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Issue 18, 2011
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PAMAM6 dendrimers and DNA: pH dependent “beads-on-a-string” behavior revealed by small angle X-ray scattering

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Abstract

DNA interactions with polycations are not only important for our understanding of chromatin compaction but also for characterizing DNA-binding proteins involved in transcription, replication and repair. DNA is known to form several types of liquid-crystalline phases depending, among other factors, on the polycation structure and charge density. Theoretical studies and simulations have predicted the wrapping of DNA around spherical positively charged polycations. As a potential mimic of the histone octamer or other DNA wrapping proteins, poly(amido amine) generation 6 (PAMAM6) dendrimers have been chosen for our study. The self-assembly of DNA induced by PAMAM6 has been investigated using small angle X-ray scattering (SAXS) in order to reveal the assemblies' structure dependence on the pH of the environment and dendrimer concentrations. We demonstrate that at pH 8.5 dense phases are formed and characterized by a 2D-columnar hexagonal lattice which is transformed into a 3D hexagonal lattice with increasing dendrimer concentration (charge ratio N/P). Moreover, a systematic analysis of the scattering data collected from diluted samples at pH 8.5 and 5.5 has led us to propose a wrapping scenario of DNA around PAMAM6 at pH 5.5.

Graphical abstract: PAMAM6 dendrimers and DNA: pH dependent “beads-on-a-string” behavior revealed by small angle X-ray scattering

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Publication details

The article was received on 08 Apr 2011, accepted on 29 Jun 2011 and first published on 04 Aug 2011


Article type: Paper
DOI: 10.1039/C1SM05632H
Citation: Soft Matter, 2011,7, 8343-8351
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    PAMAM6 dendrimers and DNA: pH dependent “beads-on-a-string” behavior revealed by small angle X-ray scattering

    R. Dootz, A. C. Toma and T. Pfohl, Soft Matter, 2011, 7, 8343
    DOI: 10.1039/C1SM05632H

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