半纤维素基pH响应性水凝胶的制备及其药物控释研究

Preparation of Hemicelluloses-based pH Sensitive Hydrogel and Its Application in Controlled Drug Release

关键词:  水不溶性半纤维素  聚乙烯醇  pH响应性水凝胶  药物控释

Key Words:water insoluble hemicelluloses  polyvinyl alcohol  pH sensitive hydrogels  drug controlled release

摘要:以从玉米芯中提取的水不溶性半纤维素（wis-AGX） （中性单糖组成为：83.09%木糖、10.03%葡萄糖、4.76%阿拉伯糖、0.76%半乳糖）为原料，在碱性介质中与丙烯酰胺接枝共聚并适度水解，在半纤维素中引入具有pH响应性的聚丙烯酸（PAA）链段，再将共聚物与聚乙烯醇（PVA）溶液共混后以戊二醛交联制备半纤维素基水凝胶。通过核磁共振仪和傅里叶变换红外光谱仪对该水凝胶的化学结构进行表征，利用扫描电子显微镜对水凝胶的形貌特征进行表征，研究了该水凝胶在去离子水和不同pH值环境下的溶胀行为。结果表明，水凝胶具有明显的pH响应性，且在pH值10时溶胀率最高，可达1210%。此外，水凝胶的溶胀率与羧基含量正相关，与戊二醛用量负相关。以茶碱作为模型药物，探讨了其在模拟胃液（pH值1.2）和肠液（pH值7.4）介质中的药物释放行为。在6 h内，担载药物后的水凝胶在模拟肠液中的药物累积释放量可达68%，明显高于其在胃液中51%的药物累积释放量，故此水凝胶有明显的药物缓释作用。

Abstract:A kind of novel pH-sensitive hemicelluloses-based hydrogels was synthesized from the water insoluble hemicelluloses (wis-AGX)（the composition of neutral monosaccharide was 83.09% xylose, 10.03% glucose, 4.76% arabinose and 0.76% galactose）extracted from corncobs via sequential graft copolymerization, saponification hydrolysis in alkaline medium, blending with polyvinyl alcohol（PVA）and crosslinkage in presence of glutaraldehyde.The chemical structure of the composite hydrogel was characterized by NMR and Fourier transform infrared spectroscopy, and the morphological characteristics of the hydrogel were characterized by scanning electron microscopy. The swelling properties of the hydrogels in distilled water and buffer solutions with different pH values were studied, respectively. The results show that the hydrogel has obvious pH sensitivity, and the swelling rate is the highest at pH=10, up to 1210%. In addition, the swelling rate of the hydrogel is positively correlated with the content of —COOH and negatively correlated with the amount of glutaraldehyde. Using theophylline as a model drug, its drug release behavior in simulated gastric fluid (pH=1.2) and intestinal fluid (pH=7.4) was investigated. Within 6 h, the cumulative release of the drug-loaded gel in the simulated intestinal fluid was up to 68%, which was significantly higher than the cumulative release of 51% of the drug in the gastric juice, so hydrogel has obvious drug sustained release effect and pH sensitivity.