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The processes of carbonization of sucrose-containing coatings on the surface of single-domain magnetite and magnetosensitive nanocomposite (MNC) Fe3O4/Al2O3 are studied. The MNC with a carbon surface is synthesized by the method of low-temperature pyrolysis of carbohydrates. As revealed, the used heat-treatment mode does not lead to deterioration of the magnetic characteristics of magnetite under the condition of preliminary creation of a protective layer of alumina on its surface. Differential thermal analysis (DTA) in combination with differential thermogravimetric analysis (DTGA) and programmed temperature-desorption mass spectrometry show that the carbonization of sucrose under these conditions is complete. The shape and dimensions of the Fe3O4, Fe3O4/Al2O3 and Fe3O4/Al2O3/С MNCs are investigated by the TEM method. As established, the values of the specific saturation magnetization of MNCs are consistent with the corresponding changes in the mass fraction of magnetite in the Fe3O4/Al2O3 and Fe3O4/Al2O3/С structures. The results of TEM studies and magnetic measurements indicate the formation of the Fe3O4/Al2O3 and Fe3O4/Al2O3/С MNCs by the core–shell type. Methylene blue is used to study the adsorption activity of the Fe3O4/Al2O3/С MNC surface. The results of the work can be used in the development of new magnetically controlled adsorption materials for medical–biological purposes. [ABSTRACT FROM AUTHOR]

One of the most widely used antitumor chemotherapeutic drugs is “Cisplatin” (active substance - cis - diaminodichloroplatinum), the side effects of which are the cumulative ototoxic, nephrotoxic and neurotoxic effects. The use of drug carrier systems for targeted delivery and adsorbents for extraction, in particular magnetite-carbon nanocomposites, will minimize unwanted toxic effects without reducing the therapeutic effect of cisplatin. For this purpose, a nanocomposite (NCs) of Fe3O4/Al2O3/С with a carbon surface was synthesized, where a layer of alumina protects magnetite during the pyrolysis of carbohydrates. The synthesized samples were characterized by TEM, XRD, mass spectrometry methods, magnetic properties and specific surface area were studied. It has been found that the used heat treatment mode (T = 500 °С, argon medium) is sufficient for complete carbonization of sucrose and preserves the phase of magnetite which does not lead to deterioration of magnetic characteristics. The results of TEM studies and magnetic measurements indicate the formation of the Fe3O4/Al2O3/С nanocomposite of the core-shell type. The adsorption of Cisplatin on the surface of NCs Fe3O4/Al2O3/С was performed and the adsorption process dependent on the contact time, pH of the solution and cisplatin concentration was studied. The experimental results of kinetic studies were analyzed for compliance with the theoretical models of Boyd and Morris-Weber, models of pseudo-first and pseudo-second orders. Langmuir and Freundlich isotherm models were used to model adsorption processes. The limiting factor of adsorption is the external diffusion mass transfer processes, which correlates with the calculated parameters of the pseudo-first-order model (r² = 0.985). The correlation of theoretical and practically obtained values of adsorption capacity indicates the possibility of using the Freundlich model to describe the adsorption of Cisplatin on the surface of Fe3O4/Al2O3/C. [ABSTRACT FROM AUTHOR]

The aim of the work is the synthesis of nanostructures based on lanthanum fluoride, promising for use in photodynamic therapy of tumors in organs of cranial cavity and bone tissues; a study of their structural properties and luminescence spectra. Synthesis of LaF3:Tb3+ was carried out by coprecipitation of components from aqueous and alcoholic (methanol) solution. As precursors were used: La(NO3)3×6H2O, TbCl3, NH4F. All reagents have qualification “chemically pure”. Distilled water and methanol were used as solvent. The synthesis of nanosized magnetite in the single-domain state was performed by the Elmore method. Synthesized nanodisperse samples are characterized by XRD analysis, DTGA, TEM. The magnetic properties and spectra of UV luminescence were also studied. It has been found that the XRD-patterns of LaF3:Tb3+ samples synthesized in water and methanol do not differ fundamentally. Under the experimental conditions, the most perfect crystals of hexagonal syngony were formed during crystallization in an autoclave. Their average size was ~ 15 nm. In TEM images, the length of the crystals exceeds the width by 3–4 times. Crystals are prone to aggregation and the formation of chain structures. The UV luminescence spectrum of the synthesized nanodisperse samples in aqueous medium at the concentration of 0.5 mg/ml and excited by ultraviolet radiation is characteristic of the structure of LaF3:Tb3+. Ensembles of particles Fe3O4/LaF3:Tb3+ NCs were synthesized. Transmission electron microscopy has shown that the shapes of particles of NCs and LaF3:Tb3+ nanocrystals are fundamentally different. Particles of Fe3O4/LaF3:Tb3+ NCs have a spherical shape, which is characteristic of structures of the core-shell type. X-ray diffraction patterns of NCs confirm this conclusion. The conditions for the synthesis of NCs did not significantly change the magnetic properties of their nuclei, single-domain Fe3O4 nanoparticles (NPs). The luminescence spectrum of Fe3O4/LaF3:Tb3+ NCs differs significantly from the spectrum of samples of nanodispersed LaF3:Tb3+ both in intensity and in the structure of the bands. These spectral differences may be due to differences in structure, features of the nanocrystalline structure, the content of the LaF3:Tb3+ scintillator and Tb3+ ions in samples of LaF3:Tb3+ nanocrystals and shells of Fe3O4/LaF3:Tb3+ nanocomposites. Composites of dispersed 60S bioglass with nanodispersed crystalline LaF3:Tb3+ in the dry state, and distilled water, showed the presence of luminescence upon excitation by UV radiation. The results of research show the prospects of the synthesized nanodispersed luminophors LaF3:Tb3+, for use as a source of luminescent radiation in optopharmacology and photodynamic therapy of tumors in organs of cranial cavity and bone tissues. Optimization of luminescent properties of the original nanodispersed luminophors, their compositions with bioactive glass, luminescent shells in the composition of magnetosensitive NCs, as well as the technology of manufacturing of these structures will significantly allow us to improve their performance characteristics. The results of the work indicate the prospects of the synthesized structures for further research under the conditions of excitation by high-permeability “soft” Xray radiation for use in optopharmacology and photodynamic therapy of tumors in organs of cranial cavity and bone tissues. Optimization of properties of the original nanodispersed luminophors, their compositions with bioactive glass and magnetosensitive carriers Fe3O4 will allow us to improve significantly their performance characteristics. [ABSTRACT FROM AUTHOR]

Сombination of properties of lectins and magnetically sensitive iron-containing nanocomposites (NC) for use in oncology is actual and promising from scientific and applied point of view. The aim of the research is to synthesize and to study new iron-containing NC and magnetic fluids containing bioactive bacterial lectin, promising for use as prototypes of new effective antitumor vector systems for targeted drug delivery and combined local therapy of cancer with minimized side effects on the body and improved compatibility with other remedies. To create vector systems, nanodisperse magnetite was synthesized by the Elmore reaction. The synthesis of aluminum-containing coating on the surface of Fe3O4 was carried out by double chemical modification with aluminum isopropylate. The obtained Fe3O4/Al2O3 NC was impregnated with sucrose solutions. Carbonization of the carbohydrate shell of NC was carried out in argon (500 °C). As a result, Fe3O4/Al2O3/C NC was obtained. The magnetic properties of nanostructures were measured using a laboratory vibration magnetometer of Foner type at room temperature. Adsorption immobilization of lectin was performed in 0.9 % NaCl solution in a dynamic mode at room temperature. Bacterial cytotoxic lectin of B. subtilis IMB B-7724 was used in the experiments. The amount of adsorbed substance (A) on the surface of nanocomposites was determined by measuring the concentration of lectin in the contact solutions before and after adsorption using a calibration graph. Measuring of the optical density and absorption spectra of lectin was performed on a spectrometer Lambda 35 UV/vis Perkin Elmer Instruments at λ = 280 nm. Standard techniques and equipment were used for biological research. The processes of adsorption immobilization of cytotoxic bacterial lectin of B. subtilis IMB B-7724 from physiologic saline on the surface of magnetite and carbon-containing Fe3O4/Al2O3/C NC were studied at room temperature. It has been found that the adsorption capacity of lectin on the surface of magnetite is 25.3 mg/g, and Fe3O4/Al2O3/C NC – 36.3 mg/g (at initial concentrations of lectin 0.06–0.4 mg/mL). The extraction extent of lectin R (%) was 12–38 % for magnetite and 46–67 % for Fe3O4/Al2O3/C NC. The dependence of the adsorption capacity on time was studied. A magnetic fluid (MF) based on single-domain Fe3O4, containing lectin was synthesized and investigated. Immobilization of lectin on MF particles was carried out in a dynamic mode at room temperature for 3 hours. The concentration of lectin in the composition of MF was 0.2 mg/mL. MF with immobilized lectin was further modified with PEG-2000. The synthesis of Fe3O4/ol.Na/lectin/PEG (ol.Na – sodium oleate) vector system was carried out in a dynamic mode for 3 hours. Modification of the surface of nanoparticles with polyethylene glycol was performed in order to increase the stability of the magnetic fluid, reducing the aggregation of particles. To determine the effect of experimental samples on the viability of MCF-7 cells in vitro, the following samples were prepared: Fe3O4/ol.Na/PEG (MF), CFe3O4 = 3 mg/mL; cytotoxic lectin of B. subtilis IMB B-7724 (CL), CCL = 0.2 mg/mL; nanobiocomposite (NBC). Nanobiocomposite based on MF and bacterial lectin was found to have a synergistic cytotoxic effect on MCF-7 human breast cancer cells, causing up to 40 % cell death. The IC50 values for the nanobiocomposite and lectin in relation to MCF-7 cells were 100 and 125 μg/mL, respectively. The results of research show that the combination of properties of lectins and magnetically sensitive ironcontaining NC for use in oncology is a promising direction in creating new effective antitumor vector systems for targeted drug delivery and combined local therapy of cancer. The use of natural components in vector systems is a way to minimize the side effects on the body and improve compatibility with other antitumor remedies. [ABSTRACT FROM AUTHOR]

Nanoscale magnetite (Fe3O4) and nanocomposite based on it (Fe3O4/SiO2) were synthesized. In solutions of different ionic strength (0.015 and 0.15 M NaCl) by pH-metry, the acid–base properties of the surface were studied: the pH value of the isoin state of the surface (рHIIP), the total concentration, and values of Ki and pK of surface hydroxyl groups active in the pH range 4–9 and are calculated dependencies of the particles of hydroxyl groups of the surface on the pH of the medium. It was found that neutral hydroxyl groups are predominant for the synthesized sample magnetically sensitive nanoparticles (MNPs), which make it possible to form centers of both acidic and base types. Thus, for Fe3O4 to pH = 6 active base centers (C=155.56⋅10−5 − 141.59⋅10−5 mol⋅g−1), the strength of which decreases with decreasing pH (pK = 2.65 ± 0.01–4.48 ± 0.01 (2.59 ± 0.003 − 4.70 ± 0.008 for 0.15 M NaCl solution). Acid centers in a very small amount (4.93⋅10−6 − 2.68⋅10−6 mol⋅g−1) are fixed in the pH range 7–9 and show weakly acidic properties (pK = 10.95 ± 0.21 − 11.31 ± 0.18 (11.34 ± 0.04 − 11.94 ± 0.17 for 0.15 M NaCl solution). For the Fe3O4/SiO2 surface, neutral centers are predominant, which are characterized by the detection of acidic properties, which makes it possible to form acid-type centers, the concentration of which is higher in 0.15 M NaCl solution (C = 237.58⋅10−5 mol⋅g−1), (C for 0.015 M NaCl solution = 150.54⋅10−5 mol⋅g−1), whose strength decreases with increasing pH (pK2=4.69 ± 0.03 − 8.6 ± 0.08 (4.91 ± 0.1 − 9.32 ± 0.09 for 0.15 M NaCl solution)). [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this work is to develop a simple, cheap and reproducible method for the synthesis of stable magnetic fluid nanocomposite chitosan/magnetite with particle size less than 100 nm and to study some of its physical and chemical properties. As a result, the method of synthesis of polyfunctional hybrid magnetic liquid nanocomposite chitosan/magnetite/sodium oleate with multilevel architecture was developed. With methods of small-angle neutron scattering, infrared Fourier spectroscopy, and transmission electron microscopy the structural characterization of the obtained magnetic nanofluids was performed. The formation of aggregates in magnetic fluids is established based on results from small-angle neutron scattering. The scattering signal from fractal particles was obtained simultaneously with the signal of small-angle neutron scattering for polydispersed spherical particles in the studied liquid systems. The mechanism of interaction of sodium oleate with chitosan in the system of chitosan/magnetite/sodium oleate is proposed. It has been shown that the binding between magnetite/sodium oleate and chitosan can be explained by the electrostatic interaction between a positively charged chitosan molecule and negatively charged coating of sodium oleate on the surface of magnetite. Strong electrostatic interaction also leads to the proton transfer from oleic acid to chitosan, thus creating a stable complex. The synthesized nanocomposite can be potentially used for targeted drug delivery and deposition of drugs in target cells and organs, for the diagnostics and therapy of diseases at the cellular level. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry, Physics & Technology of Surface / Khimiya, Fizyka ta Tekhnologiya Poverhni is the property of National Academy of Sciences of Ukraine, Chuiko Institute of Surface Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The method for chitosan (CS) covalent immobilization onto NH2-functionalized magnetite nanoparticles surface is presented. Covalent binding of CS to the magnetite surface proceeds using a free -CH2OH group of CS and a NH2-group of magnetite with epichlorohydrin (ECH) as a cross-linker. The obtained nanocomposites were functionalized by diethylenetriaminepentaacetic acid (DTPA)-groups. Composites were characterized by elemental analysis, FTIR, XPS and ASAP methods. The total content of organic phase (CS-DTPA) in the hybrid material, appreciated by thermogravimetric analysis (TGA), was 3.7%. Considering the atomic ratio between oxygen in CS and oxygen in ECH residue, the chemical structure of the hybrid material is proposed. The adsorption of Gd-DTPA and Gd3+on the obtained nanocomposite was studied. The Freundlich isotherm fits all the experimental data better than the Langmuir adsorption. [ABSTRACT FROM AUTHOR]

The synthesis has been made of patterns of single-domain magnetite and related nanocomposites: Fe3O4/dimercaptosuccinic acid, Fe3O4/hydroksylapatite, Fe3O4/γ-aminopropylsiloxane. The influence has been examined of chemical nature of surface of the synthesized nanostructures on the adsorption of cis-dichlorodiamineplatinum complexes. The isotherms and kinetics of adsorption were studied in terms of Pt2+ cations. The best adsorption parameters were observed for Fe3O4/polyacrylamide and Fe3O4/γ?-aminopropylsiloxane nanocomposites. The perspective of using nano-sized magnetite and its modified forms has been shown for the creation of magnetosensitive adsorbents of cis-dichloro-diamineplatinum complexes, in particular, for biomedical applications. [ABSTRACT FROM AUTHOR]

Preparation techniques have been developed of magnetic-sensitive nanostructures based on magnetite with incorporated gadolinium ions. Structure and composition of the nanocomposites have been examined by IR-pectroscopy, Xray analysis and X-ray photoelectron spectroscopy. Magnetic characteristics have been studied with vibrating sample magnetometer. An amorphous phase of gadolinium hydroxide has been shown to be formed on surfaces of nanosized magnetite particles. When the samples are heat treated at 800-1000 °?, a crystal phase of ferrite GdFeO3 is formed. [ABSTRACT FROM AUTHOR]