Studies of nanoscale structural ordering in planar DNA complexes with amphiphilic mono- and polycations

Formation of DNA complexes with Langmuir monolayers of cationic lipid octadecylamine (ODA) and new amphiphilic polycation poly-4-vinylpyridine with 16% cetylpyridinium groups (PVP-16) on the surface of native DNA aqueous solution with low ionic strength has been studied. AFM topographic images of DNA/ODA and DNA/PVP-16 complex Langmuir–Blodgett films deposited on the mica substrates were obtained. The complex structures and individual DNA molecules on the amphiphile monolayer surface were observed. The characteristic extended net-like structures and quasi-circular toroidal condensed conformations of the planar DNA complexes were formed in dependence on the polycationic amphiphile monolayer state during the DNA binding. The data obtained give evidence for the effectiveness of monolayer techniques for investigation the mechanisms of DNA complexation with amphiphilic mono- and polycations and demonstrate its perspectives for creation of supramolecular planar DNA-based self-organized nanostructures with nanoscale structural ordering.