[The thermodynamic stability of nanoconstructions based on the double-stranded DNA molecules].

The temperature stability of nanoconstructions formed by double-stranded DNA molecules fixed in the structure of their liquid crystalline dispersions and cross-linked by nanobridges was determined. It was shown that the heating of nanoconstructions is accompanied by a decrease in the amplitude of the negative bands in the CD spectrum both at lambda approximately 310 and lambda approximately 505 nm. Temperature "melting curves" were derived and characterzed by T(M) values. The T(M) values at lambda approximately 310 and lambda approximately 505 nm coincided with each other but differed from the T(M) value characteristic of the DNA cholesteric liquid crystalline dispersion.

[The formation of nanoconstructions based on double-stranded DNA molecules].

The properties of nanoconstructions formed by double-stranded DNA molecules fixed in the structure of their liquid crystalline dispersions and cross-linked by nanobridges were described. The dependence of the optical properties of the nanostructures on various factors (DNA concentration, nanobridge components, etc.) was examined.

[Molecular construction (superstructures) with adjustable properties based on double-stranded nucleic acids]. / Molekuliarnye konstruktsii (superstruktury) s reguliruemymi svoistvami na osnove dvukhtsepochechnykh nukleinovykh kislot.

Formation of molecular construction that consists of double-stranded molecules of nucleic acids (or synthetic polynucleotides) located at the distance 30-50 A in the spatial structure of particles of their cholesteric liquidcrystalline dispersion and crosslinked by polymeric chelate bridges is described. The resulting superstructure, which possesses peculiar physicochemical properties, could be used as integral biosensor whose properties depend on temperature, the presence of chemical or biologically active compounds of different nature, etc.

["Bridge" structures between nucleic acid molecules fixed in the structure of a liquid crystal]. / "Mostikovye" struktury mezhdu molekulami nukleinovykh kislot, fiksirovannymi v strukture zhidkogo kristalla.

The binding of daunomycin and copper ions to poly(I).poly(C) molecules fixed in a particle of a liquid-crystalline dispersion was studied. A thermodynamic model of adsorption was developed, which makes it possible to describe the formation of complexes of a particular kind, "bridges" that connect adjacent nucleic acid molecules fixed in a liquid crystal. The bridges represent chelate complexes, which incorporate the molecules of the antibiotic daunomycin and copper ions. Equations describing the dependence of the concentration of these bridges in solution on the concentration of their constituents were derived. The family of dependences of experimental amplitudes of bands in CD spectra typical of "bridge" structures on the concentration of copper ions represents a set of S-shaped curves, and, as the concentration of daunomycin in solution increases, the level of saturation of these curves increases. The analysis of experimental data with the use of this model suggests that the structures of this type compete with daunomycin molecules for the binding sites on poly(I).poly(C). By using this model, the energies of formation of bridge structures were calculated.

A novel type of microscopic size chip based on double-stranded nucleic acids.

The double-stranded molecules of nucleic acids (NA) of B- and A-families fixed in the structure of cholesteric liquid-crystalline dispersions, formed as a result of phase exclusion of these molecules from polymer-containing solution, have been used as 'building blocks' for the molecular design. Using the formation of polymeric chelate bridges between NA molecules, three-dimensional structures consisting of alternating NA, anthracycline and copper ions, were created. The formation of the polymeric chelate bridges allows one to stabilize the initial spatial mode of ordering of neighboring NA molecules in a form of so-called 'molecular constructions', immobilize these constructions onto supporting film and evaluate their sizes and shape. The creation of NA molecular constructions is accompanied by an 'extra-increase' in the amplitude of the bands in the CD spectra, despite the initial sense of cholesteric twisting characteristic of liquid-crystalline dispersions. Destroying of polymeric chelate bridges between NA molecules by action of biologically relevant compounds results in disintegration of NA liquid-crystalline molecular constructions. Three-dimensional NA molecular construction can be used as a microscopic size multifunctional chemical unit (chip) for biological or chemical needs.