  We present a comprehensive theoretical and experimental study of the solution
phase properties of DNA-based family of nanoparticles - dendrimer-like DNA
molecules (DL-DNA). These charged DNA dendrimers are novel macromolecular
aggregates, which hold high promise in targeted self-assembly of soft matter
systems in the bulk and at interfaces. To describe the behavior of this family
of dendrimers (with generations ranging from G1 to G7), we use a theoretical
model in which base-pairs of a single DL-DNA molecule are modeled by charged
monomers, whose interactions are chosen to mimic the equilibrium properties of
DNA correctly. Experimental results on the sizes and conformations of DL-DNA
are based on static and 1dynamic light scattering; at the same time, Molecular
Dynamics simulations are employed to model the equilibrium properties of
DL-DNA, which compare favorably with the findings from experiments while at the
same time providing a host of additional information and insight into the
molecular structure of the nanostructures. We also examine the
salt-responsiveness of these macromolecules, finding that despite the strong
screening of electrostatic interactions, brought about by the added salt, the
macromolecules shrink only slightly, their size robustness stemming from the
high bending rigidity of the DNA-segments. The study of these charged dendrimer
systems is an important field of research in the area of soft matter due to
their potential role for various interdisciplinary applications, ranging from
molecular cages and carriers for drug delivery in a living organism to the
development of dendrimer- and dendron-based ultra-thin films in the area of
nanotechnology. These findings are essential to determine if DL-DNA is a viable
candidate for the experimental realization of cluster crystals in the bulk, a
novel form of solids with multiple site occupancy.
