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The treatment of tuberculosis is still a challenging process due to the wide spread of pathogen strains resistant to antibacterial drugs, as well as the undesirable effects of anti-tuberculosis therapy. Hence, the development of safe and effective new anti-antitubercular agents in addition to suitable nanocarrier systems has become of utmost importance and necessity. Our research aims to develop liposomal vesicles that contain newly synthesized compounds with antimycobacterial action. The compound being studied is a derivative of imidazo-tetrazine named 3- (3,5-dimethylpyrazole-1-yl) -6-(isopropylthio) imidazo [1,2-b] [1, 2, 4, 5] tetrazine (compound 1). Several factors that affect the liposomal characteristics were studied. The maximum encapsulation efficiency was 53.62 ± 0.09. The selected liposomal formulation T8* possessed mean particle size about 205.3 ± 3.94 nm with PDI 0.282, and zeta potential was + 36.37 ± 0.49 mv. The results of the in vitro release study indicated that the solubility of compound 1 was increased by its incorporation in liposomes. The free compound and liposomal preparation showed antimycobacterial activity against M. tuberculosis H37Rv (ATCC 27294) at MIC value 0.94–1.88 µg/ml. We are predicting that the liposomes may be a good candidate for delivering of new antitubercular drugs.

Six hemoglobin isoforms were identified in the peripheral blood of male Wistar rats by PAAG electrophoresis. Erythrocytes can be separated into 6 fractions by fractional centrifugation; the fractions differ by the content of reticulocytes and cells with fetal hemoglobin. Cells in each fraction contain one light and one heavy hemoglobin isoforms, and their combination is specific to each fraction. Changes in the hemoglobin isoforms in the whole blood in case of blood loss can be associated with changes in physical and chemical properties of circulating erythrocytes, as well as with the formation of various cell populations resulting from activated erythropoiesis.

Computer vision (CV) algorithms are widely utilized in imaging processing for medical and personal electronics applications. In sensorics CV can provide a great potential to quantitate chemosensors' signals. Here we wish to describe a method for the CV-assisted spectrofluorometer-free detection of common nitro-explosive components, e.g. 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), by using polyaromatic hydrocarbon (PAH, PAH = 1-pyrenyl or 9-anthracenyl) – based bola-type chemosensors. The PAH components of these chemical bolas are able to form stable, bright emissive in a visual wavelength region excimers, which allows their use as extended matrices of the RGB colors after imaging and digital processing. In non-polar solvents, the excimers have poor chemosensing properties, while in aqueous solutions, due to the possible micellar formation, these excimers provide “turn-off” fluorescence detection of DNT and TNT in the sub-nanomolar concentrations. A combination of these PAH-based fluorescent chemosensors with the proposed CV-assisted algorithm offers a fast and convenient approach for on-site, real-time, multi-thread analyte detection without the use of fluorometers. Although we focus on the analysis of nitro-explosives, the presented method is a conceptual work describing a general use of CV for quantitative fluorescence detection of various analytes as a simpler alternative to spectrofluorometer-assisted methods.

New 2-aryl-1,2,3-triazolopyrimidines were designed, synthesized, and characterized. Their optical properties were thoroughly studied in the solid phase, in solution and in a biological environment. Density Functional Theory (DFT) based calculations were performed, including the molecular geometry optimization for both the ground state and the first singlet excited state, the prediction of the UV-Vis absorption and fluorescence spectra, the determination of the molecular electrostatic properties and the solvent effect on the optical properties. The emission intensity was revealed to increase in time upon irradiation. Mass spectrometric research, quantum mechanical calculations, and analysis of literature data suggested a possible photo-transformation pathway through the homolytic cleavage of one of the C–Cl bonds upon irradiation with UV light. The structure of the active intermediate was identified by the series of mass spectrometry experiments and via synthesis of putative transformation products. The kinetic parameters measured in different solvents allowed estimating the rate of these photo-transformations. Biological experiments demonstrated that 2-aryl-1,2,3-triazolopyrimidines penetrate cells and selectively accumulate in the cell membrane and the Golgi complex and endoplasmic reticulum. Their unique properties pave the way for new possible applications of fluorescent 8-azapurines in biology and medicine.

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.

Gelatin nanoparticles found numerous applications in drug delivery, bioimaging, immunotherapy, and vaccine development as well as in biotechnology and food science. Synthesis of gelatin nanoparticles is usually made by a two-step desolvation method, which, despite providing stable and homogeneous nanoparticles, has many limitations, namely complex procedure, low yields, and poor reproducibility of the first desolvation step. Herein, we present a modified one-step desolvation method, which enables the quick, simple, and reproducible synthesis of gelatin nanoparticles. Using the proposed method one can prepare gelatin nanoparticles from any type of gelatin with any bloom number, even with the lowest ones, which remains unattainable for the traditional two-step technique. The method relies on quick one-time addition of poor solvent (preferably isopropyl alcohol) to gelatin solution in the absence of stirring. We applied the modified desolvation method to synthesize nanoparticles from porcine, bovine, and fish gelatin with bloom values from 62 to 225 on the hundreds-of-milligram scale. Synthesized nanoparticles had average diameters between 130 and 190 nm and narrow size distribution. Yields of synthesis were 62–82% and can be further increased. Gelatin nanoparticles have good colloidal stability and withstand autoclaving. Moreover, they were non-toxic to human immune cells. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Funding: The reported study was funded by RFBR and Kaliningrad Oblast according to the research project № 19-415-393005 (preparation of fluorescence gelatin nanoparticles and study of their fluorescent properties), by RFBR research project 19-015-00408 (preparation of gelatin nanoparticles by the desolvation method), and by Ministry of Science and Higher Education of the Russian Federation within the framework of the Russian State Assignment under contract No. AAAA-А19-119112290010-7 (assessment of nanoparticles cytotoxicity).

Magnetic Fe3O4 nanoparticles (MNPs) are often used to design agents enhancing contrast in magnetic resonance imaging (MRI) that can be considered as one of the efficient methods for cancer diagnostics. At present, increasing the specificity of the MRI contrast agent accumulation in tumor tissues remains an open question and attracts the attention of a wide range of researchers. One of the modern methods for enhancing the efficiency of contrast agents is the use of molecules for tumor acidic microenvironment targeting, for example, pH-low insertion peptide (pHLIP). We designed novel organosilicon MNPs covered with poly(ethylene glycol) (PEG) and covalently modified by pHLIP. To study the specific features of the binding of pHLIP-modified MNPs to cells, we also obtained nanoconjugates with Cy5 fluorescent dye embedded in the SiO2 shell. The nanoconjugates obtained were characterized by transmission electron microscopy (TEM), attenuated total reflection (ATR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), dynamic light scattering (DLS), UV and fluorescence spectrometry, thermogravimetric analysis (TGA), CHN elemental analyses, and vibrating sample magnetometry. Low cytotoxicity and high specificity of cellular uptake of pHLIP-modified MNPs at pH 6.4 versus 7.4 (up to 23-fold) were demonstrated in vitro. The dynamics of the nanoconjugate accumulation in the 4T1 breast cancer orthotopically grown in BALB/c mice and MDA-MB231 xenografts was evaluated in MRI experiments. Biodistribution and biocompatibility studies of the obtained nanoconjugate showed no pathological change in organs and in the blood biochemical parameters of mice after MNP administration. A high accumulation rate of pHLIP-modified MNPs in tumor compared with PEGylated MNPs after their intravenous administration was demonstrated. Thus, we propose a promising approach to design an MRI agent with the tumor acidic microenvironment targeting ability.

A comparative analysis of the structure and magnetic properties of nanoparticles of Fe-Ni and Fe-Co alloys without carbon and encapsulated in carbon obtained by gas-condensation synthesis is carried out. Particular attention is paid to the study of the formation of a solid solution in nanoparticles with carbon. X-ray analysis and magnetic properties convincingly demonstrate that a disordered supersaturated solid solution of carbon in FeNi@C and FeCo@C nanoparticles is formed.

The absorption spectra of cobalt-doped anatase TiO2 nanopowders in the infrared and visible ranges have been studied after various oxidative and reductive treatments. The annealing leads to the appearance of the Drude-like contribution in the infrared region and significant change in the absorption in an visible range due to the formation of defects of the oxygen-vacancy-type and Ti3+ ions. The observed additional contribution in the absorption spectra of TiO2:Co nanopowders as compared to the spectra of undoped powders is ascribed to the d–d transitions in ions Co2+. The change in the absorption related to cobalt after annealing is explained by a change in the local environment of Co ions from the octahedral to the tetrahedral environment.

In this work, we developed and optimized conjugates of carbon-coated iron nanoparticles (Fe@C) with streptavidin and monoclonal antibodies. The conjugation procedure included two stages. First, amino groups were grafted onto the carbon shell to facilitate noncovalent sorption of bovine serum albumin (BSA). Further, the covalent attachment of proteins to the BSA layer via glutaraldehyde coupling was performed. It was established and confirmed that the synthesis procedure is reproducible and allows preparation of stable conjugates. The resulting nanoparticles are clusters of Fe@C particles coated by proteins. The size of the clusters is in the range of 100–190 nm and can be controlled via the tuning of conjugation conditions, including pH, BSA-to-Fe@C ratio, etc. Conjugates of Fe@C with streptavidin and monoclonal antibodies (sizes of approximately 140–150 nm) were synthesized. Proton T2 relaxometry was used to detect these conjugates with very high sensitivity due to the magnetic markers, Fe@C. The relaxivity (r2) of different conjugates varied within the range of 290–450 1/s*mM. Conjugate applicability for relaxometry-based assay was confirmed by direct detection of streptococcal protein G and biotinylated BSA in a dot immunoassay.

Nanopowders Ni@C synthesized by gas condensation have a core-shell structure. The size of the core is 2–10 nm and the thickness of the shell is 1–3 nm. The changes in the magnetic properties and the structure of these particles upon annealing in the 100–1100°C temperature range are investigated in this work. Analysis of changes in the magnetic properties, the structure, and the chemical stability shows that the core of the particles in the initial state after synthesis is a supersaturated solid solution of carbon in nickel, which decomposes into nickel and carbon upon high-temperature annealing. Rather slow cooling of nickel particles causes the carbon shell to form. The shell ensures their chemical stability.

Core–shell CoFe@C and NiFe@C nanocomposites were prepared by gas-condensation synthesis. CoFe@C and NiFe@C particles had bcc and fcc cores, respectively. The treatment of these nanocomposites with hydrochloric acid revealed that they are more chemically stable than Fe@C composites. The maximum specific magnetization of CoFe@C and NiFe@C nanocomposites at room temperature in the field with a strength of 27 kOe was 125 and 58 G cm3/g, respectively. The processes of longitudinal and transverse relaxation of nuclear proton spins of aqueous suspensions of nanocomposites in various magnetic fields (0.5, 1, and 2 kOe) were studied. NiFe@C and CoFe@C nanocomposites have high transverse relaxivity values and can be used as magnetic markers for detection of low concentrations of bioobjects by NMR relaxometry.

The catalytic efficiency of three different cobalt–carbon composites has been compared in the gas-phase hydrodechlorination (HDC) of chlorobenzene (CB) in a flow type fixed bed reactor. The Co@C composite was synthesized by evaporation of overheated liquid drop of Co in the flow of an argon–butene mixture; the Co/C composite – by pyrolysis of sawdust impregnated with Co(NO3)2 water solution, and the Co/CNT composite – by the impregnation of carbon nanotubes with Co(NO3)2 water solution. Different oxidation states of cobalt were observed in the studied composites according to XPS, TPR, and in situ vibrating sample magnetometry results: predominantly Co0 in Co@C, CoO in Co/C, and Co3O4 in Co/CNT. TPR showed the possibility of the reduction of Co3O4 to CoO and even to Co0 under conditions of HDC and established the temperatures of these transitions. TEM revealed that Co0 nanoparticles in the Co@C composite are encapsulated by the thin carbon shell, CoO nanoparticles in Co/C are immersed in the carbon matrix, and Co3O4 nanoparticles in Co/CNT are located both on the surface and inside the channels of CNTs. All the composites demonstrated activity in HDC of CB. The efficiency of not only Co0 but CoO in the CB HDC was shown. The CB conversion at 150–250 °C for Co/C and Co/CNT composites, containing predominantly cobalt oxides, was higher than that for Co@C one, containing Co0 nanoparticles coated with the thin carbon shell. The Co/C composite with the lowest Co content (1.3 wt.%) was more effective in HDC than Co/CNT (14.6 wt.% of Co) and Co@C (79 wt.% of Co) ones. High CB conversion for the Co@C composite at 350 °C resulted from the catalytic action of the graphene shell of Co particles, activated by subsurface Co0.

The research was supported by the Russian Science Foundation (project 16-12-10004). The authors are grateful for the contributions made by our colleagues G. S. Zakharova, A. S. Konev, K. I. Borodin, Z. A. Phatakhova, A. M. Murzakaev, and V. S. Gaviko. The X-ray investigation and magnetic measurements have been performed in the Collaborative Access Center of M. N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia.

A comparative analysis of physicochemical properties and reactivity of 3-aryl-1H-pyrazole-5-diazonium tetrafluoroborates and 5-aryl-3-diazo-3H-pyrazoles in azo coupling reactions is presented. It is shown that diazonium salts have higher reactivity compared to the respective 3-diazopyrazoles, which is in agreement with their physicochemical properties. Heterocyclization of the synthesized azo compounds provided 2-arylpyrazolo[5,1-c][1,2,4]benzotriazines, which were screened for antitumor activity against human uterine endothelium cancer cells (HeLa cell line) and human skin fibroblasts using the MTT assay and flow cytometry. It was found that all of the tested compounds exhibited moderate to high cytotoxic activity. The best results were obtained with 6,8-dimethoxy-2-phenylpyrazolo-[5,1-c][1,2,4]benzotriazine.

Computer vision (CV) algorithms are widely utilized in imaging processing for medical and personal electronics applications. In sensorics CV can provide a great potential to quantitate chemosensors' signals. Here we wish to describe a method for the CV-assisted spectrofluorometer-free detection of common nitro-explosive components

Received: 15.04.2021. Revised: 20.05.2021. Accepted: 20.05.2021. Available online: 20.05.2021. Pyrene-based compounds have a great potential as fluorescent chemosensors for various analytes including common nitroexplosives, such as 2,4,6-trinitrotoluene (TNT). Compounds having two pyrene units in one molecule, such as bispyrenylalkanes, are able to form stable, bright emissive in a visual wavelength region excimers both in non-polar and polar environments. In this work we wish to report that in non-polar solvents the excimer has poor chemosensing properties while in aqueous solutions it provides significant “turn-off” fluorescence response to TNT in the subnanomolar concentrations. This work was supported by the Russian Foundation for Basic Research (Project № 19-33-90155).

Reactions of penta-2,4-dienethioamides with acetylenedicarboxylic acid, methyl and ethyl esters, and methyl propiolate were systematically studied, and a number of new 2,3-dihydro-5H-thiazolo[3,2-a...

The method of Fe3O4 magnetic nanoparticle synthesis by co-precipitation, modification by 3-aminopropylsilane and conjugation with pH-(low)-insertion peptide (pHLIP) is reported. The characterization of nanoparticles by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, elemental and thermogravimetric analyses as well as dynamic light scattering and z-potential measurements is provided. The effect of nanoparticles on the viability of mouse and human peripheral blood mononuclear cells is tested by flow cytometry. The experimental details of nanoparticle administration to tumor-bearing mice, magnetic resonance imaging scanning as well as subsequent tumor sample collection and their processing for transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, histological and immunohistochemical analyses are described. Biodistribution of the nanoparticles in mice and blood serum analysis data for experimental animals are given. The data are useful for an experiment workflow design and for the development of theranostic systems based on magnetic nanoparticles. © 2020 The Authors Russian Foundation for Basic Research, RFBR: 18-015-00319_a Ministry of Education and Science of the Russian Federation, Minobrnauka: RFMEFI62117X0015 This work was supported by the Russian Foundation for Basic Research [grant number 18-015-00319_a ]. The ICP-AES measurements were carried out using the core facilities of TPU's “Physical and chemical methods of analysis” (project VIU-RSCBS-142/2019). The research involving PBMC experiments was carried out within the framework of the state assignment theme (No. AAAA-A18-118031490008-7) of the Siberian State Medical University. The research into nanoparticle characterization by IR spectroscopy, elemental analysis (CHN) and TGA was carried out within the framework of the state assignment theme (No. АААА-А19-119011790130-3) in the Joint-Use Center for Spectroscopy and Analysis of Organic Compounds, Postovsky Institute of Organic Synthesis UB RAS. Dynamic light scattering (DLS) and zeta potential (z P ) characterization were carried out within the framework of the state assignment theme No. АААА-А18-118020290129-5 in the Miheev Institute of Metal Physics UB RAS. The experiments with animals and MRI were carried out at the Center for Genetic Resources of Laboratory Animals at the Institute of Cytology and Genetics SB RAS, supported by the Ministry of Education and Science of Russia (Unique identifier of the project RFMEFI62117X0015 ). TEM analysis was carried out at the Multiple-access Center for Microscopy of Biological Subjects, Institute of Cytology and Genetics SB RAS.

The surface modification of Fe3O4-based magnetic nanoparticles (MNPs) with N-(phosphonomethyl)iminodiacetic acid (PMIDA) was studied, and the possibility of their use as magnetic resonance imaging contrast agents was shown. The effect of the added PMIDA amount, the reaction temperature and time on the degree of immobilization of this reagent on MNPs, and the hydrodynamic characteristics of their aqueous colloidal solutions have been systematically investigated for the first time. It has been shown that the optimum condition for the modification of MNPs is the reaction at 40 °C with an equimolar amount of PMIDA for 3.5 h. The modified MNPs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, and CHN elemental analyses. The dependence of the hydrodynamic characteristics of the MNP colloidal solutions on the concentration and pH of the medium was studied by the dynamic light scattering method. On the basis of the obtained data, we can assume that the PMIDA molecules are fixed on the surface of the MNPs as a monomolecular layer. The modified MNPs had good colloidal stability and high magnetic properties. The calculated relaxivities r2 and r1 were 341 and 102 mmol-1 s-1, respectively. The possibility of using colloidal solutions of PMIDA-modified MNPs as a T2 contrast agent for liver studies in vivo (at a dose of 0.6 mg kg-1) was demonstrated for the first time.

Bola-type organic scaffolds are of key importance for application in a wide variety of fields. In this manuscript we wish to report our results on construction of polycyclic aromatic hydrocarbon (PAH, PAH = 9-antracenyl, 1-pyrenyl)-based bola-type fluorophores/chemosensors via an unusual Clemmensen reduction of the corresponding penta-1,4-dien-3-ones. In aqueous solutions the thus obtained bola-type molecules demonstrate intensive excimer emission at 500 nm, as well as well-pronounced “turn-off” fluorescence response towards common nitro-explosive components, such as 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), as well as, hard-to-detect pentaerythritol tetranitrate (PETN).

Substantial progress in the area of nanotechnology requires special quality of magnetic nanoparticles. Conventional methods of analysis are not always efficient to the study of nanoparticles. This paper is dedicated to the problem of quantitative analysis of the phase composition of ferromagnetic nanoparticles and the fundamental issue of transition to the single domain magnetic state. A comprehensive study of Fe@C nanoparticles has been carried out, including local 57Fe NMR and Mossbauer spectroscopy methods. It has been found that the cores of nanoparticles contain phases of α-iron, iron carbides, ferromagnetic and paramagnetic phases of iron-carbon FeCx solid solutions. Annealing of the nanoparticles leads to a significant redistribution of the phase composition and leads to an increase in magnetization. Also, a nanoscale effect has been found. It consists in observation of two lines in NMR spectra corresponding to multidomain and single-domain state. The hyperfine fields obtained by NMR and Mossbauer spectroscopy methods are discussed.

The magnetic properties of an oxygen-deficient nanocrystalline undoped titanium dioxide synthesized by the gas-phase, electric-explosion, and chemical method have been studied. The defect state was controlled using reduction treatments in vacuum or in a hydrogen atmosphere. It is shown that the defect state of the surface of nanocrystalline oxides (for example, the existence of vacancies in the anion sublattice and other defects) has a dominant influence on the formation of the magnetic properties of the samples under study. The main contributions to the magnetism of TiO2 nanoparticles after the reduction treatments are the paramagnetic contribution of the matrix, the paramagnetic Curie–Weiss contribution, and the contribution of the spontaneous magnetic moment provided by the existence of regions with different spin ordering. A heterogeneous magnetic state is found to exist in the TiO2 nanopowders; for example, at low temperatures, shifted hysteresis loops are observed as a result of a possible set of magnetic states with different spin orders. It is shown that a soft compaction or grinding of nanopowders in an agate mortar lead to substantial increase in the magnetization, sometimes, by a factor of more than two, regardless of the nanopowder synthesis method and the initial phase state of TiO2 (anatase or rutile structures). This experimental fact proves the key role of the surface defects and the magnetic moment carriers with different spin configurations localized mainly on the nanoparticle surface. The compaction changes the magnetization only in the case when the initial magnetic state has a nonlinear “quasi-superparamagnetic” character of the magnetization curve. As a result of predominant exchange interaction between the nanoparticles with a frustrated character of spin ordering on the nanoparticles surface, the ferromagnetic contribution increases as nanoparticles contact.

Artificial enzymatic mimics based on nanoparticles have become a powerful tool for the improvement of analytical performance in the detection of important bioactive compounds. For the first time the intrinsic peroxidase-like activity of Fe-core/carbon shell nanoparticles (Fe@C NPs) was studied. The catalytic process was described by a typical Michaelis–Menten curve for enzyme kinetics, and the results were comparable with those previously published. The high catalytic performance of the Fe@C NPs allows the development of a new simple procedure for glucose determination with a low detection limit of 0.21 μM. To our knowledge, this is the first study showing the ability to generate active oxygen species on the Fe@C surfaces. We suppose that our investigation will open up a new direction in medicinal applications using these promising materials.

Cobalt-doped anatase Ti1–xCoxO2 (0 < x ≤ 0.04) nanopowders (with a particle size of 30–40 nm) were produced by the hydrothermal synthesis method. Morphology, structure, and thermal stability of the synthesized compounds were examined using transmission electron microscopy, infrared spectroscopy, and X-ray diffraction analysis. Using X-ray photoelectron spectroscopy, cobalt ions are shown to have an oxidation state of 2+, with titanium ions having a tetravalent state of Ti4+. In the as-prepared state, all investigated compounds of Ti1–xCoxO2 are paramagnetic, with the value of paramagnetic susceptibility growing in proportion to cobalt content; with the spin of cobalt ion equal to S = 3/2. Analysis of the electron paramagnetic resonance spectra reveals that doping TiO2 with cobalt (up to 2%) is accompanied by a significant increase in the concentration of F+ centers. Further growth of the cobalt content results in a relatively wide line (nearly 600 Oe) in the spectrum, with a g-factor of about 2.005, demon...

Interactions of bimodal (fluorescent and magnetic) nanoparticles with HeLa cells were studied. The nanoparticles, characterized by high magnetic moment and relaxing capacity, exhibited fluorescence sufficient for their use as labels in confocal microscopy and flow cytometry. Penetration of these nanoparticles into the cell depended on their surface charge: positively charged nanoparticles of this structure penetrated inside, while negatively charged particles were not found in the cells.

The efficiency of magnetic labeling with L-Lys-modified Fe

The report is devoted to an analysis of the structural and magnetic state of the nanocrystalline diluted magnetic semiconductors based on TiO2 doped with Fe and Co atoms. Structural and magnetic characterization of samples was carried out using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR) spectroscopy, SQUID magnetometry, and the density functional theory (DFT) calculations. Analysis of the experimental data suggests the presence of non-interacting paramagnetic Fe3+ and Co2+ ions in the high-spin state and negative exchange interactions between them. The important conclusions is that the distribution of dopants in the TiO2 matrix, even at low concentrations of 3d-metal dopant (less than one percent), is not random, but the 3d ions localization and dimerization is observed both on the surface and in the nanoparticles core. Thus, in the paper the quantum mechanical model for describing the magnetic properties of TiO2:(Fe, Co) was suggested. The model operates only with two parameters: paramagnetic contribution of non-interacting 3d-ions and dimers having different exchange interactions between 3d magnetic carriers.