Molecular dynamics simulation of PAMAM dendrimer in aqueous solution

The properties of ethylenediamine (EDA) cored and amine surface poly(amidoamine) (PAMAM) dendrimers of generation 1 through 7 in the explicit solvent were studied by the atomistic force field based molecular dynamics. Since amines are assumed to be protonated the simulation condition is designed to represent the dilute alkali solution. All the generations are spherical in shape, while the higher generations show edges or slightly polyhedral shape. The density profile indicates that the dendrimers are constant density spheres and the densities are independent of generation in this aqueous solution. The scaling properties of the radius of gyration with the numbers of atoms and solvent accessible surface with radius of gyration indicate the PAMAM dendrimers are densely compact structures which result from the highly flexibility confirmed by the terminal group distribution. Dynamic behaviors such as autocorrelation function of the squared radius of gyration and mean square displacement were also studied too.