Allcock H R, Ambrosio A M
Department of Chemistry, Pennsylvania State University, University Park 16802, USA.
Biomaterials. 1996 Dec;17(23):2295-302. doi: 10.1016/0142-9612(96)00073-7.
A new class of pH-sensitive hydrogels has been designed and synthesized. These are novel polyphosphazenes that bear various ratios of sodium oxybenzoate and methoxyethoxyethoxy side groups. These water-soluble macromolecules were cross-linked by 60Co gamma irradiation and the products were allowed to absorb water to form hydrogels. The hydrogels had higher equilibrium degrees of swelling in basic than in acidic buffer solutions, and polymers with a higher loading of the ionic side group showed higher swellability than those with a lower loading of this side group. The effects of ionic strength, cation charge and radiation dose on the degree of swelling were also studied. A study of the diffusion of the dye Biebrich Scarlet from the hydrogels showed complete release of the dye in 4-12 h in pH 7.4 buffer solution but significantly lower release at pH 2 even after 48 h. The release rate also varied as the side-group ratios were changed. The prehydrogel polymers were synthesized via the macromolecular substitution reactions of poly(dichlorophosphazene) with sodium methoxyethoxyethoxide and the sodium salt of propyl 4-hydroxybenzoate, followed by ester hydrolysis to yield the sodium carboxylate. The hydrogels are of interest for possible use as pH-sensitive membranes and for a number of potential biomedical applications.
已设计并合成了一类新型的pH敏感水凝胶。这些是新型聚磷腈，带有不同比例的甲氧基苯甲酸钠和甲氧基乙氧基乙氧基侧基。这些水溶性大分子通过60Coγ辐射交联，产物吸水形成水凝胶。水凝胶在碱性缓冲溶液中的平衡溶胀度高于酸性缓冲溶液，离子侧基负载量较高的聚合物比该侧基负载量较低的聚合物表现出更高的溶胀性。还研究了离子强度、阳离子电荷和辐射剂量对溶胀度的影响。对水凝胶中染料比布里希猩红扩散的研究表明，在pH 7.4缓冲溶液中，染料在4 - 12小时内完全释放，但在pH 2时，即使48小时后释放量也显著降低。释放速率也随侧基比例的变化而变化。预水凝胶聚合物通过聚（二氯磷腈）与甲氧基乙氧基乙醇钠和4 - 羟基苯甲酸丙酯钠盐的大分子取代反应合成，然后进行酯水解生成羧酸钠。这些水凝胶有望用作pH敏感膜并用于许多潜在的生物医学应用。
