Botryoidal assembly of cholesteryl-pullulan/poly(N-isopropylacrylamide) nanogels
Botryoidal assembly of cholesteryl-pullulan/poly(N-isopropylacrylamide) nanogels
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DOI：
10.1021/la0616045
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发表时间：
2007-01-02
期刊：
影响因子：
3.9
通讯作者：
Akiyoshi, Kazunari
中科院分区：
文献类型：
--
作者：
Morimoto, Nobuyuki;Winnik, Francoise M.;Akiyoshi, Kazunari
在水溶性自由基引发剂的存在下，通过N-异丙基丙烯酰胺（NIPAM）与甲基丙烯酰基取代的普鲁兰多糖（CHPMA）在50 ℃水中的接枝自由基共聚反应，合成了由胆固醇基修饰的普鲁兰多糖（CHP）和聚（N-异丙基丙烯酰胺）（PNIPAM）组成的杂化纳米凝胶。取决于初始NIPAM/CHPMA比率，在保持在20 ℃的水中，以流体动力学半径（R-h）为69.0-116.0 nm的自组装纳米颗粒的形式获得含有30.8-84.8重量% PNIPAM的CHP-PNIPAM（CN）纳米凝胶。具有足够高的NIPAM含量的杂化纳米凝胶，例如含有79.6重量% NIPAM的样品CN 90，对溶液（3 mg/mL）温度的变化表现出两步响应：随着温度从20 ℃升高至35 ℃，R-h从93 nm降低至57 nm，随后在55 ℃下R-h从57 nm急剧增加至90 nm。这两个步骤的温度响应是可逆的。CN纳米凝胶对温度的多步响应归因于纳米凝胶的形态，所述纳米凝胶被视为由通过胆固醇交联点保持在一起并通过接枝PNIPAM链保持在一起的相关天然纳米凝胶的葡萄状（葡萄状）簇组成。
Hybrid nanogels consisting of cholesteryl-modified pullulan (CHP) and poly(N-isopropylacrylamide) (PNIPAM) were synthesized by graft free-radical copolymerization of N-isopropylacrylamide (NIPAM) onto methacryloyl-substituted CHP nanogels (CHPMA) in water at 50 degrees C in the presence of a water-soluble free radical initiator. Depending on the initial NIPAM/CHPMA ratio, CHP-PNIPAM (CN) nanogels containing 30.8-84.8 wt % PNIPAM were obtained in the form of self-assembled nanoparticles with a hydrodynamic radius (R-h) of 69.0-116.0 nm in water kept at 20 degrees C. Hybrid nanogels of sufficiently high NIPAM content, such as the sample CN90, which contains 79.6 wt % NIPAM, exhibited a two-step response to changes in solution (3 mg/mL) temperature: a decrease in R-h from 93 to 57 nm as the temperature increased from 20 to 35 degrees C, followed by a sharp increase in R-h from 57 nm to 90 nm at 55 degrees C. Both steps in this temperature response were reversible. The multistep response to temperature of the CN nanogels was attributed to the morphology of the nanogels, which are seen as consisting of grape-like (botryoidal) clusters of associated native nanogels held together via cholesteryl cross-linking points and held together by the grafted PNIPAM chains.