Non-close-packed hexagonal self-assembly of Janus nanoparticles on planar membranes

The adhesion modes of an ensemble of spherical Janus nanoparticles on planar membranes are investigated through large-scale molecular dynamics simulations of a coarse-grained implicit-solvent model. We found that the Janus nanoparticles adhering to planar membranes exhibit a rich phase behavior that depends on their adhesion energy density and areal number density. In particular, effective repulsive membrane-curvature-mediated interactions between the Janus nanoparticles lead to their self-assembly into an ordered hexagonal superlattice at intermediate densities and intermediate to high adhesion energy density, with a lattice constant determined by their areal density. The melting behavior of the hexagonal superlattice proceeds through a two-stage melting scenario in agreement with the Kosterlitz-Thouless-Halperin-Nelson-Young classical theory of two-dimensional melting.