The equilibrium swelling of magnetoactive ferrogels based on the copolymer of acrylamide with 10% potassium acrylate in water is studied. The gels are filled with strontium ferrite and/or magnetite taken in amounts of 20, 40, 60, and 80 parts per 100 parts of the polymer by weight. In the absence of a magnetic field, as the content of the filler is increased, the degree of swelling tends to increase for the gels containing strontium ferrite and to decrease for the magnetite-containing gels. In the structure of hydrogels, strontium ferrite particles possessing a permanent magnetic moment form a microscopic network from chain aggregates, while the particles of magnetite, a magnetically soft material, give rise to disordered aggregates. The enthalpy of hydration of ferrogel polymeric matrices weakly depends on the nature and amount of the introduced filler: The interaction parameter takes small positive values in the range 0.10–0.18. In a homogeneous magnetic field of 365 mT, the degree of swelling decreases at a small filler content for both types of ferrogels. This effect is accompanied by elongation of a ferrogel sample along the field direction and contraction in the transverse direction. With an increase in the filler content, the inversion of both effects occurs. The applicability of concepts about the homogeneously magnetizable continuous medium to the process of magnetostriction of ferrogels is analyzed.

For hydrogels based on rarely crosslinked matrices of polyacrylamide, poly(acrylic acid), and poly(methacrylic acid) filled with aerosil, the equilibrium degrees of swelling are measured as functions of the filler contents. The differences in the behaviors of gels are analyzed in terms of the competitive intermolecular interaction in three-component systems. For this purpose, the enthalpies of swelling for preliminarily dried and partially hydrated gels are measured via isothermal microcalorimetry. On the basis of concentration dependences of the enthalpy of swelling, the values of the enthalpy Flory-Huggins parameter for polymer matrices filled and unfilled with water, the parameters of structural changes in the polymers in filled hydrogels, and the enthalpies of adhesion and adsorption interactions of polymer matrixes with the surface area of aerosil are estimated. It is shown that there is a linear correlation between the change in the Flory-Huggins parameter and the enthalpy of adsorption of subchains on the surface of aerosil particles that assumes negative values in the case of poly(acrylic acid) and positive values in the case of poly(methacrylic acid) and polyacrylamide.

Administration of monocyte-derived dendritic cells (moDCs) sensitized by cancer-associated antigens to the patient is applied to boost the T-cell mediated anti-tumor immune response. Loading moDCs with magnetic nanoparticles (MNPs) and controlling their migration to lymph nodes by an external magnetic field is a way to improve the effectiveness of immunotherapy. In this study, spherical MNPs of maghemite iron oxide with a diameter of about 14 nm were synthesized by laser target evaporation method (LTE) and examined in the context of their prospective use for the needs of moDCs immunotherapy. Characterization of the physicochemical properties of MNPs and their stabilization in physiological media, as well as the magnetic properties of MNPs in the suspensions were considered in detail. The cytotoxic effect of MNPs in growth medium on the human moDCs and MNPs uptake by the cells were also estimated. We show that up-taken MNPs and MNPs in growth medium demonstrated cytotoxic effect only at high concentrations. At the same time, at low concentrations MNPs up-taken by moDCs increased their viability causing the stimulation effect. The evaluation of the quantity of MNPs, up-taken by cells, is possible by magnetometry even for the smallest γ-Fe₂O₃ concentrations.

Alginate gels are extensively tested in biomedical applications for tissue regeneration and engineering. In this regard, the modification of alginate gels and solutions with dispersed magnetic particles gives extra options to control the rheo-elastic properties both for the fluidic and gel forms of alginate. Rheological properties of magnetic suspensions based on Na-alginate water solution with embedded magnetic particles were studied with respect to the interfacial adhesion of alginate polymer to the surface of particles. Particles of magnetite (Fe₃O₄), metallic iron (Fe), metallic nickel (Ni), and metallic nickel with a deposited carbon layer (Ni@C) were taken into consideration. Storage modulus, loss modulus, and the shift angle between the stress and the strain were characterized by the dynamic mechanical analysis in the oscillatory mode. The intensity of molecular interactions between alginate and the surface of the particles was characterized by the enthalpy of adhesion which was determined from calorimetric measurements using a thermodynamic cycle. Strong interaction at the surface of the particles resulted in the dominance of the “fluidic” rheological properties: the prevalence of the loss modulus over the storage modulus and the high value of the shift angle. Meanwhile, poor interaction of alginate polymer with the surface of the embedded particles favored the “elastic” gel-like properties with the dominance of the storage modulus over the loss modulus and low values of the shift angle.

The morphology, particle size, and thermochemical properties of the surface of oxides Al₂O₃, NiO, TiO₂, ZnO, and ZrO₂ obtained by the wire electroexplosion method were studied. The nanoparticles are spherical, with a mean diameter of 54–86 nm depending on the nature of the oxide. The hydrophilicity of the surface of metal oxide nanopowders was found to change in the series NiO-ZrO₂-TiO₂-ZnO-Al₂O₃. Nanocomposites with widely varied compositions were obtained from butyl methacrylate copolymer with 5 wt % methacrylic acid and the oxides under study. The enthalpies of dissolution of the composites in chloroform were determined by Calvet calorimetry. The enthalpies of copolymer mixing with oxides were calculated using the thermochemical cycle. The limiting enthalpies of copolymer adhesion to the oxide surface were calculated from the thermochemical data. The limiting adhesion enthalpy was shown to be negative for all oxides under study; these values decreased in magnitude as the surface hydrophilicity increased. The results were analyzed from the viewpoint of balance between the specific and dispersion interactions at the interface.