Deng X M, Li X H, Yuan M L, Xiong C D, Huang Z T, Jia W X, Zhang Y H
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 61004 1, P.R. China.
J Control Release. 1999 Mar 29;58(2):123-31. doi: 10.1016/s0168-3659(98)00147-3.
Poly-dl-lactide-polyethylene glycol (PELA) with different contents of polyethylene glycol(PEG) were synthesized and the PEG content was estimated according to the integral height of hydrogen shown in 1H-NMR. PELA microspheres containing V. cholera antigen, outer membrane protein (OMP) were prepared by a water-in-oil-in-water (W/O/W) based on solvent evaporation procedure. Antigen microspheres with smooth surface, suitable size for oral administration (0.5-5 microm), high loading efficiency (about 60%) and low level of residual solvent (lower than 20ppm) were obtained. Microspheres prepared from PELA with PEG content of about 10% achieved the highest loading efficiency among PELA copolymers and poly-dl-lactide (PLA) homopolymer, which suggested that microspheres size, morphology and the precipitation rate of polymer showed considerable relations with OMP loading efficiency. The regulation of the solvent components of the oil phase contributes to a stable emulsion W/O, and it is concluded that the stable emulsion W/O plays a significant role in improving the protein loading efficiency of obtained microspheres. The addition of stabilizer, such as gelatin and polyvinyl alcohol, into the internal water phase before emulsification produced no significant difference in OMP entrapment and microspheres size. A higher OMP loading efficiency was achieved by adding NaCl or adjusting the pH at the iso-electric point of OMP in the external water phase. It was indicated in vitro that PELA microspheres with smaller size showed larger extent of initial release and higher release rate, whereas microspheres with the diameter of 2.17 microm showed no apparent burst effect.
合成了具有不同聚乙二醇（PEG）含量的聚-dl-丙交酯-聚乙二醇（PELA），并根据1H-NMR中氢的积分高度估算PEG含量。采用基于溶剂蒸发法的水包油包水（W/O/W）技术制备了含有霍乱弧菌抗原、外膜蛋白（OMP）的PELA微球。获得了表面光滑、适合口服给药尺寸（0.5-5微米）、高负载效率（约60%）和低残留溶剂水平（低于20ppm）的抗原微球。由PEG含量约为10%的PELA制备的微球在PELA共聚物和聚-dl-丙交酯（PLA）均聚物中实现了最高的负载效率，这表明微球尺寸、形态和聚合物的沉淀速率与OMP负载效率有显著关系。油相溶剂成分的调节有助于形成稳定的W/O乳液，得出结论，稳定的W/O乳液在提高所得微球的蛋白质负载效率方面起着重要作用。在乳化前向内部水相中添加稳定剂，如明胶和聚乙烯醇，对OMP包封率和微球尺寸没有显著影响。通过在外部水相中添加NaCl或调节至OMP的等电点pH值，可实现更高的OMP负载效率。体外实验表明，尺寸较小的PELA微球初始释放程度较大且释放速率较高，而直径为2.17微米的微球没有明显的突释效应。
