pH-Dependent Conformations for Hyperbranched Poly(ethylenimine) from All-Atom Molecular Dynamics,Macromolecules

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pH-Dependent Conformations for Hyperbranched Poly(ethylenimine) from All-Atom Molecular Dynamics
Macromolecules ( IF 5.1 ) Pub Date : 2018-03-06 00:00:00 , DOI: 10.1021/acs.macromol.7b02573
In Kim ₁ , Tod A. Pascal ₂ , Seong-Jik Park ₃ , Mamadou Diallo ₁ , William A. Goddard III ₄ , Yousung Jung ₁

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Hyperbranched poly(ethylene imine) (PEI) with its high amino content is a versatile functional polymer that is widely used as a gene delivery vector in biological applications and as a ligand and precursor for ion exchange resins and membranes in water purification and metal recovery. We report here the first fully atomistic model of a 25 kDa hyperbranched PEI macromolecule. We utilized this model to carry out molecular dynamics (MD) simulations with explicit water molecules and chloride ions to study pH-dependent conformational changes. We find that growing the PEI macromolecule sequentially from the monomers yields atomistic structures whose sizes (radius of gyration) are in good agreement with the small angle neutron scattering experiments. Our analysis of the structural properties from MD simulations shows that conformations of the hyperbranched PEI exhibit oblate ellipsoidal elongation at low pH compared to high or neutral pH but with no significant changes in the corresponding sizes. This fully atomistic model of a 25 kDa hyperbranched PEI macromolecule in water provides much needed detailed atomistic information for advancing our fundamental understanding of the structures and host–guest properties of PEI-based functional reagents and materials for biomedical and sustainability related applications.

中文翻译：

从全原子分子动力学的超支化聚乙烯亚胺的pH依赖的构象。

具有高氨基含量的超支化聚乙烯亚胺（PEI）是一种多功能的功能聚合物，在生物学应用中被广泛用作基因传递载体，并且在水净化和金属回收中用作离子交换树脂和膜的配体和前体。我们在这里报告25 kDa超支化PEI大分子的第一个完全原子模型。我们利用该模型对明确的水分子和氯离子进行分子动力学（MD）模拟，以研究pH依赖的构象变化。我们发现，从单体顺序生长PEI大分子会产生原子结构，其大小（回转半径）与小角中子散射实验非常吻合。我们通过MD模拟对结构性能的分析表明，与高pH或中性pH相比，超支链PEI的构型在低pH下表现出椭圆形的椭圆形伸长，但相应尺寸无明显变化。水中25 kDa超支化PEI大分子的完全原子模型提供了急需的详细原子信息，以增进我们对基于PEI的功能性试剂和材料在生物医学和可持续性相关应用中的结构和主客体特性的基本了解。

更新日期：2018-03-06

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