DNA-lipid systems: A physical chemistry study

Abstract

It is well known that the interaction of polyelectrolytes with oppositely charged surfactants leads to an associative phase separation; however, the phase behavior of DNA and oppositely charged surfactants is more strongly associative than observed in other systems. A precipitate is formed with very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. Techniques like phase diagram determinations, fluorescence microscopy, and ellipsometry were used to study these systems. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was also investigated. We observed that DNA compacts and adsorbs onto the surface of positively charged vesicles, and that the addition of an anionic surfactant can release DNA back into solution from a compact globular complex between DNA and the cationic surfactant. Finally, DNA interactions with polycations, chitosans with different chain lengths, were studied by fluorescence microscopy, in vivo transfection assays and cryogenic transmission electron microscopy. The general conclusion is that a chitosan effective in promoting compaction is also efficient in transfection.

Cell Biological and Biophysical Aspects of Lipid-mediated Gene Delivery

“…Size and colloidal stability depend on the charge ratio of the lipid to DNA [20]. Based on size and surface charge, the structure and stability of the lipoplexes can be of three kinds, i.e., when charge ratio of lipid/DNA < 1 or 1 or >1 [101]. At charge ratio < 1 stable anionic complexes form with DNA condensing on the liposomes.…”

DNA Damage Photoinduced by Titanium Dioxide in the Presence of Anionic Vesicles under UV Illumination: Influence of Sodium Chloride Concentration

“…At the same time, the amount of the relaxed form increases slowly during the UV exposure. In these conditions, because of electrostatic repulsion, no interactions occurred between the DNA plasmids and the anionic vesicles 18) . Thus, the results as shown in can be explained by considering that a fraction of DNA could be entrapped randomly within AOT vesicles.…”

Interaction of alkyltrimethylammonium bromides with DMPC-d54 and DMPG-d54 monolayers studied by infrared reflection absorption spectroscopy (IRRAS)

“…We first determined the extinction coefficients e of the individual components and assumed that the extinction coefficients for the CD 2 …”

“…Alkyltrimethylammonium salts are used together with other cationic lipids in transfection experiments or for DNA extraction from cells. For cationic surfactant-lipid-mixtures DNA compaction at vesicles is documented [2]. The wide field of different applications is the reason for the intensive study of cationic surfactants.…”