Temperature-Induced Phase Separation in Molecular Assembly of Nanotubes Comprising Amphiphilic Polypeptoid with Poly(N-ethyl glycine) in Water by a Hydrophilic-Region-Driven-Type Mechanism
Temperature-Induced Phase Separation in Molecular Assembly of Nanotubes Comprising Amphiphilic Polypeptoid with Poly(N-ethyl glycine) in Water by a Hydrophilic-Region-Driven-Type Mechanism
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DOI：
10.1021/acs.jpcb.8b03419
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发表时间：
2018-07-19
影响因子：
3.3
通讯作者：
Kimura, Shunsaku
中科院分区：
文献类型：
--
作者：
Hattori, Tetsuya;Itagaki, Toru;Kimura, Shunsaku
两种具有不同亲水性的两亲性类肽聚（肌氨酸）-B-（L-Leu-Aib）（6）（ML 12）和聚（N-乙基甘氨酸）-B-（L-Leu-Aib）（6）（EL 12）通过两条路径自组装成相分离的纳米管。一种是通过将ML 12纳米管与EL 12纳米管粘合，另一种是由ML 12和EL 12在溶液中的混合物制备。在任何一种情况下，纳米管显示温度诱导的相分离沿着长轴，这是观察到的两种方法标记一个阶段与金纳米粒子和荧光共振能量转移之间的组件。相分离归因于聚（N-乙基甘氨酸）块的聚集超过浊点温度。相分离需要加入5%的三氟乙醇，因为疏水区中螺旋的紧密缔合应该被松开以允许待分离组分的侧向扩散。因此，基于亲水区驱动型机制的水中分子组装体的相分离需要两亲性类多肽的亲水区和疏水区之间施加的缔合力的复杂平衡。
Two kinds of amphiphilic polypeptoids having different types of hydrophilic polypeptoids, poly(sarcosine)-b-(L-Leu-Aib)(6) (ML12) and poly(N-ethyl glycine)-b-(L-Leu-Aib)(6) (EL12), were self-assembled via two paths to phase separated nanotubes. One path was via sticking ML12 nanotubes with EL12 nanotubes and the other was a preparation from a mixture of ML12 and EL12 in solution. In either case, nanotubes showed temperature-induced phase separation along the long axis, which was observed by two methods of labeling one phase with gold nanoparticles and fluorescence resonance energy transfer between the components. The phase separation was ascribed to aggregation of poly(N-ethyl glycine) blocks over the cloud point temperature. The addition of 5% trifluoroethanol was needed for the phase separation because the tight association of the helices in the hydrophobic region should be loosened to allow lateral diffusion of the components to be separated. The phase separation in molecular assemblies in water based on the hydrophilic-region-driven-type mechanism therefore requires sophisticated balances of association forces exerting among the hydrophilic and hydrophobic regions of the amphiphilic polypeptoids.