Water Structure and Dynamics in the Stern Layer of Micelles: Femtosecond Mid-Infrared Pump-Probe Spectroscopy Study.
Water Structure and Dynamics in the Stern Layer of Micelles: Femtosecond Mid-Infrared Pump-Probe Spectroscopy Study.
复制标题
胶束尾层的水结构和动力学：飞秒中红外泵浦探针光谱研究。
DOI：
10.1021/acs.jpcb.9b03183
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
M. Cho
中科院分区：
文献类型：
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作者：
Achintya Kundu;P. Verma;M. Cho
在分子水平上理解胶束Stern层中水的结构和动力学对于阐明水在膜表面生物过程中的积极作用是重要的。胶束和反胶束被认为是优良的膜模型体系。在这里，要解决的问题是否在反胶束和纳米水池系统中的水的空间限制效应在调制水动力学中发挥作用，我们考虑四种不同的水胶束溶液和研究的水动力学在斯特恩层胶束使用飞秒中红外泵浦探测光谱技术。HDO的O-D伸缩模式和叠氮酸的叠氮基伸缩模式的振动能量弛豫和旋转动力学严重依赖于表面活性剂头部基团的电荷、极性和化学结构。特别是，胶束的斯特恩层中的水分子，这是不是在空间受限的环境，是显着不同的散装水。这一发现清楚地表明，即使在空间受限的系统中，水分子的振动和旋转动力学的变化主要是由表面效应而不是空间限制效应引起的。我们相信，目前的实验结果是重要的理解水参与生物膜上的生化过程。
Molecular-level understanding of the water structure and dynamics in the Stern layer of micelles is important to elucidate the active role of water in biological processes on membrane surfaces. Micelles and reverse micelles are considered to be excellent membrane model systems. Here, to address the question of whether or not the spatial confinement effect on water in reverse micelles and nanometric water pool systems plays a role in modulating water dynamics, we consider four different aqueous micelle solutions and study the water dynamics in the Stern layer of micelles using a femtosecond mid-infrared pump-probe spectroscopy technique. Vibrational energy relaxation and rotational dynamics of the O-D stretch mode of HDO and the azido stretch mode of hydrazoic acid are critically dependent on the charge, polarity, and chemical structure of the surfactant head group. In particular, water molecules in the Stern layer of micelles, which are not in spatially confined environments, are notably different from those in bulk water. This finding clearly indicates that changes in the vibrational and rotational dynamics of water molecules, even in spatially confined systems, are mainly induced by surface effects instead of spatial confinement effects. We believe that the present experimental results are of importance for understanding water-involved biochemical processes on biological membranes.