L. I. Lopatina

DNA hydrogel as a template for synthesis of ultrasmall gold nanoparticles for catalytic applications.

DNA cross-linked hydrogel was used as a matrix for synthesis of gold nanoparticles. DNA possesses a strong affinity to transition metals such as gold, which allows for the concentration of Au precursor inside a hydrogel. Further reduction of HAuCl4 inside DNA hydrogel yields well dispersed, non-aggregated spherical Au nanoparticles of 2-3 nm size. The average size of these Au nanoparticles synthesized in DNA hydrogel is the smallest reported so far for in-gel metal nanoparticles synthesis. DNA hybrid hydrogel containing gold nanoparticles showed high catalytic activity in the hydrogenation reaction of nitrophenol to aminophenol. The proposed soft hybrid material is promising as environmentally friendly and sustainable material for catalytic applications.

Thiol-mediated anchoring of silver cations to DNA for construction of nanofibers on DNA scaffold.

The formation of metal-containing Ag-mercaptoethanol (-Ag-S(R)-)(n) complexes on DNA chain scaffold was studied by UV spectroscopy, zeta potential measurement, and fluorescence and transmission electron microscopies. Experimental results made clear the mechanism of DNA mineralization and compaction, according to which intercalation of silver cations into DNA scaffold and further formation of (-Ag-S(R)-)(n) oligomeric complexes on DNA induce efficient DNA chain compaction by terminal Ag(+) cations. By transmission electron microscopy the formation of fiber-like DNA-templated nanostructures was observed. DNA-Ag-thiol complexes are promising for DNA-templated engineering of hybrid 1D nanostructures with adjustable chemical functionalities by choosing appropriate thiol ligand.

[Growth peculiarities of hydrocarbon-oxidizing rhodococcus and pseudomonads dissociates in mono- and mixed cultures].

Growth of R-, S-, and M-dissociates of Rhodococcus rubropertinctus in mixed culture with R-, S-, and M-dissociates of Rhodococcus aeruginosa in comparison with rhodococcus monoculture cultivated on mineral nutrient medium with hexadecane has been studied. The amount of cells in the stationary growth phase has increased 10–15 times in comparison with the monoculture, and pseudomonads which dominated in population, in associations of M-dissociate of R. rubropertinctus with any dissociate of R. aeruginosa or two S-dissociates in the studied bacterial species. The emulsifying ability of the cells (maximal in R-dissociates), the synthesis of surface active compounds in pseudomonads, which is maximal in M-dissociate had the main influence on the growth of rhodococci on the nutrient medium with hydrocarbons.

Sorption and diffusion of low-molecular-weight compounds in polymer composites based on high-density polyethylene and poly(methyl methacrylate)☆

Abstract Sorption and diffusion of low-molecular-weight compounds was studied in high-density polyethylene deformed in heptane and also in polymer composites on its basis. Thermodynamic parameters characterizing the sorption have been calculated for high-density polyethylene deformed in heptane and for its composites with poly(methyl methacrylate). The relationship between structural transitions in polyethylene deformed in a liquid and the sorption characteristics is discussed.

Structure and mechanical properties of polymer composites based on isotactic polypropylene prepared by in situ polymerization and study of their structure

The method of in situ polymerization was used to prepare polymer composites based on isotactic PP, PS, polybutyl acrylate or PMMA. The composites were subjected to X-ray analysis. Molecular orientation acquired by PP is preserved intact in presence of the second polymer component. The latter exists in the composite in the form of thin fibrillar aggregates oriented horizontal to the PP stretching axis. Despite thermodynamic incompatibility these composites have very good mechanical properties owing to the high degree of dispersity of the components. The annealing temperature has a marked influence on mechanical properties of the composites, as does crosslinking of the second component.

Transformation of the structure and properties of the complex of polyacrylic acid and linear polyethyleneimide on intracomplex amidation in aqueous solutions

Abstract Light scatter and sedimentation have been used to make a comparative study of the structure and properties of the polyelectrolyte complex (PEC) of polyacrylic acid and linear polyethyleneimine and the products of its chemical conversions in which some of the intermacromolecular salt bonds are replaced by amide bonds. It is shown that the formation of the interunit amide bonds in aqueous solutions of a PEC to the point of deep conversions proceeds in intracomplex form and does not lead to the crosslinking of its particles between themselves. The formation of covalent bonds in the PEC promotes significant change in its behaviour in water-salt media.

Features of the sorption properties of polymer-polymer composites obtained by polymerization of methylmethacrylate in the isotactic polypropylene matrix

Abstract The sorption of the selective solvent CCl 4 into composites based on isotactic PP and PMMA obtained by polymerization of methylmethacrylate in a polypropylene matrix has been studied. It was found that the sorption isotherms and kinetic curves for the composites sharply differ from the corresponding data obtained for the pure matrix of isotactic polypropylene. The divergences are explained by a certain form of the spontaneous dispersion of the composite under the influence of solvent and internal stresses.