【作者】 刘源岗；

【导师】 周长忍；

【作者基本信息】 暨南大学 ， 生物医学工程， 2006， 博士

【摘要】 为了解决壳聚糖基组织工程支架材料的体内降解速率调控与匹配问题，本论文设计了一条新的思路，引入了一个“自调控”的概念。所谓“自调控”就是材料自身能够调节控制材料的降解速率而受环境的影响相对较小。利用溶菌酶的缓释调控壳聚糖支架的降解速率，可起到速率自调控和辅助介入治疗相结合的效果。溶菌酶不仅具有药理功能，且几乎分布于人体各个部位，所以将酶的缓释与支架制备相结合是安全可靠的。“自调控”技术有望解决困扰组织工程研究的壳聚糖基组织工程支架材料降解速率匹配问题。 本研究采用了W／O／W复乳技术，考察了三种分离方法(直接冷冻干燥法、过滤法、离心法)对微球形态的影响，探索出一步法构建含微粒的组织工程支架材料新方法，探讨了负载溶菌酶的PLGA微球形成机理，同时从多角度对微球的形成机理进行了阐释。 本研究较为系统地考察了制备参数对微球理化性能的影响，从应用角度出发突出了微球产率和载药释放性能。微球产率在5.7％～97.4％(w／w)之间，微球粒径可控制在30μm～100μm，载药量和包封率理想，大部分载药量接近或达到理论载药量，包封率基本在40％～90％之间，部分可达到95％以上。微球缓释效果明显，16d的释放可控制在20％～70％的较大区间内。酶活基本保持完好，大部分在90％以上。对溶菌酶缓释体系进行了数学模型模拟，结果表明，一级动力学模型对药物释放过程的拟合精度高，能够很好的描述溶菌酶缓释微球的体外释放情况。此外，采用了原子力显微镜对溶菌酶活性测定原理，即溶菌酶可降解细菌细胞壁导致体系浊度降低这一过程进行了同步跟踪。 本研究最终获得了可用于构建复合型支架的制备条件(支架形貌较为规整、弹性模量最大、孔径合适、孔隙率高)。本研究还采用了一种新的手段分析支架的表面形貌特征，即利用统计学的方法对孔径做统计分析，考察其概率分布特征，同时引入了SPAN值的概念对孔径进行数据处理，结合二者的分析结果可较好的表征支架的表面形貌特点，分析结果与直观的电镜图基本相一致。首次就水化条更多还原

【Abstract】 Chitosan is widely used as a base material of tissue engineering scaffold fabrication due to its excellent biocompatibility, biodegradability, nutritional function and pharmacological efficacy. But the degradation rate of chitosan in vivo is difficult to adjust to match the building rate of a new tissue regeneration. In this paper, a new idea, named self-controlled degradation, is employed by using the Controlled Drug Delivery System, which can control the degradation rate of chitosan scaffold by controlled release of lysozyme from the microparticles. By using this new way, we can obtain a novel intervening therapeutic and self-controlled biodegradable scaffold, which may solve the degradation problem of chitosan in tissue engineering application.Firstly, we prepared microparticles by mean of a water-in-oil-in-water technology. The basic operating parameters were determined and three separation ways, including a direct vaccum freeze-drying method, a filtration method and a centrifugation method, were investigated on the influence of morphological properties of PLGA microparticles. Results showed that the direct vacuum freeze-drying method (one step method) could prepare the microparticle-dotted fibriform network, which was a new idea in constructing some microparticle-combined polymer based scaffolds. We then described and explained the microparticle formation mechanism from different angles.Secondly, we probed into the influence of experimental conditions on the characteristics of PLGA microparticles. The results showed that the yield was between 5.7% to 97.4%, the diameter was from 30μm to 100μm, the encapsulation efficiency was from 40% to 90%, partly could achieve 95% above. The controlled release efficacy was obvious, the cumulative release ratio ranged from 20% to 70%. Most importantly, the enzyme remained its specific activity above 90%. We then mimicked the in vitro release by using mathematic models. The first order dynamic更多还原