Specific effects of monovalent counterions on the structural and interfacial properties of dodecyl sulfate monolayers.
Specific effects of monovalent counterions on the structural and interfacial properties of dodecyl sulfate monolayers.
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一价抗衡离子对十二烷基硫酸盐单层结构和界面性质的具体影响。
DOI：
10.1039/c6cp05714d
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Allen DT
中科院分区：
文献类型：
--
作者：
Allen DT
用分子动力学模拟方法研究了Li+、Na+、Cs+和NH4+离子对十二烷基硫酸酯(DS−)单分子膜的特殊离子效应。改变反离子对不同单分子膜中表面活性物质分子的结构没有明显影响。然而，不同的反离子对单分子膜的界面性质有显著的影响。特别是，我们研究了当每个反离子与DS−头基相互作用时每个反离子脱水的程度，反离子与头基之间的特定相互作用以及每个反离子引起的头基的盐桥。发现NH4+离子直接与水分子竞争，与DS−头基形成氢键，因此十二烷基硫酸铵单分子膜是所有研究中水合程度最低的。Cs+离子与头基结合较强，水化较弱，因此它们倾向于置换DS−水合壳层中的水与头基相互作用。在Li+离子的情况下，它们与DS−头基的相互作用几乎与Na+离子一样强烈，但通常水合程度低于Na+离子，因此十二烷基硫酸盐锂单分子膜的水合程度低于十二烷基硫酸钠单分子膜。因此，通过改变反离子，可以改变表面活性剂单分子膜的界面性质，从而影响其包裹难溶于水的药物分子的能力，这一点我们将在手稿中进一步讨论。
A series of molecular dynamics simulations have been conducted in order to study the specific ion effects of Li+, Na+, Cs+ and NH4+ cations on dodecyl sulfate (DS−) monolayers. Varying the counterion had no appreciable effect on the structure of the surfactant molecules within the different monolayers. However, the different counterions have a significant effect on the interfacial properties of the monolayer. In particular, we have investigated to what extent each of the counterions is dehydrated when interacting with the DS− headgroup, the specific interactions between the counterions and the headgroup and the salt bridging of the headgroups caused by each counterion. The NH4+ ions are found to directly compete with water molecules to form hydrogen bonds with the DS− headgroup and as a result the ammonium dodecyl sulfate monolayer is the least hydrated of any of those studied. The Cs+ ions are strongly bound to the headgroup and weakly hydrated, such that they would prefer to displace water in the DS− hydration shell to interact with the headgroups. In the case of the Li+ ions, they interact almost as strongly with the DS− headgroups as the Na+ ions, but are generally less hydrated than the Na+ ions and consequently the lithium dodecyl sulfate monolayers are less hydrated than the sodium dodecyl sulfate monolayers. Therefore, by changing the counterion, one can modify the interfacial properties of the surfactant monolayer, and thus affect their ability to encapsulate poorly water soluble drug molecules, which we discuss further in the manuscript.
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DOI：
10.1021/jz200167q
发表时间：
2011
期刊：
The journal of physical chemistry letters
影响因子：
--
作者：
Pastor RW;Mackerell AD Jr
通讯作者：
Mackerell AD Jr
影响因子：
3.3
作者：
Klauda, Jeffery B.;Venable, Richard M.;Freites, J. Alfredo;O'Connor, Joseph W.;Tobias, Douglas J.;Mondragon-Ramirez, Carlos;Vorobyov, Igor;MacKerell, Alexander D., Jr.;Pastor, Richard W.
通讯作者：
Pastor, Richard W.
影响因子：
3.9
作者：
Shi, Liu;Tummala, Naga Rajesh;Striolo, Alberto
通讯作者：
Striolo, Alberto
水-油和水-蒸气界面离子表面活性剂单分子层的固有界面结构
DOI：
--
发表时间：
2011
期刊：
Proceedings of the Royal Society A
影响因子：
--
作者：
H. Martínez;E. Chacón;P. Tarazona;F. Bresme
通讯作者：
F. Bresme
DOI：
10.1021/jp909219k
发表时间：
2010-02-11
期刊：
The journal of physical chemistry. B
影响因子：
--
作者：
Willard AP;Chandler D
通讯作者：
Chandler D