海藻酸-壳聚糖-聚乳酸羟乙醇酸复合微球的制备及其对蛋白释放的调节

目的制备蛋白的海藻酸-壳聚糖-聚乳酸羟乙醇酸(PLGA)复合微球，以增加蛋白药物的包封率、减少突释和不完全释放。方法以牛血清白蛋白为模型药物采用修饰的乳化、醇洗法制备小粒径海藻酸微囊，再以壳聚糖孵育制得海藻酸-壳聚糖双层微囊，并进一步用PLGA包裹制得复合微球。采用微量BCA试剂盒测定蛋白浓度，考察其包封率及释放行为，改变各种制备因素调节微球的释放特性。结果复合微球粒径约30 μm，形态圆整。与单纯PLGA微球相比，包封率由60%-70%上升至80%以上。复合微球在磷酸盐缓冲液的1 h突释量由40%-50%下降至25%以下，在生理盐水中则进一步下降至5%以下。结论海藻酸-壳聚糖-PLGA复合微球提高了蛋白药物的包封率，减少了药物的突释，并可通过调节PLGA比例调节药物的释放。

Preparation of alginate-chitosan-poly (lactic-co-glycolic acid) composite microsphere and its regulation of protein release

AIM: To elevate the encapsulation efficiency, decrease the burst release and improve the release of protein entrapped in poly (lactic-co-glycolic acid) (PLGA) microspheres. The bovine serum albumin (BSA) composite microspheres of alginate-chitosan-PLGA were prepared and the release characteristics of BSA from this composite microspheres were studied. METHODS: The much smaller calcium alginate microcapsules were first prepared by a modified emulsification method in an isopropyl alcohol-washed way and coated with chitosan, then the alginate-chitosan microcapsules were further entrapped in PLGA to form the composite microspheres. The protein concentration was determined using a BCA protein assay kit. The release profiles were changed with various formulation factors. RESULTS: The average diameter of the composite microcapsules was about 30 microm. Comparing with 60% to 70% of the conventional PLGA microspheres, the average encapsulation efficiency was more than 80%, and the burst releases in phosphate buffer solution of the composite microspheres decreased from 40% and 50% to 25% and further to 5% in saline solution. CONCLUSION: The novel composite microspheres were prepared, the drug encapsulation efficiency increased and the burst release decreased. The desired release profiles could be obtained by regulating the ratios of PLG and PLA in the composite microspheres.