Formation of water pore in a bilayer induced by shock wave: Molecular dynamics simulation

Abstract

The irradiation of a shock wave or ultrasound with micro-bubbles has the potential to make transient pores on cell membranes. Although such pores are believed to contribute to the molecular delivery thorough the membrane, the detailed mechanisms of the pore formation with shock waves and the subsequent molecular delivery through the pores into cells are still unclear. To investigate the mechanism at a molecular level, the molecular dynamics simulations of the interaction of the shock wave with a lipid bilayer are conducted. The water penetration into the hydrophobic region by the shock wave is observed in picoseconds. As a next step, structural changes of the bilayer containing water molecules in the hydrophobic region are investigated. The water pore is formed in 3 ns when the large number of water molecules is inserted. The lifetime of the water pore is more than 70 ns. The radius of the water pore is ca. 1.0 nm, which is three times larger than the Stoke’s radius of a typical anticancer drug (5FU). Finally, the diffusion of the anticancer drug in the water pore is investigated.