Chen Lingyun, Tian Zhigang, Du Yumin
Department of Environmental Science, Wuhan University, Wuhan 4300072, China.
Biomaterials. 2004 Aug;25(17):3725-32. doi: 10.1016/j.biomaterials.2003.09.100.
Novel polyampholyte hydrogels based on carboxymethyl chitosans (CMC) of various degree of deacetylation (DD) and substitution (DS) were prepared by crosslinking with glutaraldehyde. The hydrogel showed typical amphoteric character responding to pH of the external medium. At the isoelectric point (IEP), the hydrogel shrunk most, when the pH deviated from IEP, the swelling degree (Ds) increased. With increasing DD or DS value, the hydrogel changed from polyampholyte into polycations or polyanions, respectively. Osmotic forces and intermolecular interactions among CMC chains regulate the swelling behavior of CMC gel. The carboxymethyl chitin hydrogels were loaded with bovine blood proteins (BSA), and their release studies were performed in both the simulated gastric and intestinal pH conditions. The release was much quicker in pH 7.4 buffer than pH 1.2 solution; the release followed Fickian diffusion in the first 4h and then steadily increased with the dissolution of the hydrogels.
通过与戊二醛交联制备了基于不同脱乙酰度（DD）和取代度（DS）的羧甲基壳聚糖（CMC）的新型聚两性电解质水凝胶。该水凝胶表现出响应外部介质pH的典型两性特征。在等电点（IEP）时，水凝胶收缩最大，当pH偏离IEP时，溶胀度（Ds）增加。随着DD或DS值的增加，水凝胶分别从聚两性电解质转变为聚阳离子或聚阴离子。CMC链之间的渗透力和分子间相互作用调节CMC凝胶的溶胀行为。羧甲基几丁质水凝胶负载牛血蛋白（BSA），并在模拟胃和肠的pH条件下进行其释放研究。在pH 7.4缓冲液中的释放比在pH 1.2溶液中快得多；在前4小时内释放遵循菲克扩散，然后随着水凝胶的溶解而稳定增加。
