取代度对O-羧甲基壳聚糖/海藻酸钠水凝胶溶胀和质构性能的影响

Studies on Influence of Degree of Substitution on Swelling Characteristics and TPA Properties of O-Carboxymethyl Chitosan/Alginate Hydrogels

O-羧甲基壳聚糖(OCC)是壳聚糖的一种重要衍生物,具有良好的水溶性和胶凝性。以Ca Cl2为交联剂制备OCC/海藻酸钠(SAL)水凝胶,研究Ca Cl2浓度、Ca Cl2溶液p H值、交联温度、OCC与SAL质量比和OCC取代度对水凝胶在p H 1.2、p H 6.8和p H 7.4溶液中溶胀性的影响,同时测定不同取代度的OCC与SAL形成的水凝胶的质构特性,以期获得可实现肠道靶向释放且具有良好机械强度的p H敏感性水凝胶载体。结果表明:当OCC和SAL以质量比1∶1混合,Ca Cl2浓度为0.09 mol/L,交联p H 7,反应温度55℃时制备的水凝胶,在p H 1.2溶液中溶胀率最小,在p H 7.4溶液中溶胀率最大,呈现出较强的p H敏感性。OCC取代度对水凝胶的溶胀性与质构特性均有影响。取代度为0.51的OCC与SAL形成的水凝胶不具有p H敏感性,而取代度为0.35和0.87的OCC/SAL水凝胶在p H 1.2溶液中溶胀率较低,在p H 7.4溶液中溶胀率较高,表现出很强的p H敏感性。不同取代度OCC与SAL形成的水凝胶均具有良好的弹性,且硬度随着取代度的增加而降低。

O-carboxymethyl chitosan（OCC） is an important derivative of chitosan with good water solubility and gelling ability. In this paper, the preparation of Ca2＋-crosslinked OCC/sodium alginate（SAL） hydrogel was studied and the effects of Ca Cl2 concentration, crosslinking p H, temperature, OCC/SAL ratio and the degree of substitution of OCC on the swelling ratios of the resultant hydrogels in p H 1.2, p H 6.8 and p H 7.4 solutions were investigated. Additionally, the texture properties of the hydrogels prepared with OCC of different degrees of substitution were also determined. The re sults indicated that hydrogels yielded by reaction at OCC/SAL ratio 1 ∶1, SAL concentration 1.5%, Ca Cl2concentration0.09 mol/L, temperature 55 ℃ and p H 7 had the lowest swelling ratio at p H 1.2 and highest swelling ratio at p H 7.4.The degree of substitution of OCC significantly influenced the swelling and texture properties of the hydrogels. The hydrogel prepared with OCC of 0.35 and 0.87 degree of substitution showed excellent p H-sensitive behavior while the hydrogel prepared with OCC of 0.51 degree of substitution showed no p H-sensitive property. All the hydrogels exhibited good flexibility and the hardness decreased with the increase of degree of substitution of OCC.