【作者】 刘袖洞；

【导师】 袁权； 马小军；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 化学工程， 2002， 博士

【摘要】 蛋白质和多肽类生化药物临床应用需求与药物制剂水平相对滞后的矛盾，直接推动了稳定、有效、安全的生化药物释放系统的研究与开发。以海藻酸钙凝胶珠外覆壳聚糖膜形成的微胶囊（ACA微胶囊）因其良好的材料特性（生物相容性、可降解性和粘附性）及温和的反应特性而成为最具潜力的生化药物释放载体。作为极具潜力的海藻酸钙凝胶珠及ACA微胶囊规模制备技术，乳化／内部凝胶化法中乳化产生的高剪切力不利于包埋生物物质的活性保持，且造成凝胶珠尺寸分布不均匀；缺少对凝胶珠真实结构的直观和定量认识；对于认识和解释凝胶珠结构、性能及二者之间的关系十分重要的过程机理尚未研究。针对上述问题，本论文建立了膜乳化／内部凝胶化新方法，并力图认识内部凝胶化过程规律和机理，研究过程机理——凝胶珠结构——性能之间关系及其对微胶囊膜结构与性能的影响。 首先，利用膜乳化技术能够在温和条件下制备均匀乳化液滴或微粒的特点，将其与内部凝胶化过程结合，成功制备出表面光洁、球形度好、尺寸小且分布均匀的海藻酸钙凝胶珠。考察了过程参数（如膜孔径、压力、连续相流速和分散相浓度等）对凝胶珠尺寸、分布及球形度的影响规律，从而可以根据需要优化工艺条件。 其次，考察了内部凝胶化过程海藻酸钙凝胶珠中Ca含量及凝胶珠重量变化规律，并结合理论分析，认为内部凝胶化过程是由一步扩散和四步反应构成的复杂反应过程，即 HAc（油相） HAc（水相） HAc H⁺+Ac^- 2H⁺CaCO₂ Ca²⁺+H₂O+CO₂ 2Alg^-+Ca²⁺ Ca（Alg）₂ 2H⁺+Ca（Alg）₂ Ca²⁺+2HAlg 进而通过分析、计算与比较，确定HAc扩散过程是内部凝胶化过程的控制步骤。 再次，引入激光共聚焦显微扫描技术（CLSM），首次获得了海藻酸钙凝胶珠在含水状态下的直观、真实结构图像及孔尺寸定量结果。通过比较内、外部凝胶化胶珠结构，发现凝胶化过程机理的不同导致了凝胶珠结构的差异。而这种结构上的差异又进一步造成物质在凝胶珠中扩散性能的差异。 接着，利用激光共聚焦显微扫描技术，考察了外覆壳聚糖的ACA微胶囊膜结构。发现微胶囊膜结构是由海藻酸钙凝胶珠结构决定的，且比凝胶珠结构更为致密。而且首次获得膜孔结构的三维信息，表明膜孔并不是直通孔，而是沿Z轴的非对称孔。进一步研究表明微胶囊膜强度性能是受膜结构影响的。 最后，以牛血红蛋白（Hb，分子量 64，500 Dation）为模型药物，制备载药ACA微胶囊，考察了成膜反应条件对其载药量、包封率及释放性能的影响，结果表明本文体系中微胶囊具有一定的缓释能力。更多还原

【Abstract】 The research and development of stable, efficient and safe drug delivery system for biopharmaceuticals have been promoted by the contradiction between clinical demands and relative hysteretic preparation level. Alginate/chitosan microcapsules (ACA microcapsules) have been proven to be potential drug delivery carrier for biopharmaceuticals, due to material characteristics (biocompatibility, biodegradability and biadhesiveness) and mild reaction characteristics. As potential mass production technique of calcium alginate gel beads and ACA microcapsules, there still exist some problems in emulsification-internal gelation. The big shearing force of emulsification process makes against the maintenance of biological material activity, and the size distribution of beads is not uniform; there are lack of the illustrative and quantitative understanding to real structure of beads, and the process mechanism is not investigated though it is important to know and interpret the structure, properties and the relationship between them. Aiming at the problem above, membrane emulsification combined with internal gelation technology was developed in this dissertation, and the mechanism of internal gelation process was analyzed.Furthermore, the correlation among process mechanism------structure of gel beads--properties of beads was carried out, and its effect on microcapsule membrane structure and properties was also investigated.Firstly, membrane emulsification technology was combined with internal gelation process, making use of its ability of preparing uniform emulsion or microparticles under mild conditions. The small size and narrow distribution gelbeads with smooth surface and good sphericity were successfully obtained. Then the understanding of the effect of process parameters on the bead size, distribution and morphology would be in favor of optimizing process conditions.Secondly, based on the investigation of Ca content change in gel beads and bead weight change, together with theoretical analysis, internal gelation process was thought to be a complicate reaction process, composed of 1 diffusion process and 4 reaction steps, that is,After analyzing, calculating and comparing, HAc diffusion process was determined as the control step of internal gelation.Thirdly, confocal laser scanning microscopy (CLSM) was introduced into structure characterization of calcium alginate gel beads. The illustrative, real structure and quantitative pore size of beads with over 95% water were observed for the first time. Comparing the bead structure by internal gelation and external gelation, respectively, it was also found that it was the mechanism difference of gelation that resulted in different bead structure. Furthermore, the structure difference contributed to the material diffusion difference.Fourthly, structure of ACA microcapsule membrane was observed using CLSM. It was noticed that the membrane structure was determined by bead structure, and was denser than the latter. It was shown for the first time that the membrane pores were asymmetric along Z axis instead of straight through ones. Further studies revealed that the membrane strength of microcapsules was affected by membrane structure.Finally, taking hemoglobin (Hb, Mw 64,500 Dalton) as model drug, the Hb-ACA microcapsules were prepared. The effect of membrane formation reaction conditions on drug loading, entrapment efficiency and release property were investigated, which showed sustained release behaviour to a certain extent.更多还原