Smeijers A F, Pieterse Koen, Hilbers Peter A J, Markvoort Albert J
Computational Biology Group, Department of Biomedical Engineering, and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Macromolecules. 2019 Apr 9;52(7):2778-2788. doi: 10.1021/acs.macromol.8b02357. Epub 2019 Mar 21.
Multivalency is an important instrument in the supramolecular chemistry toolkit for the creation of strong specific interactions. In this paper we investigate the multivalency effect in a dendritic host-guest system using molecular dynamics simulations. Specifically, we consider urea-adamantyl decorated poly(propyleneimine) dendrimers that together with compatible mono-, bi-, and tetravalent ureidoacetic acid guests can form dynamic patchy nanoparticles. First, we simulate the self-assembly of these particles into macromolecular nanostructures, showing guest-controlled reduction of dendrimer aggregation. Subsequently, we systematically study guest concentration dependent multivalent binding. At low guest concentrations multivalency of the guests clearly increases relative binding as tethered headgroups bind more often than free guests' headgroups. We find that despite an abundance of binding sites, most of the tethered headgroups bind in close proximity, irrespective of the spacer length; nevertheless, longer spacers do increase binding. At high guest concentrations the dendrimer becomes saturated with bound headgroups, independent of guest valency. However, in direct competition the tetravalent guests prevail over the monovalent ones. This demonstrates the benefit of multivalency at high as well as low concentrations.
多价性是超分子化学工具包中用于创建强特异性相互作用的重要手段。在本文中，我们使用分子动力学模拟研究树枝状主客体系统中的多价性效应。具体而言，我们考虑用尿素 - 金刚烷基修饰的聚（丙烯亚胺）树枝状大分子，它们与兼容的单价、二价和四价脲基乙酸客体一起可形成动态的多斑点纳米颗粒。首先，我们模拟这些颗粒自组装成大分子纳米结构，显示客体控制的树枝状大分子聚集减少。随后，我们系统地研究客体浓度依赖性多价结合。在低客体浓度下，由于连接的头基比游离客体的头基更频繁地结合，客体的多价性明显增加相对结合力。我们发现，尽管存在大量结合位点，但大多数连接的头基紧密结合，与间隔长度无关；然而，较长的间隔确实会增加结合。在高客体浓度下，树枝状大分子被结合的头基饱和，与客体价态无关。然而，在直接竞争中，四价客体胜过单价客体。这证明了多价性在高浓度和低浓度下的益处。
