Long-lived ionic nano-domains can modulate the stiffness of soft interfaces.
Long-lived ionic nano-domains can modulate the stiffness of soft interfaces.
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DOI：
10.1039/c8nr06339g
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发表时间：
2019-03
期刊：
影响因子：
6.7
通讯作者：
William Trewby;J. Faraudo;Kislon Voïtchovsky
中科院分区：
文献类型：
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作者：
William Trewby;J. Faraudo;Kislon Voïtchovsky
金属离子支撑着生物界面上的无数过程，包括维持电中性，改变机械性能和驱动生物能量活动。这些过程通常通过离子表现为独立扩散的点电荷来描述。在这里，我们表明，Na+和K+离子，而不是自发地形成相关的纳米级网络，在几秒钟内在溶液中的阴离子双层的界面处演变。结合单离子水平原子力显微镜和分子动力学模拟，我们调查的配置和动力学的Na+，K+，Rb+在脂质表面。我们确定了两种不同的离子状态：众所周知的直接静电相互作用与脂质头基和水介导的相互作用，可以驱动形成显着长寿的离子网络，在许多秒内演变。我们表明，该第二状态通过相关的离子-离子相互作用诱导离子网络形成，产生-0.4kBT/离子的有效能量阱。这些网络局部地降低了膜的刚度，提供了一种自发的机制，用于以纳米级精度调节其机械性能。普遍存在的水介导的相互作用表明，我们的研究结果具有深远的影响，控制软界面的性能。
Metal ions underpin countless processes at bio-interfaces, including maintaining electroneutrality, modifying mechanical properties and driving bioenergetic activity. These processes are typically described by ions behaving as independently diffusing point charges. Here we show that Na+ and K+ ions instead spontaneously form correlated nanoscale networks that evolve over seconds at the interface with an anionic bilayer in solution. Combining single-ion level atomic force microscopy and molecular dynamic simulations we investigate the configuration and dynamics of Na+, K+, and Rb+ at the lipid surface. We identify two distinct ionic states: the well-known direct electrostatic interaction with lipid headgroups and a water-mediated interaction that can drive the formation of remarkably long-lived ionic networks which evolve over many seconds. We show that this second state induces ionic network formation via correlative ion-ion interactions that generate an effective energy well of -0.4kBT/ion. These networks locally reduce the stiffness of the membrane, providing a spontaneous mechanism for tuning its mechanical properties with nanoscale precision. The ubiquity of water-mediated interactions suggest that our results have far-reaching implications for controlling the properties of soft interfaces.