三价富离子壳层控制的聚电解质构象。

Polyelectrolyte Conformation Controlled by a Trivalent-Rich Ion Jacket.

机构信息

Materials Department, University of California, Santa Barbara, California 93106, USA.

Materials Department and Physics Department, University of California, Santa Barbara, California 93106, USA.

出版信息

Phys Rev Lett. 2019 Nov 1;123(18):187801. doi: 10.1103/PhysRevLett.123.187801.

DOI:10.1103/PhysRevLett.123.187801

PMID:31763890

Abstract

The configuration of charged polymers is heavily dependent on interactions with surrounding salt ions, typically manifesting as a sensitivity to the bulk ionic strength. Here, we use single-molecule mechanical measurements to show that a charged polysaccharide, hyaluronic acid, shows a surprising regime of insensitivity to ionic strength in the presence of trivalent ions. Using simulations and theory, we propose that this is caused by the formation of a "jacket" of ions, tightly associated with the polymer, whose charge (and thus effect on configuration) is robust against changes in solution composition.

摘要

带电荷聚合物的构象严重依赖于与周围盐离子的相互作用，通常表现为对本体离子强度的敏感性。在这里，我们使用单分子力学测量表明，在三价离子存在的情况下，带电荷的多糖透明质酸对离子强度表现出惊人的不敏感。通过模拟和理论，我们提出这是由于形成了一个与聚合物紧密相关的“离子套”，其电荷（因此对构象的影响）对溶液组成的变化具有很强的稳定性。