Guanidinium Can Break and Form Strongly Associating Ion Complexes
Guanidinium Can Break and Form Strongly Associating Ion Complexes
复制标题
胍可以分解并形成强缔合离子络合物
DOI：
10.1021/acsmacrolett.8b00824
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发表时间：
2019
影响因子：
7.015
通讯作者：
Shull, Kenneth R.
中科院分区：
文献类型：
--
作者：
Sadman, Kazi;Wang, Qifeng;Shull, Kenneth R.
胍是自然界最强的变性剂之一，也是出现在几种界面环境中的基序，如参与细胞粘附的RGD序列、细胞穿透肽和抗微生物分子。重要的是要量化胍的离子特异性相互作用的起源，使其独特的行为可以在合成应用中利用。本工作表明，胍离子可以打破和形成强缔合离子络合物在上下文依赖性的方式。这些见解胍的行为阐明使用双金属络合物（佩奇），其中带相反电荷的聚合物之间的互聚物离子对在确定材料稳定性中发挥重要作用。不同的聚阳离子-聚阴离子组合可以跨越大范围的缔合亲和力，其中更强的缔合复合物可以在浓盐溶液和极端pH条件下保持不溶。这种高稳定性在佩奇的几种应用环境中是理想的，但也使它们难以加工，因此难以研究，因为它们不能溶解在聚合物溶液中。在这里，我们证明了胍盐是非常有效的溶解聚（苯乙烯磺酸盐）/聚（烯丙基胺）（PSS：PAH）复合物，它具有最高的报道聚阳离子-聚阴离子缔合亲和力之一。我们还证明了电荷身份的重要性，通过官能化胍直接到聚（烯丙基胺）的络合现象，导致在高度变性条件下保持稳定的复合物。PSS：PAH的模型系统是用来收集洞察胍的变性活动，以及广泛评论的性质，在带电的大分子离子特异性相互作用。
Guanidinium is one of nature’s strongest denaturants and is also a motif that appears in several interfacial contexts such as the RGD sequence involved in cell adhesion, cell penetrating peptides, and antimicrobial molecules. It is important to quantify the origin of guanidinium’s ion-specific interactions so that its unique behavior may be exploited in synthetic applications. The present work demonstrates that guanidinium ions can both break and form strongly associating ion complexes in a context-dependent way. These insights into guanidinium’s behavior are elucidated using polyelectrolyte complexes (PECs), where interpolymer ion pairs between oppositely charged polymers play an important role in determining material stability. Different polycation–polyanion combinations can span a large range of association affinities, where more strongly associating complexes can remain insoluble in concentrated salt solutions and in extreme pH conditions. This high stability is desirable in several application contexts for PECs, but also renders them challenging to process and, therefore, to study since they cannot be dissolved into polymer solutions. Here we demonstrate that guanidinium salts are very effective in dissolving the poly(styrenesulfonate)/poly(allylamine) (PSS:PAH) complex, which has one of the highest reported polycation–polyanion association affinities. We also demonstrate the importance of charge identity in complexation phenomena by functionalizing guanidinium directly into poly(allylamine), resulting in a complex that remains stable under highly denaturing conditions. The model system of PSS:PAH is used to glean insights into guanidinium’s denaturing activity, as well as to broadly comment on the nature of ion-specific interactions in charged macromolecules.