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C. Jochum, N. Adzić, G. Kahl, C. N. Likos:
"Equilibrium properties of DNA-dendrimers in electrolyte solutions";
Vortrag: 12th Christmas Biophysics Workshop, Golte; 11.12.2017 - 12.12.2017; in: "12th Christmas Biophysics Workshop Book of Abstracts", (2017), S. 33.

Equilibrium properties of DNA-­dendrimers in electrolyte solutions

Dendrimers are synthetic macromolecules possessing a highly branched and regular internal structure. They are synthesized in a step-wise fashion by repeating units from various central multifunctional cores, on which radially branched shells called generations are covalently attached. Charging these dendrimers leads to conformational responsiveness, one of the most important ingredients for envisioned applications of the same, which is essentially lacking for their neutral counterparts.

Recently, Dan Luo and co-workers at Cornell University synthesized dendrimer-like DNA (DL-DNA) from the enzymatic ligation of Y-shaped DNA (Y-DNA) building blocks [1]. These charged DNA dendrimers are novel macromolecule aggregates, which hold high promise in bringing about targeted self-assembly of soft-matter systems in the bulk and
at interfaces.

Inspired by these findings, we study systems of such DL-DNA molecules in order to advance the theoretical analysis of novel self-assembled structures. First, we simulate a single DL-DNA molecule, whose base-pairs are modeled by charged monomers. Their interactions are chosen to mimic the equilibrium properties of DNA correctly. We then employ MD simulations to measure the dependence of equilibrium properties, e.g. the influence of salinity, the tensor of gyration, and form factors, on the dendrimer´s generation. The obtained results are compared to experiments.

In the future, we plan to use DL-DNA to investigate the phenomenon of cluster crystals in the bulk [2], a novel form of solids with multiple site occupancy. Furthermore, we want to study two-dimensional surface ordering of low-generation DL-DNA and Y-DNA with tunable rigidity around the junction point [3]. The study of these charged dendrimer-systems is an important field of research in the area of soft matter due to their potential role to various interdisciplinary applications [4, 5], ranging from molecular cages and carriers for drug and gene delivery in a living organism to the development of dendrimer/dendron-based ultra-thin films (monolayers and multi-layers) in the area of nanotechnology.

[1] Y. Li, Y. Tseng, and D. Luo, Nat. Mater. 3, 38 (2004).
[2] B. Mladek, M. Neumann, G. Kahl, and C. Likos, Phys. Rev. Lett. 96, 045701 (2006).
[3] C. Velasco, C. Likos, and G. Kahl, Mol. Phys. 113, 2699-2706 (2015).
[4] D. Tully and J. Fréchet, Chem. Commun. 14, 1229 (2001).
[5] C. Lee, J. MacKay, J. Fréchet, and F. Szoka, Nat. Biotechnol. 23, 1517 (2005).

dna, soft matter

Projektleitung Gerhard Kahl:
DFS