壳聚糖/三元共聚物微胶囊的制备及表征

利用多聚电解质间的凝聚作用，在细胞生理条件下制备了一种液核带正电的新型微胶囊体系.该微胶囊的液核为N-乙酰化率50%的壳聚糖衍生物（HNC) 溶液，壳膜由HNC与异丁烯酸 (MAA)-羟乙基异丁烯 (HEMA)-甲基丙烯酸甲酯 (MMA) 三元共聚物(MAA-HEMA-MMA)凝聚而成.从N-乙酰化率15.3%的市售壳聚糖（FNC）出发，乙酰化制备的HNC在细胞生理pH条件下具有良好的溶解特性和质子化率.黏度80～3000 cPa•s间的HNC溶液可制备外观整齐、尺度均一的球形微胶囊.HNC分子量及浓度、pH、凝聚时间等对微胶囊的壳膜结构和表面特性都有一定影响，并进一步影响微胶囊的渗透性和强度.高浓度HNC有利于制备高强度的微胶囊，而低浓度HNC则有利于制备渗透性较好的微胶囊.

Preparation and characterization of chitosan/terpolymer microcapsule

Half N-acetylated chitosan (HNC)-based microcapsules were prepared under neutral conditions by coacervating with methacrylic acid (MAA) (20.4%)-hydroxyethyl methacrylate (HEMA) (27.4%)-methyl methacrylate (MMA) (52.2%) terpolymer (MAA-HEMA-MMA). The formed microcapsules consisted of a liquid inner core of HNC and an outer complexation shell derived from HNC and terpolymer. Prepared from 15.3% N-acetylated chitosans (FNC), HNC maintained good solubility and supplied enough protonated amino groups to coacervate with terpolymer to form microcapsules under physiological conditions. The viscosity of HNC solution between 80 and 3000 cPa•s guaranteed the formed microcapsules with good spherical shape. The preparation parameters, including pH, HNC molar mass, chitosan concentration and reaction time, greatly influenced the intrinsic coating membrane features such as morphology, thickness and network porosity, and further determined microcapsules’ permeability and mechanical stability. Low concentration of HNC favored the permeability of microcapsules, whereas high concentration was good for the resistance of microcapsules to shear force.