;PHBV/PCL共混体系中PHBV的结晶机制没有改变,而PCL的结晶机制改变了;共混物中PCL的结晶结构基本没变,而PHBV的结晶结构有改变,共混后材料的结晶度比单独的PCL、PHBV的结晶度都低。力学性能测试结果表明,PHBV和PCL,力学性能得到了互补,共混材料的强度虽然相比纯PHBV有所降低,但是改善了其脆性,韧性增加了。尤其是PHBV含量在40%左右时综合力学性能最佳,可以满足用作组织工程材料力学性能要求。通过接触角和吸水率测试,可以得出通过两材料的共混后,材料的表面结构和内部结构有改变,当PHBV含量在40%时其亲水性能最佳。降解试验结果表明,脂肪酶加速了PHBV/PCL的降解速率。降解15周后,不加酶的降解试验最高失重率是8%左右,而有酶参与的降解最高失重率达到了16%左右,这是因为脂肪酶有促进水解的作用。亲水性越好则降解越快,这是因为聚酯的降解其实主要是水解,亲水好的材料能与降解媒介接触充分,从而加速了降解。共混材料中当PHBV含量在40%时,其亲水性最好,故无论是加酶降解还是不加酶降解,其失重率都是最高的。通过溶剂浇注/粒子沥滤法和纤维粘结法都能成功制备三维多孔支架,前者制备的支架孔隙率能达到90%左右,后者只能达到70%左右。本文研究表明,经过一定比例共混改性后,PHBV/BCL共混材料具备优良的力学性能和生物性能,在组织工程支架材料中应用前景广阔。在支架制备方法中,可以制得高性能的三维多孔支架,同时实现一定范围内对微孔结构的可控调节,满足组织工程的不同需要。更多还原

【Abstract】 Acting as templates for cell adhesion and growth, scaffolds play an important role in construct of tissue engineering. Thus, scaffold biomaterials should meet a series of physical, chemical and mechanical need such as surface and degradation characteristics, blood and cell compatibilities etc. PHBV is microbially produced materials with many excellent properties such as biodegradability , biocompatibility , non-toxicity etc. And PCL also have those excellent properties. But due to its high crystallinity and large spherulite, PHBV shows high brittleness and strong hydrophobic property. At the same time, its processing scope is rather narrow. PCL has important application in the field of biomedical engineering and tissue engineering. But it also has disadvantage. For example, its strength is too lower to be used effectively in tissue engineering. So, it is very necessary to further improve its intensity. In addition, the bone binding ability of the PHBV/PCL blend will be improved, because the PCL have better bone binding ability.In this paper, poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly (ε-caprolactone) (PCL) were blended by co-solution casting method and co-melt spinning method. The properties of PHBV/PCL blends were investigated. Such as crystallization , miscibility , biodegradability, mechanical property, etc. At the same time, three dimensional scaffolds were prepared by fiber bonding method and Solvent Casting /Particulate Leaching method. The result indicated that there is immiscibility for PHBV and PCL blends. Crystallization of PHBV and PCL was studied and analyzed by Avrami equation using two-step crystallization in the PHBV/PCL blends. The crystallization rate of PHBV at 70℃decreased with the increase of PCL in the blends, while the crystallization mechanism did not change. In the case of the isothermal crystallization of PCL at 40℃, the crystallization rate increased with the addition of PHBV, and the crystallization mechanism changed, too. And the Crystallinity of the PHBV/PCL blends is less than the pure PHBV and pure PCL. The processing ability was improved after adding PCL, which is due to decrease of the melting temperature and the crystallinity. With the tenacity and elongation increased much , PHBV/PCL blends mechanism property was improved, especially when the PHBV content 40%. After water absorption and contact angle tested and analyzed, the results indicated that the surface and interior structure were changed. Hydrophilic property is improved, especially when PHBV content 40%. The degradation behavior of PHBV/PCL blends was investigated in the phosphate solution and lipase phosphate solution by weight loss and SEM, etc. The results indicated that the degradation rate increased twice than before with the addition of lipase. Scaffolds fabricated via SC/PL could be applied in tissue engineering of cartilage with porosity higher than 90% and appropriate pore size. The porosity of scaffolds obtained from fiber bonding method could reach 70% with pore size between 70-300μm. Scaffolds fabricated from two methods hold good hydrophilic, which was favorable for cell adhesion and generation.PHBV/PCL owning excellent biological and physical properties should be an attracting prospect as scaffold biomaterial. For scaffold fabrication, improving of traditional methods and new attempted melt bonding process both were feasible to obtain high performance in microstructures which were controllable for different applications.更多还原