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A two-dimensional columnar phase in mixtures of DNA complexed with cationic liposomes has been found in the lipid composition regime known to be significantly more efficient at transfecting mammalian cells in culture compared to the lamellar (LalphaC) structure of cationic liposome-DNA complexes. The structure, derived from synchrotron x-ray diffraction,(More)
Cationic liposomes complexed with DNA (CL-DNA) are promising synthetically based nonviral carriers of DNA vectors for gene therapy. The solution structure of CL-DNA complexes was probed on length scales from subnanometer to micrometer by synchrotron x-ray diffraction and optical microscopy. The addition of either linear lambda-phage or plasmid DNA to CLs(More)
Ptychographic coherent X-ray diffractive imaging (PCDI) has been combined with nano-focus X-ray diffraction to study the structure and density distribution of unstained and unsliced bacterial cells, using a hard X-ray beam of 6.2keV photon energy, focused to about 90nm by a Fresnel zone plate lens. While PCDI provides images of the bacteria with(More)
We report a synchrotron x-ray scattering study of linear DNA chains and cationic liposome mixtures which spontaneously self-assemble into a coupled two-dimensional (2D) smectic phase of DNA chains imbedded between lipid bilayers of a 3D smectic phase. The DNA peak is quantitatively described by anisotropic exponentially decaying chain-chain correlations.(More)
We have studied the spatial coherence properties of a nano-focused x-ray beam by grating (Talbot) interferometry in projection geometry. The beam is focused by a fixed curvature mirror system optimized for high flux density under conditions of partial coherence. The spatial coherence of the divergent exit wave emitted from the mirror focus is measured by(More)
Cationic lipid-DNA (CL-DNA) complexes comprise a promising new class of synthetic nonviral gene delivery systems. When positively charged, they attach to the anionic cell surface and transfer DNA into the cell cytoplasm. We report a comprehensive x-ray diffraction study of the lamellar CL-DNA self-assemblies as a function of lipid composition and lipid/DNA(More)
We report a synchrotron small-angle x-ray scattering ~SAXS! study of the mutilayered, self-assembled structure ~complex! that is formed by mixing DNA with cationic liposomes. In these complexes the DNA is confined between charged lipid bilayers and orders as a two-dimensional ~2D! smectic liquid crystal. The power-law bilayer-bilayer correlations of the 3D(More)
We have studied the collective short wavelength dynamics in deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine (DMPC) bilayers by inelastic neutron scattering. The corresponding dispersion relation variant Planck's over 2pi omega(Q) is presented for the gel and the fluid phase of this model system. The temperature dependence of the inelastic(More)
We have investigated the mechanical properties of spider dragline fibers of three Nephila species under varied relative humidity. Force maps have been collected by atomic force microscopy. The Young’s modulus E was derived from the indentation curves of each pixel by the modified Hertz model. An average decrease in E by an order of magnitude was observed(More)
We have investigated the structure of lipid bilayers containing varied molar ratios of different lipids and the antimicrobial peptides magainin and alamethicin. For this structural study, we have used x-ray reflectivity on highly aligned solid-supported multilamellar lipid membranes. The reflectivity curves have been analyzed by semi-kinematical(More)