Hu F Q, Li Y H, Yuan H, Zeng S
School of Pharmaceutical Science, Zhejiang University, 353,Yan'an Road, Hangzhou 310031, P.R. China.
Pharmazie. 2006 Mar;61(3):194-8.
A novel hydrophobically modified chitosan oligosaccharide (CSO) containing 5.4 stearic acid (SA) groups per 100 anhydroglucose units was synthesized by an 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling reaction. The purified copolymer was structurally characterized by IR spectroscopy. Characteristics of self-aggregates of the amphiphilic copolymers were studied by fluorescence spectroscopy and dynamic light scattering. The critical aggregation concentration (cac) value of the self-aggregates in aqueous solution was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. Mean diameter of self-aggregates in pH 7.0 PBS was 25.0 +/- 14.7 nm with a unimodal size distribution. The diameter, as well as the zeta potential of self-aggregates increased when the pH value of dispersion medium decreased. Bovine serum albumin (BSA) was further enveloped in the interface of different single self-aggregate and formed nanoparticles. The size of BSA-loaded stearic acid modified CSO nanoparticles depended on the pH values of the dispersed aqueous vehicle, and the size diminished when the pH values of the dispersed aqueous vehicle decreased, whilst, the BSA encapsulation efficiency enhanced. The nanoparticles were characterized by Transmission Electron Microscopy (TEM). BSA release from stearic acid modified CSO nanoparticles decreased when the pH values of the delivery media decreased, in the range from 7.2 to 5.8.
通过1-乙基-3-(3-二甲基氨基丙基)碳二亚胺(EDC)介导的偶联反应合成了一种新型疏水改性壳寡糖(CSO)，每100个脱水葡萄糖单元含有5.4个硬脂酸(SA)基团。通过红外光谱对纯化的共聚物进行结构表征。利用荧光光谱和动态光散射研究了两亲共聚物自聚集体的特性。以芘为荧光探针，通过测量芘的荧光强度来测定自聚集体在水溶液中的临界聚集浓度(cac)值。在pH 7.0的磷酸盐缓冲液(PBS)中，自聚集体的平均直径为25.0±14.7 nm，粒径分布呈单峰。当分散介质的pH值降低时，自聚集体的直径和zeta电位均增加。牛血清白蛋白(BSA)进一步包裹在不同单个自聚集体的界面上，形成纳米颗粒。负载BSA的硬脂酸修饰CSO纳米颗粒的大小取决于分散水相载体的pH值，当分散水相载体的pH值降低时，颗粒尺寸减小，同时BSA的包封效率提高。通过透射电子显微镜(TEM)对纳米颗粒进行表征。在7.2至5.8的范围内，当递送介质的pH值降低时，硬脂酸修饰的CSO纳米颗粒中BSA的释放减少。
