Issue 14, 2011

DNA condensation with spermine dendrimers: interactions in solution, charge inversion, and morphology control

Abstract

In this report, we characterize the formation of structured condensates of 884 base pair, double stranded DNA and spin-labeled, second generation dendrons (SL-G2) that are spermine-based and cationic using continuous wave electron paramagnetic resonance spectroscopy (CW EPR) and transmission electron microscopy (TEM). The electrostatic interaction between DNA and SL-G2 in solution leads to condensation of DNA into densely packed structures. At a particular charge ratio of 2.3 (cationic charges/anionic charges), the structures appear as thick rod-like condensates of parallelly ordered, stretched DNA and SL-G2. Depending on the concentration of DNA, the charge ratio and the ionic strength, which has been adjusted with monovalent salts, a large variety of structures were observed by TEM. By adding manganese(II) salts charge inversion of DNA could be observed by CW EPR. This could be achieved, because paramagnetic Mn2+ ions are usually electrostatically bound to the strong DNA polyions immediately after adding the salt and only give rise to an EPR signal when expelled from the DNA molecules. At a charge ratio of 2.3 the Mn(II) ions are expelled from the formed DNA dendriplexes, which indicates an inverted charge of the DNA. Since CW EPR spectra of the nitroxide-based SL-G2 and Mn2+-ions are spectroscopically distinct, the interaction of the condensation agent with DNA and the interaction of DNA with Mn2+ counterions could be observed simultaneously. While the interaction between condensation agent and DNA did not change, irrespective of the conditions present in the solution, condensate/aggregate morphology changed drastically when the conditions were varied, as could be inferred from the Mn2+ signal and TEM data.

Graphical abstract: DNA condensation with spermine dendrimers: interactions in solution, charge inversion, and morphology control

Supplementary files

Article information

Article type
Paper
Submitted
21 Mar 2011
Accepted
11 May 2011
First published
15 Jun 2011

Soft Matter, 2011,7, 6695-6704

DNA condensation with spermine dendrimers: interactions in solution, charge inversion, and morphology control

D. Kurzbach, C. Velte, P. Arnold, G. Kizilsavas and D. Hinderberger, Soft Matter, 2011, 7, 6695 DOI: 10.1039/C1SM05485F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements