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Fe3O4 Nanoparticles (fe3o4 + nanoparticle)
Selected AbstractsThe Oriented Self-Assembly of Magnetic Fe3O4 Nanoparticles into Monodisperse Microspheres and Their Use as Substrates in the Formation of Fe3O4 NanorodsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Guangcheng Xi Abstract We describe a facile solvothermal route for the large-scale preparation of ferromagnetic Fe3O4 sub-micrometer spheres and nanorods by using FeCl3 as the iron source, oleic acid as the surfactant, and ethylene glycol as the reducing agent and solvent. The as-synthesized Fe3O4 microspheres are composed of a mess of Fe3O4 nanoparticles with a size of 10 nm and have nearly monodisperse diameters that can be controlled in the range 100,410 nm. HRTEM images and SAED patterns show that these microspheres present a "single-crystalline" nature, which can be attributed to the highly oriented assembly of the small Fe3O4 nanoparticles. Interestingly, by using the pre-synthesized Fe3O4 microspheres as the growth substrate, single-crystalline Fe3O4 nanorods can be formed on the surfaces of the microspheres. These nanorods are about 7,20 nm in diameter and 120,400 nm in length, and have smooth surfaces. The formation mechanisms of the Fe3O4 microspheres and nanorods have been investigated and discussed. Furthermore, the magnetic properties of the as-synthesized microspheres and nanorods have also been investigated and the magnetization saturation values are 74.6 and 92.3 emu/g, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Preparation of Uniform, Water-Soluble, and Multifunctional Nanocomposites with Tunable SizesADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Dechao Niu Abstract Novel, thiol-functionalized, and superparamagnetic, silica composite nanospheres (SH-SSCNs) with diameters smaller than 100,nm are successfully fabricated through the self-assembly of Fe3O4 nanoparticles and polystyrene100 - block -poly(acrylic acid)16 and a subsequent sol-gel process. The size and magnetic properties of the SH-SSCNs can be easily tuned by simply varying the initial concentrations of the magnetite nanoparticles in the oil phase. By incorporating fluorescent dye molecules into the silica network, the composite nanospheres can be further fluorescent-functionalized. The toxicity of the SH-SSCNs is evaluated by choosing three typical cell lines (HUVEC, RAW264.7, and A549) as model cells, and no toxic effects are observed. It is also demonstrated that SH-SSCNs can be used as a new class of magnetic resonance imaging (MRI) probes, having a remarkably high spin,spin (T2) relaxivity (r2*,=,176.1,mM,1 S,1). The combination of the sub-100-nm particle size, monodispersity in aqueous solution, superparamagnetism, and fluorescent properties of the SH-SSCNs, as well as the non-cytotoxicity in vitro, provides a novel and potential candidate for an earlier MRI diagnostic method of cancer. [source] Superparamagnetic Hyperbranched Polyglycerol-Grafted Fe3O4 Nanoparticles as a Novel Magnetic Resonance Imaging Contrast Agent: An In Vitro AssessmentADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Liang Wang Abstract Hyperbranched polyglycerol-grafted, magnetic Fe3O4 nanoparticles (HPG-grafted MNPs) are successfully synthesized by surface-initiated ring-opening multibranching polymerization of glycidol. Reactive hydroxyl groups are immobilized on the surface of 6,9,nm Fe3O4 nanoparticles via effective ligand exchange of oleic acid with 6-hydroxy caproic acid. The surface hydroxyl groups are treated with aluminum isopropoxide to form the nanosized macroinitiators. The successful grafting of HPG onto the nanoparticles is confirmed by infrared and X-ray photoelectron spectroscopy. The HPG-grafted MNPs have a uniform hydrodynamic diameter of (24.0,±,3.0) nm, and are very stable in aqueous solution, as well as in cell culture medium, for months. These nanoparticles have great potential for application as a new magnetic resonance imaging contrast agent, as evidenced by their lack of cytotoxicity towards mammalian cells, low uptake by macrophages, excellent stability in aqueous medium and magnetic fields, and favorable magnetic properties. Furthermore, the possibility of functionalizing the hydroxyl end-groups of the HPG with cell-specific targeting ligands will expand the range of applications of these MNPs. [source] Dendrimer-Functionalized Iron Oxide Nanoparticles for Specific Targeting and Imaging of Cancer Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2007H. Wang Abstract We demonstrated a unique approach that combines a layer-by-layer (LbL) self-assembly method with dendrimer chemistry to functionalize Fe3O4 nanoparticles (NPs) for specific targeting and imaging of cancer cells. In this approach, positively charged Fe3O4 NPs (8.4,nm in diameter) synthesized by controlled co-precipitation of FeII and FeIII ions were modified with a bilayer composed of polystyrene sulfonate sodium salt and folic acid (FA)- and fluorescein isothiocyanate (FI)-functionalized poly(amidoamine) dendrimers of generation 5 (G5.NH2 -FI-FA) through electrostatic LbL assembly, followed by an acetylation reaction to neutralize the remaining surface amine groups of G5 dendrimers. Combined flow cytometry, confocal microscopy, transmission electron microscopy, and magnetic resonance imaging studies show that Fe3O4/PSS/G5.NHAc-FI-FA NPs can specifically target cancer cells overexpressing FA receptors. The present approach to functionalizing Fe3O4 NPs opens a new avenue to fabricating various NPs for numerous biological sensing and therapeutic applications. [source] Dendrimer-Functionalized Shell-crosslinked Iron Oxide Nanoparticles for In-Vivo Magnetic Resonance Imaging of Tumors,ADVANCED MATERIALS, Issue 9 2008Xiangyang Shi A powerful magnetic nanoprobe with folic acid (FA)-targeting ligands is fabricated by dendrimer functionalization of Fe3O4 nanoparticles (NPs) precoated with crosslinkable and biocompatible polymer multilayer shells. This magnetic probe allows for magnetic resonance imaging of FA receptor-overexpressing tumor cells in vitro and of an early-stage tumor model in vivo (see picture). [source] Ultra-deep desulfurization adsorbents for hydrotreated diesel with magnetic mesoporous aluminosilicatesAICHE JOURNAL, Issue 5 2010Wangliang Li Abstract Magnetic mesoporous aluminosilicates (MMAS) were synthesized by hydrothermal method and applied as ultra-deep desulfurization adsorbents for hydrotreated diesel. The size of oleic-coated magnetic Fe3O4 nanoparticles prepared by coprecipitation method was about 20 nm. MMAS shows better desulfurization properties for removal of sulfur compounds than NaY and MCM-41. The amount of Fe3O4 nanoparticles has significant effects on specific surface area/pore volume and acidic properties, thus, can affect the desulfurization properties of MMAS. Desulfurization properties of MMAS can be improved with the increase of temperature from 30,70°C and decrease the oil to adsorbent ratio. With the increase of Fe3O4 content, adsorption capacity first increased and then decreased. The sulfur adsorption of MMAS was due to the synergetic effect of strong molecular affinity of the magnetite to the sulfur compound and large surface area/pore volume of the mesoporous aluminosilicates. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Synthesis of magnetic, reactive, and thermoresponsive Fe3O4 nanoparticles via surface-initiated RAFT copolymerization of N -isopropylacrylamide and acroleinJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2010Zhong-Peng Xiao Abstract A reversible addition-fragmentation chain transfer (RAFT) agent was directly anchored onto Fe3O4 nanoparticles in a simple procedure using a ligand exchange reaction of S -1-dodecyl- S,-(,,,,-dimethyl-,,-acetic acid)trithiocarbonate with oleic acid initially present on the surface of pristine Fe3O4 nanoparticles. The RAFT agent-functionalized Fe3O4 nanoparticles were then used for the surface-initiated RAFT copolymerization of N -isopropylacrylamide and acrolein to fabricate structurally well-defined hybrid nanoparticles with reactive and thermoresponsive poly(N -isopropylacrylamide- co -acrolein) shell and magnetic Fe3O4 core. Evidence of a well-controlled surface-initiated RAFT copolymerization was gained from a linear increase of number-average molecular weight with overall monomer conversions and relatively narrow molecular weight distributions of the copolymers grown from the nanoparticles. The resulting novel magnetic, reactive, and thermoresponsive core-shell nanoparticles exhibited temperature-trigged magnetic separation behavior and high ability to immobilize model protein BSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 542,550, 2010 [source] Facile one-step synthesis of electromagnetic functionalized polypyrrole/Fe3O4 nanotubes via a self-assembly processJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2010Wei-Dong Zhang Abstract This article reports a simple self-assembly process for facile one-step synthesis of novel electromagnetic functionalized polypyrrole (PPy)/Fe3O4 composite nanotubes using p -toluenesulfonic acid (p -TSA) as the dopant and FeCl3 as the oxidant. The key trick of the present method is to use FeCl3 as the oxidant for both PPy and Fe3O4 in the same time to synthesize PPy/Fe3O4 composite nanotubes in one-step. This facile one-step method is much simpler than the conventional approach using the Fe3O4 nanoparticles as the additives. Compared to the similar composites synthesized using the conventional method, the as-prepared PPy- p -TSA/Fe3O4 composite nanotubes using the facile one-step self-assembly process show much higher room-temperature conductivity. Moreover, the composite nanotubes display interesting ferromagnetic behavior. The electrical properties of the PPy- p -TSA/Fe3O4 composite nanotubes are dominated by the amount of FeCl3 while their magnetic properties are controlled by the amount of FeCl2. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 320,326, 2010 [source] Adsorption Kinetics and Thermodynamics of Acid Dyes on a Carboxymethylated Chitosan-Conjugated Magnetic Nano-AdsorbentMACROMOLECULAR BIOSCIENCE, Issue 3 2005Yang-Chuang Chang Abstract Summary: The monodisperse chitosan-conjugated Fe3O4 nanoparticles with a mean diameter of 13.5 nm were fabricated by the carboxymethylation of chitosan and its covalent binding onto Fe3O4 nanoparticles via carbodiimide activation. The carboxymethylated chitosan (CMCH)-conjugated Fe3O4 nanoparticles with about 4.92 wt.-% of CMCH had an isoelectric point of 5.95 and were shown to be quite efficient as anionic magnetic nano-adsorbent for the removal of acid dyes. Both the adsorption capacities of crocein orange G (AO12) and acid green 25 (AG25), as the model compounds, decreased with increasing pH, and the decreasing effect was more significant for AO12. On the contrary, the increase in the ionic strength decreased the adsorption capacity of AG25 but did not affect, obviously, the adsorption capacity of AO12. By the addition of NaCl and NaOH, both AO12 and AG25 could desorb and their different desorption behavior could be attributed to the combined effect of pH and ionic strength. From the adsorption kinetics and thermodynamics studies, it was found that both the adsorption processes of AO12 and AG25 obeyed the pseudo-second-order kinetic model, Langmuir isotherm, and might be surface reaction-controlled. Furthermore, the time required to reach the equilibrium for each one was significantly shorter than those using the micro-sized adsorbents due to the large available surface area. Also, based on the weight of chitosan, the maximum adsorption capacities were 1,883 and 1,471 mg,·,g,1 for AO12 and AG25, respectively, much higher than the reported data. Thus, the anionic magnetic nano-adsorbent could not only be magnetically manipulated but also possessed the advantages of fast adsorption rate and high adsorption capacity. This could be useful in the fields of separation and magnetic carriers. Acid dyes adsorption onto the CMCH-conjugated Fe3O4 nanoparticles. [source] Multifunctional Magnetoplasmonic Nanoparticle Assemblies for Cancer Therapy and Diagnostics (Theranostics),MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2010Wei Chen Abstract In this work, we describe the preparation and biomedical functionalities of complex nanoparticle assemblies with magnetoplasmonic properties suitable for simultaneous cancer therapy and diagnostics (theranostics). Most commonly magnetoplasmonic nanostructures are made by careful adaptation of metal reduction protocols which is both tedious and restrictive. Here we apply the strategy of nanoscale assemblies to prepare such systems from individual building blocks. The prepared superstructures are based on magnetic Fe3O4 nanoparticles encapsulated in silica shell representing the magnetic module. The cores are surrounded in a corona-like fashion by gold nanoparticles representing the plasmonic module. As additional functionality they were also coated by poly(ethyleneglycol) chains as a cloaking agent to extend the blood circulation time. The preparation is exceptionally simple and allows one to vary the contribution of each function. Both modules can carry drugs and, in this study, they were loaded with the potential anticancer drug curcumin. A comprehensive set of microscopy, spectroscopy and biochemical methods were applied to characterize both imaging and therapeutic function of the nanoparticle assemblies against leukemia HL-60 cells. High contrast magnetic resonance images and high apoptosis rates demonstrate the success of assembly approach for the preparation of magnetoplasmonic nanoparticles. This technology allows one to easily "dial in" the functionalities in the clinical setting for personalized theranostic regiments. [source] A Novel Approach to Magnetic Nanoadsorbents with High Binding Capacity for Bovine Serum AlbuminMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2007Yabin Sun Abstract Magnetic nanoadsorbents using Fe3O4 nanoparticles as cores and poly(methyl acrylic acid) (PMAA) as ionic exchange groups were prepared through our novel approach. Two steps were involved in this approach: the first was to functionalize the magnetic nanoparticles (MNPs) with methacrylate double bonds via the combination of ligand exchange and condensation of methacryloxypropyltrimethoxysilane(MPS); the second was to graft PMAA chains onto the surface of MNPs through radical polymerization. The success of the various surface functionalization steps was ascertained using FTIR and XPS. The as-synthesized PMAA-coated MNPs were effective in binding bovine serum albumin (BSA) with a high capacity of 1,300 mg,·,g,1. [source] Surface Functionalization of Fe3O4 Magnetic Nanoparticles via RAFT-Mediated Graft PolymerizationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2006Wen-Cai Wang Abstract Summary: Surface functionalization of Fe3O4 magnetic nanoparticles (MNP) via living radical graft polymerization with styrene and acrylic acid (AAc) in the reversible addition-fragmentation chain transfer (RAFT)-mediated process was reported. Peroxides and hydroperoxides generated on the surface of Fe3O4 nanoparticles via ozone pretreatment facilitated the thermally initiated graft polymerization in the RAFT-mediated process. A comparison of the MNP before and after the RAFT-mediated process was carried out using transmission electron microscopy (TEM) analysis, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Gel permeation chromatography (GPC) was used to determine the molecular weight of the free homopolymer in the reaction mixture. Well-defined polymer chains were grown from the MNP surfaces to yield particles with a Fe3O4 core and a polymer outer layer. The resulting core,shell Fe3O4 - g -polystyrene and Fe3O4 - g -poly(acrylic acid) (PAAc) nanoparticles formed stable dispersions in the organic solvents for polystyrene (PS) and PAAc, respectively. Schematic illustration of thermally induced graft polymerization of styrene and AAc with the ozone-treated Fe3O4 MNP. [source] Binding and Sulfonation of Poly(acrylic acid) on Iron Oxide Nanoparticles: a Novel, Magnetic, Strong Acid Cation Nano-AdsorbentMACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2005Sou-Yee Mak Abstract Summary: A novel, magnetic, strong acid cation nano-adsorbent has been developed by the covalent binding of poly(acrylic acid) on the surface of Fe3O4 nanoparticles followed by sulfonation using sulfanilic acid via carbodiimide activation. The nano-absorbent can be easily recovered or manipulated with an external magnetic field and shows a good capacity for the rapid and efficient adsorption of multivalent metal cations from aqueous solutions. An illustration for the binding and sulfonation of PAA on Fe3O4 nanoparticles to produce a magnetic, strong acid cation nano-adsorbent. [source] Synthesis and stability of iron nanoparticles for lunar environment studiesMETEORITICS & PLANETARY SCIENCE, Issue 6 2010Ching-Cheh HUNG However, unlike the true lunar dust, today's simulants do not contain nanophase iron. Two different processes have been developed to fabricate nanophase iron to be used as part of a lunar dust simulant. (1) The first is to sequentially treat a mixture of ferric chloride, fluorinated carbon, and soda lime glass beads at about 300 °C in nitrogen, at room temperature in air, and then at 1050 °C in nitrogen. The product includes glass beads that are gray in color, can be attracted by a magnet, and contains ,-iron nanoparticles (which seem to slowly lose their lattice structure in ambient air during a period of 12 months). This product may have some similarity to the lunar glassy agglutinate, which contains FeO. (2) The second is to heat a mixture of carbon black and a lunar simulant (a mixed metal oxide that includes iron oxide) at 1050 °C in nitrogen. This process simulates lunar dust reactions with the carbon in a micrometeorite at the time of impact. The product contains a chemically modified simulant that can be attracted by a magnet and has a surface layer whose iron concentration increased during the reaction. The iron was found to be ,-iron and Fe3O4 nanoparticles, which appear to grow after the fabrication process. This growth became undetectable after 6 months of ambient air storage, but may last for several years or longer. [source] Ternary magnetic nanocomposites based on core,shell Fe3O4/polyaniline nanoparticles distributed in PVDF matrixPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2010Mykhaylo Petrychuk Abstract Magnetic, electric, and radioprotector properties of hybrid nanocomposites of Fe3O4 nanoparticles with and without a shell of polyaniline (PANI), which is doped with dodecylbenzenesulfonic acid (DBSA), dispersed in polyvinylidene fluoride (PVDF) matrix have been studied. It has been found that the presence of PANI,DBSA as a separate filler in the ternary nanocomposite film, which also contains as another filler the core,shell Fe3O4/PANI,DBSA nanoparticles, facilitates dispersion of the magnetic filler due to the improvement of its compatibility with the PVDF matrix. This leads both to the decrease in coefficient of squareness of the hysteresis loop and to the increase in electromagnetic energy (EME) absorption of the nanocomposite film. [source] EPR studies on Na-oleate coated Fe3O4 nanoparticlesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004Y. Köseo Abstract Superparamagnetic iron oxide nanoparticles were prepared by the co-precipitation technique. Then, fine iron oxide nanoparticles were coated by Na-oleate. Magnetic properties of Na-oleate coated and uncoated iron oxide nanoparticles were investigated by Electron Paramagnetic Resonance (EPR) technique. At room temperature, a single, strong and broad EPR signal was observed for both samples with effective g-values of 2,0839 and 2,18838 for coated and uncoated samples, respectively. The intensity, line width and the resonance field for both coated and uncoated samples are strongly temperature dependent. When the sample is coated with Na-oleate, the line width and the resonance field values of the EPR signal increase due to the decrease in the magnetic interaction between the particles. The total effective magnetic moment of such coated particles is found to decrease, which is most likely due to a non-collinear spin structure originated from the pinning of the surface spins and coated surfactant at the interface of nanoparticles. [source] ESR studies on superparamagnetic Fe3O4 nanoparticlesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004Y. Köseo Abstract In this study we have investigated temperature and frequency dependence of magnetic properties of superparamagnetic iron oxide nanoparticles (SPION). ESR measurements have been carried out in a temperature range of 10,300 K. A single, relatively broad and temperature dependent EPR signal was observed at all measurement temperatures. The linewidth slightly increases with decreasing temperature down to 100 K, then it sharply increases down to 60 K. Below 60 K the trend is reversed and the linewidth start to decrease. The resonance field remains almost constant down to 100 K and decreases sharply as the temperature is decreased further. The resonance field of the ESR spectra of Fe3O4 shows a linear dependence on microwave frequency. By using experimental results, the effective g-value and internal field are deduced as 1.9846 and ,40 G, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticlesPOLYMER INTERNATIONAL, Issue 3 2006Guihua Qiu Abstract Ultrasonically initiated miniemulsion polymerization of styrene was conducted in the presence of Fe3O4 nanoparticles. Stable polystyrene (PS)/Fe3O4 nanocomposite emulsions were prepared and magnetic PS/Fe3O4 composite particles were obtained through magnetic separation. The whole procedure comprised two steps. First, Fe3O4 nanoparticles were dispersed in the monomer phase with the aid of stabilizer Span-80. Second, miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles was carried out under an ultrasonic field in the absence of a chemical initiator. The affecting factors, including stabilizer concentration, surfactant concentration, hexadecane concentration and the amount of Fe3O4, were systematically studied. Stabilizer concentration, surfactant concentration and hexadecane concentration strongly affected the formation of the coagulation. The least amount of coagulation was formed at 2.5 wt% Span-80 concentration. The addition of Fe3O4 nanoparticles drastically increased the polymerization rate owing to the fact that Fe3O4 nanoparticles increased the acoustic intensity and Fe2+ reacted with H2O2 to produce hydroxyl radicals and increase the number of radicals. The increase in cosurfactant concentration and power output also increased the polymerization rate. Copyright © 2005 Society of Chemical Industry [source] | ||||||||||||||||||||||||||||