S. V. Valueva

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.

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).

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.

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.

Selenium-containing nanosystems based on biocompatible polymer stabilizers: Kinetics, morphology, and thermodynamics

Selenium-containing nanosystems based on biocompatible polymer stabilizers (PS) polyvinylpyrrolidone (Mw = (10–55) × 103) and poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate (Mw = (30–13 000) × 103) are studied by means of light scattering and UV spectrophotometry in the range of the saturated adsorption capacity of selenium nanoparticles (ν = 0.1). Investigation of the self-organization of PS/Se0 nanosystems at ν = 0.1 shows that rate constant k* of nanostructure (NS) formation is determined by the nature of the PS, regardless of the polymer molecular weight (MW). Morphological and thermodynamic characteristics of selenium-containing NSes are determined, depending on the nature and MM of a PS. The formation of spherical polymolecular dense NSes is established.

Atomic-force microscopy and spectral characteristics of hybrid nanosystems for photodynamic therapy in oncology

The structural-morphological parameters of hybrid nanosystems, which are promising as photosensitizers (PS) for photodynamic therapy (PDT), are comparatively studied by atomic force microscopy (AFM), ultraviolet (UV) spectroscopy, photoluminescence (PL) and dynamic light scattering. The nanosystems are nanoparticles of zinc selenide (ZnSe) prepared using the hydrothermal synthesis method, stabilized by various polymer matrices: bovine serum albumin (BSA), polymethacrylic acid (PMAA) and, the second generation PS, photoditazin (PD). Comparison of the nanostructure size characteristics in ZnSe nanoparticles/polymer + PD systems (in a solution by means of the molecular optics and PL, and on a surface of a silicon wafer in air by means of AFM) at the same concentration of reagents in the reaction mixture shows that nanocluster sizes in the solution are two times larger than those in a thin film prepared on the substrate surface. When the order of the BSA and PD introduction into the system is changed, the nanosystem morphology changes strongly (nanocluster sizes and shape), which is due to the competition of the polymer stabilizers during complex formation with ZnSe nanoparticles. Analysis of the photoluminescence excitation and emission spectra of PD and the triple-system aqueous solutions shows that the ZnSe/BSA nanostructures do not suppress PD photoluminescence in the triple system ZnSe/BSA + PD, i.e., do not affect their ability to generate active forms of oxygen and make them promising as the basis for the creation of photosensitive compounds for PDT in oncology.

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.