Solitons in the Heimburg–Jackson model of sound propagation in lipid bilayers are enabled by dispersion of a stiff membrane

Experiments show that elastic constants of lipid bilayers vary greatly during the liquid-to-gel phase transition. This fact forms the cornerstone of the Heimburg–Jackson model of soliton propagation along membranes of axons, in which the action potential is accompanied by a traveling phase transitio...

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Published in:The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2022-09, Vol.45 (9), p.79-79, Article 79
Main Authors: Drab, Mitja, Daniel, Matej, Kralj-Iglič, Veronika, Iglič, Aleš
Format: Article
Language:English
Subjects:
Axons
Biological and Medical Physics
Biophysics
Complex Fluids and Microfluidics
Complex Systems
Condensed matter physics
Elastic properties
Lipids
Membranes
Nanotechnology
Phase transitions
Physics
Physics and Astronomy
Polymer Sciences
Propagation
Regular Article - Soft Matter
Series expansion
Soft and Granular Matter
Soft Matter and Food
Solitary waves
Sound propagation
Surfaces and Interfaces
Thin Films
Wave equations
Wave propagation
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Summary:Experiments show that elastic constants of lipid bilayers vary greatly during the liquid-to-gel phase transition. This fact forms the cornerstone of the Heimburg–Jackson model of soliton propagation along membranes of axons, in which the action potential is accompanied by a traveling phase transition. However, the dispersion term, which is crucial for the existence of solitons, is added to the Heimburg–Jackson model ad hoc and set to fit experimental observations. In the present paper, we aim to consolidate this view with continuous membrane mechanics. Using literature data, we show that the compression modulus of a DPPC membrane is smaller by approximately an order of magnitude during phase transition. With a series expansion of the compression modulus, we write the action of a membrane and solve the corresponding wave equation analytically using an Exp-function method. We confirm that membrane solitons with speeds around 200 m/s are possible with amplitudes inversely proportional to their speed. We conclude that dispersion necessary for existence of solitons is directly related to a membrane’s bending properties, offering a possible explanation for h . Our findings are in general agreement with existing literature and give insight into a general mechanism of wave propagation in membranes close to transition. Graphical abstract
ISSN:1292-8941
1292-895X
DOI:10.1140/epje/s10189-022-00233-y