  We study the adsorption of charged patchy particle models (CPPMs) on a thin
film of a like-charged and dense polyelectrolyte (PE) brush (of 50 monomers per
chain) by means of implicit-solvent, explicit-salt Langevin dynamics computer
simulations. Our previously introduced set of CPPMs embraces well-defined one-,
and two-patched spherical globules, each of the same net charge and (nanometer)
size, with mono- and multipole moments comparable to those of small globular
proteins. We focus on electrostatic effects on the adsorption far away from the
isoelectric point of typical proteins, i.e., where charge regulation plays no
role. Despite the same net charge of the brush and globule we observe large
binding affinities up to tens of the thermal energy, kT, which are enhanced by
decreasing salt concentration and increasing charge of the patch(es). Our
analysis of the distance-resolved potentials of mean force together with a
phenomenological description of all leading interaction contributions shows
that the attraction is strongest at the brush surface, driven by multipolar,
Born (self-energy), and counterion-release contributions, dominating locally
over the monopolar and steric repulsions.
