【作者】 李勇；

【导师】 尹光福；

【作者基本信息】 四川大学 ， 生物医学工程， 2004， 硕士

【摘要】 对骨缺损修复材料的探索一直是生物医用材料领域的研究热点之一。骨组织修复材料作为骨缺损的替换材料,具有功能上的特殊性――应用于负载的力学性能、生物相容性、骨传导性及骨诱导性。因此,应用骨组织工程技术的基本原理对骨修复材料的探索研究已经成为骨支架材料的发展方向。传统的β-磷酸三钙(β-tricalcium phosphate,β-TCP)生物陶瓷材料,具有良好的生物相容性、耐腐蚀等优点,其成分与骨矿物组成类似,但单独作为骨修复材料使用时,β-TCP存在脆性大、韧性差及模量过高等缺陷,限制了它在骨科方面的临床应用。为了满足骨组织修复材料的力学性能和生物学性能要求,人们对β-TCP与高聚物之间的复合材料展开了研究。本研究围绕β-TCP/聚L-乳酸(Poly L-latic acid,PLLA)复合材料的生物降解性、合适的力学性能、材料表面微环境的可调控性及材料易加工性等要求制备出具有良好的生物相容性及稳定性的生物复合材料。1、本研究首先将自制的高纯、超细CaCO3粉末调和成浆料,按Ca/P比为1.5配料向磷酸溶液中快速加入CaCO3粉料;然后,以CaCO3/H3PO4为体系制得粒度细(0.5～2μm)而均匀的TCP前驱体,在950℃下煅烧TCP前驱体制得β-TCP超细粉末,烘干;最后,β-TCP粉末表面改性处理,将烘干的β-TCP粉末加入到1wt%棕榈酸乙醇溶液中,在超声分散作用下搅拌20min,抽滤、烘干,备用。通过润湿角测量仪测得改性β-TCP粉末的水性接触角为145.0°;扫描电镜(SEM)下观察到改性β-TCP粉末分散均匀,近似球状颗粒,颗粒的粒径约在0.2～1.0μm之间;通过X光电子能谱(XPS)分析得知:棕榈酸的H+与β-TCP中PO43-的一个O之间形成了-OH基团,此基团能与<WP=7>PLLA的-C=O之间发生氢键结合,提高了复合材料的力学性能。2、研究选择了改性β-TCP与PLLA按2:1、1:1、1:2重量比混合、以NaCl颗粒为致孔剂、采用“溶液浇铸—热压成形—颗粒沥滤”方法制备了多孔β-TCP /PLLA复合骨支架材料;选用了用量为40、50、60、70、80wt% NaCl颗粒制得了复合材料孔隙率的范围:39～75%。研究表明:在6MPa的成形压强、120℃的成形温度以及致孔剂NaCl用量为60wt%时,万能测试机测得复合材料的抗压强度约为8MPa,相当于松质骨的抗压强度,制得的复合材料的力学性能基本符合骨力学性能要求。通过SEM及透射电镜(TEM)观察到:改性β-TCP粉末在PLLA基体中分散均匀;复合材料有着开口的、均匀的及相互贯通的孔隙,且孔径约为100~400μm。3、本实验研究了β-TCP/ PLLA复合材料模拟体液中的降解。将上述制得的β-TCP/ PLLA复合材料浸泡在模拟体液(SBF)中,置于37℃恒温水浴摇床里,进行体外降解,分别在1w、3w、5w、9w、13w、17w取样。通过红外光谱仪(FTIR)及X射线衍射仪(XRD)分析,发现有少量的β-TCP转化为类骨性羟基磷灰石,并且降解材料力学测试结果表明,材料的力学强度随降解时间而下降。4、本论文研究了体外细胞培养。将经成骨诱导、多次传代的骨髓间充质干细胞与上述支架材料复合培养,发现细胞能在支架材料上粘附、增殖,细胞形貌正常,说明材料的加入不影响细胞的生物学行为,且β-TCP/PLLA=2∶1、60~70%孔隙率以及100~400μm的支架材料表现出的生物相容性最好。更多还原

【Abstract】 The research on bone tissue replacement materials is one of the most attractive aspects of biomedical engineering. Materials for defect replacement and repairing process special functional requirements for mechanical properties for bone-bearing, biocompatibility, osteoconductivity and osteoinductivity. Therefore, the exploration of the bone replacement materials based on tissue engineering technology has become a heated topic in this field. Traditional bioceramic such as β-tricalcium phosphate(β-TCP) has a component simulated with bone minerals, and possesses a good biocompatibility. However,β-TCP has disadvantages like big brittleness, poor toughness and high elastic modulus, which limits it application in clinic. To satisfy the demand for mechanical and biological properties of bone replacement materials, composite materials betweenβ-TCP and polymer have been studied.In this dissertation, β-TCP/ Poly L-latic acid(PLLA) composite materials with good mechanical compatibility and stability has been prepared. Adjustable biodegradation, suitable mechanical properties, controllable surface microenvironment and feasible processability of the materials are emphasized.1. CaCO3 powers were prepared to β-TCP powers. First, High-purity and ultrafine CaCO3 powers were mixed to slurry with water. Then, CaCO3 slurry was poured rapidly into phosphoric acid solution according to Ca/P=1.50 in ultrasonic agitation to obtain ultrafine and uniform TCP precursor powders (0.5~2m). Finally,ultrafineβ-TCP powers were prepared by calcining TCP precursor at 950℃. Palmitic acid modifiedβ-TCP powders were obtained by adding ultrafine β-TCP powers into 1wt% palmitic acid / alcohol solution, and following ultrasonic agitation for 20min , pumping, filtrating and drying. <WP=4>The modification parameter was determined, and the modification effect had been tested. Scanning electron microscope (SEM) observations indicate that: 1). Surface modified β-TCP microparticles disperse uniformly; 2).The diameter of the particles is about 0.2~1.0m; 3). The particles could be uniformly distributed within PLLA matrix. The contact angle of modifiedβ-TCP powder for distilled water reaches 145.5°. The mechanical properties of β-TCP/PLLA could be enhanced by modifyingβ-TCP surface with palmitic acid. XPS test prove that a -OH group has been formed between H+ of palmitic acid and [O] of PO43- inβ-TCP. This –OH group could form hydrogen bond with –C=O of PLLA, by which the mechanical properties of the composite could be reinforced.2. The composites were prepared by mixing the modified β-TCP and PLLA according to the weight ratio of β-TCP /PLLA=2:1, 1:1, and 1:2 in this study. A process which consist of solvent casting, compression molding and leaching stage had been used to fabricate macro-porous composite materials ofβ-TCP/PLLA composite. The porosity of the composites ranges from 39~75% when the porogen-NaCl added is 40, 50, 60, 70, 80% respectively. According to the melting point and the crystallinity of the composites measured by DSC, the influence of molding temperature, molding pressure and pressure time on mechanical properties, degradation of the composites and cell culture effects in vitro were studied. The effects of the porogen NaCl, of the pressure and temperature of molding on the porosity, the volume density and the mechanical characterization of composite had been investigated. The relationship between soaking time of composite and porogen-NaCl relative leaching concentration had been studied. SEM observation indicate that the scaffolds prepared have an open, uniform and interconnected porous structure with a pore size of 100–400m. Compressive strength of ~8MPa equivalent to that of cancellous bone is achieved. The porosity of scaffolds has reached ~ 60%. The porousβ-TCP/ PLLA composite materials molding in 6MPa, 120℃and adding 60wt% porogen-NaCl possess a good mechanical properties. 3. The degradation of β-TCP/ PLLA composites in vitro was studied. The composite samples were immersed in stimulated body fluid (SBF更多还原