壳聚糖支架制备过程中的改性处理研究

发布时间：2019-01-01 15:58

【摘要】：本课题组利用壳聚糖的氨基在稀酸中阳离子化和再加碱溶液中和会凝胶化的特点制备三维有序壳聚糖支架。为了进一步的改进其强度、降解、稳定性、以及羟基磷灰石的结晶性能等以满足骨组织修复的需要。本文从不良溶剂对壳聚糖基体的影响方面出发,对壳聚糖存在的三个状态进行了研究：1)溶液态、2)凝胶态和3)支架态。 (1)首先研究了壳聚糖乙醇溶液的流变学性质。壳聚糖乙醇溶液随着乙醇含量的增加,先是向牛顿流体转变,而后又开始偏离牛顿流体,表现为流体指数的先增加后减小,这与粘度和凝胶点的变化一致。 (2)本文以壳聚糖和羟基磷灰石前躯体为原料采用了原位沉析法制备了壳聚糖/羟基磷灰石复合凝胶,并用乙醇和丙三醇对其进行了处理。支架的表面形貌变得粗糙,微孔增加,有大量的纳米羟基磷灰石结晶(宽度为25～180nm,长度为50～500nm)分布于基体中。与未处理的支架相比,乙醇处理的支架孔径降低、分布均匀；丙三醇处理的支架孔径类似与未处理支架,随羟基磷灰石的含量增加孔隙率却增加,在湿态环境下的力学强度增强。而且处理过的两种支架共同的特点是热稳定性降低,吸水率明显提高,体外的降解速率降低,细胞生长增殖状态良好。 (3)通过氢氧化锂和尿素的混合溶液成功地制备一种具有自发形成凝胶的壳聚糖溶液。随着壳聚糖溶液浓度和温度的升高,这种趋势越明显,形成凝胶的时间越短。用6%硫酸溶液可诱导壳聚糖碱溶液快速凝胶,制备了具有明显层状结构和孔连通性优良的支架,其表面具有凹凸起伏的粗糙形貌。通过模拟生物矿化,该支架表面生成了块状的羟基磷灰石结晶,具有促进成骨细胞在支架表面的粘附的作用和刺激细胞活性的特点。
[Abstract]:The objective of this study was to prepare three dimensional ordered chitosan scaffolds by using the characteristics of chitosan amino groups cationizing in dilute acid and neutralization of alkali-added solution. In order to further improve its strength, degradation, stability, and hydroxyapatite crystallization to meet the needs of bone tissue repair. In this paper, we studied the three states of chitosan: 1) solution state, 2) gel state and 3) scaffold state from the point of view of the influence of bad solvent on chitosan matrix. The main results are as follows: (1) the rheological properties of chitosan ethanol solution were studied. With the increase of ethanol content, the chitosan ethanol solution first changes to Newtonian fluid and then deviates from Newtonian fluid, which shows that the fluid index first increases and then decreases, which is consistent with the change of viscosity and gel point. (2) chitosan / hydroxyapatite composite gel was prepared by in situ precipitation from chitosan and hydroxyapatite precursor, and treated with ethanol and glycerol. The surface morphology of the scaffold became rough and the micropores increased. A large number of nano-hydroxyapatite crystals (width 25 ~ 180nm, length 50~500nm) were distributed in the matrix. Compared with the untreated scaffolds, the pore size of ethanol treated scaffolds was decreased and distributed evenly. The pore size of the scaffolds treated with glycerol is similar to that of the untreated scaffolds, but the porosity increases with the increase of hydroxyapatite content, and the mechanical strength increases in wet environment. The common characteristics of the two scaffolds were the decrease of thermal stability, the increase of water absorption, the decrease of degradation rate in vitro, and the good state of cell growth and proliferation. (3) A chitosan solution with spontaneous gel formation was successfully prepared by the mixture of lithium hydroxide and urea. With the increase of chitosan concentration and temperature, this trend is more obvious and the time of gel formation is shorter. Chitosan alkali solution was induced by 6% sulfuric acid solution, and the scaffold with obvious layered structure and good pore connectivity was prepared. The surface of the scaffold was rough with ups and downs. By simulating biomineralization, massive hydroxyapatite crystals were formed on the surface of the scaffold, which promoted the adhesion of osteoblasts to the scaffold surface and stimulated cell activity.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.08

【参考文献】