Nanoparticle-Supported Lipid Bilayers: Differences in Equilibrium Structures and Properties Unraveled by Molecular Dynamics Simulations*

Molecular Dynamics (MD) simulations are conducted to unravel the equilibrium properties of the nanoparticle-supported lipid bilayers (NPSLBLs) in atomistic details and the findings are compared with that of the similar-sized nanovesicles (NVs). Three key differences emerge. First, the NV is found to contain significantly larger number of lipid molecules in the outer layer/leaflet, while the NPSLBL has equal number of lipid molecules in inner and outer layers. Second, for the NV the lipid molecules in the outer and inner layers showed identical diffusivities, while for the NPSLBL the diffusivity of the lipid molecules in the outer layer was more than double than that of in the inner layer. Finally, the nanoconfined water (located in the cavity for the NV, while being present as a few layers between the inner leaflet and the NP core for the NPSLBL) showed much lesser diffusivity for the NPSLBL as compared to that for the NV. The findings will be key to better understand the structure of this important nanomaterial (namely NPSLBL) with applications in a plethora of disciplines ranging from targeted drug and gene delivery to characterization of curvature-sensitive biomolecules.