pH敏感的聚(L-谷氨酸)-交联聚丙烯酸水凝胶的合成与性能研究

通过在聚L-谷氨酸侧链部分接枝甲基丙烯酸2-羟乙酯得到含有双键的聚(L-谷氨酸),将其与丙烯酸共聚得到由聚(L-谷氨酸)侧链接枝并交联聚丙烯酸的pH敏感水凝胶.研究水凝胶在不同pH的缓冲溶液中的溶胀性、溶胀动力学,并通过SEM观察水凝胶的微观结构.结果表明,水凝胶在低pH环境下的溶胀率明显低于高pH环境中的溶胀率,不同...

SYNTHESIS AND SWELLING BEHAVIOR OF DEGRADABLE pH-SENSITIVE HYDROGELS COMPOSED OF POLY ( L-GLUTAMIC ACID) AND POLY ( ACRYLIC ACID)

A biodegradable pH-sensitive hydrogel composed of poly(acrylic acid)(PAA) and poly(L-glutamic acid)(PGA) was synthesized.The swelling behavior of the hydrogel samples was studied.PGA is both biodegradable and pH-sensitive,with the pKa at 4.51.The hydrogels showed different swelling ratios(SR) in buffers at different pH values,indicating the pH-sensitivity.The hydrogels exhibited lower swelling ratios in an acidic medium because of the deprotonation of both PAA and PGA.While in a basic medium(pH 8.3),the highest swelling ratios were 5 to 10 times higher than those in the acidic medium.The SR increased sharply when the pH was increased from 4,which was consistent to the pKa of PAA and PGA.In neutral medium,the sample with the lowest SR was the one composed of 50% PGA and 50% PAA,of which the SR was only about 30.In contrast,with either more PGA or more PAA,the SR got higher.The SR of the sample with 70% of PAA was 66.3,while the SR of hydrogel composed of 70% PGA was 121.4.The swelling kinetics studies showed that all the hydrogel samples underwent a rapid swelling process in 20 min,followed by gradual decrease of the swelling rate.The samples reached swelling balance at 2 h.Because of the pH-sensitivity of the hydrogels,drugs can be protected at acidic pH,and released at neutral pH.Therefore,the hydrogels may have potential applications as oral drug delivery systems.