Hino Tomoaki, Tanimoto Masao, Shimabayashi Saburo
Faculty of Pharmaceutical Sciences, The University of Tokushima, Sho-machi 1-78-1, Tokushima 770-8505, Japan.
J Colloid Interface Sci. 2003 Oct 1;266(1):68-73. doi: 10.1016/s0021-9797(03)00584-8.
Silk microspheres prepared by spray-drying were exposed to humid atmosphere (89% relative humidity, RH). Change in the secondary structure of silk fibroin during preparation of silk microspheres and exposure to high humidity was studied. Scoured silk fiber was dissolved in an aqueous solution of calcium chloride mixed with ethanol. After dialysis against purified water, theophylline was added to the solution as a model drug. Silk microspheres were obtained by spray-drying. Silk fibroin and theophylline were found to be amorphous in the microsphere by means of powder X-ray diffractometry. Fibroin assumed a beta-sheet conformation in the scoured silk fiber while it has an irregular structure in the microsphere, according to FTIR and Raman spectra. Fibroin recrystallized and its secondary structure changed to beta-sheet conformation by exposure of the microspheres to an atmosphere of 89% RH.
通过喷雾干燥制备的丝素微球暴露于潮湿气氛（相对湿度89%，RH）中。研究了丝素微球制备过程中以及暴露于高湿度环境下丝素蛋白二级结构的变化。将精练蚕丝纤维溶解于氯化钙与乙醇的混合水溶液中。对纯净水进行透析后，将茶碱作为模型药物添加到溶液中。通过喷雾干燥获得丝素微球。借助粉末X射线衍射法发现丝素蛋白和茶碱在微球中呈无定形。根据傅里叶变换红外光谱（FTIR）和拉曼光谱，丝素蛋白在精练蚕丝纤维中呈β折叠构象，而在微球中具有不规则结构。通过将微球暴露于相对湿度89%的气氛中，丝素蛋白重结晶，其二级结构转变为β折叠构象。
