Mechanism of membrane poration by shock wave induced nanobubble collapse: a molecular dynamics study

We performed coarse-grained molecular dynamics simulations in order to understand the mechanism of membrane poration by shock wave induced nanobubble collapse. Pressure profiles obtained from the simulations show that the shock wave initially hits the membrane and is followed by a nanojet produced by the nanobubble collapse. While in the absence of the nanobubble, the shock wave with an impulse of up to 18 mPa s does not create a pore in the membrane, in the presence of a nanobubble even a smaller impulse leads to the poration of the membrane. Two-dimensional pressure maps depicting the pressure distributed over the lateral area of the membrane reveal the differences between these two cases. In the absence of a nanobubble, shock pressure is evenly distributed along the lateral area of the membrane, while in the presence of a nanobubble an unequal distribution of pressure on the membrane is created, leading to the membrane poration. The size of the pore formed depends on both shock wave velocity and shock wave duration. The results obtained here show that these two properties can be tuned to make pores of various sizes.