Production of Nano-Sized Co<sub>3</sub>O<sub>4</sub> by Pyrolysis of Organic Extracts

The most promising application field of materials based on nano-sized Co3O4 is catalysis. The method of production is one of the factors, which greatly affects the catalytic activity of Co3O4 catalysts. The aim of this research is to study possibilities of a new promising extractive-pyrolytic method (EPM) for the production of Co3O4 nanopowders and silica- and ceria-supported Co3O4 nanocomposites. Solutions of cobalt hexanoate in hexanoic acid and trioctylammonium tetrachlorocobaltate in toluene preliminary produced by solvent extraction were used as precursors. The precursors’ thermal stability, phase composition, morphology and the magnetic properties of the final products of pyrolysis we…

Superparamagnetic iron oxide/oleic acid nanoparticles with immobilized organosilicon derivatives ofN-(2-hydroxyethyl)tetrahydroisoquinoline: synthesis, morphology and interaction with normal and tumour cells

Superparamagnetic iron oxide/oleic acid nanoparticles bearing lipid-like organosilicon N-(2-hydroxyethyl)-1,2,3,4-tetrahydroisoquinoline derivatives have been synthesized with the aim of their potential biomedical application. X-ray diffraction analysis, Dynamic light-scattering measurements, method of magnetogranulometry and some others have been employed to investigate the morphology and properties of the nanoparticles synthesized. The magnetic core diameter of mixed covered nanoparticles ranged between 4.8 and 9.6 nm. The magnetization analyses showed that the particles are superparamagnetic at room temperature. In vitro cell cytotoxicity and intracellular NO generation caused by the wat…

Characteristics of Sintered Materials Obtained from Ferrite Nanopowders Synthesised with Different Methods

Ferrite materials, especially those containing nickel and cobalt, are popular due to their unique mechanical and magnetic properties. Single phase NiFe2O4 and CoFe2O4 nanopowders obtained by different methods were used for sintering studies. Chemical sol-gel self-propagating combustion method, co-precipitation technology combined with hydrothermal synthesis or spray-drying method, and high frequency plasma chemical synthesis have been used to synthesize ferrite nanopowders. Relatively dense (95-99%) materials with high saturation magnetization (MS = 80-84 emu/g for CoFe2O4 and MS = 46-48 emu/g for NiFe2O4) were obtained at 1100-1200 °C temperatures.

Impact of gadolinium on the structure and magnetic properties of nanocrystalline powders of iron oxides produced by the extraction-pyrolytic method

The work has been done in frame of the TransFerr project. It has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 778070. This research was also supported by Latvian Research Council project lzp-2018/1-0214. A.I.P. appreciates support from the Estonian Research Council grant (PUT PRG619).

Switchable Light Reflectance in Dilute Magneto-Optical Colloids Based on Nickel Ferrite Nanowires

Study of the structural phase transformation of iron oxide nanoparticles from an Fe2+ ion source by precipitation under various synthesis parameters and temperatures

Abstract Magnetite nanoparticles were precipitated from a pure aqueous ferrous salt solution in an air atmosphere. The influence of the solution molarity, the rate of precipitator agent addition, stirring time and annealing temperature was studied. The morphology, crystalline phase purity and magnetic properties of the obtained powders were studied by X-Ray powder diffraction (XRD), Scanning electron microscopy (SEM), Differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and Vibrating sample magnetometer (VSM). The synthesis conditions were seen to have an effect on phase composition. It was possible to obtain near stoichiometric Fe…

Synthesis, physico-chemical and biological study of trialkylsiloxyalkyl amine coated iron oxide/oleic acid magnetic nanoparticles for the treatment of cancer

New original water-soluble magnetic nanoparticles based on natural components, magnetite–oleic acid–biologically active silyl modified alkanolamine, were synthesized. Physico-chemical characterization, i.e. magnetic properties, concentration of magnetite, size of iron oxide core, of the nanoparticles synthesized and the corresponding magnetic fluids obtained, was carried out. Magnetic fluids were screened for in vitro cytotoxicity concerning human fibrosarcoma (HT-1080), mouse hepatoma (MG-22A) monolayer tumour cell lines and normal mouse fibroblasts (NIH 3T3). They possess low or moderate cytotoxic effects, are non-toxic, exhibit high NO-induction ability and strongly change tumour cell mo…

Iron oxide/oleic acid magnetic nanoparticles possessing biologically active choline derivatives

Abstract In recent years, synthetic magnetic nanoparticles have made a major contribution to biomedicine. Interest in iron oxide magnetic nanoparticles conditioned by the fact that they are nontoxic, and possess the unique opportunity to deliver medicines to certain organs by external magnetic field. We have developed a synthetic procedure, which is based on binding of the first biologically active substance with the magnetic core, and subsequent immobilization of another biologically active substance (ligand) on the modified surface of nanoparticles thus creating plasma membrane-like structures. Using the proposed methodology, we have obtained new nontoxic magnetic nanoparticles, functiona…

Preparation and cytotoxic properties of goethite-based nanoparticles covered with decyldimethyl(dimethylaminoethoxy) silane methiodide

The present work describes the synthesis, physico-chemical and biological properties of the first water-soluble goethite nanoparticles covered with biologically active components: oleic acid and cytotoxic decyldimethyl(dimethylaminoethoxy)silane methiodide. The structure of initial goethite nanoparticles synthesized was proved by XRD analysis and the rough estimation of nanoparticles core size gave the value of 8 nm. The size of colloidal water-soluble nanoparticles, determined by dynamic light scattering, was within 19–35 nm. Magnetic properties and cytotoxicity (against HT-1080 and MG-22A tumor cell lines) of the nanoparticles obtained were investigated. Copyright © 2009 John Wiley & Sons…

Synthesis and properties of magnetic iron oxide/platinum nanocomposites

Iron oxide/platinum nanocomposites have been synthesized by the extractive-pyrolytic method (EPM) involving gradual decomposition of iron capronate and n-trioctylammonium hexachloroplatinate initially produced by solvent extraction. The content of platinum in the composites was 1.2 wt%, 2.4 wt% and 4.8 wt%. Phase composition, morphology and magnetic properties of the produced materials were investigated. XRD analysis and magnetic measurements show that the magnetic phase (magnetite Fe3O4) dominates in a carrier sample produced by the pyrolysis of iron carboxylate, but hematite α-Fe2O3 exists there as an admixture. Referring to the TEM results, the produced composites contain ultra-disperse …

Iron oxide superparamagnetic nanocarriers bearing amphiphilic N-heterocyclic choline analogues as potential antimicrobial agents

Magnetic nanoparticles represent an advanced tool in biomedicine because they can be simultaneously functionalized and guided using a magnetic field. Iron oxide magnetic nanoparticles precoated with oleic acid and bearing novel antimicrobial N-heterocyclic choline analogues, namely O-, N- and O,N-bis-undecyl-substituted N-(2-hydroxyethyl)-1,2,3,4-tetrahydroisoquinolinium derivatives, have been obtained as potential biomedical agents for drug delivery and antimicrobial therapy. Structural and size determinations for the novel synthesized magnetic nanosystems were carried out based upon magnetogranulometry, dynamic light-scattering measurements and X-ray diffraction analysis. The most expecte…

Hydrothermal Synthesis of Cobalt Ferrite Nanosized Powders

Cobalt ferrite powders are synthesized by the co-precipitation technology, combined with the hydrothermal synthesis method and crystallite size, specific surface area (SSA), magnetic properties of synthesized products are obtained. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 10-16 nm the SSA of 60±5 m2/g and the calculated particle size of 20±2 nm. Synthesized Co ferrites are characterized by the saturation magnetization MS of 59-60 emu/g, remanent magnetization Mr of 23 emu/g and coercivity Hc of 570-650 Oe.

The Synthesis, Characterization and Sintering of Nickel and Cobalt Ferrite Nanopowders

The NiFe2O4 and CoFe2O4 ferrites were synthesized by two methods – chemical sol-gel self-combustion method and the high frequency plasma chemical synthesis and magnetic properties, crystallite size, specific surface area of synthesized products are characterized. Nanopowders synthesized in the high frequency plasma are with specific surface area in the range of (28 – 30) m2/g (the average particle size (38 – 40) nm, crystallite size ~40 nm). The ferrite nanopowders obtained by sol-gel self-combustion method have the specific surface area of (37 – 43) m2/g (average particle size (26 – 31) nm, crystallite size (10 – 20) nm). All synthesized nanopowders were sintered via pressure-less sinterin…

Filling carbon nanotubes with magnetic particles

Magnetic carbon nanotube composites were obtained by filling carbon nanotubes with paramagnetic iron oxide particles. Measurements indicate that these functionalized nanotubes are superparamagnetic at room temperature. Details about the production and characterization of these materials are described along with the experimental procedures employed. These magnetic carbon nanotubes have the potential to be used in a wide range of applications, in particular, the production of nanofluids, which can be controlled by appropriate magnetic fields.

STRUCTURE AND MAGNETIC PROPERTIES OF COBALT FERRITE PARTICLES PRODUCED BY METHOD OF PYROLYTIC SYNTHESIS

ABSTRACT Magnetic fine particles of cobalt ferrite have been prepared by method of pyrolytic synthesis. X-ray diffraction confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 6–50 nm. The size of the particles varies depending on matrix dispersity and mass content in the organic precursors. A large coercivity observed to be small for smaller single-domain particles due to superparamagnetic behavior.

Thermodiffusion motion of electrically charged nanoparticles

AbstractThe present work deals with experimental studies to examine the theoretical model of thermodiffusion of electrically charged nanoparticles. Three different ionic magnetic colloid samples have been synthesized and profoundly analyzed. The theoretical model is a classical one, based on the calculation of the temperature and the electric potential distribution around nanoparticles. The discrepancy between experimental data and theory turns out not to exceed 20%. We focus on applying different approximations between calculated electrical double layer in the theoretical model and experimental determination of the surface charge density of colloidal particles. We assume this is the main r…

Neutron scattering study of structural and magnetic size effects in NiO

Nickel oxide powders with the grain size of 13–1500 nm have been studied by neutron scattering, scanning electron microscopy and vibrating sample magnetometry. We have found that the atomic structure and the antiferromagnetic ordering are nearly independent of the average size of grains. The existence of the uncompensated spins in nanoparticles with the grain size below 100 nm has been detected.

Optofluidic microconvection with magnetic nanoparticles: Novel interaction of thermal diffusion and magnetic field

Abstract Light-matter interactions are exploited in many applications, whereas superparamagnetic nanoparticles allow to introduce magnetic field control in diverse fluid environments. We study the structure of laser-induced thermal lens in thin layers of ferromagnetic colloid and predict significant magnetoconvective motion around the beam spot. It was found that localized heating depletes/accumulates magnetic nanoparticles in the beam-spot by thermal diffusion and collective magnetic interactions of nanoparticles produce strong microconvective currents. This mode of mass transport can be controlled by magnetic field. We expect the novel magnetosolutal microconvective coupling, which we des…

Magnetic field control of gas-liquid mass transfer in ferrofluids

Abstract Gas-liquid mass transfer plays a key role in a broad range of industrial processes. The magnetic field control over the morphology of the gas-liquid interface and solute transport is an attractive feature if it can be realized efficiently. However, the magnetic properties of typical liquids and gases are rather weak. The experimental investigation is carried out to evaluate the effect of the magnetic field, which is mediated by magnetic nanoparticles, on the gas-liquid mass exchange during the sparging run through a hydrocarbon ferrofluid. The results indicate that the gradient field is especially effective at controlling the gas-liquid contact volume: the foaming of the liquid dur…

Features of magnetorheology of biocompatible chain-forming ferrofluids with multi-core magnetic nanoparticles: Experiment and simulation

Abstract We study the magnetorheological properties and structural transitions in novel aqueous colloidal suspensions of magnetic nanoparticles developed for biomedical applications. Defined-shape field-tunable superparamagnetic nanoparticles with clustered cores and their suspensions are produced. The region of intermediate magnetic coupling strength between colloidal ferrofluids and magnetorheological suspensions is systematically studied for the first time. Hybrid numerical simulations with hydrodynamic interactions provide full structural information. The distinctive features of the rheograms are related to transitions between Brownian and persistent microstructure, shape anisotropy, co…

Fabrication and characterization of magnetic FePt nanoparticles prepared by extraction–pyrolysis method

We are grateful to Prof. E. Kotomin for useful discussions. The research leading to these results has received funding from the ERAF (2017) Project, while A. I. Popov thanks IMIS-2 for the funding support.

Properties of Nanosized Ferrite Powders and Sintered Materials Prepared by the Co-Precipitation Technology, Combined with the Spray-Drying Method

Cobalt and nickel ferrites powders are synthesized by the co-precipitation technology, combined with the spray-drying method. The crystallite size, specific surface area (SSA), magnetic properties of synthesized products are investigated. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 5-6 nm, the SSA of 80-85 m2/g and the calculated particle size of 13-15 nm. After spray-drying granules of the size up to 10 μm are obtained. After thermal treatment at 550 and 950 °C SSA decreases to 40-50 m2/g and 20-22 m2/g, respectively. The saturation magnetization at these temperatures increase from 17 to 40 emu/g for NiFe2O4 and from 51 to 77 emu/g for C…

Relating magnetization, structure and rheology in ferrofluids with multi-core magnetic nanoparticles

Abstract Due to their magnetic moments solubilized magnetic nanoparticles are able to spontaneously assemble into dipolar mesostructures, which affect the flow behavior. Multi-core magnetic nanoparticles developed for biomedical applications have enhanced magnetic properties and show significant magnetoviscous effect, but the quantitative interpretation of this phenomenon is incomplete. We apply rheological measurements, magnetic granulometry and dimensional scaling to show the existence of a master curve for magnetorheology of these materials. Using the developed approach the magnetoviscous effect can now be interpreted in a unified way within the stochastic chain model.

Water-soluble magnetic nanoparticles with biologically active stabilizers

We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11 nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed obse…

Precipitation synthesis of magnetite Fe3O4 nanoflakes

Precipitation can be applied to synthesize magnetite Fe3O4 nanoflakes in an ambient air atmosphere without using any surfactant, templates or special equipment. Magnetite nanoflakes were precipitated from only Fe2+ chloride solution without adding Fe3+. The formation of Fe3O4 nanoflakes is suggested to occur due to formation of an intermediate goethite phase, thus providing anisotropic crystal growth. Compared to other methods, the method presented here is fast and suitable for large scale synthesis.

Synthesis and characterization of nanoparticles with an iron oxide magnetic core and a biologically active trialkylsilylated aliphatic alkanolamine shell

Water-soluble double-coated magnetic nanoparticles (NPs) containing cytotoxic decyldimethyl(β-dimethylaminoethoxy)silane methiodide (AA) molecule sorbed at biocompatible magnetic particles, which consist of magnetite pre-coated with oleic acid (OA), have been prepared. X-ray line profile broadening analysis was used for crystallite size determination. The method of magnetogranulometry has been used for determination of diameter of iron oxide magnetic core and magnetic properties of NPs prepared. In vitro cytotoxicity on monolayer tumor cell lines HT-1080 (human fibrosarcoma), MG-22A (mouse hepatoma) and normal mouse fibroblasts (NIH 3T3) has been studied. It was revealed that all the water-…