Association of Amphiphiles and Polyelectrolytes with DNA

Abstract: DNA- cationic amphiphile and DNA-cationic polymer systems were studied with respect to the intermolecular interactions, as well as structure and stability of formed complexes. The thesis is divided in two parts: one section is a summary and the other section contains five papers. The summary is organized as follows; Chapter 2 gives an overview on the behavior of polyelectrolytes in solutions with empasis on DNA particularities and introduction of the fluorescence microscopy method. The main types of surfactants, lipids and their aggregates as well as the method of their imaging (cryo-TEM) are descibed in chapter 3. In Chapter 4 the DNA interactions with oppositely charged polymers and amphiphilic aggregates are overviewed and the SAXS technique is considered with respect to the structural study of formed complexes. An introduction to the applications of DNA-lipid and DNA-polycation complexes is given in Chapter 5. In Chapter 6 the main findings from the papers are summarized and discussed. Finally, some conclusions and future perspectives are given in Chapter 7. Aside from the summary, five papers are included in this thesis and their brief description follows below. Paper I describes the DNA condensation in the presence of synthetic double-chain cationic surfactant and the effect of neutral liposomes on DNA- surfactant complexes. Paper II reports the condensation and compaction of long DNA molecules in the presence of pH-sensitive cationic surfactant. The comparison of the surfactant ability to condense DNA depending on its state (micellar or incorporated into vesicles) and its charge (cationic or nonionic) was performed. Papers III and IV present a study on the effect of neutral lipid on DNA condensation in the presence of mixed cationic liposomes and on the properties of DNA-mixed lipid complexes. Finally, Paper V characterizes the novel DNA delivery system based on natural polycations, and correlation between some physico-chemical properties of formed complexes and their transgene expression was established.