γ-Fe2O3 Magnetic Nanoparticles Research Articles

Adsorption of the dye Remazol Red 198 (RR198) by O-carboxymethylchitosan-N-lauryl/γ-Fe2O3 magnetic nanoparticles

O-Carboxymethylchitosan-N-lauryl/γ-Fe2O3 magnetic nanoparticles (OCh-LM) were synthesized and characterized using FT-IR, TGA, SEM and VSM. The OCh-LM was essentially spherical in shape, with a mean particle size of 11.1±3.4nm and saturated magnetization of 18.4emu/g. The nanoparticle was used to remove the anionic dye Remazol Red 198 (RR198) from aqueous solution by the batch system. The kinetic data and adsorption isotherm were best fitted by the pseudo-second order kinetic model, and the Langmuir–Freundlich isotherm, respectively. Thermodynamic parameters such as change in enthalpy, change in Gibbs free energy and change in entropy were estimated, and the results indicated that the adsorption process was spontaneous and endothermic. The maximum adsorption capacity, calculated through the Langmuir–Freundlich model at 25°C, was 216mg/g. Desorption of the dye and reuse of the adsorbent were performed in four cycles. These results show that OCh-LM can be potentially used as a magnetic adsorbent to remove RR198 and probably other anionic reactive dyes from aqueous solution for avoiding the secondary pollution.

An effective and recyclable adsorbent for the removal of heavy metal ions from aqueous system: Magnetic chitosan/cellulose microspheres

Development of highly cost-effective, highly operation-convenient and highly efficient natural polymer-based adsorbents for their biodegradability and biocompatibility, and supply of safe drinking water are the most threatening problems in water treatment field. To tackle the challenges, a new kind of efficient recyclable magnetic chitosan/cellulose hybrid microspheres was prepared by sol–gel method. By embedding magnetic γ-Fe2O3 nanoparticles in chitosan/cellulose matrix drops in NaOH/urea aqueous solution, it combined renewability and biocompatibility of chitosan and cellulose as well as magnetic properties of γ-Fe2O3 to create a hybrid system in heavy metal ions removal.

Highly Efficient Labeling of Human Lung Cancer Cells Using Cationic Poly-l-lysine-Assisted Magnetic Iron Oxide Nanoparticles.

Cell labeling with magnetic iron oxide nanoparticles (IONPs) is increasingly a routine approach in the cell-based cancer treatment. However, cell labeling with magnetic IONPs and their leading effects on the biological properties of human lung carcinoma cells remain scarcely reported. Therefore, in the present study the magnetic γ-Fe2O3 nanoparticles (MNPs) were firstly synthesized and surface-modified with cationic poly-l-lysine (PLL) to construct the PLL-MNPs, which were then used to magnetically label human A549 lung cancer cells. Cell viability and proliferation were evaluated with propidium iodide/fluorescein diacetate double staining and standard 3-(4,5-dimethylthiazol-2-diphenyl-tetrazolium) bromide assay, and the cytoskeleton was immunocytochemically stained. The cell cycle of the PLL-MNP-labeled A549 lung cancer cells was analyzed using flow cytometry. Apoptotic cells were fluorescently analyzed with nuclear-specific staining after the PLL-MNP labeling. The results showed that the constructed PLL-MNPs efficiently magnetically labeled A549 lung cancer cells and that, at low concentrations, labeling did not affect cellular viability, proliferation capability, cell cycle, and apoptosis. Furthermore, the cytoskeleton in the treated cells was detected intact in comparison with the untreated counterparts. However, the results also showed that at high concentration (400 µg mL−1), the PLL-MNPs would slightly impair cell viability, proliferation, cell cycle, and apoptosis and disrupt the cytoskeleton in the treated A549 lung cancer cells. Therefore, the present results indicated that the PLL-MNPs at adequate concentrations can be efficiently used for labeling A549 lung cancer cells and could be considered as a feasible approach for magnetic targeted anti-cancer drug/gene delivery, targeted diagnosis, and therapy in lung cancer treatment.

Fabrication, superhydrophobicity, and microwave absorbing properties of the magnetic γ-Fe2O3/bamboo composites

Abstract Magnetic γ-Fe2O3 nanoparticles were successfully deposited on the surface of the bamboo via a coprecipitation process at room temperature. Spherical-like magnetic γ-Fe2O3 nanoparticles with a diameter of about 17 nm displayed well superparamagnetic behavior and were chemically bonded to the bamboo surface through the combination of hydrogen groups. With further modification by 1H,1H,2H,2H-perfluorodecyltri ethoxysilane (FAS-17), magnetic γ-Fe2O3/bamboo composites (MBCs) expressed superhydrophobic performances to not only water but also common liquids like coffee, milk, ink, tea, and coke. When immersed into the corrosive solutions including strong acid (pH = 1), heavy alkaline (pH = 14), and salt with high concentration (5 M) for 24 h, superhydrophobic magnetic γ-Fe2O3/bamboo composites (SMBC) still remained magnetism as well as superhydrophobicity. Also, under harsh conditions like boiled at 100 °C for 4 h, frozen at − 40 °C for 24 h, SMBCs were kept a robust magnetism and superhydrophobicity. Additionally, SMBC was a typical ferromagnet and exhibited some microwave absorbabilities.

Altering the response of intracellular reactive oxygen to magnetic nanoparticles using ultrasound and microbubbles

Engineered iron oxide magnetic nanoparticles (MNPs) are one of the most promising tools in nanomedicine-based diagnostics and therapy. However, increasing evidence suggests that their specific delivery efficiency and potential long-term cytotoxicity remain a great concern. In this study, using 12 nm γ-Fe2O3 MNPs, we investigated three types of uptake pathways for MNPs into HepG2 cells: (1) a conventional incubation endocytic pathway; (2) MNPs co-administrated with microbubbles under ultrasound exposure; and (3) ultrasound delivery of MNPs covalently coated on the surface of microbubbles. The delivery efficiency and intracellular distribution of MNPs were evaluated, and the cytotoxicity induced by reactive oxygen species (ROS) was studied in detail. The results show that MNPs can be delivered into the lysosomes via classical incubation endocytic internalization; however, microbubbles and ultrasound allow the MNPs to pass through the cell membrane and enter the cytosol via a non-internalizing uptake route much more evenly and efficiently. Further, these different delivery routes result in different ROS levels and antioxidant capacities, as well as intracellular glutathione peroxidase activity for HepG2 cells. Our data indicate that the microbubble–ultrasound treatment method can serve as an efficient cytosolic delivery strategy to minimize long-term cytotoxicity of MNPs.

Dielectric properties of magnetic nanoparticles’ suspension in a ferroelectric liquid crystal

Colloids of elongated γ-Fe2O3 magnetic nanoparticles (NPs) in a ferroelectric liquid crystal (FLC) were studied. Decreasing the dielectric strength of the Goldstone mode and changing the value of Cole–Cole parameter were found in the suspensions. It was also shown that the effect of introducing magnetic particles into a FLC consists of increasing the electric field strength magnitude required for unwinding its helical structure. Effect of magnetic field on dielectric properties of the FLC colloid was also studied. Dielectric constant measured under static magnetic field is different for the FLC host and FLC doped with the NPs.

Effect of magnetic gamma-iron oxide nanoparticles on the efficiency of dye-sensitized solar cells

Magnetic γ-Fe2O3 nanoparticles are introduced into the photoanodes to improve the performance of DSSCs by the γ-Fe2O3 nanoparticles-induced internal magnetic field effect.

Study on γ-Fe<sub>2</sub>O<sub>3</sub> Magnetic Fluid by Thermal Oxidizing of Fe<sub>3</sub>O<sub>4</sub> Nanoparticles

In this paper, Fe3O4magnetic nanoparticles were synthesized by chemical co-precipitation method and their surface was modified by sodium oleate. The γ-Fe2O3magnetic nanoparticles were achieved by thermal oxidizing of Fe3O4. The γ-Fe2O3magnetic fluid was prepared by using silicone oil as carrier liquid and oleic acid as surface modification agent, and the saturation magnetization of prepared γ-Fe2O3magnetic fluid hits 14.25emu/g.

Polyethylenimine mediated magnetic nanoparticles for combined intracellular imaging, siRNA delivery and anti-tumor therapy

PEI–magnetic γ-Fe2O3nanoparticles (MNPs) were modified with fluorescent FITC for intracellular imaging and were also used for survivin siRNA delivery. The results suggested that the fabricated PEI–MNPs are a promising nanovehicle for efficient anti-tumor therapy.

Magnetic γ-Fe2O3, Fe3O4, and Fe nanoparticles confined within ordered mesoporous carbons as efficient microwave absorbers.

A series of magnetic γ-Fe2O3, Fe3O4, and Fe nanoparticles have been successfully introduced into the mesochannels of ordered mesoporous carbons by the combination of the impregnation of iron salt precursors and then in situ hydrolysis, pyrolysis and reduction processes. The magnetic nanoparticles are uniformly dispersed and confined within the mesopores of mesoporous carbons. Although the as-prepared magnetic mesoporous carbon composites have high contents of magnetic components, they still possess very high specific surface areas and pore volumes. The magnetic hysteresis loops measurements indicate that the magnetic constituents are poorly-crystalline nanoparticles and their saturation magnetization is evidently smaller than bulky magnetic materials. The confinement of magnetic nanoparticles within the mesopores of mesoporous carbons results in the decrease of the complex permittivity and the increase of the complex permeability of the magnetic nanocomposites. The maximum reflection loss (RL) values of -32 dB at 11.3 GHz and a broad absorption band (over 2 GHz) with RL values <-10 dB are obtained for 10-Fe3O4-CMK-3 and 10-γ-Fe2O3-CMK-3 composites in a frequency range of 8.2-12.4 GHz (X-band), showing their great potentials in microwave absorption. This research opens a new method and idea for developing novel magnetic mesoporous carbon composites as high-performance microwave absorbing materials.

Influence of Process Factors on Diameter of Core (γ-Fe2O3)/Shell (Polyvinyl Alcohol) Structure Magnetic Nanofibers During Co-Axial Electrospinning

In this study, magnetic nanofibers were fabricated using polyvinyl alcohol (PVA) as a shelter for (γ-Fe2O3) magnetic nanoparticles suspension. Two-level full factorial experiments with center and augmented axial points were performed where process parameters studied were flow rate, applied voltage, distance between needle and collector, and collector rotating speed. The response variables analyzed were morphology and fiber diameter distribution. The model obtained from the experimental design revealed that the flow rate, voltage, the two-way interaction of these factors and the second order effect of flow rate-A2 were significant in determining nanofiber diameters. Nanofibers with smaller diameters tend to have higher tensile strength contributed by the better alignment of lamellae along the fibers axis and molecular orientation. The fabricated (γ-Fe2O3)/PVA nanofibers were ultra-fine with nano size diameter within the range of approximately 280–500 nm.

Formation of highly crystalline maghemite nanoparticles from ferrihydrite in the liquid phase

Fe5O7(OH)·4H2O ferrihydrite is a low-crystallinity antiferromagnetic material. γ-Fe2O3 (maghemite) magnetic nanoparticles were prepared from a ferrihydrite precursor, by chemically induced transformation in FeCl2/NaOH solution. The magnetization, morphology, crystal structure and chemical composition of the products were determined by vibrating sample magnetometry, transmission electron microscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy (XPS). Ferrihydrite underwent aggregation growth and transformed into α-FeO(OH) (goethite) particles, which subsequently transformed into γ-Fe2O3 nanoparticles, that became coated with NaCl. The γ-Fe2O3 particles had a flake-like morphology, when prepared from 0.01 mol/L FeCl2 and a FeCl2:NaOH molar ratio of 0.4. The γ-Fe2O3 particles were more spherical, when prepared from a FeCl2:NaOH molar ratio of 0.6. The Fe content of the flake-like particles was lower than that of the spherical particles. Their magnetizations were similar, and the coercivity of the flake-like particles was larger. The differences in morphology and magnetization were attributed to the surface effect, and the difference in coercivity to the shape effect.

Piperidine and Piperazine Immobilized on Iron Oxide Nanoparticles as Magnetically Recyclable Heterogeneous Catalysts for One-Pot Synthesis of β-Phosphonomalonates

Piperidine and piperazine immobilized on silica-coated γ-Fe2O3 magnetic nanoparticles were synthesized as new supported bases via the reaction of chloro-functionalized γ-Fe2O3@SiO2 with piperidine and piperazine, respectively. The resulting bases were employed as magnetically recyclable heterogeneous catalysts for the efficient one-pot three-component synthesis of β-phosphonomalonates. The catalysts were easily separated from the reaction mixture by using a magnet and recycled for five times without significant loss of the catalytic activity.

Palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles: A new catalyst for C[sbnd]C bond formation via Mizoroki⬜Heck cross-coupling reaction

In this paper, palladium-DABCO complex supported on γ-Fe2O3 magnetic nanoparticles (Pd-DABCO-γ-Fe2O3) was synthesized and characterized by HRTEM, SEM, XRD, XPS, ICP, FT-IR, TGA, VSM and elemental analysis. The synthesized catalyst was successfully applied as a new magnetically recyclable heterogeneous catalyst in Mizoroki⬜Heck cross-coupling reaction of aryl halides with alkyl acrylates and styrene under solvent-free conditions.

Multifunctional hybrid silica nanoparticles based on [Mo6Br14]2− phosphorescent nanosized clusters, magnetic γ-Fe2O3 and plasmonic gold nanoparticles

We report on the synthesis, characterization and photophysical study of new luminescent and magnetic hybrid silica nanoparticles. Our method is based on the co-encapsulation of single maghemite γ-Fe2O3 nanoparticles and luminescent molybdenum cluster units [Mo6Bri8Bra6]2− through a water-in-oil (W/O) microemulsion technique. The as-prepared core–shell [Cs2Mo6Br14-γFe2O3]@SiO2 nanoparticles (45–53nm) possess a single magnetic core (6, 10.5 or 15nm) and the cluster units are dispersed in the entire volume of the silica sphere. The [Cs2Mo6Br14-γFe2O3]@SiO2 nanoparticles have a perfect spherical shape with a good monodispersity and they display red and near-infrared (NIR) emission in water under UV excitation, whose intensity depends on the magnetic core size. The hybrid nanoparticles have been characterized by transmission electron microscopy (TEM), high annular angular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDX), UV–Vis–NIR spectroscopy and magnetometer SQUID analysis. Small gold nanoparticles were successfully nucleated at the surface of the hybrid silica nanoparticles in order to add plasmonic properties.

Neocuproine-functionalized silica-coated magnetic nanoparticles for extraction of copper(II) from aqueous solution.

Neocuproine has been covalently bound to silica-coated maghemite (γ-Fe2O3) magnetic nanoparticles (MNPs) by a phenyl ether linkage. The resulting MNPs are able to remove Cu(II) from 12 ppm aqueous solution with an extraction efficiency of up to 99% at pH 2.

Immobilisation of Phenanthroline-Bis Triazine (C1-BTPhen) on Magnetic Nanoparticles for Co-Extraction of Americium(III) and Europium(III)

The present work reports a convenient route for the immobilisation of a phenanthroline-bis triazine (C1-BTPhen) group on the surface of zirconia-coated maghemite (γ-Fe2O3) magnetic nanoparticles. The magnetic nanoparticles functionalized with C1-BTPhen were able to co-extract Am(III) and Eu(III) from nitric acid (HNO3). The extraction efficiency of these C1-BTPhen-functionalized magnetic nanoparticles for both Am(III) and Eu(III) was 20% at 4M HNO3. The interaction between C1-BTPhen and metal cations is reversible. These functionalized magnetic nanoparticles can be used for the co-extraction of traces of Am(III) and Eu(III).

Effective separation of Am(III) and Eu(III) from HNO3 solutions using CyMe4-BTPhen-functionalized silica-coated magnetic nanoparticles.

It has been shown that CyMe4-BTPhen-functionalized silica-coated maghemite (γ-Fe2O3) magnetic nanoparticles (MNPs) are capable of quantitative separation of Am(III) from Eu(III) from HNO3 solutions. These MNPs also show a small but significant selectivity for Am(III) over Cm(III) with a separation factor of around 2 in 4 M HNO3. The water molecule in the cavity of the BTPhen may also play an important part in the selectivity.

Formation of nitrogen-doped graphene nanoscrolls by adsorption of magnetic γ-Fe2O3 nanoparticles

Graphene nanoscrolls are Archimedean-type spirals formed by rolling single-layer graphene sheets. Their unique structure makes them conceptually interesting and understanding their formation gives important information on the manipulation and characteristics of various carbon nanostructures. Here we report a 100% efficient process to transform nitrogen-doped reduced graphene oxide sheets into homogeneous nanoscrolls by decoration with magnetic γ-Fe2O3 nanoparticles. Through a large number of control experiments, magnetic characterization of the decorated nanoparticles, and ab initio calculations, we conclude that the rolling is initiated by the strong adsorption of maghemite nanoparticles at nitrogen defects in the graphene lattice and their mutual magnetic interaction. The nanoscroll formation is fully reversible and upon removal of the maghemite nanoparticles, the nanoscrolls return to open sheets. Besides supplying information on the rolling mechanism of graphene nanoscrolls, our results also provide important information on the stabilization of iron oxide nanoparticles.

Ni2+ supported on hydroxyapatite-core-shell γ-Fe2O3 nanoparticles: a novel, highly efficient and reusable lewis acid catalyst for the regioselective azidolysis of epoxides in water

In this research, Ni2+ supported on hydroxyapatite-core-shell magnetic γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ni2+) as a novel, efficient, reusable and heterogeneous catalyst was reported. In this protocol, we used this catalyst for the ring opening of epoxide with sodium azide in water. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.