Spectroscopic study of thin multilayer films of the complexes of nucleic acids with cationic amphiphiles and polycations: their possible use as sensor elements

Two types of multilayer films of DNA complexes with amphiphilic molecules of dioctadecyldimethylammonium (DODA) and polycations: polyallylamine, polyethylenimine and poly- l-lysine were obtained using Langmuir-Blodgett (LB) technique and successive alternating adsorption method (SA films) correspondingly. Structure and affinity properties of the films were studied by IR, UV-VIS and CD spectroscopy. IR spectral criteria of polynucleotide conformation [M. Ghomi, R. Lettelier, J. Liquier, E. Taillandier, Int. J. Biochem., 22 (1990) 691–699] show DNA conserves its double helical structure in all the films. Low frequency shift of IR absorption bands of DNA in the films indicates electrostatic interaction between PO 2 - groups of DNA and positively charged groups of polycations or polar heads of DODA molecules. Water molecules were found to penetrate into all types of the films and to bind with DNA hydration centers (phosphatic groups). In contrast to usual DNA films, the hydration in the LB and SA films does not initiate B-to-A conformational transition of double helix. The binding of DNA-contained films with different DNA-intercalated molecules, including antitumor drug—daunomycin, has been also studied.