Cellular entry of graphene nanosheets: the role of thickness, oxidation and surface adsorption

Coarse grained molecular dynamics simulations are conducted to study the interaction of graphene nanosheets with a lipid bilayer, focusing on the effects of graphene thicknesses (single/multi-layered graphene), oxidation and surface absorption by lipid molecules. The results show that a hydrophobic corner of graphene can pierce into the bilayer, while different oxidations of the nanosheets affect their final equilibrium configurations in the bilayer: lying across or within the hydrophobic core of the bilayer. The underlying mechanism is clarified by calculating the energy barrier for graphene piercing into the bilayer. Our studies provide fundamental guidance towards understanding how graphene enters cells, which is important for biomedical diagnostics and therapies, and for managing health impacts following occupational or environmental exposure.