Exploring gas permeability of lipid membranes using coarse-grained molecular dynamics

Molecular transport through biological membranes occurs in a range of interesting processes. To understand basic permeation functions of a biomembrane, we have carried out molecular dynamics (MD) simulations using dipalmitoylphosphatidylcholine (DPPC) as the bilayer membrane. By reducing the degrees of freedom and employing suitable potentials, a coarse-grained (CG) model can provide direct insight into collective phenomena in biological membranes at longer time and length scales. We used a CG model for DPPC bilayer, which had been parametrised to mimic fundamental structural properties. The permeation process of small molecules such as Xe, O2 and CO2 through the lipid bilayers was investigated. The density profiles and the local diffusion coefficients of the permeating gases across the bilayer membranes are obtained from the MD simulations. By studying gas molecules permeating through the lipid bilayer, we obtain an improved understanding of transport processes across membranes in biological systems in the absence of specialised channels. We also explore conditions that will give better control of the gas permeability and the possibility of membrane applications in environment-friendly separation processes.