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Characterization of the Nanostructure of Complexes Formed by a Redox-Active Cationic Lipid and DNA

DOI: 10.1021/jp7103903 DOI Help

Authors: Claire L. Pizzey (Diamond Light Source) , Christopher M. Jewell (University of Wisconsin-Madison) , Melissa E. Hays (University of Wisconsin-Madison) , David M. Lynn (University of Wisconsin-Madison) , Nicholas L. Abbott (University of Wisconsin-Madison) , Yukishige Kondo (Tokyo University of Science,Japan) , Sharon Golan (Technion-Israel Insitute of Technology,Haifa,Isra) , Yeshayahu Talmon (Technion-Israel Insitute of Technology,Haifa,Isra)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Physical Chemistry , VOL 112 (18) , PAGES 5849-5857

State: Published (Approved)
Published: April 2008

Abstract: We report characterization of the nanostructures of complexes formed between the redox-active lipid bis(n-ferrocenylundecyl)dimethylammonium bromide (BFDMA) and DNA using small-angle neutron scattering (SANS) and cryogenic transmission electron microscopy (cryo-TEM). A particular focus was directed to the influence of lipid oxidation state ( WHERE reduced BFDMA has a net charge of +1 and oxidized BFDMA has a charge of +3) on the nanostructures of the solution aggregates formed. Complexes were characterized over a range of charge ratios of reduced BFDMA to DNA (1.1:1, 2.75:1, and 4:1) in solutions of 1 mM Li2SO4. For these complexes, a single peak in the SANS data at 1.2 nm-1 indicated that a nanostructure with a periodicity of 5.2 nm was present, similar to that observed with complexes of the classical lipids DODAB/DOPE and DNA (multilamellar spacing of 7.0 nm). The absence of additional Bragg peaks in all the SANS data indicated that the periodicity did not extend over large distances. Both inverse Fourier transform analysis and form factor fitting suggested formation of a multilamellar vesicle. These results were confirmed by cryo-TEM images in which multilamellar complexes with diameters between 50 and 150 nm were observed with no more than seven lamellae per aggregate. In contrast to complexes of reduced BFDMA and DNA, Bragg peaks were absent in SANS spectra of complexes formed by oxidized BFDMA and DNA at all charge ratios investigated. The low-q behavior of the SANS data obtained using oxidized BFDMA and DNA complexes suggested that large, loose aggregates were formed, consistent with complementary cryo-TEM images showing predominantly loose disordered aggregates. Some highly ordered spongelike and cubic phase nanostructures were also detected in cryo-TEM images. We conclude that control of BFDMA oxidation state can be used to manipulate the nanostructures of lipidāˆ’DNA complexes formed using BFDMA.

Subject Areas: Chemistry, Biology and Bio-materials, Materials

Instruments: NONE-No attached Diamond beamline

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