Rapid pH/temperature-responsive cationic hydrogels with dual stimuli-sensitive grafted side chains
Rapid pH/temperature-responsive cationic hydrogels with dual stimuli-sensitive grafted side chains
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DOI：
10.1016/j.polymer.2009.03.044
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发表时间：
2009-05-22
期刊：
影响因子：
4.6
通讯作者：
Chu, Liang-Yin
中科院分区：
文献类型：
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作者：
Zhang, Jie;Xie, Rui;Chu, Liang-Yin
通过将具有自由移动末端的聚合物链（由N-异丙基丙烯酰胺（NIPAM）链段和N,N-二甲基氨基乙基甲基丙烯酸酯（DMAEMA）链段组成）接枝到交联聚（NIPAM-co-DMAEMA）网络的主链上，成功合成了温度和pH双重敏感的梳型接枝阳离子水凝胶。研究了所制备的水凝胶对 pH 和/或温度的平衡和动态溶胀/消溶胀特性。制备的水凝胶表现出约 34 摄氏度的较低临界溶液温度 (LCST) 和约 pH 7.3 的 pK(a) 值。在较低pH和较低温度下，梳型接枝水凝胶的溶胀度和溶胀速率均大于普通型交联水凝胶。梳型接枝聚(NIPAM-co-DMAEMA)水凝胶在固定温度下响应pH值从2.0跃升至11.0，表现出比普通型水凝胶更快的消溶胀速率。当环境温度从18℃突然升高到高于LCST的温度时，聚(NIPAM-co-DMAEMA)水凝胶的体积变化在一系列固定缓冲溶液中急剧变化。梳型接枝聚（NIPAM-co-DMAEMA）水凝胶响应同时的双重温度和 pH 刺激而表现出相当快的收缩行为。当环境温度和pH值同步变化时，所制备的聚(NIPAM-co-DMAEMA)水凝胶在体外进行药物释放。结果表明，模型药物维生素 B-12 从梳型接枝水凝胶中的释放速度比从普通型水凝胶中的释放速度要快得多。本研究中提出的双温度/pH敏感梳型接枝阳离子聚(NIPAM-co-DMAEMA)水凝胶可能具有多种潜在应用，例如用于制造快速响应智能传感器、执行器和化学/药物载体等。 (C) 2009 Elsevier Ltd. 保留所有权利。
Dual temperature- and pH-sensitive comb-type grafted cationic hydrogels are successfully synthesized by grafting polymeric chains with freely mobile ends, which are composed of both N-isopropylacrylamide (NIPAM) segments and N,N-dimethylamino ethyl methacrylate (DMAEMA) segments, onto the backbone of crosslinked poly(NIPAM-co-DMAEMA) networks. Equilibrium and dynamic swelling/deswelling properties of the prepared hydrogels responding to pH and/or temperature are investigated. The prepared hydrogels demonstrate a lower critical solution temperature (LCST) at about 34 degrees C and a pK(a) value at about pH 7.3. At lower pH and lower temperature, both the swelling degree and the swelling rate of the comb-type grafted hydrogel are larger than those of the normal-type crosslinked hydrogel. The comb-type grafted poly(NIPAM-co-DMAEMA) hydrogel exhibits a more rapid deswelling rate than that of the normal-type hydrogel in response to a pH jump from 2.0 to 11.0 at a fixed temperature. The volume changes of the poly(NIPAM-co-DMAEMA) hydrogels are acute in a series of fixed buffer solutions with an abrupt increase of environmental temperature from 18 degrees C to a temperature higher than the LCST. The comb-type grafted poly(NIPAM-co-DMAEMA) hydrogels show quite fast shrinking behaviors in response to simultaneous dual temperature and pH stimuli. Drug-release in vitro from the prepared poly(NIPAM-co-DMAEMA) hydrogels is carried out when the environmental temperature and pH are changed synchronously. The results show that the model drug Vitamin B-12 is released much more rapidly from the comb-type grafted hydrogel than that from the normal-type hydrogel. The proposed dual temperature/pH-sensitive comb-type grafted cationic poly(NIPAM-co-DMAEMA) hydrogel in this study may find various potential applications, e.g., for fabricating rapid-response smart sensors, actuators, and chemical/drug carriers and so on. (C) 2009 Elsevier Ltd. All rights reserved.