摘要
目的 研究白蛋白喷雾干燥微球经加热变性后的水溶性及酶降解性 ,探讨热变性机理。方法 用喷雾干燥工艺制成粉末状白蛋白微球 ,进一步加热变性处理。热变性条件分别为 :温度 12 0℃ ,时间 3～ 2 4h ;温度 10 0～16 0℃ ,时间 6h。用紫外分光光度法测定微球在水中的溶解百分率 ,在 37℃的恒温水浴中以胰蛋白酶的磷酸盐缓冲介质考察微球被酶解完全的时间。以傅立叶变换红外光谱法研究热变性引起白蛋白二级结构的改变。结果 白蛋白微球的水溶性随热变性时间的延长和温度升高而显著降低 ,酶解时间也随之延长。热变性条件对蛋白质酰胺I谱带所表征的空间构象影响较大。结论 加热变性程度对白蛋白微球的水溶性及酶解性均有显著的影响 ,这可能与白蛋白二级结构的改变及疏水性基团的暴露有关。通过选择适当的加热条件 ,可以调控白蛋白微球的体外溶解与降解特性 。
AIM To study the effect of thermal denaturation on the water solubility and enzymatic degradation of spray dried bovine serum albumin (BSA) microspheres (MS), and to investigate the mechanism of thermal denaturatiom. METHODS Microspheres were prepared by spray drying of BSA solution, and further stabilization of the spray dried powder in a hot air oven at 120℃ for 3, 6, 12 and 24 h or for 6 h at 100, 120, 140 and 160℃,respectively. UV analysis was used to determine the percentage of the BSA dissolved in water. Microsphere degradation in trypsin medium was studied by naked eyes and optically microscopic examination. Fourier transform infrared spectroscopy was used to study the secondary structure of the spray dried albumin microspheres. RESULTS BSA MS water solubility was significantly decreased, and the time for enzymatic total degradation increased, as the heating time prolonged and temperature elevated. These demonstrate the influence of heating time and temperature on microsphere degradation. CONCLUSION The functions of thermal denaturation may have something to do with the changes of secondary structure of albumin. Thermal denaturation may affect the α helix and β sheet structure content of the microspheres. Water solubility and enzymatic degradation of BSA MS can be controlled through choosing appropriate thermal denaturation conditions, which suggests that the release rate of spray dried drug loaded BSA MS, as a controlled drug delivery system, can thus be controlled to a desired extent.
出处
《药学学报》
CAS
CSCD
北大核心
2000年第7期535-538,共4页
Acta Pharmaceutica Sinica
关键词
白蛋白微球
热变性
水溶性
酶降解性
albumin
microspheres
water solubility
enzymatic degradation
