Viscosity of mixed lipid bilayers: Comparison between atomistic and coarse grained models
1Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
The Journal of Chemical Physics
|August 25, 2025
Summary
Membrane surface viscosity in mixed lipid bilayers is complex. Opposite spontaneous curvatures in lipids cause the greatest non-ideal viscosity, a trend not captured by coarse-grained models.
Area of Science:
- Biophysics
- Computational Biology
- Materials Science
Background:
- Membrane fluidity, measured by surface viscosity, is vital for cellular functions.
- Understanding compositional effects on mixed lipid bilayer viscosity is crucial but underexplored.
Purpose of the Study:
- Investigate how lipid structural differences impact surface viscosity in binary mixtures.
- Evaluate the accuracy of molecular dynamics simulations, including coarse-grained models, in predicting these trends.
Main Methods:
- Utilized atomistic and coarse-grained molecular dynamics simulations.
- Analyzed simulation data with the Redlich-Kister model for non-ideal mixing.
- Examined lipid mixtures with varying acyl chain lengths, spontaneous curvatures, and head group structures.
Main Results:
- Lipid mixtures with opposite spontaneous curvatures exhibited the most significant deviations from ideal viscosity.
- Coarse-grained models inaccurately predicted viscosity trends in complex systems.
- Interfacial friction is not adequately represented in reduced-resolution models.
Conclusions:
- Compositional heterogeneity, particularly opposite spontaneous curvatures, strongly influences membrane surface viscosity.
- Atomistic simulations are necessary for accurate predictions of viscosity in complex lipid mixtures.
- Coarse-grained models require refinement to capture interfacial friction effects.
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