[Preparation and study of Langmuir films of nucleic acid and octadecylamine complexes]

Formation conditions of langmuir films of nucleic acids (DNA and poly-U)-octadecylamine complexes are determined. Successive transfer of the monolayers of these complexes from the aqueous subphase surface to solid substances (quartz, silicon) is carried out. The structure of multilayer langmuir films of nucleic acid-octadecylamine complexes is studied by small angle X-ray scattering, ellipsometry and UV-spectroscopy. The produced films are shown to have high lamellar orderliness with the multilayer structure period D = 57.0 A. A scheme of the realized structure of these films is proposed in which the nucleic acids are located between octadecylamine bilayers. A suggestion is discussed based on similar results for poly-U and DNA containing langmuir films concerning possible untwisting of double helical DNA in the langmuir film of octadecylamine, as well as biological significance of the discovered phenomena.