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BP: Fachverband Biologische Physik

BP 19: Biosensors and Biofunctionalized Systems

BP 19.1: Talk

Wednesday, March 28, 2007, 15:30–15:45, H43

Dependence of DNA/Dendrimer Nanoscale Structures on pH and Composition — •Rolf Dootz and Thomas Pfohl — MPI for Dynamics and Self-Organization, Bunsenstraße 10, 37073 Göttingen

DNA condensation by nanoscale objects represents the process by which the genetic information is packed and protected. Moreover, using artificial nanoscale 3D structures leads to novel DNA-containing nanostructures which exhibit great potential not only as genetic but also as generic materials possessing many valuable functional and material properties. However, a profound knowledge of the manifold DNA organization factors is still missing. Here, the self-assembly behavior of DNA and PAMAM dendrimers generation 6 (P6) is studied as a function of the overall complex composition and the pH of the solution, which is known to affect the dendritic structure and charge significantly. The complexation is found to result in DNA condensation through which the dendrimer-bound DNA chains are aggregated significantly to form ordered structures. At low pH values, a liquid crystalline phase is formed which shows a weak dependence of the complex composition. At high pH values, increasing the dendrimer fraction first results in a condensed nematic phase in which the locally oriented DNA chains do not exhibit a coherent positional order. Subsequently, the condensed DNA structure transforms into a long-range ordered dual lattice phase which has not been described previously. To rule out the nature of the observed phases, the evolution of the interaction between P6 and DNA is studied accomplishing hydrodynamic focussing experiments in crossed microchannel devices.