Computer simulations of the interaction of fullerene clusters with lipid membranes

Extensive coarse-grained simulations were performed to investigate the interactions of C-60 fullerene cluster with DMPC (dimyristoyl phosphatidyl choline) lipid membranes. The self-organised structures of pristine C-60 molecules in aqueous solutions are comparable with that in full-atomistic simulations. We find that the interaction between C-60 and membranes depends on the initial aggregation state of fullerene molecules. The insertion of aggregates with small size induced an increase of the bilayer thickness and membrane area. They disaggregate after entering the membrane interior, while larger ones can penetrate into the membrane as solid-like nanoparticles. Our simulations show that the lipids can be extracted from the outer monolayer of the membrane to accommodate the cluster during the insertion process. Particularly, multiple lipid and water molecules under the cluster can be transferred to the opposite side of the membrane, which can cause membrane asymmetry and osmotic pressure for small unilamellar vesicles. Our results suggest that mechanical damage may be a potential mechanism for membrane disruption and fullerene toxicity.