  Macromolecules based on dendritic or hyperbranched polyelectrolytes have been
emerging as high potential candidates for biomedical applications. Here we
study the charge and solvation structure of dendritic polyglycerol sulphate
(dPGS) of generations 0 to 3 in aqueous sodium chloride solution by
explicit-solvent molecular dynamics computer simulations. We characterize dPGS
by calculating several important properties such as relevant dPGS radii,
molecular distributions, the solvent accessible surface area, and the partial
molecular volume. In particular, as the dPGS exhibits high charge
renormalization effects, we address the challenges of how to obtain a
well-defined effective charge and surface potential of dPGS for practical
applications. We compare implicit- and explicit-solvent approaches in our
all-atom simulations with the coarse-grained simulations from our previous
work. We find consistent values for the effective electrostatic size (i.e., the
location of the effective charge of a Debye--H\"{u}ckel sphere) within all the
approaches, deviating at most by the size of a water molecule. Finally, the
excess chemical potential of water insertion into dPGS and its thermodynamic
signature are presented and rationalized.
