Molecular Dynamics Simulations of Structural Changes of Lipid Bilayers Under High Pressure

The structural changes of biological membranes under a high-pressure environment underlie the development of various pressure-related biomedical engineering techniques. We performed molecular dynamics simulations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers under high hydrostatic pressure of 100, 400 MPa, and 1 GPa. With the pressure increase, hydrophobic chains of lipids for the POPC bilayer become aligned locally, exhibiting nonuniformity of the bilayer thickness. The trend becomes prominent for the POPC bilayer at the pressure of 400 MPa and 1 GPa. On the other hand, the response of the DOPC bilayer is weak, which agrees with previous experimental and simulation results. Under stretching for a high-pressure environment, the membrane rupture of the POPC bilayer starts with necking around the thin bilayer thickness, which may relate to the lipid bilayer phase transition for a highe-pressure environment.