L. N. Borovikova

The influence of the nature of a nanoparticle and polymer matrix on the morphological characteristics of polymeric nanostructures

Comparative studies of the morphological characteristics of selenium- and platinum-containing nanostructures were performed by molecular optics methods. The nanostructures were based on an ionogenic polymeric stabilizer, poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate, and a non-ionogenic polymeric stabilizer, oxyethylcellulose. Studies were performed in aqueous solutions at a fixed ratio between components. The adsorption of a considerable number of polymer macromolecules on nanoparticles with the formation of superhigh-molecular-weight nanostructures with shapes close to spherical was observed for all the nanosystems studied. The thermodynamic state of nanosystems was characterized. Certain morphological characteristics of nanostructures were substantially influenced by the nature of both nanoparticles and polymer matrix.

Formation of a composite from Se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter xylinum cellulose gel films

Formation of a composite from Se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter xylinum cellulose gel films was studied. The optimal sorption parameters at which the amorphous form of the selenium complex is preserved in the composite were suggested.

Morphology and thermodynamic characteristics of selenium-containing nanostructures based on polymethacrylic acid

The morphology and thermodynamic characteristics of nanostructures formed as a result of the reduction of the selenium ion in a selenite-ascorbate redox system in water solutions of polymethacrylic acid were studied by molecular optics and atomic-force microscopy. The dependence of the morphology of the selenium-containing nanostructures on the mass selenium-to-polymer ratio (ν) in solution was determined. It was established that a large number of macromolecules (up to 4300) is adsorbed on the selenium nanoparticles, leading to the formation of nanostructures with super-high molecular mass and an almost spherical form. It was shown that the density of the nanostructures, as calculated on the basis of the experimental data on the size and molecular mass of the nanocomposite, depends substantially on the selenium concentrations in the solution. The thermodynamic state of the solutions of nanostructures is described.

The influence of the ratio between the selenium: Polyvinylpyrrolidone complex components on the formation and morphological characteristics of nanostructures

Optical and spectral methods were used to study nanostructures formed in the reduction of ionic selenium in the selenite-ascorbate redox system in aqueous solutions of polyvinylpyrrolidone, a physiologically active polymer. The weight ratio between the selenium: polymer complex components (ν) was varied over a wide range (ν = 0.01−0.2). The adsorption of a substantial number of macromolecules (up to 1000 at ν = 0.1−0.2) on selenium nanoparticles was observed experimentally. This resulted in the formation of supramolecular spherical nanostructures with a high polymeric shell density. The Gibbs energies of macromolecule-Se0 nanoparticle interactions were calculated for polymeric nanostructures in the region of the formation of stable dispersions. The flow birefringence, dynamic light scattering, and spectrophotometry methods were used to determine the region of saturation of the adsorption capacity of selenium nanoparticles in selenium-containing nanocomposites (ν = 0.1−0.2).

Network Model of Acetobacter Xylinum Cellulose Intercalated by Drug Nanoparticles

It was shown that Acetobacter xylinum cellulose gel-films can sorb silver and selenium nanoparticles stabilized by N-poly(vinyl-2-pirrolidone). The structure of original cellulose matrix, isolated nanoparticles and cellulose with sorbed nanoparticles was characterized by electron diffraction, electron microscopy, small- and wide-angle x-ray scattering methods, and atomic force microscopy. It was found that in static culture Acetobacter xylinum bacterium (strain VKM B-880) may synthesize high-molecular cellulose with narrow molecular weight distribution and a considerable number of carbon sources. The structures of cellulose microfibrilles and ribbons correspond mainly to polymorphous Iβ modification. We concluded from structural studies that textured cellulose films were formed. The sorption conditions of poly(vinylpyrrolidone)-Se° and poly(vinylpyrrolidone)-Ag° nanoparticles were optimized to obtain a cellulose template that can be used in medical practice.

Structural-morphological and biological properties of selenium nanoparticles stabilized by bovine serum albumin

Nanostructures formed during the reduction of ionic selenium in the selenite-ascorbate redox system in an aqueous solution of bovine serum albumin (BSA) were studied using static and dynamic light scattering and flow birefringence. It was established that this process results in the formation of stable aggregates of selenium nanoparticles that adsorb BSA molecules. It was found that highly-ordered superhigh-molecular-weight spherical nanostructures with high density and unique morphology are formed. Experiments with a cell culture of promyelocytic leukemia HL-60 showed that BSA adsorbed on selenium nanoparticles can inhibit the growth of tumor cells and deactivate free radicals with an efficiency comparable with that of sodium selenite.

Interaction of Se0 nanoparticles stabilized by poly(vinylpyrrolidone) with gel films of cellulose Acetobacter xylinum

The sorption and desorption of poly(vinylpyrrolidone)-Se0 (PVP-Se0) nanoparticles on gel films of cellulose Acetobacter xylinum (CAX) are investigated. It is revealed that the hydrodynamic radius Rh of PVP-Se0 nanoparticles decreases from 57 nm in the initial solution (without CAX gel films) to 25 nm after the sorption of nanostructures on gel films and then increases to approximately 100 nm after the desorption of nanoparticles with water from dry samples of the CAX gel film-PVP-Se0 nanocomposite. It is found that selenium atoms do not penetrate into crystallites of the cellulose nanofibrils and replace water molecules sorbed by the primary hydroxyl groups of their walls. Poly(vinylpyrrolidone)-Se0 nanoclusters differ in the number and size upon their sorption inside the cellulose gel film and on the film surface.

Biogenic nanosized systems based on selenium nanoparticles: Self-organization, structure, and morphology

Selenium-containing biogenic nanosized systems based on polymer stabilizers (PSts) of different natures are obtained. A comparative investigation of the kinetic parameters of self-organization and the dimensional characteristics of forming nanostructures and their shapes is performed by means of light scattering, UV spectrophotometry, atomic force microscopy, and small angle X-ray scattering. The effect of the nature of PSts on the structural and morphological parameters (hydrodynamic radius, mean-squared radius of gyration, selenium core radius, and density) of selenium-containing nanostructures is established.

Stabilizing Selenium Nanoparticles with Chymotrypsin: The Effect of pH and Nanoparticle-Enzyme Concentration Ratios on the Stability of Nanocomplexes

Conditions of the formation of soluble chymotrypsin complexes with selenium nanoparticles are studied. It is established that the aggregative stability of the nanocomplexes is determined by their conditions of preparation, depending also on the medium pH and ratio of selenium: chymotrypsin concentration. It is shown that chymotrypsin has a “protective” effect due to its hydrophobic adsorption on the surface of selenium nanoparticles and hence the hydrophilization of their surfaces due to ionized groups of the protein.

Morphology and electronic structure of platinum-containing polymer nanosystems

Morphological characteristics and electronic structures of platinum-containing nanosystems obtained during a redox reaction in water medium at different concentrations of a stabilizing polymer and platinum were studied by atomic-force microscopy (AFM), X-ray photoelectron spectroscopy, and dynamic light scattering. It was shown that individual and associated structures of different morphologies were formed on the silicon substrate surface. Comparison of the dimension characteristics of nanoclusters in the Pt nanoparticle-polymer systems (in solution by means of molecular optics, on the silicon substrate surface in air by means of AFM) for ionogenic and nonionogenic polymer matrices upon the change of the mass ratio ν has shown that the nanocluster sizes in solution are two to three times larger than those in a thin film formed on the substrate surface. The size dependences of the nanoclusters on ν obtained by these methods exhibit the same character.