Functionalized porous silica&maghemite core-shell nanoparticles for applications in medicine: design, synthesis, and immunotoxicity

Aim To determine cytotoxicity and effect of silica-coated magnetic nanoparticles (MNPs) on immune response, in particular lymphocyte proliferative activity, phagocytic activity, and leukocyte respiratory burst and in vitro production of interleukin-6 (IL-6) and 8 (IL-8), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and granulocyte macrophage colony stimulating factor (GM-CSF). Methods Maghemite was prepared by coprecipitation of iron salts with ammonia, oxidation with NaOCl and modified by tetramethyl orthosilicate and aminosilanes. Particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Cytotoxicity and lymphocyte proliferative activity were assessed using [3H]-thymidine incorporation into DNA of proliferating human peripheral blood cells. Phagocytic activity and leukocyte respiratory burst were measured by flow cytometry; cytokine levels in cell supernatants were determined by ELISA. Results γ-Fe2O3&SiO2-NH2 MNPs were 13 nm in size. According to TEM, they were localized in the cell cytoplasm and extracellular space. Neither cytotoxic effect nor significant differences in T-lymphocyte and T-dependent Bcell proliferative response were found at particle concentrations 0.12-75 μg/cm2 after 24, 48, and 72 h incubation. Significantly increased production of IL-6 and 8, and GMCSF cytokines was observed in the cells treated with 3, 15, and 75 μg of particles/cm2 for 48 h and stimulated with pokeweed mitogen (PHA). No significant changes in TNF-α and IFN-γ production were observed. MNPs did not affect phagocytic activity of monocytes and granulocytes when added to cells for 24 and 48 h. Phagocytic respiratory burst was significantly enhanced in the cultures exposed to 75 μg MNPs/cm2 for 48 h. Conclusions The cytotoxicity and in vitro immunotoxicity were found to be minimal in the newly developed porous core-shell γ-Fe2O3&SiO2-NH2 magnetic nanoparticles

Magnetic Superporous Poly(2-hydroxyethyl methacrylate) Hydrogel Scaffolds for Bone Tissue Engineering

Magnetic maghemite (γ-Fe2O3) nanoparticles obtained by a coprecipitation of iron chlorides were dispersed in superporous poly(2-hydroxyethyl methacrylate) scaffolds containing continuous pores prepared by the polymerization of 2-hydroxyethyl methacrylate (HEMA) and ethylene dimethacrylate (EDMA) in the presence of ammonium oxalate porogen. The scaffolds were thoroughly characterized by scanning electron microscopy (SEM), vibrating sample magnetometry, FTIR spectroscopy, and mechanical testing in terms of chemical composition, magnetization, and mechanical properties. While the SEM microscopy confirmed that the hydrogels contained communicating pores with a length of ≤2 mm and thickness of ≤400 μm, the SEM/EDX microanalysis documented the presence of γ-Fe2O3 nanoparticles in the polymer matrix. The saturation magnetization of the magnetic hydrogel reached 2.04 Am2/kg, which corresponded to 3.7 wt.% of maghemite in the scaffold; the shape of the hysteresis loop and coercivity parameters suggested the superparamagnetic nature of the hydrogel. The highest toughness and compressive modulus were observed with γ-Fe2O3-loaded PHEMA hydrogels. Finally, the cell seeding experiments with the human SAOS-2 cell line showed a rather mediocre cell colonization on the PHEMA-based hydrogel scaffolds; however, the incorporation of γ-Fe2O3 nanoparticles into the hydrogel improved the cell adhesion significantly. This could make this composite a promising material for bone tissue engineering

Multifunctional polypyrrole@maghemite@silver composites: synthesis, physico-chemical characterization and antibacterial properties

Maghemite (γ-Fe2O3) nanoparticles were synthesized by coprecipitation of ferrous and ferric salts with ammonia and oxidation with sodium hypochlorite. Polypyrrole (PPy) was obtained, by the chemical oxidative polymerization of pyrrole in an aqueous solution in the presence of iron oxide nanoparticles. The morphology of PPy was turned from globular to nanofibers by addition of dyes. The resulting PPy@γ-Fe2O3 hybrid composites were characterized by transmission electron microscopy, magnetic and electrical conductivity measurements and energy dispersive X-ray spectroscopy. Both the electrical conductivity and magnetic properties of the PPy@γ-Fe2O3 nanocomposites were controlled by the maghemite content due to the insulating properties of magnetic iron oxide nanoparticles added to the conducting polymer. Antibacterial activity of all materials was defined by determination of minimal inhibitory concentration. Antibacterial properties of native materials were improved by the reduction of silver ions from an aqueous solution to obtain PPy@γ-Fe2O3@silver composites. Due to the antibacterial properties of these composites, especially of those with silver particles, they can be considered for the applications where bacterial contamination can deteriorate the functionality of material. © 2018, Institute of Chemistry, Slovak Academy of Sciences.Czech Science Foundation [17-05095S]; TBU in Zlin [IGA/ CPS/2018/001