Simulation study of the G=4 PAMAM dendrimer in water at different pH conditions

We report an analysis of Molecular Dynamics simulations carried out for the PAMAM-EDA dendrimer in water, considering neutral dendrimer, or high pH conditions, or assuming that all the amine groups are fully protonated at low pH (the addition of chloride counterions ensures the global charge neutrality of the system in this case). These simulations were performed considering the PCFF force-field with explicit consideration of hydrogen bonds and using the TIP3P molecular parameters for the water molecules. Our data indicate a remarkably different orientational distribution of dendrimer units for the two systems, low or high pH, with stronger segregation of dendrons in the former case Neutral dendrimers adsorb more water molecules.