Counterion distribution and ζ-potential in PAMAM dendrimer

Using several hundred nanosecond long fully atomistic molecular dynamics simulations, we investigate the monomer and counterion local concentrations in poly amido amide (PAMAM) dendrimer systems for various generations at neutral pH. We also calculate the zeta potential as a function of dendrimer generation. It is found that the zeta potential increases with dendrimer generation, but slowly at high generation. The zeta potential behavior is remarkably well reproduced when employing Monte Carlo simulations and the Poisson-Boltzmann theory for colloidal particles with size and effective charge of the dendrimer as relevant input parameters from the fully atomistic simulations.