【作者】 孙瑞雪；

【导师】 陈丽娟；

【作者基本信息】 中国科学院研究生院（理化技术研究所） ， 物理化学， 2009， 博士

【摘要】 明胶微球具有许多优良的物理、化学和生物性能,被广泛应用于医药工程、生物技术、材料科学和电子信息产业等领域。随着明胶微球在不同领域中用途的增多,人们对其形态、结构和性能提出了更高的要求。由于乳化装置的不断改进,现已能够制备出纳米级~亚微米级的明胶微球,但是难以制备尺寸均一的微球,这将给明胶微球的实际应用带来阻碍。因此,如何制备出粒径可控、尺寸均一的明胶微球,一直是研究者们关注的问题,也是本论文研究的重点之一。明胶/羟基磷灰石(HAP)复合微球是近年来备受关注的一种骨修复材料,与其他种类的骨替代材料相比,明胶/HAP复合材料的生物相容性和生物降解性是很理想的,与骨组织也可以达成良好的结合。但是,与天然骨相比,这种骨修复材料的力学性能,即弹性模量、断裂韧性和抗拉强度还有待改进。这是本论文的又一工作重点,并对两相在微观结构上的复合进行了初步的机理探讨。主要的研究工作包括:1.采用条件温和的乳化-凝胶法制备明胶微球,通过扫描电子显微镜(SEM)和粒径分布曲线,系统研究了制备参数对明胶微球粒径和形貌的影响,得出如下结论:降低明胶溶液浓度、减小水油比例、增大乳化剂用量等都能够减小明胶微球的粒径;提高乳化的搅拌速率、选择合适的乳化时间和乳化温度等有利于改善微球的分散性和圆整度。通过研究,可以实现微球尺寸的可控制备。2.研究了四种不同种类的油相,它们的主要脂肪酸成分对明胶微球大小和形态的影响。疏水能力强的油脂,制备出的微球粒径小;疏水能力弱的油脂,制备出的微球粒径大。这一研究表明,制备明胶微球油相的类型不可忽视。3.研究了阳离子型乳化剂CTAB、非离子型乳化剂Tween/Span、阴离子型乳化剂SDS和复合乳化剂等对明胶微球形成的影响。结果表明,非离子型乳化剂较为温和,阳离子型乳化剂CTAB在用量较少的情况下即可达到满意的乳化效果,阴离子型乳化剂的乳化效果较差;CTAB/Span 80为1:1时所得的微球平均粒径仅6.5μm,球型圆整,是制备明胶微球的理想复合乳化剂。4.通过研究明胶微球在不同乳化时间下的形态变化,并测试明胶在形成微球前后理化性质的改变,对明胶微球的形成机理进行了初步探讨。5.在油包水的乳液体系中,通过原位合成的方法使HAP在明胶链上化学沉积,改变明胶溶液的浓度,制得了一系列的明胶/ HAP复合物微球。采用XRD、FTIR、SEM、TEM和TGA等测试手段对产物的组成、形貌以及热失重情况进行了表征。结果表明,明胶用量对复合物微球中HAP的形成具有重要影响。随着明胶用量由少到多,HAP晶体经历了棒状-针状-颗粒状的变化,在明胶溶液浓度为0.025 g/mL时,复合物微球中无机相含量达40%。另外,对HAP晶体变化的原因进行了理论推测。更多还原

【Abstract】 Gelatin microspheres (GMs) have been known to display a variety of applications in different technological fields including medicine, biology, chemical and electronic information industry because of their diverse and excellent physical, chemical, biological and amphoteric properties. As the widely use of GMs in different field, People has brought forward higher call for its morphology, structure and properties. Although nano- and micro- GMs could be prepared thanks to the development of emulsifying devices, uniform-sized microspheres are still difficult to synthesized. In this dissertation an attempt was made to optimize the manufacturing conditions, in order to prepare homogeneous and size-controlled GMs.Gelatin/hydroxyapatite (HAP) composite microspheres have been extensively investigated because of their similar composition and structure to natural bone, perfect biocompatibility and osteoconductive activity. However, to be an ideal bone repair material, low elastic modulus, high fracture toughness and tensile strength are needed. Therefore, an attempt of optimizing the preparation conditions was performed with the aim to improve the microstructure and properties of the composite microspheres. The main research work in the present dissertation can be summarized as follows:1. A series of GMs were prepared by emulsification-coacervation method in water-in-oil (w/o) emulsions. The influence of preparation parameters on particle size, surface morphology and dispersity of GMs were examined. The experimental results indicated that increasing the concentration of gelatin solution and water /oil ratio would increase the particle size of GMs. On the contrary, increasing the concentration of the emulsifier and stirring speed would decrease the particle size of GMs. At proper emulsifying time and temperature would get the best sphericity of GMs. According to the practical application, size tunable GMs can be prepared.2. Four kinds of oil phase were used to study its influence on the particle size and morphology of GMs. The experimental results indicated that GMs with smaller size can be obtained by using the oil phase with higher hydrophobicity. Accordingly, lower hydrophobic oil can lead to larger particle size.3. The influences of CTAB, Tween/Span, SDS and composite emulsifiers on the formation of GMs were investigated. The results showed that Span was a tender emulsifier, lower dosage of CTAB could have good effect, and SDS was not an ideal choice for this study. We also found that the mean diameter of GMs was just 6.5μm when the ratio of CTAB and Tween 80 was 1:1.4. The mechanism of GMs’formation was carried out preliminarily by study the changes of morphology and physicochemical properties of gelatin during the emulsifying time.5. By changing the concentration of gelatin solutions, a series of Gelatin/ HAP composite microspheres were prepared through in-suit synthesis method in water-in-oil (w/o) emulsions. The products were characterized by XRD、FTIR、SEM、TEM and TGA. The experimental results indicated that the concentration of gelatin solutions had great influence on the formation of HAP. The initial rod-like crystalline shape of HAP changed to needle-like, and then to granules. The binding of gelatin and HAP had a maximum value at gelatin concentration around 0.025 g/mL. In addition, the reasons of the HAP crystal formation were presupposed theoretically.更多还原