Self-organization of a stable pore structure in a phospholipid bilayer.

We demonstrate the self-organization process of a stable pore structure in a phospholipid bilayer by unsteady and nonequilibrium molecular dynamics simulations. The simulation is started from an initial state including some amount of water molecules in its hydrophobic region, which is a model of a cell membrane stimulated by ultrasound radiation for the membrane permeabilization (sonoporation). We show that, in several nanoseconds, the bilayer-water system can spontaneously develop into a water-filled pore structure without any mechanical and electrical forcing from outside, when the initial number of water molecules in the hydrophobic region exceeds a critical value. The increase in the initial number of water molecules enhances the probability of pore formation, and sometimes induces the formation of transient micellelike structures of phospholipid molecules.