Kim B-Y, Kang H-S, Kim J-D
Department of Chemical & Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
J Microencapsul. 2002 Sep-Oct;19(5):661-9. doi: 10.1080/02652040210144225.
The thermo-sensitive polymer, PNIPAM-grafted ethylcellulose, was synthesized and it was confirmed by FTIR spectroscopy that PNIPAM was successfully grafted onto ethylcellulose. Microparticles were prepared by the spray-drying method using a B-191 Mini Spray Dryer. Their morphology, observed by scanning electron microscopy (SEM), showed irregular spheres with rugged surfaces, and narrow size distribution. In a model delivery system, ethylcelullose-g-PNIPAM was used as the polymer wall material and allopurinol was used as the model drug. The release rate of allopurinol from ECGPN8 microparticles was slower at 40 degrees C (above the LCST) than that of 25 degrees C (below the LCST), probably due to the collapse of PNIPAM chains by temperature. Although PNIPAM was the large part of wall material, the thermo-sensitive release behavior was not so obvious. It is believed that the release of allopurinol from the microparticles is more dependent on the porous structure of microparticles than the conformational change of PNIPAM, created by the rapid evaporation of solvent during the spray-drying process.
合成了热敏聚合物聚N-异丙基丙烯酰胺接枝乙基纤维素，通过傅里叶变换红外光谱（FTIR）证实聚N-异丙基丙烯酰胺已成功接枝到乙基纤维素上。使用B-191迷你喷雾干燥机通过喷雾干燥法制备微粒。通过扫描电子显微镜（SEM）观察其形态，显示出表面粗糙的不规则球体，且粒径分布狭窄。在模型给药系统中，乙基纤维素-g-聚N-异丙基丙烯酰胺用作聚合物壁材，别嘌醇用作模型药物。别嘌醇从ECGPN8微粒中的释放速率在40℃（高于最低临界溶液温度）时比在25℃（低于最低临界溶液温度）时慢，这可能是由于聚N-异丙基丙烯酰胺链因温度而塌陷。尽管聚N-异丙基丙烯酰胺是壁材的主要成分，但热敏释放行为并不十分明显。据信，微粒中别嘌醇的释放更多地取决于微粒的多孔结构，而非喷雾干燥过程中溶剂快速蒸发所导致的聚N-异丙基丙烯酰胺的构象变化。
