Zhang Xian-Zheng, Wu Da-Qing, Chu Chih-Chang
Department of Textiles and Apparel and Biomedical Engineering Program, Cornell University, Ithaca, NY 14853-4401, USA.
Biomaterials. 2004 Aug;25(17):3793-805. doi: 10.1016/j.biomaterials.2003.10.065.
A method was developed to prepare thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with an interpenetrating polymer network (IPN) structure for the purpose of improving its mechanical properties, response rate to temperature and sustained release of drugs. Although the differential scanning calorimetry data exhibited similarly lower critical solution temperature (LCST) between IPN- and non-IPN-PNIPAAm hydrogels, an increase in the glass transition temperature (Tg) of the IPNs relative to the normal PNIPAAm hydrogel was observed. In addition, the mechanical properties of the IPNs were greatly improved when compared with the normal PNIPAAm hydrogel. The interior morphology of the IPN-PNIPAAm hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a fibrillar-like porous network structure that normal PNIPAAm did not have. Furthermore, by measuring the temperature dependence of the swelling ratio and deswelling kinetics, these IPN hydrogels also exhibited improved intelligent characteristics (e.g., controllable faster response rate) that depended on the composition ratio of the two network components. From the applications viewpoint, the effects of a shrinking-reswelling cycle around the LCST on the properties of the IPN hydrogels were examined to determine if these properties would be stable for potential applications. Bovine serum albumin was chosen as the model protein for examining its release from the IPNs at different temperatures. The release data suggested that an improved controlled release could be achieved by the IPN-PNIPAAm hydrogels without losing their intelligent properties.
为了改善其机械性能、对温度的响应速率以及药物的持续释放，开发了一种制备具有互穿聚合物网络（IPN）结构的热敏性聚（N-异丙基丙烯酰胺）（PNIPAAm）水凝胶的方法。尽管差示扫描量热法数据显示IPN-PNIPAAm水凝胶和非IPN-PNIPAAm水凝胶之间具有相似的较低临界溶液温度（LCST），但相对于普通PNIPAAm水凝胶，观察到IPN的玻璃化转变温度（Tg）有所升高。此外，与普通PNIPAAm水凝胶相比，IPN的机械性能有了很大提高。通过扫描电子显微镜（SEM）揭示了IPN-PNIPAAm水凝胶的内部形态；IPN水凝胶呈现出普通PNIPAAm所没有的纤维状多孔网络结构。此外，通过测量溶胀率和去溶胀动力学对温度的依赖性，这些IPN水凝胶还表现出改善的智能特性（例如，可控的更快响应速率），这取决于两种网络组分的组成比。从应用的角度来看，研究了围绕LCST的收缩-再溶胀循环对IPN水凝胶性能的影响，以确定这些性能对于潜在应用是否稳定。选择牛血清白蛋白作为模型蛋白，以研究其在不同温度下从IPN中的释放情况。释放数据表明，IPN-PNIPAAm水凝胶可以实现更好的控释，而不会丧失其智能特性。
