Probing the structure and dynamics of confined water in AOT reverse micelles.
Probing the structure and dynamics of confined water in AOT reverse micelles.
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探讨 AOT 反胶束中承压水的结构和动力学。
DOI：
10.1021/jp402270e
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Straub,JohnE
中科院分区：
文献类型：
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作者：
Martinez,AnnaVictoria;Dominguez,Laura;Malolepsza,Edyta;Moser,Adam;Ziegler,Zack;Straub,JohnE
反胶团是一种具有吸引力的纳米尺度系统，用于结构和化学反应（包括蛋白质折叠和聚集）研究中的分子限制。由于非极性、极性和带电基团之间相互作用的多样性，反胶束的模拟（其中水“池”通过表面活性剂层与非极性体相分离）对经验力场构成了重大挑战。我们已经探索了系统密度，反胶束结构，和水的构型弛豫时间作为反胶束组合物的函数，包括水：表面活性剂的比例，水分子的绝对数量，和力场使用分子动力学模拟的依赖。由此产生的结构和动力学被发现更多地依赖于所使用的力场，而不是在不同的解释的水：表面活性剂的比例方面的反胶束的绝对尺寸。在所有无约束的模拟中观察到与球形反胶束几何形状的实质性偏差。旋转各向异性衰减时间和水的停留时间显示出很强的依赖力场和水模型，但观察到独立的力场的幂律松弛时间。我们的研究结果表明，需要进一步的实验研究的反胶束，可以提供深入了解这些复杂的系统中的形状波动的分布和动力学。
Reverse micelles are attractive nanoscale systems used for the confinement of molecules in studies of structure and chemical reactions, including protein folding, and aggregation. The simulation of reverse micelles, in which a water “pool” is separated from a nonpolar bulk phase by a surfactant layer, poses significant challenges to empirical force fields due to the diversity of interactions between nonpolar, polar, and charged groups. We have explored the dependence of system density, reverse micelle structure, and water configurational relaxation times as a function of reverse micelle composition, including water:surfactant ratio, absolute number of water molecules, and force field using molecular dynamics simulations. The resulting structures and dynamics are found to depend more on the force field used than on varying interpretations of the water:surfactant ratio in terms of absolute size of the reverse micelle. Substantial deviations from spherical reverse micelle geometries are observed in all unrestrained simulations. Rotational anisotropy decay times and water residence times show a strong dependence on force field and water model used, but power-law relaxation in time is observed independent of the force field. Our results suggest the need for further experimental study of reverse micelles that can provide insight into the distribution and dynamics of shape fluctuations in these complex systems.