A. G. Savchenko

Synthesis and Characterization of Stable Iron Oxide Nanoparticle with Amino Covalent Binding on the Surface for Biomedical Application

The success for biomedical application of nonmaterial always depends upon its colloidal stability. Thus, in the current study we report a suitable method for preparation and functionalization of Iron oxide nanoparticles with amino group at its terminal end. The optimization of magnetite was studied to enhance physico-chemical and magnetic properties. Thus, the particles were first coated with amino groups and then subjected for surface functionalization using polyethylene glycol. The surface topography and average size distribution of the nanoparticles was determined by performing characterization using Transmission electron microscopy, dynamic light scattering and diffraction pattern. The zeta potential and hydrodynamic size was studied as function of pH. An adequate surface modification involving covalent approach based on surface chemistry of salts provides PEG modified iron oxide nanoparticlesxa0as suitable for biomedical application as it may increase circulation of the particles in blood as new monolayer is capable of conjugating and allowing targeted uptake of biomolecules into tumors.

Nanoscale engineering of hybrid magnetite–carbon nanofibre materials for magnetic resonance imaging contrast agents

Magnetic nanomaterials show significant promise as contrast agents for magnetic resonance imaging (MRI). We have developed a new highly efficient one-step procedure for the synthesis of magnetically- functionalised hollow carbon nanofibres, where (i) the carbon nanofibres act as both a template and a support for the nucleation and growth of magnetite nanoparticles and (ii) the structural (size, dispersity and morphology) and functional (magnetisation and coercivity) properties of the magnetic nanoparticles formed on nanofibres are strictly controlled by the mass ratio of the magnetite precursor to the nanofibres and the solvent employed during synthesis. We have shown that our magnetite-nanofibre materials are effectively solubilised in water resulting in a stable suspension that has been employed as a ‘‘negative’’ MRI contrast agent with an excellent transverse relaxivity (r2) of (268 13) mM s 1, surpassing current commercial materials and state-of-the-art magnetic nanoscale platforms in performance for MRI contrast at high magnetic fields. The preparation and evaluation of this unique hybrid nanomaterial represents a critical step towards the realisation of a highly efficient ‘‘smart’’ MRI theranostic agent – a material that allows for the combined diagnosis (with MRI), treatment (with magnetic targeting) and follow-up of a disease (with MRI) – currently in high demand for various clinical applications, including stratified nanomedicine.

Microstructure and Magnetic Properties of Melt-Spun Nd-Rich Nd-Fe Alloys

The effect of composition on the magnetic properties and microstructure of Nd-rich Nd-Fe alloys prepared by melt-spinning were investigated. Several magnetic phases with ordering temperatures at about 10, 37, 48, and 420-480 K were detected from the temperature dependence of magnetization. The first transition is due to the presence of the double-hexagonal-close-packed Nd phase. The magnetic transitions at 37 and 48 K may be related to the face-centered-cubic Nd-based phase and the Nd-rich nanocrystals. The high-temperature ferromagnetic-paramagnetic transitions at 420-480 K may be connected with the amorphous-like Fe-Nd phase enriched in Fe, which is observed by transmission electron microscopy in the intergranular regions. At temperatures below 100 K, the magnetization of the Nd-Fe ribbons did not saturate in a magnetic field as high as 7200 kA/m. The correlations between the microstructure and coercivity of the Nd-rich Nd-Fe ribbons are discussed.

Nanohybride Materials Based on Magnetite-Gold Nanoparticles for Diagnostics of Prostate Cancer: Synthesis and In Vitro Testing

We synthesized a fluorescence conjugate and modified magnetite-gold nanoparticles carrying prostate specific membrane antigen (PSMA) as the ligand. Analysis of their binding to human prostate cancer cell lines PC-3 (PSMA–) and LNCaP (PSMA+) showed selective interaction of the synthesized conjugate and modified nanoparticles with LNCaP cells. These findings suggest that these nanoparticles can be used in tissue-specific magnetic-resonance imaging.

Synthesis of Iron Oxide Nanoclusters by Thermal Decomposition

Herein, we report a novel one-step solvothermal synthesis of magnetite nanoclusters (MNCs). In this report, we discuss the synthesis, structure, and properties of MNCs and contrast enhancement in T2-weighted MR images using magnetite nanoclusters. The effect of different organic acids, used as surfactants, on the size and shape of MNCs was investigated. The structure and properties of samples were determined by magnetic measurements, TGA, TEM, HRTEM, XRD, FTIR, and MRI. Magnetic measurements show that obtained MNCs have relatively high saturation magnetization values (65.1-81.5 emu/g) and dependence of the coercive force on the average size of MNCs was established. MNCs were transferred into an aqueous medium by Pluronic F-127, and T2-relaxivity values were determined. T2-Weighted MR phantom images clearly demonstrated that such magnetite nanoclusters can be used as contrast agents for MRI.

Сore–shell magnetite–gold nanoparticles: Preparing and functionalization by chymotrypsin

In this work we present the results of the synthesis of magnetite–gold nanoparticles with a core–shell structure. The preparation is carried out in several stages: synthesis of the core, coating with a gold shell, purification of magnetite–gold particles from an uncoated magnetite, and functionalization of the surface with sulfur-containing ligands. The conditions needed for the functionalization of nanoparticles with lipoic acid and mercapto-methoxy polyethylene glycol are indicated in detail, making it possible to determine the optimal conditions needed to achieve an efficient purification and a maximum concentration of the particles in a solution required for biological tests. The possibility of remotely controlling the chymotrypsin properties using an alternating magnetic field has been demonstrated by the example of magnetite–gold nanoparticles. The magnetite–gold nanoparticles which we have obtained are promising for future biomedical applications.

Synthesis and characterization of PEG-silane functionalized iron oxide(II, III) nanoparticles for biomedical application

In this paper we report the synthesis, functionalization, and characterization of ferromagnetic iron oxide (II, III) nanoparticles with different shapes and sizes. Using a number of chemical methods, magnetite nanoparticles having a spherical shape and size of 9 ± 2 nm (coprecipitation), 22 ± 4 nm and 50 ± 6 nm (redox reaction), and 40 ± 5 nm cubes were synthesized. Special attention in this paper is devoted to the covalent modification of magnetite nanoparticles by polymers such as silane-polyethylene glycol (Peg-silane). The main advantage of magnetic nanoparticles modified by polymer is low toxicity, colloidal stability of the prepared magnetite nanoparticles, and the possibility for post functionalization. We determined coercivity and saturated magnetism. Also, the relaxivity T2 was measured by magnetic resonance imaging (MRI). Prepared nanoparticles are of great interest and potential for use in biomedical imaging.

Magnetite-Gold nanohybrids as ideal all-in-one platforms for theranostics

High-quality, 25u2009nm octahedral-shaped Fe3O4 magnetite nanocrystals are epitaxially grown on 9u2009nm Au seed nanoparticles using a modified wet-chemical synthesis. These Fe3O4-Au Janus nanoparticles exhibit bulk-like magnetic properties. Due to their high magnetization and octahedral shape, the hybrids show superior in vitro and in vivo T2 relaxivity for magnetic resonance imaging as compared to other types of Fe3O4-Au hybrids and commercial contrast agents. The nanoparticles provide two functional surfaces for theranostic applications. For the first time, Fe3O4-Au hybrids are conjugated with two fluorescent dyes or the combination of drug and dye allowing the simultaneous tracking of the nanoparticle vehicle and the drug cargo in vitro and in vivo. The delivery to tumors and payload release are demonstrated in real time by intravital microscopy. Replacing the dyes by cell-specific molecules and drugs makes the Fe3O4-Au hybrids a unique all-in-one platform for theranostics.

Phase Composition and Magnetic Properties of Nd2Fe14B/α-Fe Nanocomposites Prepared by Mechanical Alloying

Combined studies of hard magnetic Nd2Fe14B/α-Fe nanocomposites are performed. They were prepared by mechanical alloying of melt-quenched Nd7.4Pr2.0Fe76.6Co4.2Zr3.4B6.4 and Nd5.8Fe80Co4.9Ti1.5Si2.5B5.3 alloys taken in mass proportions of 90/10 and 70/30. It is found that, after mechanical alloying, an amorphous–crystalline structure is formed; it consists of the hard magnetic Nd2Fe14B and soft magnetic (amorphous and α-Fe) phases. Subsequent annealing at ~500°C initiates the decomposition of the amorphous phase and the formation of the nanocrystalline Nd2Fe14B and α-Fe phases. This leads to an increase in the coercivity and the residual magnetization-to-saturation magnetization ratio (σr/σs ≥ 0.5). It is assumed that the magnetic hardening of powders is due to the formation of an exchange-coupled state, which results from the exchange interaction between α-Fe nanocrystals and the Nd2Fe14B phase.

Anisotropic Iron-Oxide Nanoparticles for Diagnostic MRI: Synthesis and Contrast Properties

The scientific and technical literature addressing the synthesis of anisotropic iron-oxide nanoparticles of various shapes (cubic, rod-like, clustered, etc.) sized from 10 to 100 nm and their application for diagnostic magnetic resonance imaging (MRI) of tissues and organs is analyzed. The analysis indicates that the nanoparticle shape, size, and surface chemistry affect considerably relaxation parameters T1 and T2. Thus, cubic iron-oxide nanoparticles had the greatest T2 values. Furthermore, rod-like and octapodal nanoparticles also exhibit rather high T2 values so that they can be used as contrast agents for diagnostic MRI.