Figueroa-Pizano María Dolores, Vélaz Itziar, Martínez-Barbosa María Elisa
Department of Polymers and Materials Research, University of Sonora.
Department of Chemistry, Faculty of Sciences, University of Navarra;
J Vis Exp. 2020 Jan 14(155). doi: 10.3791/59636.
Chitosan-poly(vinyl alcohol) hydrogels can be produced by the freeze-thawing method without using toxic crosslinking agents. The applications of these systems are limited by their characteristics (e.g., porosity, flexibility, swelling capacity, drug loading and drug release capacity), which depend on the freezing conditions and the kind and ratio of polymers. This protocol describes how to prepare hydrogels from chitosan and poly(vinyl alcohol) at 50/50 w/w % of polymer composition and varying the freezing temperature (-4 °C, -20 °C, -80 °C) and freeze-thawing cycles (4, 5, 6 freezing cycles). FT-IR spectra, SEM micrograph and porosimetry data of hydrogels were obtained. Also, the swelling capacity and drug loading and release of diflunisal were assessed. Results from SEM micrographs and porosimetry show that the pore size decreases, while the porosity increases at lower temperatures. The swelling percentage was higher at the minor freezing temperature. The release of diflunisal from the hydrogels has been studied. All the networks maintain the drug release for 30 h and it has been observed that a simple diffusion mechanism regulates the diflunisal release according to Korsmeyer-Peppas and Higuchi models.
壳聚糖-聚乙烯醇水凝胶可通过冻融法制备，无需使用有毒交联剂。这些体系的应用受到其特性（如孔隙率、柔韧性、溶胀能力、载药量和药物释放能力）的限制，而这些特性取决于冷冻条件以及聚合物的种类和比例。本方案描述了如何以50/50 w/w%的聚合物组成，通过改变冷冻温度（-4℃、-20℃、-80℃）和冻融循环次数（4、5、6次冷冻循环），由壳聚糖和聚乙烯醇制备水凝胶。获得了水凝胶的傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）图像和孔隙率测定数据。此外，还评估了双氯芬酸的溶胀能力、载药量和释放情况。扫描电子显微镜图像和孔隙率测定结果表明，在较低温度下，孔径减小，而孔隙率增加。在较低的冷冻温度下，溶胀百分比更高。对双氯芬酸从水凝胶中的释放进行了研究。所有网络均能维持药物释放30小时，并且根据Korsmeyer-Peppas和Higuchi模型观察到，一种简单的扩散机制调节着双氯芬酸的释放。
