Zhang Rhongsheng, Tang Mingguo, Bowyer Adrian, Eisenthal Robert, Hubble John
Department of Chemical Engineering, University of Bath, Claverton Down Bath, Banes BA2 7AY, UK.
Biomaterials. 2005 Aug;26(22):4677-83. doi: 10.1016/j.biomaterials.2004.11.048. Epub 2005 Jan 19.
A fast and simple method for the preparation of pH-sensitive hydrogel membranes for drug delivery and tissue engineering applications has been developed using carbodiimide chemistry. The hydrogels were formed by the intermolecular cross-linking of carboxymethyl dextran (CM-dextran) using 1-ethyl-(3-3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Infrared spectra of the hydrogels suggest the formation of ester bonds between the hydroxyl and carboxyl groups in the CM-dextran. The porosity of the hydrogels produced, as shown by protein diffusion, increases in response to changes in the pH and the ionic strength of the external medium. The results show pH-dependent swelling behaviour arising from the acidic pedant groups in the polymer network. The diffusion of the protein lysozyme through the hydrogel membranes increased with increases in both pH (5.0-9.0) and ionic strength. The effect of changes of pH and ionic strength on the hydrogel's permeability was shown to be reversible. Scanning electron microscopy of these hydrogels showed that pH-dependent changes in permeability are mirrored by morphological changes in gel structure.
利用碳二亚胺化学方法，开发了一种快速简便的制备用于药物递送和组织工程应用的pH敏感水凝胶膜的方法。水凝胶是通过使用1-乙基-（3-二甲基氨基丙基）碳二亚胺盐酸盐（EDC）和N-羟基琥珀酰亚胺（NHS）使羧甲基葡聚糖（CM-葡聚糖）进行分子间交联而形成的。水凝胶的红外光谱表明在CM-葡聚糖的羟基和羧基之间形成了酯键。如蛋白质扩散所示，所制备水凝胶的孔隙率会随着外部介质pH值和离子强度的变化而增加。结果表明，聚合物网络中的酸性侧基导致了pH依赖性溶胀行为。蛋白质溶菌酶通过水凝胶膜的扩散随着pH值（5.0 - 9.0）和离子强度的增加而增加。结果表明，pH值和离子强度的变化对水凝胶渗透性的影响是可逆的。这些水凝胶的扫描电子显微镜显示，渗透性的pH依赖性变化反映在凝胶结构的形态变化上。
