Monte Carlo simulation of two-component bilayers: DMPC/DSPC mixtures

Area of Science:

• Biophysics
• Computational Chemistry
• Materials Science

Background:

• Phospholipid bilayers are fundamental to cell membranes.
• Understanding their phase transitions is crucial for biological and material applications.
• Mixtures of different phospholipids, like DMPC/DSPC, exhibit complex phase behaviors.

Purpose of the Study:

• To develop a simple lattice model for simulating two-component, two-state phospholipid bilayers.
• To investigate the gel-fluid transition and lateral component distributions in DMPC/DSPC mixtures.
• To compare simulation results with experimental data, including excess heat capacity and fluorescence recovery after photobleaching.

Main Methods:

• Application of Monte Carlo methods to a lattice model.
• Simulation of excess heat capacity versus temperature curves.
• Analysis of lateral component distributions and bilayer energy distribution functions.
• Percolation theory applied to gel clusters.

Main Results:

• The model successfully simulates excess heat capacity curves for DMPC/DSPC mixtures.
• The gel-fluid transition is identified as continuous for all compositions.
• Configurational property temperatures correlate with excess heat capacity maxima.
• Threshold temperatures from simulations align with experimental fluorescence recovery data.

Conclusions:

• The lattice model provides a robust framework for studying phospholipid bilayer behavior.
• The study confirms continuous gel-fluid transitions in DMPC/DSPC mixtures.
• Percolation analysis offers insights into lipid cluster dynamics and phase transitions.