Permeation of Nanoparticle Across Lipid Membranes Using Coarse-Grained Molecular Dynamics Simulation

The interaction of nanoparticle with cells and lipid membranes plays a critical role in the applications of nanoparticles for therapy, cellular image, biodiagnostics and drug delivery systems. It has been shown that such interactions and the deformation of lipid membranes are often determined by physicochemical properties of nanomaterials, such as size, shape and surface composition. Here, we carry out molecular dynamic simulations using various sizes of nanocrystals as a probe to explore the transport of nanomaterials across dipalmitoylphosphatidylcholine (DPPC). A Coarse-Grained model was used to provide insight at large time and length scales. The dynamics properties of the nanocrystals, as well as the structural properties of lipid membrane arising from the interaction between the nanocrystal and the lipid membrane are investigated. Our simulation results are in satisfactory agreement with available experimental. We found that the minimum pressure for penetrating the first layer is almost independent of the size of the particles while the minimum pressure for permeating both layers is smaller for the larger size particles. Observation of the lipid curvature profile shows the elastic property of the lipid membrane. The thickness of the lipid membrane exhibits recovery ability to the original status. We found that the order parameter of the tails of the bulk lipids change only slightly, while the tails of those surrounding lipids are more ordered than the remote lipids during the permeation of nanocrystals. All these findings are consistent with the ability of lipid membranes to heal after penetration by bare nanocrystals, which have no strong or specific interactions with lipid molecules. We also investigate the interactions between lipid membrane and gold nanoparticles functionalized with hydrophobic surface coatings. The findings described in our work will lead to better understanding of nanomaterial-lipid membrane interactions and the mechanical and dynamic properties of lipid membranes during nanoparticle permeation.