期刊
NANOSCALE
卷 11, 期 10, 页码 4376-4384出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c8nr06339g
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资金
- Engineering and Physical Sciences Council (UK) [1452230, EP/M023915/1]
- European Council [631186]
- Spanish Ministry of Economy and Competitiveness [MAT2015-64442-R]
- Severo Ochoa Programme for Centres of Excellence in RD [SEV-2015-0496]
- EPSRC [EP/M023915/1] Funding Source: UKRI
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 -0.4k(B)T/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.
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