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.
Highlights
The interactions in mixed solutions of DNA with surfactants or polyelectrolytes as co-solutes have been attracting a rapidly increasing interest among physicists, chemists and biologists as candidates for vectors of gene transfection (Figure 1) [1], but the systems are of general physicochemical relevance.Most of our work is related to the interactions between DNA and quaternary ammonium surfactants
Our main motivation in these studies is the use of our knowledge of the physical chemistry of amphiphiles in single and complex surfactant systems and polymer-surfactants in general, to understand the efficiency of the DNA compaction they induce (DNA is highly compacted within the cells)
It should be noted that these amphiphiles in general behave like the lipids used for gene delivery, so they can be used as models that are less expensive and easier to work with
Summary
The interactions in mixed solutions of DNA with surfactants or polyelectrolytes as co-solutes have been attracting a rapidly increasing interest among physicists, chemists and biologists as candidates for vectors of gene transfection (Figure 1) [1], but the systems are of general physicochemical relevance. Most of our work is related to the interactions between DNA and quaternary ammonium surfactants. Our main motivation in these studies is the use of our knowledge of the physical chemistry of amphiphiles in single and complex surfactant systems and polymer-surfactants in general, to understand the efficiency of the DNA compaction they induce (DNA is highly compacted within the cells). We review our findings about DNA-surfactant systems and the understanding we have obtained after recently starting to work in the area
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