Al-Kahtani Ahmed A, Sherigara B S
Department of Industrial Chemistry, School of Chemical Science, Kuvempu University, Shankaraghatta, 577-451 Karnataka, India.
J Mater Sci Mater Med. 2009 Jul;20(7):1437-45. doi: 10.1007/s10856-009-3704-6. Epub 2009 Feb 28.
Semi-interpenetrating network microspheres of chitosan-(dextran-g-acrylamide) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. Graft copolymerization of dextran with acrylamide (Dx-g-AAm) was carried out by aqueous free-radical polymerization using ceric ammonium nitrate (CAN) as initiator. The grafting efficiency was found to be 92%. Theophylline (TH), antiasthmatic drug, was successfully encapsulated into semi-INP microspheres by varying the ratio of Dx-g-AAm and amount of GA. The laser light scattering technique shows that the particles size increased with increasing amount of graft copolymer and decrease with increasing amount of GA. The % encapsulation efficiency was found to vary between 50 and 78. MPs were characterized by FTIR spectroscopy and differential scanning calorimetry (DSC) techniques to confirm the graft copolymer, formation of semi-IPN structure of MPs and molecular distribution of the drug molecules in the polymer matrix. In vitro release studies of TH from these matrices have been investigated at Ph 1.2 and 7.4 media and the slow release were extended up to 18 h at 37 degrees C. The release rates were fitted to an empirical equation to estimate the diffusion exponent n, which indicated that the release from the MPs follows non-Fickian type.
以戊二醛（GA）为交联剂，采用乳液交联法制备了壳聚糖 - （葡聚糖 - g - 丙烯酰胺）半互穿网络微球。以硝酸铈铵（CAN）为引发剂，通过水溶液自由基聚合法进行葡聚糖与丙烯酰胺的接枝共聚反应（Dx - g - AAm）。接枝效率为92%。通过改变Dx - g - AAm的比例和GA的用量，成功地将平喘药物茶碱（TH）包封到半互穿网络微球中。激光散射技术表明，随着接枝共聚物用量的增加，颗粒尺寸增大，而随着GA用量的增加，颗粒尺寸减小。包封效率在50%至78%之间变化。通过傅里叶变换红外光谱（FTIR）和差示扫描量热法（DSC）技术对微球进行表征，以确认接枝共聚物、微球半互穿网络结构的形成以及药物分子在聚合物基质中的分子分布。在pH 1.2和7.4的介质中研究了TH从这些基质中的体外释放情况，在37℃下缓释长达18小时。将释放速率拟合到一个经验方程中以估计扩散指数n，这表明从微球中的释放遵循非菲克型。
