A. I. Kipper

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.

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).

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.

Immobilization of chymotrypsin on silver nanoparticles

The method of immobilization of chymotrypsin based on the reduction reaction of silver nitrate with sodium borohydride in an aqueous medium in the presence of the enzyme was developed. Chymotrypsin was simultaneously a stabilizer of silver nanoparticles in solution. The dimensional characteristics, as well as proteolytic and bactericidal activity of the synthesized nanocomposites were studied. It is shown that the hybrid organic-inorganic nanocomposites based on chymotrypsin and silver nanoparticles are able to perform an increased proteolytic activity in comparison with the native enzyme in the pH range corresponding to wound surface, and suppress pathogenic flora of various microorganisms.

Biogenic selenium-containing nanosystems based on polyelectrolyte complexes

The kinetic, structural, and morphological studies showed that the composition of polyelectrolyte complexes (PECs) and the selenium/PEC mass ratio affected the formation of biogenic selenium-containing nanosystems and their structural and morphological properties.

Effect of the conditions of synthesis and the pH of the medium on the dimensional characteristics of nanocomplexes of selenium with chymotrypsin

The possibility of controlling the dimensions of nanocomplexes of chymotrypsin with selenium nanoparticles by varying the amount of the reducing agent during synthesis, the ratio of the reacting substances’ concentrations, and the pH of the medium is shown by means of static and dynamic light scattering.

Formation and morphological characteristics of selenium-containing nanostructures based on rigid-chain cellulose derivatives

Nanostructures arising from the reduction of ionic selenium by a selenite-ascorbate redox system in aqueous solutions of oxyethyl cellulose, methyl cellulose, and carboxymethyl cellulose have been studied by using a set of optical methods (flow birefringence and static and dynamic light scattering) and viscometry. The adsorption of a substantial amount of macromolecules (up to 3200) on selenium nanoparticles has been experimentally discovered. This effect leads to the formation of superhigh-molecular-mass spherical nanostructures with a high density of the polymer shell. The thermodynamic state of solutions of nanostructures has been characterized. In the region of occurrence of stable dispersions, the values of the free energy of macromolecule-selenium nanoparticle interaction have been calculated for polymer nanostructures. Radii of amorphous selenium nanoparticles occurring in the nuclei of nanostructures and the thickness of the polymer shell have been estimated. Given the fixed molecular mass and comparable rigidity of a polymer matrix, the structure of the monomer unit of the cellulose derivative defines the morphology of the nanostructure being formed.

Formation of Se0 Nanoparticles in an Aqueous Cationic Polyelectrolyte

The nanostructures formed by reduction of Se(IV) in the selenite-ascorbate redox system in an aqueous solution of supermacromolecular polycation, poly[trimethyl(methacryloyloxyethyl)ammonium] methyl sulfate, were studied by static and dynamic optical scattering and flow birefringence.

Morphological characteristics of selenium-polyethylene glycol nanocomposites

Hybrid organo-inorganic nanocomposites containing selenium nanoparticles stabilized with polyethylene glycols with different molecular masses were synthesized and studied by the static and dynamic scattering methods. It was shown that the morphological characteristics of nanocomposites can be regulated by varying the molecular mass of polyethylene glycols and the ratio of the selenium-polyethylene glycol components during the synthesis.