Spherical Fe3O4 Nanoparticles Research Articles

Highly magnetic iron carbide nanoparticles as effective T2contrast agents

This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (~20 nm in diameter) exhibit strong contrast enhancement with an r2 value of 283.2 mM(-1) S(-1), which is about twice as high as that of spherical Fe3O4 nanoparticles (~140.9 mM(-1) S(-1)). In vivo experiments demonstrate that Fe5C2 nanoparticles are able to produce much more significant MRI contrast enhancement than conventional Fe3O4 nanoparticles in living subjects, which holds great promise in biomedical applications.

The effect of initial alignment on the optical properties of Fe3O4 nanoparticles doped in nematic liquid crystals

Recently the nonlinear effects of the different materials doped liquid crystals are more interesting. In all previous works, nonlinearity of samples with the homeotropic alignment is investigated because of the larger component of the refractive index in this direction. Here, there are spherical Fe3O4 nanoparticles that have both parallel and perpendicular components. We were looking for the effect of initial alignment on the nonlinearity of pure and doped nematic liquid crystals (NLCs). The experimental results emphasize, even the same compositional percentage of nanoparticles prepared by two different alignment configurations are showing different results when dispersed in the same NLCs. Comparing nonlinear studies, the magnitude of nonlinear refraction index, n2 and nonlinear absorption coefficient, β increase 102 and 101 times, respectively, in homeotropic alignment samples and the sign of these parameters is changed rather than homogeneous ones.

Magnetite Nanoparticles Synthesized Using Pulsed Plasma in Liquid

Iron oxide nanoparticles have attracted much attention over the last few years owing to their fundamental importance and technological applications. In this work, spherical ferromagnetic Fe3O4 nanoparticles with an average diameter of 19 nm were synthesized by a simple and one-step method, pulsed plasma in liquid. Pulsed plasma, induced by a low-voltage spark discharge, was submerged in a dielectric liquid at a voltage of 200 V, a current of 6 A, a frequency of 60 Hz, and a single discharge duration of 10 µs. Water with different concentrations of 1-hexadecylpyridinium bromide (CPyB) was applied as a liquid, and several experiments made evident that the surfactant concentration affects the phase compositions of the produced materials. The purity of the magnetite phase in the sample increased (from 65 to 98%) with increasing CPyB concentration (from 0.10 to 0.84 g) in 200 ml of water. The crystal structure of magnetite (Fe3O4) nanoparticles with the Fd3̄m space group and a lattice parameter of a = 0.8393 nm was evident from X-ray diffraction results. Magnetite nanoparticles were investigated further by high-resolution transmission electron microscopy/energy-dispersive spectroscopy and thermogravimetrical analysis, and using a vibrating sample magnetometer.

One-pot synthesis of magnetic nanoparticles assembled on polysiloxane rod and their response to magnetic field

Rod-like assembled magnetite (Fe3O4) nanoparticles (NPs) were successfully synthesized in a one-pot process using a polysiloxane template derived from a dialkoxysilane. The assembly was constructed using the thiol-ene click reaction between thiol groups on the polysiloxane chain and allyl groups on Fe3O4 NPs. The thiol-containing polysiloxane chain and the allyl-containing Fe3O4 NPs were synthesized by the hydrolysis–condensation of 3-mercaptopropyl(dimethoxy)methylsilane and iron (III) allylacetylacetonate, respectively. Fe3O4 NPs of around 5 nm were uniformly dispersed on the siloxane rods and exhibited neither remanent magnetization nor coercivity. A fluid containing a dispersion of rod-like assembled Fe3O4 NPs showed yield stress even without the application of an external magnetic field, whereas spherical Fe3O4 NPs exhibited no yield stress. The rod-like assembled Fe3O4 NPs on anisotropic siloxane clearly exhibited typical magnetorheological behavior.

Photo-induced electric polarizability of Fe3O4 nanoparticles in weak optical fields

Using a developed co-precipitation method, we synthesized spherical Fe3O4 nanoparticles with a wide nonlinear absorption band of visible radiation. Optical properties of the synthesized nanoparticles dispersed in an optically transparent copolymer of methyl methacrylate with styrene were studied by optical spectroscopy and z-scan techniques. We found that the electric polarizability of Fe3O4 nanoparticles is altered by low-intensity visible radiation (I ≤ 0.2 kW/cm2; λ = 442 and 561 nm) and reaches a value of 107 Å3. The change in polarizability is induced by the intraband phototransition of charge carriers. This optical effect may be employed to improve the drug uptake properties of Fe3O4 nanoparticles.PACS33.15.Kr78.67.Bf42.70.Nq

Facile and straightforward synthesis of superparamagnetic reduced graphene oxide–Fe3O4 hybrid composite by a solvothermal reaction

A superparamagnetic reduced graphene oxide–Fe3O4 hybrid composite (rGO–Fe3O4) was prepared via a facile and straightforward method through the solvothermal reaction of iron (III) acetylacetonate (Fe(acac)3) and graphene oxide (GO) in ethylenediamine (EDA) and water. By this method, chemical reduction of GO as well as the formation of Fe3O4 nanoparticles (NPs) can be achieved in one step. The Fe3O4 NPs are firmly deposited on the surfaces of rGO, avoiding their reassembly to graphite. The rGO sheets prevent the agglomeration of Fe3O4 NPs and enable a uniform dispersion of these metal oxide particles. The size distribution and coverage density of Fe3O4 NPs deposited on rGO can be controlled by varying the initial mass ratio of GO and iron precursor, Fe(acac)3. With an initial mass ratio of GO and Fe(acac)3 of 5:5, the surfaces of rGO sheets are densely covered by spherical Fe3O4 NPs with an average size of 19.9 nm. The magnetic-functionalized rGO hybrid exhibits a good magnetic property and the specific saturation magnetization (Ms) is 13.2 emu g−1. The adsorption test of methylene blue from aqueous solution demonstrates the potential application of this rGO-Fe3O4 hybrid composite in removing organic dyes from polluted water.

Iodide-induced adsorption of lead(II) ion on a glassy carbon electrode modified with ferroferric oxide nanoparticles

Spherical Fe3O4 nanoparticles (NPs) were prepared by hydrothermal synthesis and characterized by scanning electron microscopy and X-ray diffraction. A glassy carbon electrode was modified with such NPs to result in a sensor for Pb(II) that is based on the strong inducing adsorption ability of iodide. The electrode gives a pair of well-defined redox peaks for Pb(II) in pH 5.0 buffer containing 10 mM concentrations of potassium iodide, with anodic and cathodic peak potentials at −487 mV and −622 mV (vs. Ag/AgCl), respectively. The amperometric response to Pb(II) is linear in the range from 0.10 to 44 nM, and the detection limit is 40 pM at an SNR of 3. The sensor exhibits high selectivity and reproducibility.

Photoacoustic Method for Measurement of Thermal Effusivity of Fe3O4 Nanofluid

Photoacoustic (PA) sensor was designed and developed to evaluate thermal effusivity of Fe3O4 nanofluid. The PA sensor is based on open cell mode (OPC) to measure acoustic signals from low concentration of nanoparticulate suspensions in ethylene glycol (EG). Spherical Fe3O4 nanoparticles (NPs) were obtained by chemical precipitation method in powder form. The obtained NPs were stabilized by acetylacetone (acac) in EG. Thermal conductivity estimation was carried out with the help of transient hot wire method. The developed PA sensor was calibrated by measuring thermal effusivity of standard samples. The acoustic signals of the PA experiments have been analyzed with a simple Rosencwaig-Gersho theoretical model.

Synthesis of Monodisperse Magnetite Nanocrystals via Partially Reduced Precipitation Method

Ferromagnetic Fe3O4 nanocrystals with sphere-like morphology have been successfully synthesized by a partial reduction-precipitated crystallization method using ferric chloride as single iron source, hydroxylammonium chloride (HONH3Cl) as reducing reagent, and ammonia as precipitating reagent. This synthesis is carried out in a reducing atmosphere in the absence of inert gas. The chemical composition and morphology of the sample were characterized by X-ray power diffraction (XRD), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM). The experiment results clearly show that the synthesized sample mainly consists of a large quantity of spherical Fe3O4 nanoparticles with a size of about 5–11 nm, and HONH3Cl plays important roles in the formation of the products. Besides, the magnetic property of the sample has been investigated using a vibrating sample magnetometer (VSM) and the magnetization saturation value is approximately 43.5 emu/g.

In situ synthesis of Fe3O4/cellulose microspheres with magnetic-induced protein delivery

Regenerated cellulose microspheres (RCS) were successfully prepared by using the sol-gel transition (SGT) method from cellulose drops in 7 wt% NaOH/12 wt% urea aqueous solution precooled to −12 °C. Subsequently, novel magnetic Fe3O4/cellulose microspheres (MRCS) were fabricated by in situ synthesis of Fe3O4nanoparticles into the cellulose pores of RCS, which were used as the solid template microreactor. Their structure and morphology were analysed using optical photomicrographs, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicated that the spherical magnetic Fe3O4nanoparticles were dispersed uniformly and immobilized in the cellulose matrix, and the structure and nature of Fe3O4 were conserved perfectly. The magnetometric measurements revealed that the MRCS exhibited sensitive magnetic-induced delivery, and had extremely small hysteresis loop and low coercivity. Moreover, MRCS displayed excellent adsorption and controlled release capabilities on bovine serum albumin (BSA). The Fe3O4nanoparticles in the cellulose microspheres play an important role in both the creation of the magnetic-induced transference and the improvement of the targeting protein delivery and release. It will be important for applications in the biomaterials field.

Synthesis and characterization of biocompatible Fe3O4 nanoparticles

In this study, magnetite (Fe3O4) nanoparticles with a size range of 8-20 nm were prepared by the modified controlled chemical coprecipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline medium. In the process, two kinds of surfactant (sodium oleate and polyethylene glycol) were studied; then, sodium oleate was chosen as the apt surfactant to attain ultrafine, nearly spherical and well-dispersed (water-base) Fe3O4 nanoparticles, which had well magnetic properties. The size and size distribution of nanoparticles were determined by particle size analyzer. And the magnetite nanoparticles was characterized by X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction (ED) photography, Fourier transform infrared spectrometer (FT-IR), and vibrating-sample magnetometer (VSM). Also the effect of many parameters on the Fe3O4 nanoparticles was studied, such as reaction temperature, pH of the solution, stirring rate and concentration of sodium oleate. And the 5-dimethylthiazol-2-yl-2,5- diphenyltetrazolium bromide (MTT) assay was performed to evaluate the biocompatibility of magnetite nanoparticles. The results showed that the Fe3O4 nanoparticles coated by sodium oleate had a better biocompatibility, better magnetic properties, easier washing, lower cost, and better dispersion than the magnetite nanoparticles coated by PEG.

E-PROMs graduate to 256-K density with scaled [formula omitted] process : M. Van Buskirk, M. Holler, G. Korsh, B. Lee, S. Lee, D. Tang, G. Teng, S. Fouts, P. Dang and W. Fisher. Electronics, 89 (24 February 1983)

The sandwich quaternary composite of [email protected]3O4@PANI decorated with WO3 particles was successfully synthesized using simple hydrothermal method and chemical oxidation polymerization. The microstructure, chemical composition and morphology of the samples were investigated in detail. The spherical Fe3O4 and WO3 nanoparticles with an average diameter of 300–500 nm and 50–150 nm, respectively, were distributed between [email protected] layers. The as-prepared samples were made into cylinder shape with a paraffin matrix to obtain electromagnetic parameters by a vector network analyzer at 2–18 GHz. The electromagnetic wave absorbing performances of [email protected]3O4@[email protected]3 composite are significantly enhanced compared with [email protected]3O4, [email protected]3O4@PANI, with the maximum absorption as high as −46.7 dB for a coating of 4 mm and the maximum absorbing bandwidth (≤10 dB) of 1.8 GHz (from 12.4 to 14.2 GHz) at only 1.5 mm. The results demonstrate that the sandwich structure composite with improving microwave absorption properties can be used as a promising absorber in weakening electromagnetic wave irradiation.