Characterization of Interfaces between Graphene Films and Support Substrates by Observation of Lipid Membrane Formation

Chemical properties of graphene film surfaces are investigated by observing lipid membrane formation on them in liquid environment for bioapplications of graphene. It is found that water molecules form a layered structure at the interface between graphene films and support substrates in liquid. Lipid monolayer membranes are selectively formed on the graphene film surfaces above the hydrophilic domains of the sapphire surface that is phase-separated into hydrophilic and hydrophobic domains. This means that the hydrophilicity/hydrophobicity of the support substrate is permeable through the graphene film to the graphene surface not only in air but also in liquid environment. Controllability of the graphene film properties by the substrate surface will be useful for application of graphene to biotechnology where liquid environment is required.