Sah H K, Toddywala R, Chien Y W
Controlled Drug-Delivery Research Center, College of Pharmacy, Rutgers-State University of New Jersey, Piscataway, NJ 08854, USA.
J Microencapsul. 1995 Jan-Feb;12(1):59-69. doi: 10.3109/02652049509051127.
A water-in-oil-in-water (w/o/w) technique, sometimes known as in-water drying method, was used to prepare microcapsules consisting of polylactic acid and poly(lactide-co-glycolide). The influence of shear force to produce an initial water-in-oil (w/o) emulsion on the characteristics of microcapsules and protein release was investigated. Bovine serum albumin (BSA) was used as the model protein drug for encapsulation. The initial w/o emulsion was prepared by a Polytron homogenizer. The shear rate was varied from 11 to 23 krpm to produce w/o emulsions with different shear forces. This study revealed pronounced effects of shear force on the characteristics of microcapsules and release profiles of BSA. Depending on the degree of the shear applied, the inner structure of microcapsules showed very different morphology, which was responsible for different release patterns. A low shear produced microcapsules with a high initial burst release of BSA, whereas microcapsules using a high shear exhibited a controlled release of protein without any initial burst release. Also, at a given shear force, a variation in polymer composition of microcapsules was found to be effective in controlling the release characteristics of protein. Thus, the homogenization technique should be carefully considered in designing microcapsules with desirable release profiles of proteins and an adequate period of protein delivery.
采用水包油包水（w/o/w）技术，有时也称为水中干燥法，制备了由聚乳酸和聚（丙交酯-乙交酯）组成的微胶囊。研究了剪切力对制备初始水包油（w/o）乳液的影响，以及其对微胶囊特性和蛋白质释放的影响。牛血清白蛋白（BSA）用作包封的模型蛋白药物。初始w/o乳液由Polytron匀浆器制备。剪切速率从11至23 krpm变化，以产生具有不同剪切力的w/o乳液。本研究揭示了剪切力对微胶囊特性和BSA释放曲线有显著影响。根据施加的剪切程度，微胶囊的内部结构呈现出非常不同的形态，这导致了不同的释放模式。低剪切力制备的微胶囊具有较高的BSA初始突释，而使用高剪切力制备的微胶囊则表现出蛋白质的控释，且无任何初始突释。此外，在给定的剪切力下，发现微胶囊聚合物组成的变化对控制蛋白质的释放特性有效。因此，在设计具有理想蛋白质释放曲线和足够蛋白质递送期的微胶囊时，应仔细考虑匀浆技术。
