Tunable stimuli-responsive self-assembly system that forms and stabilizes nanoparticles by simple mixing and heating/cooling of selected block copolymers
Tunable stimuli-responsive self-assembly system that forms and stabilizes nanoparticles by simple mixing and heating/cooling of selected block copolymers
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DOI：
10.1039/c1py00004g
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发表时间：
2011-01-01
影响因子：
4.6
通讯作者：
Aoyagi, Takao
中科院分区：
文献类型：
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作者：
Kotsuchibashi, Youhei;Ebara, Mitsuhiro;Aoyagi, Takao
我们在这里提出了一个独特的协议，以产生刺激响应的自组装使用两个嵌段共聚物，聚（N-异丙基丙烯酰胺）（PNIPAAm）-b-P（NIPAAm-co-N-（羟甲基）丙烯酰胺（HMAAm））和PNIPAAm-b-P（NIPAAm-co-钠2-丙烯酰胺基-2-甲基丙磺酸（AMPS））。这些嵌段共聚物是通过原子转移自由基聚合（ATRP）方法合成的。选择PNIPAAm作为在高于下临界溶解温度（LCST）的水环境中触发大分子组装的共同嵌段。稳定的核-壳组件，因此，只有通过混合两个嵌段共聚物以上的PNIPAAm的LCST（第一个LCST）时，共同的嵌段变得疏水。在加热到P（NIPAAm-co-HMAAm）的LCST（第二LCST）以上时，第二嵌段变得脱水并且观察到组装体的尺寸增长。然而，P（NIPAAm-co-AMPS）仍然形成水合壳，其由于通过AMPS的阴离子基团的静电稳定而防止进一步聚集和沉淀。换句话说，在第二LCST以上组装的纳米组装体可以通过P（NIPAAm-co-AMPS）稳定在期望的尺寸。通过改变HMAAm含量来控制第二LCST和所得纳米组装体直径。纳米组装体也可以在低于LCST的温度下可逆地解缠结，回收可溶性嵌段共聚物链。因此，所提出的协议，使刺激响应的纳米组件和定制的大小，通过简单的混合和加热/冷却所选择的嵌段共聚物的容易的制备。使用温度作为一个单一的开关参数，以诱导在水中的自组装规避了使用有机溶剂的需要。本文报道的系统可能潜在地用于一系列应用，包括药物和基因递送、生物传感或生物分子分离。
We propose here a unique protocol to produce stimuli-responsive self-assemblies using two block copolymers, poly(N-isopropylacrylamide) (PNIPAAm)-b-P(NIPAAm-co-N-(hydroxymethyl)acrylamide (HMAAm)) and PNIPAAm-b-P(NIPAAm-co-sodium 2-acrylamido-2-methylpropane sulfonic acid (AMPS)). These block copolymers were synthesized by an atom transfer radical polymerization (ATRP) method. PNIPAAm was selected as the common block to trigger macromolecular assembly in an aqueous environment above the lower critical solution temperature (LCST). Stable core-shell assemblies were, therefore, produced only by mixing two block copolymers above the LCST of PNIPAAm (the first LCST) when the common blocks became hydrophobic. Upon heating above the LCST of P(NIPAAm-co-HMAAm) (the second LCST), the second block became dehydrated and the size growth of assemblies was observed. The P(NIPAAm-co-AMPS), however, still formed a hydrated shell that prevented further aggregation and precipitation due to electrostatic stabilization through the anionic groups of AMPS. In other words, nanoassemblies, assembled above the second LCST, could be stabilized at the desired size by P(NIPAAm-co-AMPS). The second LCST and the resulting nanoassemblies diameter were controlled by varying the HMAAm content. Nanoassemblies can also be reversibly disentangled at temperatures below the LCSTs, with recovery of soluble block copolymer chains. Thus, the proposed protocol enables the facile preparation of stimuli-responsive nanoassemblies and customization of their size by simple mixing and heating/cooling of the selected block copolymers. Using temperature as a single on-off parameter to induce self-assembly in water circumvents the need for using organic solvents. The system reported here may be potentially useful for a range of applications, including drug and gene delivery, biosensing, or separation of biological molecules.