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Long-lived ionic nano-domains can modulate the stiffness of soft interfaces

Trewby, W; Faraudo, J; Voïtchovsky, K

Long-lived ionic nano-domains can modulate the stiffness of soft interfaces Thumbnail


W Trewby

J Faraudo


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.


Trewby, W., Faraudo, J., & Voïtchovsky, K. (2019). Long-lived ionic nano-domains can modulate the stiffness of soft interfaces. Nanoscale, 11(10), 4376-4384.

Journal Article Type Article
Acceptance Date Feb 12, 2019
Online Publication Date Feb 25, 2019
Publication Date Mar 14, 2019
Deposit Date Feb 20, 2019
Publicly Available Date Feb 26, 2019
Journal Nanoscale
Print ISSN 2040-3364
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 11
Issue 10
Pages 4376-4384


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