(398c) Using Coarse-grained Computer Simulations to Probe Interactions between Nanoparticles and Lipid Bilayers

We use a coarse-grained numerical simulation-dissipative particle dynamics-to consider two different scenarios involving nanoparticles and lipid bilayers. In the first case, the particles are nanoscopic Janus beads that comprise both hydrophobic and hydrophilic portions.

We demonstrate that when the membrane rips and forms a hole due to an external stress, these nanoparticles diffuse to the edge of the hole and form a stable pore, which persists after the stress is released.

Once the particle-lined pore is formed, a small increase in membrane tension readily reopens the pore, allowing transport through the membrane. Besides the application of an external force, the membrane tension can be altered by varying, for example, temperature or pH.

Thus, the findings provide guidelines for designing nanoparticle-bilayer assemblies for targeted delivery, where the pores open and the cargo is released only when the local environmental conditions reach a critical value. In the second case, we examine the penetration of amphiphilic, nanoscale cylinders into lipid bilayers. We vary the physical features of these nanoparticles to determine the conditions where they will insert into and span the bilayer. The results yield design rules for creating artificial proteins that permit transport through the membrane.