Ding Weiwei, Lin Shaoliang, Lin Jiaping, Zhang Liangshun
Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
J Phys Chem B. 2008 Jan 24;112(3):776-83. doi: 10.1021/jp076939p. Epub 2007 Dec 23.
The effect of chain conformation change on the self-assembly behavior of poly(gamma-benzyl- l-glutamate)-block-poly(ethylene glycol) (PBLG-b-PEG) was studied both experimentally by transmission electron microscopy, laser light scattering, and circular dichroism and computationally using molecular dynamics (MD) simulation. It was found that, by introducing trifluoroacetic acid to the PBLG-b-PEG solution, the conformation of the PBLG chain transforms from alpha-helix to random coil, which results in a change of the micelle structures formed by PBLG-b-PEG from rod to sphere. Meanwhile, the MD simulations were performed by using Brownian dynamics on the self-assembly behavior of model AB-type diblock copolymers with various chain rigidities of the A-block. The results show that, by decreasing the fraction of rigid chain conformation of the A-block, which corresponds to the helix-coil transition in the PBLG-b-PEG sample, the aggregate structure transforms from rod to sphere. The MD simulations also provide chain packing information in the micelles. On the basis of both experimental and MD simulation results, the mechanism regarding the effect of the conformation change of the polypeptide block copolymer on its self-association behavior is suggested.
通过透射电子显微镜、激光光散射和圆二色性实验研究了链构象变化对聚（γ-苄基-L-谷氨酸）-嵌段-聚（乙二醇）（PBLG-b-PEG）自组装行为的影响，并使用分子动力学（MD）模拟进行了计算研究。结果发现，通过向PBLG-b-PEG溶液中引入三氟乙酸，PBLG链的构象从α-螺旋转变为无规卷曲，这导致PBLG-b-PEG形成的胶束结构从棒状变为球状。同时，利用布朗动力学对具有不同A嵌段链刚性的模型AB型二嵌段共聚物的自组装行为进行了MD模拟。结果表明，通过降低A嵌段刚性链构象的比例，这与PBLG-b-PEG样品中的螺旋-卷曲转变相对应，聚集体结构从棒状转变为球状。MD模拟还提供了胶束中的链堆积信息。基于实验和MD模拟结果，提出了多肽嵌段共聚物构象变化对其自缔合行为影响的机制。
