Coupling field theory with mesoscopic dynamical simulations of multicomponent lipid bilayers

Area of Science:

• * Biophysics and Soft Matter Physics
• * Computational Materials Science

Background:

• * Lipid bilayer membranes exhibit complex mechanical properties influenced by composition and curvature.
• * Mesoscopic simulation methods are crucial for bridging atomic-scale detail and macroscopic behavior.

Purpose of the Study:

• * To develop and validate a mesoscopic simulation method for two-component lipid bilayer membranes.
• * To investigate the relationship between membrane composition, elastic properties, and curvature dynamics.

Main Methods:

• * Modeling the membrane as an elastic network with composition-dependent spring constants derived from atomistic simulations.
• * Employing the Cahn-Hilliard equation to govern composition field dynamics, coupled with a free energy functional.
• * Modulating bond strengths based on local composition and fitting to nonequilibrium molecular dynamics data.

Main Results:

• * The simulation method successfully parameterizes bond strengths using microscopic bulk modulus.
• * Enhanced mean curvature is observed when bond strength is modulated by local composition.
• * The bending modulus is treated as a composition-dependent variable.

Conclusions:

• * The developed mesoscopic simulation method provides a novel approach to study lipid bilayer mechanics.
• * The findings suggest that local composition fluctuations significantly impact membrane curvature and stress response.
• * The method offers potential for investigating phase coexistence effects on membrane stress and exploring renormalization by thermal undulations.