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Volume 2017 (2017), Article ID 8047149, 12 pages
Research Article

Transfection Studies with Colloidal Systems Containing Highly Purified Bipolar Tetraether Lipids from Sulfolobus acidocaldarius

Department of Pharmaceutics and Biopharmaceutics, University of Marburg, Marburg, Germany

Correspondence should be addressed to Udo Bakowsky; moc.loa@ykswokabu

Received 1 September 2016; Revised 4 December 2016; Accepted 22 December 2016; Published 23 January 2017

Academic Editor: Nejat Düzgünes

Copyright © 2017 Konrad H. Engelhardt et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Lipid vectors are commonly used to facilitate the transfer of nucleic acids into mammalian cells. In this study, two fractions of tetraether lipids from the archaea Sulfolobus acidocaldarius were extracted and purified using different methods. The purified lipid fractions polar lipid fraction E (PLFE) and hydrolysed glycerol-dialkyl-nonitol tetraether (hGDNT) differ in their structures, charge, size, and miscibility from conventional lipids. Liposomes were prepared by mixing tetraether lipids with cholesterol (CH) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) resulting in stable vectors for gene delivery. Lipoplexes were prepared by complexation of liposomes with a luciferase expressing plasmid (pCMV-luc) at certain nitrogen-to-phosphorus (N/P) ratios and optimised for the transient transfection of ovarian adenocarcinoma cells (SK-OV-3). Complexation efficacy was investigated by gel-red fluorescence assay. Biophysical properties, like size, surface charge, and morphology, were investigated by differential light scattering (DLS), atomic force microscopy (AFM), and scanning electron microscopy (Cryo-SEM), respectively, revealing structural differences between liposomes and lipoplexes. A range of stable transfecting agents containing tetraether lipids were obtained by incorporating 5 mol% of tetraether lipids. Lipoplexes showed a decrease in free gel-red with increasing N/P ratios indicating efficient incorporation of plasmid DNA (pDNA) and remarkable stability. Transfection experiments of the lipoplexes revealed successful and superior transfection of SK-OV-3 cell line compared to the commercially available DOTAP and branched polyethyleneimine (25 kDa bPEI).