This work is devoted to the search for new massive nanodisperse catalytic systems based on molybdenum disulfide (MoS2) produced by a direct solid-phase method using a cryogenic approach. Single-component nanoscale powders (NP) of molybdenum disulfide were prepared under cryogenic conditions (77 K) in various gaseous media. Two-component composites based on molybdenum disulfide in combination with gas-phase nanopowders of cobalt (Co) and nickel (Ni), both with and without catalytic promoters, have been studied, when a pyrocarbon shell is present on the surface of NP Co. To obtain aAnew series of samples, mono-molybdenum disulfide of a layered structure was subjected to fine grinding in cryogenic media of various chemical compositions in combination with or without gas-phase NP Co and Ni. Dispersion, porosity, and catalytic activity in the hydrodesulfurization reactions of dibenzothiophene (DBT), as well as diesel fractions (DF), were determined for cryo-NP samples. The hydrogenation ability of the tested catalyst samples was evaluated. It was shown that using the cryogenic approach makes it possible to obtain new cryocatalysts with a high level of hydrodesulfurization ability of both model S-compounds and components of native raw materials. Possible relationships between the specific characteristics that were determined during the studies of the prepared cryo-samples and their catalytic activity were discussed. It was found that the addition of gas-phase NP in a pyrocarbon shell to MoS2 greatly reduces the catalytic activity of a two-component catalyst. It has been shown that cryo-catalysts based on mono-molybdenum disulfide of a layered structure with a micro-and mesoporous structure are characterized by high activity and stability in the hydrodesulfurization reactions of DBT and diesel oil fractions.

Transmission of microwaves through a composite plate containing Fe nanoparticles in an epoxyamine matrix, as well as reflection of waves from it, has been investigated. The experiments were performed at the frequencies from 26 to 38 GHz in the magnetic fields up to 12 kOe. The ferromagnetic resonance line in the composites with the weight fraction of Fe particles from 10% to 30% has been studied. The magnetic field dependence of the microwave power dissipation has been plotted. Field dependence of the transmission and reflection coefficients have been calculated, as well as qualitative, and in some cases quantitative, agreement has been obtained. The penetration depth of microwaves into the composites has been analyzed. Spectrum of the FMR has been constructed. Results of interaction of microwaves with Fe nanoparticles are discussed taking into account magnetic properties and composite structure.

In this study, ferrihydrite (Fhy) nanoparticles (NPles) synthesized by the radiation chemical method (RCM) from an iron nitrate alcohol solution were annealed in air at temperatures ranging from 100 to 1200 degrees C. The effects of annealing temperature on the phase transformation and basic physicochemical properties of the annealed Fhy nanopowders (NPs) were investigated. Fhy NPles annealed at 400 degrees C and above can be converted to hematite NPles. The X-ray diffraction (XRD) pattern of the RCM-synthesized product corresponded to two-line (2 L) Fhy NPles, with no additional peaks, confirming their chemical purity. Up to 200 degrees C, no significant phase transformation of Fhy NPles was observed; at 300 degrees C, Fhy transformed into maghemite, which further transformed into hematite at 400 degrees C. TEM/HRTEM analysis showed the formation of mesoporous agglomerates consisting of amorphous-crystalline NPles approximately 2 nm in size in the Fhy S95 sample annealed at 95 degrees C. Selected area electron diffraction (SAED) images indicated the presence of two crystalline phases in sample S95: FeO and zero-valence Fe. The specific surface area (SSA) of mesoporous Fhy NPles varied non-monotonically between 100 and 500 degrees C, peaking at 53.2 m(2)/g at 300 degrees C. X-ray photoelectron spectroscopy (XPS) analysis revealed a minor nitrogen impurity, likely from the initial iron nitrate precursor, and a significant amount of adsorbed carbon on the developed porous surface of Fhy NPles. The phase composition of annealed Fhy samples correlated with their photoluminescent (PL) spectra. In samples S400 and S500 containing hematite, a small ferromagnetic contribution emerged, disrupting the linear magnetization-field dependence observed in samples S0-S200. Thus, the properties of 2 L Fhy nanoparticles produced by the radiation chemical method can be modified through thermal annealing while maintaining their potential biomedical applications as nanocontainers for drug delivery and contrast agents.

A new method for the preparation of hydrodesulfurization catalysts based on the mechanochemical treatment of molybdenum under cryogenic conditions was proposed. The results of direct one-stage mechanochemical grinding of molybdenum at 77 K in gaseous media of He and H2 and in liquid N2, as well as in the presence of solid Ar, are reported. The physicochemical properties of the cryopowders and their catalytic activity in the model hydrodesulfurization reactions of dibenzothiophene and diesel fraction were examined.

In this study, 2 -line ferrihydrite (2L Fh) nanoparticles (NPles)were synthesized by radiation -chemical method from an alcoholic solution of iron (III) nitrate for the first time. The X-ray diffraction analysis confirmed that the synthetic powder exhibited the characteristic pattern of 2L Fh NPles. DSC-TG analysis conducted in air atmosphere further verified the formation of 2L Fh. SEM analysis showed the presence of mesoporous plate -like structures in the 2L Fh powder, consisting of aggregates of NPs with an average size of approximately 20 nm. The absence of impurity peaks on the X-ray diffractograms and energy dispersion spectra (EDX) confirmed the chemical purity of the produced 2L Fh NPles. Additionally, the XPS method detected the presence of nitrogen and carbon adsorbed to the developed surface of the 2L Fh plates. 2L Fh NPles, when dried in air at a temperature of 50 degree celsius, rapidly dissolved in water. 2L Fh NPles alcohol suspensions were stabilized using surfactants polyethylenimine (PEI) and acetylacetone (AcAs). 2L Fh NPles showed good photocatalytic properties when irradiated with ultraviolet light of methyl violet (MV) dye. These 2L Fh NPles, synthesized using an environmentally friendly radiation -chemical method, have immense potential for applications in biomedicine and photocatalysis.

A benefit of biomedical application of nanosystems is implementation of a precise effect at the level of an individual cell, and magnetic nanoparticles (MNPs) are some of the best candidates for the development of an intelligent nanosystem with remote control. To develop a nanosystem for precise therapy, a deep understanding of the nanosystem's in vivo behavior is required. Here, we studied penetration and distribution of PEGylated iron oxide MNPs unmodified or modified with the pH low insertion peptide (a ligand for smart targeting of the tumor acidic microenvironment) in vivo in a 4T1 mouse tumor. We revealed that MNPs penetrate into the tumor via both vascular burst and endothelial transcytosis. By implementing an approach based on single-cell high-throughput RNA sequencing, we identified the populations of the cells that took up MNPs in the 4T1 tumor and revealed preferential accumulation of MNPs in regulatory Trem2+ tumor-associated macrophages.

The purpose of this research is to design nanocomposite materials for biomedical applications. New conjugates of PEG derivatives of RGD peptides and magnetic nanoparticles, based on Fe3O4 (MNPs) with silica coating covalently labelled with fluorescent dye Cyanine5, were obtained. It was shown that a higher loading level of RGD peptides occurred in the case of MNPs with SiO2/aminopropylsilane coating, synthesised using N-(phosphonomethyl)iminodiacetic acid (PMIDA) as a surfactant. To confirm the structure and chemical purity of the new RGD-PEG conjugate, a number of methods were used, including 1H NMR, HRMS, and RP-HPLC. The characterisation of MNPs was carried out using the following physical methods: TEM, FTIR, EDX, CHN analysis, DLS, fluorescence spectrometry, vibration magnetometry, and relaxometry. Samples obtained from PMIDA-stabilised MNPs contained a greater amount of the peptide and possessed better hydrodynamic characteristics than samples obtained from non-stabilised MNPs. A comparative study of the MNP cytotoxicity was carried out towards 4T1 and MDA-MB231 cell lines (MTT test), and the possibility of cell labelling was assessed. The cellular uptake was more efficient for nanoconjugates obtained without PMIDA. The data obtained can be used for the design of materials for cell labelling and visualisation.

Using the method of evaporation by pulsed electron beam in vacuum the mesoporous nanopowder of CaF2 with a specific surface area up to 91.5 m2/g was produced. The effect of annealing in different media and irradiation with a nanosecond electron beam (700 keV) on the evolution of the magnetic, luminescent and textural properties of CaF2 nanoparticles have been studied. For the first time, a joint effect of the annealing medium and the absorbed dose of a relativistic electron beam irradiation on the specific surface area and magnetization of mesoporous nanopowders of the CaF2 was discovered, which confirms the defective nature of ferromagnetism at room temperature of CaF2 nanopowders. The effect of nanopowder surface properties on ferromagnetism at room temperature after annealing in different media is shown, a parameter for assessing this influence is proposed.It was found that annealing and irradiation caused a significant change only in the visible range, of the pulse cathodoluminescence spectra of the CaF2 nanopowder, with the temperature and medium of the nanopowder pre-annealing as well as the irradiation dose being important. The relationship between luminescent and magnetic properties of nanopowder was shown.

Ag doped Bi2O3 nanopowders (NPs) were produced by pulsed electron beam evaporation (PEBE) under vacuum. The solid phase synthesis in an electric furnace on air was used for silver doping of bismuth oxide. Different physicochemical properties of NPs have been studied. The specific surface area of (SSA) Ag- Bi2O3 NPs was 23.7 m2/g. Air annealing (200 °C) caused decreased crystallinity and an increase in the SSA of both pure and Ag-doped bismuth oxide. The dominant phase in not annealed/annealed Ag doped Bi2O3 NPs at 200 °C and 300 °C was β -phase Bi2O3. The thermal stability of the pure and Ag-doped Bi2O3 NPs was maintained at 300–350 °C. The phase transition β→α occurred with a further increase in temperature. The annealing temperature could effectively change the physicochemical properties of the Bi2O3 NPs.

The widespread presence of microplastic particles in aquatic environments requires methods of their extraction from water for counting and analysis and for water purification technologies. In this study, new magnetic composite nanoparticles (FNP) were designed, characterized and explored to be used as magnetic seeds for extracting polyethylene terephthalate microparticles (MPET, 5-30 mu m) from water by magnetic sedimentation. The engineered seeds have a complex morphology, with magnetic cores of Fe3O4 dispersed in an environmentally compatible polymer matrix of silicon dioxide, chitosan or gelatine. Mechanisms of the heteroaggregation of FNP and MPET are considered and the main influencing factors (particles concentrations, major ions, duration of the preliminary exposure and of the sedimentation) are studied. The heteroaggregates are removed from water using a gradient magnetic field (Bzmax = 0.44 T) generated by a system of permanent magnets. The mass concentration of magnetic nanoseeds for more than 98 % capture of PET particles in pure and in salted water after 0.5 hour of magnetic sedimentation was detected to be 0.002 g/L. It is two orders of magnitude lower than that reported for uncovered magnetite-based particles. Using magnetic composite seeds with ecofriendly coatings allows to perform a high efficient magnetic separation of microplastic particles from water both for analytical purpose and for potential water cleaning technologies, while strongly reducing the synthetic flocculant sludge volume.

Microwave transmission through plates of a composite material containing spherical Fe nanoparticles epoxyamine matrix and reflection from plates have been studied. Measurements were carried out quencies from 26 to 32 GHz in the magnetic fields up to 12 kOe. The ferromagnetic resonance phenomenon composite has been investigated. The theory of electromagnetic waves transmitting through a composite containing ferromagnetic particles, taking into account aggregating the particles, has been developed. agreement of calculation results and experimentally obtained field dependences of the transmission reflection coefficients, as well as microwaves dissipation, has been achieved.

Sorption of doxorubicin (Dox) on Fe3O4 magnetic nanoparticles coated with iron and silicon glycerolates (ISG-MNPs) was studied. The Dox sorption experiments were carried out in water at different concentrations of ISG-MNPs and Dox. The loading efficiency was assessed by UV spectroscopy. It was demonstrated that at an ISG-MNPs concentration of 0.2 wt.

Epoxyamine matrix-based composites containing 15 wt% of Fe nanoparticles and 1.5 or 2 wt% of carbon nanotubes, as well as composites containing only Fe particles, have been studied using microwave methods and various scanning probe microscopy techniques, such as scanning capacitance microscopy and scanning Kelvin probe force microscopy. The composites were prepared using technological methods that improve their homogeneity. Probe current dependences investigated by applying different voltages to the probe in the Kelvin probe force microscopy mode have shown that the falling regions of the dependences at both positive and negative values of the bias voltage are found only for the sample containing both the Fe particles and the CNT in the "soft epoxy" matrix. Microwave measurements of the transmission and reflection coefficients were performed in the frequency range from 26 to 38 GHz. The field dependences of the microwave power dissipation have been plotted. The ferromagnetic resonance in the composites has been investigated. Frequency dependences of the complex dielectric permittivity of the composites have been determined. Microwave properties of the CNT-containing and CNT-free composites have been compared.

The architecture of a nanoparticles' surface formed due to a modification with a ligand and protein corona formation in biofluids is critical for interactions with cells in vivo. Here we studied interactions of immune cells with magnetic nanoparticles (MNPs) covalently modified with polyethylene glycol (PEG) and their counterparts conjugated with peptides: a pH (low) insertion peptide (pHLIP) and cycloRGD as a targeting ligand in human serum. The conjugation of MNPs-PEG with pHLIP, but not with cycloRGD, enhanced the association of these particles with mononuclear phagocytic cells in vitro and in vivo. We did not find a clear difference in protein corona composition between the pHLIP-modified and parental PEGylated nanoparticles. Analysis of the effect of autologous human serum on MNP uptake by monocytes showed that the efficiency of endocytosis varies among healthy donors and depends on intrinsic properties of serum. Nevertheless, using classic blood, coagulation, biochemical tests, and anti-PEG IgG serum level, we failed to identify the cause of the observed interdonor variation. These individual differences should be taken into consideration during testing of nanotherapeutics.

This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO2:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO2:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe3+ ions with rhombohedral distortions. The fraction of Fe3+ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe3+ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe3+ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.

In this paper, the electron and magnetic state of iron placed either on the surface or in the core of TiO2 nanoparticles were investigated using magnetometric methods, electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. It was demonstrated that the EPR spectra of TiO2 samples with iron atoms localized both on the surface and in the core of specific features depending on the composition and size of the nanoparticles. Theoretical calculations using the density functional theory (DFT) method demonstrated that the localization of Fe atoms on the surface is characterized by a considerably larger set of atomic configurations as compared to that in the core of TiO2 nanoparticles. Mössbauer spectra of the samples doped with Fe atoms both on the surface and in the core can be described quite satisfactorily using two and three doublets with different quadrupole splitting, respectively. This probably demonstrates that the Fe atoms on particle surface and in the bulk are in different unlike local surroundings. All iron ions, both on the surface and in the core, were found to be in the Fe3+ high-spin state.

New nanocomposites based on Fe3O4 magnetic nanoparticles coated with SiO2 or SiO2/aminopropylsilane (APS), including those using N-(phosphonomethyl)iminodiacetic acid (PMIDA), were obtained, and the immobilization of the antitumor agent doxorubicin (Dox) on nanocomposites was examined. It has been shown that the binding of Dox to the negatively charged surface of SiO2 particles occurs more efficiently than that to the APS-modified surface with positively charged amino groups; the presence of PMIDA molecules on the surface significantly increased the loading content. Based on DFT calculations, a mechanism for Dox binding to the surface of the synthesized nanocomposites was proposed.

Metal-dielectric nanocomposites containing spherical Fe particles in an epoxyamine matrix were synthesized. The average diameter of the particles is about 60 nm, their weight fractions in the composites are from 15 wt.% to 30 wt.%. Magnetic and microwave properties of the composite were measured. In the field dependences of the transmission and reflection coefficients, there are the minima caused by the ferromagnetic resonance. A model of dynamic magnetic permeability is constructed, and the components of the permeability tensor are determined. The field dependences of the transmission and reflection coefficients, as well as microwave power dissipation, are calculated and compared with the measured ones. Qualitative and, in some cases, quantitative correspondence between the measured and calculated dependences is obtained. Analysis carried out has shown that the low field absorption (LFA) is not realized in the considered composites.

Micro- and nanofragments resulting from the decomposition of disposable plastic items might be dangerous for the environment and humans. A new approach based on a “green” environmental technology of microplastic particles removal by magnetic sedimentation is suggested. In order to remove polyethylene (PE, 10–200 µm) and polyethylene terephthalate (PET, 5–30 µm) particles from model aqueous suspensions (starting concentration of 0.1 mg/l), the composite magnetic Fe–C–NH2 particles (4–8 nm) were added, afterward, the magnetic sedimentation of the formed heteroaggregates in a gradient magnetic field produced by permanent magnets was conducted. Magnetic nanoseeds were synthesized by the gas condensation method and characterized by magnetization measurements. The conditions for the heteroaggregation and for the magnetic sedimentation of the heteroaggregates have been investigated. For this, the dynamic light scattering analysis, SEM, optical microscopy, XRD and UV-visible spectrophotometry were used. The amount of the added magnetic nanoparticles (0.005 g/l) is less for the PET compared to the PE microparticles, which can be caused by a combination of several factors, in particular, by a higher hydrophilicity of PET particles which promotes a more active attachment of magnetic nanoparticles. For a more efficient removal of both plastic and magnetic particles from water, an increased up to 3–5 h time exposure for the heteroaggregation is recommended. At the magnetic field gradients up to dB/dz = 90 T/m, a 100-fold reduction in the plastics concentration in water after 15 min was achieved.

A series of nanoparticles of the bimetallic core and carbon shell type FexCo1-x@C (x = 0.4 - 0.8) have been obtained by the gas condensation synthesis method. The microstructural peculiarities and magnetic behaviour of the nanoparticles is analysed depending on the composition and thermal treatment. Collateral phases, which are difficult to detect by traditional methods, are identified. The 59Co,57Fe NMR and 57Fe Mossbauer spectroscopies have shown that homogeneity of the composition and removal of carbon from the metallic core can be reached by annealing. The combination of methods has quantified the fraction of superparamagnetic particles, the proportion of paramagnetic inclusions. A simplified visual interpretation of the 59Co NMR spectra is proposed for binary FeCo alloys.