Deformability of poly(amidoamine) dendrimers
Department of Physics, Harrison M. Randall Laboratory, The University of Michigan, 500 E. University Ave., Ann Arbor, MI 48109-1120, USA
2 Center for Biologic Nanotechnology, The University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109-0648, USA
3 Michigan Center for Biological Information, The University of Michigan Medical School, 3600 Green Court, Suite 700, Ann Arbor, MI 48105, USA
4 Department of Chemistry, The University of Michigan, 930 N., University Ave., Ann Arbor, MI 48109-1055, USA
Published online: 2 June 2004
Experimental data indicates that poly(amidoamine) (PAMAM) dendrimers flatten when in contact with a substrate, i.e. they are no longer spherical, but resemble flat disks. In order to better understand the deformation behavior of these branched polymers, a series of atomistic molecular dynamics simulations is performed. The resulting flattened dendrimer conformations are compared to atomic force microscopy (AFM) images of individual dendrimers at air/mica and water/mica interfaces. The ability of the polymers to deform is investigated as a function of dendrimer generation (2-5) and the required energies are calculated. Our modeling results show good agreement with the experimental AFM images, namely that dendrimers are highly flexible and capable of forming multiple interaction sites between most of their branch ends and the substrate. The deformation energy scales with dendrimer generation and does not indicate an increase in stiffness between generations 2 and 5 due to steric effects.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2004