Two-component coarse-grained molecular-dynamics model for the human erythrocyte membrane.

Area of Science:

• Biophysics
• Computational Biology
• Materials Science

Background:

• Erythrocyte membranes exhibit complex mechanical properties arising from their lipid bilayer and underlying spectrin cytoskeleton.
• Simulating these properties at large length and timescales is computationally challenging.

Purpose of the Study:

• To develop a coarse-grained molecular dynamics model for simulating erythrocyte membranes.
• To capture both the fluidic behavior of the lipid bilayer and the elastic properties of the cytoskeleton.
• To enable simulations across micrometer length and millisecond timescales.

Main Methods:

• A two-component coarse-grained model was developed using three particle types: lipid clusters, actin junctions, and band-3 complexes.
• Interaction potentials were tuned to control membrane diffusivity and bending rigidity.
• Simulations of membrane shearing were performed to analyze stress contributions.

Main Results:

• The model successfully integrated lipid bilayer fluidity and cytoskeleton elasticity.
• Shear stress at low strain rates was dominated by the spectrin network; lipid bilayer viscosity became significant at higher rates.
• Reduced spectrin network connectivity decreased the membrane's shear modulus.

Conclusions:

• The proposed model provides a powerful tool for studying erythrocyte membrane mechanics.
• It allows for the investigation of how structural components influence macroscopic membrane properties.
• The findings offer insights into red blood cell mechanics under different physiological and pathological conditions.