  Amorphous carbon films have been routinely used to enhance the preparation of
frozen-hydrated transmission electron microscopy (TEM) samples, either in
retaining protein concentration, providing mechanical stability or dissipating
sample charge. However, strong background signal from the amorphous carbon
support obstructs that of the sample, and the insulating properties of
amorphous carbon films preclude any efficiency in dispersing charge. Graphene
addresses the limitations of amorphous carbon. Graphene is a crystalline
material with virtually no phase or amplitude contrast and unparalleled, high
electrical carrier mobility. However, the hydrophobic properties of graphene
have prevented its routine application in Cryo-TEM. This letter reports a
method for rendering graphene TEM supports hydrophilic - a convenient approach
maintaining graphene's structural and electrical properties based on
non-covalent, aromatic functionalization.
