[Superparamagnetic Cobalt Ferrite Nanoparticles "Blow up" Spatial Ordering of Double-stranded DNA Molecules]

The formation of cholesteric liquid-crystalline dispersions formed by double-stranded DNA molecules, handled by positively charged superparamagnetic cobalt ferrite nanoparticles, as well as action of these nanoparticles on DNA dispersion, are considered. The binding of magnetic nanoparticles to the linear double-stranded DNA in solution of high ionic strength (0.3 M NaCl) and subsequent phase exclusion of these complexes from polyethylene glycol-containing solutions lead to their inability to form dispersions, whose particles do possess the spatially twisted arrangement of neighboring double-stranded DNA molecules. The action of magnetic nanoparticles on DNA dispersion (one magnetic nanoparticle per one double-stranded DNA molecule) results in such "perturbation" of DNA structure at sites of magnetic nanoparticles binding that the regular spatial structure of DNA dispersion particles "blows up"; this process is accompanied by disappearance of both abnormal optical activity and characteristic Bragg maximum on the small-angle X-ray scattering curve. Allowing with the fact that the physicochemical properties of the DNA liquid-crystalline dispersion particles reflect features of spatial organization of these molecules in chromosomes of primitive organisms, it is possible, that the found effect can have the relevant biological consequences.