  Using molecular dynamics simulations, we investigated an integrated bio-nano
interface consisting of a \b{eta}-sheet protein stacked onto graphene. We found
that the stacking assembly of the model protein on graphene could be controlled
by water molecules. The interlayer water filled within interstices of the
bio-nano interface could suppress the molecular vibration of surface groups on
protein, and could impair the CH...{\pi} interaction driving the attraction of
the protein and graphene. The intermolecular coupling of interlayer water would
be relaxed by the relative motion of protein upon graphene due to the
interaction between water and protein surface. This effect reduced the
hindrance of the interlayer water against the assembly of protein on graphene,
resulting an appropriate adsorption status of protein on graphene with a deep
free energy trap. Thereby, the confinement and the relative sliding between
protein and graphene, the coupling of protein and water, and the interaction
between graphene and water all have involved in the modulation of behaviors of
water molecules within the bio-nano interface, governing the hindrance of
interlayer water against the protein assembly on hydrophobic graphene. These
results provide a deep insight into the fundamental mechanism of protein
adsorption onto graphene surface in water.

Biological Physics;Mesoscale and Nanoscale Physics;Materials Science;Soft Condensed Matter;Chemical Physics