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Sample records for octahedral fe3o4 microcrystals

  1. Large tunneling magnetoresistance in octahedral Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mitra, Arijit; Barick, Barun; Mohapatra, Jeotikanta; Sharma, H.; Meena, S. S.; Aslam, M.

    2016-05-01

    We have observed large tunneling Magnetoresistance (TMR) in amine functionalized octahedral nanoparticle assemblies. Amine monolayer on the surface of nanoparticles acts as an insulating barrier between the semimetal Fe3O4 nanoparticles and provides multiple tunnel junctions where inter-granular tunneling is plausible. The tunneling magnetoresistance recorded at room temperature is 38% which increases to 69% at 180 K. When the temperature drops below 150 K, coulomb staircase is observed in the current versus voltage characteristics as the charging energy exceeds the thermal energy. A similar study is also carried out with spherical nanoparticles. A 24% TMR is recorded at room temperature which increases to 41% at 180 K for spherical particles. Mössbauer spectra reveal better stoichiometry for octahedral particles which is attainable due to lesser surface disorder and strong amine coupling at the <111> facets of octahedral Fe3O4 nanoparticles. Less stoichiometric defect in octahedral nanoparticles leads to a higher value of spin polarization and therefore larger TMR in octahedral nanoparticles.

  2. A Facile Solvothermal Synthesis of Octahedral Fe3O4 Nanoparticles

    SciTech Connect

    Ooi, Frances; DuChene, Joseph S.; Qiu, Jianqing; Graham, Jeremy O.; Engelhard, Mark H.; Cao, Guixin; Gai, Zheng; Wei, Wei

    2015-06-01

    Magnetic nanoparticles are of great technological interest because they promise numerous potential opportunities in biomedicine and data storage. Although intriguing, these applications require exquisite control over nanostructure morphology in order to appropriately harness their magnetic properties. Most synthesis strategies reported to date are unable to routinely produce anisotropic Fe3O4 nanostructures with appropriate sizes to enable integration into biological systems. Here, we report a simple solvothermal synthesis for obtaining octahedral Fe3O4 nanoparticles with suitable sizes for cellular internalization. Furthermore, these ferromagnetic Fe3O4 octahedrons exhibit substantial saturation magnetization with minimal remanence, suggesting their potential applicability for a host of biomedical applications.

  3. Hydrothermal fabrication of octahedral-shaped Fe3O4 nanoparticles and their magnetorheological response

    NASA Astrophysics Data System (ADS)

    Jung, H. S.; Choi, H. J.

    2015-05-01

    Octahedral-shaped Fe3O4 nanoparticles were synthesized in the presence of 1,3-diaminopropane using a hydrothermal method and assessed as a potential magnetorheological (MR) material. Their morphology, crystal structure, and magnetic properties were examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively. The MR characteristics of the octahedral-shaped, Fe3O4 nanoparticle-based MR particles when dispersed in silicone oil with a 10 vol. % particle concentration were examined using a rotational rheometer under an external magnetic field. The resulting MR fluids exhibited a Bingham-like behavior with a distinctive yield stress from their flow curves.

  4. Nonequivalence of the octahedral site of cubic Fe3O4 magnetite

    NASA Astrophysics Data System (ADS)

    Steinle-Neumann, G.; Wenzel, M. J.

    2006-12-01

    Despite considerable advances in computational methods within density functional theory (DFT) for solids the electronic structure for transition metal containing compounds are not accurately described with standard approximations to the exchange and correlation potential, due to the localized and strongly interacting electronic states. This shortcoming is prominent in the iron oxides (FeO, Fe3O4, Fe2O3) and has traditionally been attempted to be overcome by the so-called LDA+U method, where additional orbital dependent interactions are added to LDA or GGA calculations. Adding the U has improved the description of the magnetic and electronic state of transition metal oxides. Similar to previous work we here employ the GGA+U method for Fe3O4 magnetite at ambient pressure lattice constants and consider physical properties of Fe3O4, in particular local parameters that could monitor charge ordering on the octahedral B site in Fe3O4 structure (inverse spinel), breaking their symmetry equivalence. We vary the U parameter from 0 eV to 4.5 eV, covering a wide range of previously employed values. We find that for values of U ≥ 2.5 eV the B sites become inequivalent in terms of magnetic moment, charge and electric field gradient. This is in contrast to experimental findings that suggest that the B sites are equivalent.

  5. A facile solvothermal synthesis of octahedral Fe3O4 nanoparticles

    DOE PAGESBeta

    DuChene, Joseph S.; Qiu, Jingjing; Graham, Jeremy O.; Engelhard, Mark H.; Cao, Guixin; Gai, Zheng; Wei, Wei David; Ooi, Frances

    2015-01-26

    Anisotropic Fe3O4 octahedrons are obtained via a simple solvothermal synthesis with appropriate sizes for various technological applications. Here, a complete suite of materials characterization methods confirms the magnetite phase for these structures, which exhibit substantial saturation magnetization and intriguing morphologies for a wide range of applications.

  6. Controlled one-step synthesis of Pt decorated octahedral Fe3O4 and its excellent catalytic performance for CO oxidation

    NASA Astrophysics Data System (ADS)

    Li, Gengnan; Li, Liang; Wu, Binghan; Li, Jinxia; Yuan, Yuan; Shi, Jianlin

    2015-10-01

    A facile one-step co-precipitation method has been applied for the synthesis of a Pt decorated octahedral Fe3O4 catalyst. The simple addition of a Pt4+ and Fe2+ mixture into a KOH solution leads to the simultaneous formation of an octahedral Fe3O4 and in situ reduction of Pt4+. HAADF-STEM analysis demonstrates the good dispersion of the Pt species on the Fe3O4 (111) plane, and the resulting material exhibits excellent catalytic activity for CO oxidation under moisture conditions. The inevitably existing moisture contributes to the formation of reaction intermediate [COOH] and hence promotes the catalytic activity, which has been proved through in situ DRIFTS analysis.A facile one-step co-precipitation method has been applied for the synthesis of a Pt decorated octahedral Fe3O4 catalyst. The simple addition of a Pt4+ and Fe2+ mixture into a KOH solution leads to the simultaneous formation of an octahedral Fe3O4 and in situ reduction of Pt4+. HAADF-STEM analysis demonstrates the good dispersion of the Pt species on the Fe3O4 (111) plane, and the resulting material exhibits excellent catalytic activity for CO oxidation under moisture conditions. The inevitably existing moisture contributes to the formation of reaction intermediate [COOH] and hence promotes the catalytic activity, which has been proved through in situ DRIFTS analysis. Electronic supplementary information (ESI) available: The structural analysis of the catalysts, the effect of the concentration of reactants during the CO oxidation process, the effect of pre-treatment for CO oxidation, the comparison of the present work with the literature, and the hysteresis loops of as-prepared octahedral Fe3O4 nanoparticles. See DOI: 10.1039/c5nr05933j

  7. Ni doped Fe3O4 magnetic nanoparticles.

    PubMed

    Larumbe, S; Gómez-Polo, C; Pérez-Landazábal, J I; García-Prieto, A; Alonso, J; Fdez-Gubieda, M L; Cordero, D; Gómez, J

    2012-03-01

    In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure. PMID:22755104

  8. Fe3O4@polydopamine Composite Theranostic Superparticles Employing Preassembled Fe3O4 Nanoparticles as the Core.

    PubMed

    Ge, Rui; Li, Xing; Lin, Min; Wang, Dandan; Li, Shuyao; Liu, Shuwei; Tang, Qi; Liu, Yi; Jiang, Jinlan; Liu, Lidi; Sun, Hongchen; Zhang, Hao; Yang, Bai

    2016-09-01

    Iron oxide (Fe3O4), polydopamine (PDA), and in particular their composites are examples of the safest nanomaterials for developing multifunctional nanodevices to perform noninvasive tumor diagnosis and therapy. However, the structures and performances of Fe3O4-PDA nanocomposites should be further perfected to enhance the theranostic efficiency. In this work, we demonstrate the fabrication of PDA-capped Fe3O4 (Fe3O4@PDA) superparticles (SPs) employing preassembled Fe3O4 nanoparticles (NPs) as the cores. Owing to the collective effect of preassembled Fe3O4 NPs, the superparamagnetism and photothermal performance of Fe3O4@PDA SPs are greatly enhanced, thus producing nanodevices with improved magnetic resonance imaging (MRI)-guided photothermal efficiency. Systematical studies reveal that the molar extinction coefficient of the as-assembled Fe3O4 SPs is 3 orders of magnitude higher than that of individual Fe3O4 NPs. Also due to the high aggregation degree of Fe3O4 NPs, the T2-weighted MRI contrast is greatly enhanced for the SPs with r2 relaxivity of 230.5 mM(-1) s(-1), which is ∼2.5 times larger than that of individual Fe3O4 NPs. The photothermal stability, physiological stability, and biocompatibility, as well as the photothermal performance of Fe3O4 SPs, are further improved by enveloping with PDA shell. PMID:27560801

  9. Superparamagnetic Au-Fe3O4 nanoparticles: one-pot synthesis, biofunctionalization and toxicity evaluation

    NASA Astrophysics Data System (ADS)

    Pariti, A.; Desai, P.; Maddirala, S. K. Y.; Ercal, N.; Katti, K. V.; Liang, X.; Nath, M.

    2014-09-01

    Superparamagnetic Au-Fe3O4 bifunctional nanoparticles have been synthesized using a single step hot-injection precipitation method. The synthesis involved using Fe(CO)5 as iron precursor and HAuCl4 as gold precursor in the presence of oleylamine and oleic acid. Oleylamine helps in reducing Au3+ to Au0 seeds which simultaneously oxidizes Fe(0) to form Au-Fe3O4 bifunctional nanoparticles. Triton® X-100 was employed as a highly viscous solvent to prevent agglomeration of Fe3O4 nanoparticles. Detailed characterization of these nanoparticles was performed by using x-ray powder diffraction, transmission electron microscopy, scanning tunneling electron microscopy, UV-visible spectroscopy, Mössbauer and magnetometry studies. To evaluate these nanoparticles’ applicability in biomedical applications, L-cysteine was attached to the Au-Fe3O4 nanoparticles and cytotoxicity of Au-Fe3O4 nanoparticles was tested using CHO cells by employing MTS assay. L-cysteine modified Au-Fe3O4 nanoparticles were qualitatively characterized using Fourier transform infrared spectroscopy and Raman spectroscopy; and quantitatively using acid ninhydrin assay. Investigations reveal that that this approach yields Au-Fe3O4 bifunctional nanoparticles with an average particle size of 80 nm. Mössbauer studies indicated the presence of Fe in Fe3+ in A and B sites (tetrahedral and octahedral, respectively) and Fe2+ in B sites (octahedral). Magnetic measurements also indicated that these nanoparticles were superparamagnetic in nature due to Fe3O4 region. The saturation magnetization for the bifunctional nanoparticles was observed to be ˜74 emu g-1, which is significantly higher than the previously reported Fe3O4 nanoparticles. Mössbauer studies indicated that there was no significant Fe(0) impurity that could be responsible for the superparamagnetic nature of these nanoparticles. None of the investigations showed any presence of other impurities such as Fe2O3 and FeOOH. These Au-Fe3O4 bifunctional

  10. Spin-dependent transport properties of Fe3O4/MoS2/Fe3O4 junctions

    NASA Astrophysics Data System (ADS)

    Wu, Han-Chun; Coileáin, Cormac Ó.; Abid, Mourad; Mauit, Ozhet; Syrlybekov, Askar; Khalid, Abbas; Xu, Hongjun; Gatensby, Riley; Jing Wang, Jing; Liu, Huajun; Yang, Li; Duesberg, Georg S.; Zhang, Hong-Zhou; Abid, Mohamed; Shvets, Igor V.

    2015-11-01

    Magnetite is a half-metal with a high Curie temperature of 858 K, making it a promising candidate for magnetic tunnel junctions (MTJs). Yet, initial efforts to exploit its half metallic nature in Fe3O4/MgO/Fe3O4 MTJ structures have been far from promising. Finding suitable barrier layer materials, which keep the half metallic nature of Fe3O4 at the interface between Fe3O4 layers and barrier layer, is one of main challenges in this field. Two-dimensional (2D) materials may be good candidates for this purpose. Molybdenum disulfide (MoS2) is a transition metal dichalcogenide (TMD) semiconductor with distinctive electronic, optical, and catalytic properties. Here, we show based on the first principle calculations that Fe3O4 keeps a nearly fully spin polarized electron band at the interface between MoS2 and Fe3O4. We also present the first attempt to fabricate the Fe3O4/MoS2/Fe3O4 MTJs. A clear tunneling magnetoresistance (TMR) signal was observed below 200 K. Thus, our experimental and theoretical studies indicate that MoS2 can be a good barrier material for Fe3O4 based MTJs. Our calculations also indicate that junctions incorporating monolayer or bilayer MoS2 are metallic.

  11. Spin-dependent transport properties of Fe3O4/MoS2/Fe3O4 junctions

    PubMed Central

    Wu, Han-Chun; Coileáin, Cormac Ó; Abid, Mourad; Mauit, Ozhet; Syrlybekov, Askar; Khalid, Abbas; Xu, Hongjun; Gatensby, Riley; Jing Wang, Jing; Liu, Huajun; Yang, Li; Duesberg, Georg S.; Zhang, Hong-Zhou; Abid, Mohamed; Shvets, Igor V.

    2015-01-01

    Magnetite is a half-metal with a high Curie temperature of 858 K, making it a promising candidate for magnetic tunnel junctions (MTJs). Yet, initial efforts to exploit its half metallic nature in Fe3O4/MgO/Fe3O4 MTJ structures have been far from promising. Finding suitable barrier layer materials, which keep the half metallic nature of Fe3O4 at the interface between Fe3O4 layers and barrier layer, is one of main challenges in this field. Two-dimensional (2D) materials may be good candidates for this purpose. Molybdenum disulfide (MoS2) is a transition metal dichalcogenide (TMD) semiconductor with distinctive electronic, optical, and catalytic properties. Here, we show based on the first principle calculations that Fe3O4 keeps a nearly fully spin polarized electron band at the interface between MoS2 and Fe3O4. We also present the first attempt to fabricate the Fe3O4/MoS2/Fe3O4 MTJs. A clear tunneling magnetoresistance (TMR) signal was observed below 200 K. Thus, our experimental and theoretical studies indicate that MoS2 can be a good barrier material for Fe3O4 based MTJs. Our calculations also indicate that junctions incorporating monolayer or bilayer MoS2 are metallic. PMID:26522127

  12. Magnetically separable mesoporous Fe3O4/silica catalysts with very low Fe3O4 content

    NASA Astrophysics Data System (ADS)

    Grau-Atienza, A.; Serrano, E.; Linares, N.; Svedlindh, P.; Seisenbaeva, G.; García-Martínez, J.

    2016-05-01

    Two magnetically separable Fe3O4/SiO2 (aerogel and MSU-X) composites with very low Fe3O4 content (<1 wt%) have been successfully prepared at room temperature by co-condensation of MPTES-functionalized Fe3O4 nanoparticles (NPs) with a silicon alkoxide. This procedure yields a homogeneous incorporation of the Fe3O4 NPs on silica supports, leading to magnetic composites that can be easily recovered using an external magnetic field, despite their very low Fe3O4 NPs content (ca. 1 wt%). These novel hybrid Fe3O4/SiO2 materials have been tested for the oxidation reaction of 3,3‧,5,5‧-tetramethylbenzidine (TMB) with hydrogen peroxide showing an enhancement of the stability of the NPs in the Fe3O4/silica aerogel as compared to the Fe3O4 NPs alone, even after five catalytic cycles, no leaching or agglomeration of the Fe3O4/SiO2 systems.

  13. Magnetoresistance effect in Ag-Fe3O4 and Al-Fe3O4 composite films

    NASA Astrophysics Data System (ADS)

    Hsu, Jen-Hwa; Chen, Shang-Yi; Chang, Wen-Ming; Jian, T. S.; Chang, Ching-Ray; Lee, Shan-Fan

    2003-05-01

    The Agx-(Fe3O4)1-x and Agx-(Fe3O4)1-x composite films were prepared by dc sputtering on Si(100) substrates. The x-ray diffraction results show that the films contain essentially only the cubic inverse spinal phase from Fe3O4 and face-centered cubic phase from Ag or Al. The transmission electron microscopy images indicate that the metal granules are randomly distributed with Fe3O4 grains. The resistivity determined from the four-probe method decreases rapidly with increasing metal content. At x≒0.5, a percolation occurs. The conducting path is formed from metal granules in series with Fe3O4 grains. The magnetoresistance (MR) is defined to be {R(H=0.8 T)-R(H=0)}/R(H=0). It has been found that MR is isotropic and the appearance of Ag granules has significant impact on the MR effect. Furthermore, a positive MR region appears with 0.011Fe3O4)1-x. On the contrary, the incorporation of Al granules does not have the same effect on MR as in Agx-(Fe3O4)1-x. A slow increase of MR with Al content might be due to Coulomb blockade. The extra contribution to MR in Agx-(Fe3O4)1-x can be attributed to spin injection from Fe3O4 into Ag granules so that spin accumulation in Ag granules impedes the current causing a larger resistance under a field.

  14. Surface controlled magnetic properties of Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohapatra, Jeotikanta; Mitra, Arijit; Bahadur, D.; Aslam, M.

    2013-02-01

    To understand the influence of surface organic-inorganic interactions on the magnetic properties of magnetic nanoparticles, magnetite (Fe3O4) of mean size 4-16 nm (standard deviation σ ≤ 15 %) are synthesized by three different thermolysis techniques. The surface functionality is controlled through either amine or amine-acid both taking as surfactant for Fe3O4 nanoparticles synthesis. Magnetic investigations revealed that samples prepared using amine as a multifunctional agent (only one surfactant) shows superior magnetic properties than the nanoparticles produced by the approach utilizing oleic acid and oleylamine.

  15. Photoluminescent Fe3O4/carbon nanocomposite with magnetic property.

    PubMed

    He, Xiaodie; Liu, Yang; Li, Haitao; Huang, Hui; Liu, Jinglin; Kang, Zhenhui; Lee, Shuit-Tong

    2011-04-01

    Fe(3)O(4)/carbon nanocomposite has been prepared by a facile chemical method, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy and scanning electron microscopy. The fluorescent and magnetic properties of the sample were investigated by fluorescence spectroscopy and vibrating-sample magnetometer, respectively. The results indicate that the Fe(3)O(4)/carbon nanocomposite exhibit good photoluminescent (emission ranging from 425 to 550 nm) and strong magnetic (saturation magnetization of 44.2 emu/g) properties. PMID:21269640

  16. Bio and nanomaterials based on Fe3O4.

    PubMed

    Xu, Jia-Kun; Zhang, Fang-Fang; Sun, Jing-Jing; Sheng, Jun; Wang, Fang; Sun, Mi

    2014-01-01

    During the past few years, nanoparticles have been used for various applications including, but not limited to, protein immobilization, bioseparation, environmental treatment, biomedical and bioengineering usage, and food analysis. Among all types of nanoparticles, superparamagnetic iron oxide nanoparticles, especially Fe3O4, have attracted a great deal of attention due to their unique magnetic properties and the ability of being easily chemical modified for improved biocompatibility, dispersibility. This review covers recent advances in the fabrication of functional materials based on Fe3O4 nanoparticles together with their possibilities and limitations for application in different fields. PMID:25532846

  17. Schottky barrier effect on the electrical properties of Fe3O4/ZnO and Fe3O4/Nb : SrTiO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Yang, Kiwon; Kim, D. H.; Dho, Joonghoe

    2011-09-01

    The current-voltage (I-V) characteristics of Fe3O4/Nb-doped SrTiO3(Nb : STO) and Fe3O4/ZnO junctions prepared by pulsed laser deposition were investigated as a function of temperature. The rectifying behaviour was more distinctive in Fe3O4/Nb : STO than in the Fe3O4/ZnO. Contrary to Fe3O4/Nb : STO, remarkably, the current flow in Fe3O4/ZnO was slightly larger for negative bias voltages than for positive bias voltages. The threshold voltage in Fe3O4/Nb : STO dramatically shifted to a higher voltage by decreasing the temperature, and hysteresis behaviour with a cyclic voltage sweep appeared below 120 K. Upon cooling, the rectifying behaviour in Fe3O4/ZnO gradually disappeared within the measurement range. The observed difference between Fe3O4/Nb : STO and Fe3O4/ZnO could be explained by the shape and height of the Schottky barrier which was determined by the relative magnitude of the work functions of the two contact materials. The formation of the Schottky barrier presumably resulted from an upward shift of the interface band in Fe3O4/Nb : STO, while a little downward shift of the interface band occurred in Fe3O4/ZnO. In addition, Al-doping into ZnO induced a complete disappearance of the Schottky barrier in the Fe3O4/Al-doped ZnO junction.

  18. Antifungal activity of multifunctional Fe 3O 4-Ag nanocolloids

    NASA Astrophysics Data System (ADS)

    Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Upadhyay, R. V.; Mehta, R. V.

    2011-05-01

    In recent years, rapid increase has been observed in the population of microbes that are resistant to conventionally used antibiotics. Antifungal drug therapy is no exception and now resistance to many of the antifungal agents in use has emerged. Therefore, there is an inevitable and urgent medical need for antibiotics with novel antimicrobial mechanisms. Aspergillus glaucus is the potential cause of fatal brain infections and hypersensitivity pneumonitis in immunocompromised patients and leads to death despite aggressive multidrug antifungal therapy. In the present article, we describe the antifungal activity of multifunctional core-shell Fe 3O 4-Ag nanocolloids against A. glaucus isolates. Controlled experiments are also carried out with Ag nanocolloids in order to understand the role of core (Fe 3O 4) in the antifungal action. The minimum inhibitory concentration (MIC) of nanocolloids is determined by the micro-dilution method. MIC of A. glaucus is 2000 μg/mL. The result is quite promising and requires further investigations in order to develop a treatment methodology against this death causing fungus in immunocompromised patients.

  19. Microbial synthesis of Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites for catalytic reduction of nitroaromatic compounds

    PubMed Central

    Tuo, Ya; Liu, Guangfei; Dong, Bin; Zhou, Jiti; Wang, Aijie; Wang, Jing; Jin, Ruofei; Lv, Hong; Dou, Zeou; Huang, Wenyu

    2015-01-01

    Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts. PMID:26310728

  20. Controllable synthesis of Cu2O petalody octahedral microcrystals and multi-patterned evolution.

    PubMed

    Ding, Yanbo; Ge, Dengteng; Yang, Lili; Li, Zhenyu; Xin, Wuhong; Li, Yao; Wu, Xiaohong; Zhao, Jiupeng

    2013-02-15

    The fabrication of cuprous oxide (Cu(2)O) with various morphologies has attracted extensive interest due to its applications in solar energy conversion, electrode materials, sensors, and catalysts. Herein, we report a facile controllable route for Cu(2)O microcrystals with various architectures via a hydrothermal method without using templates or surfactants. Six types of Cu(2)O microcrystals including petalody octahedral, concave truncated octahedron, truncated octahedron, octahedron, sphere-like, and sphere are obtained accompanying with Cu precipitation or urchin-like CuO particles due to the modifying of pH values. The petalody octahedral pattern of Cu(2)O is for the first time found here under the condition of pH 7-8. Additionally, possible growth mechanism for multi-patterned Cu(2)O and compositional evolution is discussed via preferential growths induced by selective absorption of acrylic acid and decomposition of lactic acid in the present reaction system. These experimental results prove a versatile and facile strategy for Cu(2)O microcrystals with special and complex architectures, which may highlights their potential applications due to the improved surface activity, catalytic, or photoelectric performance. PMID:23127874

  1. Electrostatic Force Microscopy of Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mottaghizadeh, A.; Lang, P. L.; Cui, L.; Lesueur, J.; Zimmers, A.; Aubin, H.; Li, J.; Zheng, D. N.; Rebuttini, V.; Pinna, N.

    2012-02-01

    The electronic compressibility is a fundamental property that characterizes the electronic properties of materials submitted to an external electric field. In metals (insulators), the electronic compressibility is large (small) and leads to a small (large) screening length. Variations of the screening length can be observed through measurements of the ``quantum'' capacitance between one material and a metallic counter-electrode. Using an Electrostatic Force Microscope (EFM), we measured maps of the local capacitance of 8 nm magnetite nanoparticles synthesized following the ``benzyl alcohol route'' deposited on a metallic substrate. Magnetite, an inverse spinel structure of composition Fe3O4, is a material with strongly correlated electronic properties and presents a metal-insulator transition at 120 K, the so-called Verwey transition. We present EFM measurements of these nanoparticles as a function of tip-sample distance and temperature.

  2. Electrochemical sensing behaviour of Ni doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2014-01-01

    Ni doped Fe3O4 nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe3O4 nanoparticles. The optical property of Ni doped Fe3O4 nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe3O4 nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe3O4 nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  3. In situ preparation of monodispersed Ag/polyaniline/Fe3O4 nanoparticles via heterogeneous nucleation

    PubMed Central

    2013-01-01

    Acrylic acid and styrene were polymerized onto monodispersed Fe3O4 nanoparticles using a grafting copolymerization method. Aniline molecules were then bonded onto the Fe3O4 nanoparticles by electrostatic self-assembly and further polymerized to obtain uniform polyaniline/Fe3O4 (PANI/Fe3O4) nanoparticles (approximately 35 nm). Finally, monodispersed Ag/PANI/Fe3O4 nanoparticles were prepared by an in situ reduction reaction between emeraldine PANI and silver nitrate. Fourier transform infrared and UV-visible spectrometers and a transmission electron microscope were used to characterize both the chemical structure and the morphology of the resulting nanoparticles. PMID:23819820

  4. Chitosan and O-carboxymethyl chitosan modified Fe3O4 for hyperthermic treatment

    NASA Astrophysics Data System (ADS)

    Thu Trang Mai, Thi; Thu Ha, Phuong; Pham, Hong Nam; Thu Huong Le, Thi; Linh Pham, Hoai; Bich Hoa Phan, Thi; Tran, Dai Lam; Phuc Nguyen, Xuan

    2012-03-01

    In this study magnetic fluids were manufactured by the adsorption of chitosan (CS) and O-carboxymethyl chitosan (OCMCS) on Fe3O4 nanoparticles to be used as hyperthermic thermoseeds. Fe3O4 particles were characterized by physico-chemical methods such as: thermogravimetry analysis (TGA), x-ray diffraction (XRD), Raman spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The SEM images and XRD patterns showed that the synthesized Fe3O4 nanoparticles were of single phase and spherical shape with 10–15 nm in diameter. The VSM measurements showed that Fe3O4 particles were superparamagnetic with saturation magnetization of 70 emu g‑1. The adsorbed layers of CS and OCMCS on the magnetite surface (Fe3O4/CS) and (Fe3O4/OCMCS) were confirmed by FTIR, Raman spectra and SEM. In the ac magnetic field of 80 Oe and 236 kHz, the saturation heating temperatures of the sample Fe3O4/CS and Fe3O4/OCMCS were 100 and 98 °C, respectively. At the same concentration of Fe3O4 nanoparticles in suspension, the two magnetic fluids exhibited quite high heating capacity, with different behaviors of concentration dependence. The Fe3O4/CS and Fe3O4/OCMCS nanoparticles would serve as good thermoseeds for localized hyperthermia treatment of cancers.

  5. Effect of Fe3O4 Nanoparticles on Skin Tumor Cells and Dermal Fibroblasts

    PubMed Central

    Alili, Lirija; Chapiro, Swetlana; Marten, Gernot U.; Schmidt, Annette M.; Zanger, Klaus; Brenneisen, Peter

    2015-01-01

    Iron oxide (Fe3O4) nanoparticles have been used in many biomedical approaches. The toxicity of Fe3O4 nanoparticles on mammalian cells was published recently. Though, little is known about the viability of human cells after treatment with Fe3O4 nanoparticles. Herein, we examined the toxicity, production of reactive oxygen species, and invasive capacity after treatment of human dermal fibroblasts (HDF) and cells of the squamous tumor cell line (SCL-1) with Fe3O4 nanoparticles. These nanoparticles had an average size of 65 nm. Fe3O4 nanoparticles induced oxidative stress via generation of reactive oxygen species (ROS) and subsequent initiation of lipid peroxidation. Furthermore, the question was addressed of whether Fe3O4 nanoparticles affect myofibroblast formation, known to be involved in tumor invasion. Herein, Fe3O4 nanoparticles prevent the expression alpha-smooth muscle actin and therefore decrease the number of myofibroblastic cells. Moreover, our data show in vitro that concentrations of Fe3O4 nanoparticles, which are nontoxic for normal cells, partially reveal a ROS-triggered cytotoxic but also a pro-invasive effect on the fraction of squamous cancer cells surviving the treatment with Fe3O4 nanoparticles. The data herein show that the Fe3O4 nanoparticles appear not to be adequate for use in therapeutic approaches against cancer cells, in contrast to recently published data with cerium oxide nanoparticles. PMID:26090418

  6. Biocompatible polyurethane/thiacalix[4]arenes functionalized Fe3O4 magnetic nanocomposites: Synthesis and properties.

    PubMed

    Mohammadi, Abbas; Barikani, Mehdi; Lakouraj, Moslem Mansour

    2016-09-01

    In this study, a series of magnetic polyurethane/Fe3O4 elastomer nanocomposites were prepared by covalently embedding novel thiacalix[4]arenes (TC4As) functionalized Fe3O4 nanoparticles (TC4As-Fe3O4) which contain macrocycles with reactive hydroxyl groups. Surface functionalization of Fe3O4 nanoparticles with TC4As macrocycles as unique reactive surface modifier not only gives specific characteristics to Fe3O4 nanoparticles but also improves the interphase interaction between nanoparticles and the polyurethane matrices through covalent attachment of polymer chains to nanoparticle surfaces. The novel synthesized TC4As-Fe3O4 nanoparticles were characterized by FTIR, XRD, TGA, VSM and SEM analysis. Furthermore, the effect of functionalization of Fe3O4 nanoparticles on the various properties of resulting nanocomposites was studied by XRD, TGA, DMTA, SEM, and a universal tensile tester. It was found that the functionalization of nanoparticles with TC4As affords better mechanical and thermal properties to polyurethane nanocomposites in comparison with unmodified nanoparticles. The SEM analysis showed finer dispersion of TC4As-Fe3O4 nanoparticles than unmodified Fe3O4 nanoparticles within the polyurethane matrices, which arising from formation of covalent bonding between TC4As functionalized Fe3O4 nanoparticles and polyurethane matrices. Moreover, the investigation of in vitro biocompatibility of novel nanocomposites showed that these samples are excellent candidate for biomedical use. PMID:27207044

  7. Spin-resolved photoelectron spectroscopy of Fe3O4

    SciTech Connect

    Morton, Simon; Waddill, Dan; Kim, S H.; Schuller, I K.; Chambers, Scott A.; Tobin, James G.

    2002-08-01

    The existence of a new class of magnetic materials displaying metallic character for one electron spin population and insulating character for the other was first populated by DeGroot et al. in 1983 based on theoretical band structure calculations of the ferromagnetic Heusler alloy NiMnSb. Since then such half metallic materials, which by definition possess 100% electron polarization at the Fermi energy, have attracted considerable theoretical, experimental, and technological interest as potential pure spin sources for use in spintronic devices. In addition to Heusler alloys (e.g. NiMnSb, PtMnSb), half metallic character has also been predicted to occur in a wide range of manganites (e.g. La1-xCaxMnO3, La1-x-SrxMnO3), metallic oxides (e.g. Fe3O4, CrO2) and CMR systems. However, such predictions have proven to be extremely difficult to confirm experimentally. Possible reasons for this include the theoretical limitations arising from the complex crystallographic structure of many such materials and limitations in applying the single electron picture to materials where strong electron correlation may be present; this is compounded by experimental difficulties posed by their structural complexity and issues such as surface contamination, segregation, and reconstruction.

  8. Optimization of Fe3 O4 Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Vila, E.; Stojak Repa, K.; Srikanth, H.; Phan, Mh

    Magnetic nanoparticles have been of great interest for the past several decades due to the increasing demands of technology as a direct result of device miniaturization. Additionally, they are interesting for biomedical applications, such as magnetic hyperthermia, because of their controllable size and shape, which can make them compatible with biological entities such as cells or viruses. In this study, iron oxide nanoparticles were synthesized through a thermal decomposition process. The original recipe was altered by changing the type and amounts of reagents used; the reaction time was also changed. Specifically, the amount of surfactants and solvent were altered, and the typical co-surfactant, 1,2-hexadecanediol was substituted by 1,2-tetradecanediol. Finally, a systematic reflux time study was conducted to determine the importance of reaction time to the synthetic process. Each sample was analyzed structurally via XRD to confirm the Fe3O4 phase and TEM to confirm their size. Several samples were also measured in a standard magnetometer to observe changes in their magnetic properties. Results from the systematic study will be presented here.

  9. Superparamagnetic Fe3O4 particles formed by oxidation of pyrite heated in an anoxic atmosphere

    USGS Publications Warehouse

    Thorpe, A.N.; Senftle, F.E.; Talley, R.; Hetherington, S.; Dulong, F.

    1990-01-01

    As a follow-up to previous gas analysis experiments in which pyrite was heated to 681 K in an anoxic (oxygen starved) atmosphere, the first oxidation product, FeSO4, was studied as a bulk material. No decomposition of FeSO4 to Fe3O4 was observed in the temperature range studied. The lack of decomposition of bulk FeSO4 to Fe3O4 suggests that FeS2 oxidizes directly to Fe3O4, or that FeSO4, FeS2 and O2 react together to form Fe3O4. Magnetic susceptibility and magnetization measurements, along with magnetic hysteresis curves, show that small particles of Fe3O4 form on the pyrite surface, rather than a continuous layer of bulk Fe3O4. A working model describing the oxidation steps is presented. ?? 1990.

  10. Ultrasonic synthesis of polyaniline nanotubes containing Fe 3O 4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lu, Xiaofeng; Mao, Hui; Chao, Danming; Zhang, Wanjin; Wei, Yen

    2006-08-01

    Polyaniline (PANI) nanotubes containing Fe 3O 4 nanoparticles were synthesized under ultrasonic irradiation of the aqueous solutions of aniline, ammonium peroxydisulfate (APS), phosphoric acid (H 3PO 4), and the quantitative amount of Fe 3O 4. It was found that the obtained samples had the morphologies of nanotubes. TEM images and selected area electronic diffractions showed that Fe 3O 4 nanoparticles were embedded in PANI nanotubes. We thought that the mechanism of the formation of PANI/Fe 3O 4 nanotubes could be attributed to the ultrasonic irradiation and the H 3PO 4-aniline salt template. The molecular structure of PANI/Fe 3O 4 nanotubes were characterized by Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectra and X-ray diffraction (XRD). The conductivity and magnetic properties of the PANI nanotubes containing Fe 3O 4 nanoparticles were also investigated.

  11. Octahedral iron phosphate hydroxide microcrystals: Fast microwave-hydrothermal preparation, influencing factors and the shape evolution

    SciTech Connect

    Zhou, Quanyi; Ni, Yonghong; Ni, Hui; Ma, Xiang; Zhou, Yunyou

    2012-09-15

    Graphical abstract: Octahedral Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} microcrystals have been successfully prepared by a microwave-assisted hydrothermal route at 170 °C for 20 min. The morphology of Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} could be tuned by the Na{sub 2}SO{sub 3}/HAc molar ratio. Highlights: ► Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} octahedra had been hydrothermally prepared under the microwave assistance. ► The morphology of the final product could be tuned by the original molar ratio of Na{sub 2}SO{sub 3}/HAc. ► Low or high temperatures were unfavorable for the formation of Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} octahedra. ► The time-dependent shape evolution of the final product was investigated. -- Abstract: Octahedral Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} microcrystals have been successfully prepared by a microwave-assisted hydrothermal route at 170 °C for 20 min, employing FeCl{sub 3}·6H{sub 2}O and NaH{sub 2}PO{sub 4}·2H{sub 2}O as the starting materials in the presence of proper amounts of Na{sub 2}SO{sub 3} and acetic acid (HAc). The phase and morphology of the as-prepared product were characterized by means of powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Some factors influencing the formation of octahedral Fe{sub 4}(PO{sub 4}){sub 3}(OH){sub 3} microcrystals were systematically investigated, including the reaction temperature, time, and the molar ratio of Na{sub 2}SO{sub 3}/HAc.

  12. Magnetic characterization of radio frequency heat affected micron size Fe3O4 powders: a bio-application perspective.

    PubMed

    Roul, B K; Mishra, D K; Ray, M; Sahu, D R; Mishra, P K; Srinivasu, V V; Pradhan, A K

    2009-05-01

    Micron size Fe3O4 powders were chemically prepared and processed by radio frequency (13.56 MHz) oxygen plasma irradiation technique at different elevated temperatures using low radio frequency (RF) power level. Low magnetic field RF superconducting quantum interference device (SQUID) magnetization studies were performed up to a maximum magnetic field of 100 Oe, which was well below the magnetic field tolerance factor of human beings and at different temperatures (down to 5 K). Heat-treated powders in RF oxygen plasma showed significant changes in blocking temperature, magnetization and susceptibility, which are important parameters for bio-applications. It is observed that blocking temperature is decreased under identical RF heat treatment in oxygen plasma and noted to be dependent on average particle size. Microscopic rise in electron temperature during RF heating may likely to enhance the electron-hopping rate between Fe(+2) and Fe(+3) in the octahedral site of Fe3O4 molecular crystal structure, which in turn exhibit changes in blocking temperature including low field magnetization and susceptibility. These properties of Fe3O4 fine powder are likely to play important role in generating and processing biocompatible Ferro-fluid down to nanoscopic size for biomaterials applications. PMID:19452992

  13. Electrochemical sensing property of Mn doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-02-01

    The Mn doped Fe3O4 nanoparticles were synthesized by hydrothermal method. The prepared nanoparticles were characterized by X-ray diffraction (XRD) analysis, UV-Visible spectroscopy (UV-Vis) and field emission scanning electron microscopy (FE-SEM). The electrochemical sensing property of pure and Mn doped Fe3O4 nanoparticles were examined using uric acid (UA) as an analyte. The obtained results indicated that the Mn doped Fe3O4 nanoparticles exhibited higher electrocatalytic activity towards UA.

  14. Facile synthesis of superparamagnetic Fe3O4@Au nanoparticles for photothermal destruction of cancer cells.

    PubMed

    Ren, Jinfeng; Shen, Shun; Pang, Zhiqing; Lu, Xiaohui; Deng, Chunhui; Jiang, Xinguo

    2011-11-14

    Superparamagnetic Fe(3)O(4) nanoparticles with positive surface ξ-potential were synthesized via a solvothermal route. After Fe(3)O(4) was mixed with HAuCl(4) and NaBH(4), the reduced Au nanoparticles could be directly adsorbed onto the surface of Fe(3)O(4) nanoparticles. The as-synthesized nanocomposites were successfully applied to photothermal destruction of cancer cells. PMID:21952492

  15. Synthesis, characterization and magnetorheological study of 3-aminopropyltriethoxysilane-modified Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Guangshuo; Ma, Yingying; Tong, Yu; Dong, Xufeng

    2016-03-01

    In this study, monodisperse Fe3O4 nanoparticles were synthesized successfully using a sonochemical method in the presence of 3-aminopropyltriethoxysilane (APTES). The morphology, microstructure and magnetic properties of the bare Fe3O4 and APTES-coated Fe3O4 were investigated in detail by TEM, XRD, FTIR and SQUID. It was found that APTES-coated Fe3O4 showed relatively good dispersion with a narrow size distribution of 8.4 ± 2.1 nm diameter. The functionalization of Fe3O4 was proved to be covalent linking between Fe3O4 and APTES. The field-dependent magnetization curve indicated superparamagnetic behavior of Fe3O4-APTES with a saturation magnetization (M s) of 70.5 emu g-1 at room temperature. A magnetorheological (MR) fluid was prepared using the obtained Fe3O4-APTES nanoparticles with 25 wt% particles, and its MR properties were tested using a Physica MCR301 rheometer fitted with an MRmodule. The results showed that the as-prepared APTES-coated Fe3O4 nanoparticle-based MR fluid exhibited typical MR effects, with increasing viscosity, shear stress and yield stress depending on the applied magnetic field strength.

  16. Efficient synthesis of core@shell Fe3O4@Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Alonso-Cristobal, Paulino; Laurenti, Marco; Lopez-Cabarcos, Enrique; Rubio-Retama, Jorge

    2015-07-01

    The synthesis of Fe3O4@Au nanoparticles has received much attention due to promising applications in the biomedical field. In this work, we produced Fe3O4@Au nanoparticles by using a two-step solvothermal route that employed Fe3O4 nanoparticles as seeds for the Au deposition. Although this protocol leads to highly monodisperse and reproducible Fe3O4@Au nanoparticles it was necessary to perform a systematic study to have a better understanding, improve the yield and allow us to obtain a tunable result. We demonstrated that the Au:Fe3O4 ratio is a key parameter that, contrary to what could be expected, does not influence the Au shell thickness. However, this parameter should be optimized because it strongly influences the yield. When the Au:Fe3O4 ratio was low there were plenty of uncoated Fe3O4 nanoparticles, whereas when the Au:Fe3O4 ratio was high there could be some pure Au nanoparticles together with the desired Fe3O4@Au nanoparticles. Furthermore we demonstrated that the Au shell thickness can be tuned by varying the reaction temperature. This paper describes the influence of both parameters and proposes a mechanism of the synthetic process by studying parametrically the morphological and structural evolution of the nanoparticles by TEM, DLS, SQUID and UV-vis spectroscopy.

  17. [Synthesis and spectral characteristic of Ga-Fe3O4 at room temperature].

    PubMed

    Wang, Jing; Deng, Tong; Yang, Cai-Qin; Lin, Yu-Long; Wang, Wei; Wu, Hai-Yan

    2008-03-01

    Gallium bearing ferrites with different gallium content were synthesized by oxidation of ferrous and gallium ions under alkaline condition and room temperature. The samples were subjected to IR, XRD, Mossbauer spectral analysis and magnetization characterization. The results indicated that the green-rust intermediate phase would be produced during the procedure of Ga-Fe3O4 formation, and the green-rust intermediate phase was converted to ferrites with spinel structure during the drying under hot-N2 atmosphere. With the introduction of gallium into the spinel structure, the interplanar crystal spacing of the spinel structure decreased, as indicated from XRD spectra, and the lattice vibration of M(T)-O-M(o) moved to the high-frequency resulting from IR spectra. A small amount gallium introduction entered the tetrahedral sites preferentially rather than the octahedral sites, and increasing gallium introduction would enhance the occupation of octahedral sites. Furthermore, a small content of gallium in the initial solution could prevent the formation of non-magnetic Fe2O3. PMID:18536451

  18. 99mTc radiolabelling of Fe3O4-Au core-shell and Au-Fe3O4 dumbbell-like nanoparticles

    NASA Astrophysics Data System (ADS)

    Felber, M.; Alberto, R.

    2015-04-01

    The development of nanoparticle-based dual-modality probes for magnetic resonance imaging (MRI) and positron emission tomography (PET) or single photon emission computed tomography (SPECT) is increasingly growing in importance. One of the most commonly used radionuclides for clinical SPECT imaging is 99mTc and the labelling of Fe3O4 nanoparticles with 99mTc was shown to be a successful strategy to obtain dual-modality imaging agents. In this work, we focus on gold containing magnetic nanomaterials. The radiolabelling of magnetic Fe3O4-Au core-shell and Fe3O4-Au dumbbell-like nanoparticles with the [99mTc(CO)3]+ fragment is described. The key elements for this 99mTc labelling approach are novel coating ligands, consisting of an anchor for the Au surface, a polyethylene glycol linker and a strong chelator for the [99mTc(CO)3]+ moiety.The development of nanoparticle-based dual-modality probes for magnetic resonance imaging (MRI) and positron emission tomography (PET) or single photon emission computed tomography (SPECT) is increasingly growing in importance. One of the most commonly used radionuclides for clinical SPECT imaging is 99mTc and the labelling of Fe3O4 nanoparticles with 99mTc was shown to be a successful strategy to obtain dual-modality imaging agents. In this work, we focus on gold containing magnetic nanomaterials. The radiolabelling of magnetic Fe3O4-Au core-shell and Fe3O4-Au dumbbell-like nanoparticles with the [99mTc(CO)3]+ fragment is described. The key elements for this 99mTc labelling approach are novel coating ligands, consisting of an anchor for the Au surface, a polyethylene glycol linker and a strong chelator for the [99mTc(CO)3]+ moiety. Electronic supplementary information (ESI) available: Analyses of Fe3O4-Au core-shell nanoparticles; analyses of Au-Fe3O4 dumbbell-like nanoparticles; 99mTc labelling of Fe3O4-Au core-shell nanoparticles; 99mTc complexes; 99mTc labelling of Au-Fe3O4 dumbbell-like nanoparticles; syntheses coating ligands. See

  19. Preparation and characterization of magnetic Fe3O4-chitosan nanoparticles loaded with isoniazid

    NASA Astrophysics Data System (ADS)

    Qin, H.; Wang, C. M.; Dong, Q. Q.; Zhang, L.; Zhang, X.; Ma, Z. Y.; Han, Q. R.

    2015-05-01

    A novel and simple method has been proposed to prepare magnetic Fe3O4-chitosan nanoparticles loaded with isoniazid (Fe3O4/CS/INH nanocomposites). Efforts have been made to develop isoniazid (INH) loaded chitosan (CS) nanoparticles by ionic gelation of chitosan with tripolyphosphate (TPP). The factors that influence the preparation of chitosan nanoparticles, including the TPP concentration, the chitosan/TPP weight ratio and the chitosan concentration on loading capacity and encapsulation efficiency of chitosan nanoparticles were studied. The magnetic Fe3O4 nanoparticles were prepared by co-precipitation method of Fe2+ and Fe3+. Then the magnetic Fe3O4/CS/INH nanocomposites were prepared by ionic gelation method. The magnetic Fe3O4 nanoparticles and magnetic Fe3O4/CS/INH nanocomposites were characterized by XRD, TEM, FTIR and SQUID magnetometry. The in vitro release of Fe3O4/CS/INH nanocomposites showed an initial burst release in the first 10 h, followed by a more gradual and sustained release for 48 h. It is suggested that the magnetic Fe3O4/CS/INH nanocomposites may be exploited as potential drug carriers for controlled-release applications in magnetic targeted drugs delivery system.

  20. An effective way to increase the high-frequency permeability of Fe3O4 nanorods.

    PubMed

    Ren, Xiao; Yang, Haitao; Tang, Jin; Li, Zi-An; Su, Yi Kun; Geng, Sai; Zhou, Jun; Zhang, Xiangqun; Cheng, Zhaohua

    2016-07-14

    Uniform Fe3O4 magnetic nanorods (NRs) were successfully synthesized and oriented in epoxy resin under a rotating magnetic field. Magnetic induction fields within and around a single Fe3O4 nanorod in the remanence state were obtained by off-axis electron holography. The induction fields indicated a single domain state of the highly anisotropic Fe3O4 nanorod due to its strong magnetic shape anisotropy. Quantitative magnetic moment analysis of the obtained phase image yielded an average magnetization of 0.53 T of a single Fe3O4 nanorod. Moreover, the real part of the permeability (μ') of magnetic-oriented Fe3O4 NRs is obviously higher than that of random Fe3O4 NRs in the GHz range. The oriented Fe3O4 NRs exhibit a higher resonance peak at 4.75 GHz compared to the bulk counterpart (1.2 GHz) in the frequency dependence of μ in the range of 1-10 GHz. Moreover, the calculated μ value of the oriented Fe3O4 NRs could be improved to 4.22 with the increased dipolar interaction strength using the OOMMF software. These results could play a guiding significance in the development of an effective method to improve the permeability of magnetic nanomaterials at GHz working frequency. PMID:27305587

  1. Magnetite Fe3O4 nanoparticles synthesis by wet chemical reduction and their characterization

    NASA Astrophysics Data System (ADS)

    Chaki, S. H.; Malek, Tasmira J.; Chaudhary, M. D.; Tailor, J. P.; Deshpande, M. P.

    2015-09-01

    The authors report the synthesis of Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its characterization. Ferric chloride hexa-hydrate (FeCl3 · 6H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the synthesized Fe3O4 nanoparticles was determined by energy dispersive analysis of x-rays technique. The x-ray diffraction (XRD) technique was used for structural characterization of the nanoparticles. The crystallite size of the nanoparticles was determined using XRD data employing Scherrer’s formula and Hall-Williamson’s plot. Surface morphology of as-synthesized Fe3O4 nanoparticles was studied by scanning electron microscopy. High resolution transmission electron microscopy analysis of the as-synthesized Fe3O4 nanoparticles showed narrow range of particles size distribution. The optical absorption of the synthesized Fe3O4 nanoparticles was studied by UV-vis-NIR spectroscopy. The as-synthesized nanoparticles were analyzed by Fourier transform infrared spectroscopy technique for absorption band study in the infrared region. The magnetic properties of the as-synthesized Fe3O4 nanoparticles were evaluated by vibrating sample magnetometer technique. The thermal stability of the as-synthesized Fe3O4 nanoparticles was studied by thermogravimetric technique. The obtained results are elaborated and discussed in details in this paper.

  2. Spectroscopic characterization of magnetic Fe3O4@Au core shell nanoparticles.

    PubMed

    Fouad, Dina M; El-Said, Waleed A; Mohamed, Mona B

    2015-04-01

    The magnetic nanoparticles iron oxide (Fe3O4) nanoparticles and iron oxide/gold core-shell (Fe3O4/Au) nanoparticles were synthesized and their catalytic photo-degradation activity towards malathion as example of organophosphorus pesticides were reported. Iron oxide (Fe3O4) magnetic nanoparticle was successfully prepared through co-precipitation method by the reduction of ferric chloride (FeCl3) using ascorbic acid. The morphology of the prepared nanoparticles was characterized by the TEM and XRD (X-ray diffraction) techniques. Degradation of 10 ppm of malathion in the presence of these nanoparticles under UV radiation was monitored using (HPLC) and UV-visible spectra. Fe3O4/Au nanoparticles showed higher efficiency in photo-degradation of malathion than Fe3O4 ones. PMID:25617979

  3. Inversion of spin dependent photocurrent at Fe3O4/modulation doped GaAs heterointerfaces

    NASA Astrophysics Data System (ADS)

    Shirahata, Y.; Wada, E.; Itoh, M.; Taniyama, T.

    2011-04-01

    We demonstrate inversion of the spin dependent photocurrent across an Fe3O4/modulation doped GaAs interface under optical spin orientation condition. The spin dependent photocurrent for fully epitaxial Fe3O4/GaAs and Fe/GaAs interfaces clearly show the opposite magnetic field dependence, where the spin filtering efficiency for the Fe3O4/GaAs decreases with increasing magnetic field. The results clearly indicate that the spin polarization of the Fe3O4 layer has the opposite sign to that of Fe at the Fermi energy, consistent with theoretical predictions, and the result is a consequence of the atomically flat Fe3O4/GaAs interface we obtained.

  4. Fates of Fe3O4 and Fe3O4@SiO2 nanoparticles in human mesenchymal stem cells assessed by synchrotron radiation-based techniques.

    PubMed

    Tian, Fei; Chen, Guangcun; Yi, Peiwei; Zhang, Jichao; Li, Aiguo; Zhang, Jing; Zheng, Lirong; Deng, Zongwu; Shi, Qin; Peng, Rui; Wang, Qiangbin

    2014-08-01

    Superparamagnetic iron oxide nanoparticles (SPIOs) have been widely used as the magnetic resonance imaging (MRI) contrast agent in biomedical studies and clinical applications, with special interest recently in in vivo stem cell tracking. However, a full understanding of the fate of SPIOs in cells has not been achieved yet, which is particularly important for stem cells since any change of the microenvironment may disturb their propagation and differentiation behaviors. Herein, synchrotron radiation-based X-ray fluorescence (XRF) in combination with X-ray absorption spectroscopy (XAS) were used to in situ reveal the fate of Fe3O4 and Fe3O4@SiO2 NPs in human mesenchymal stem cells (hMSCs), in which the dynamic changes of their distribution and chemical speciation were precisely determined. The XAS analysis evidences that Fe3O4 NPs cultured with hMSCs are quite stable and almost keep their initial chemical form up to 14 days, which is contradictory to the previous report that Fe3O4 NPs were unstable in cell labeling assessed by using a simplified lysosomal model system. Coating with a SiO2 shell, Fe3O4@SiO2 NPs present higher stability in hMSCs without detectable changes of their chemical form. In addition, XRF analysis demonstrates that Fe3O4@SiO2 NPs can label hMSCs in a high efficiency manner and are solely distributed in cytoplasm during cell proliferation, making it an ideal probe for in vivo stem cell tracking. These findings with the help of synchrotron radiation-based XAS and XRF improve our understanding of the fate of SPIOs administered to hMSCs and will help the future design of SPIOs for safe and efficient stem cells tracking. PMID:24814428

  5. Fe3O4/carbon coated silicon ternary hybrid composite as supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Oh, Ilgeun; Kim, Myeongjin; Kim, Jooheon

    2015-02-01

    In this study, Fe3O4/carbon-coated Si ternary hybrid composites were fabricated. A carbon layer was directly formed on the surface of Si by the thermal vapor deposition. The carbon-coating layer not only prevented the contact between Si and reactive electrolyte but also provided anchoring sites for the deposition of Fe3O4. Fe3O4 nanoparticles were deposited on the surface of carbon-coated Si by the hydrazine reducing method. The morphology and structure of Fe3O4 and carbon layer were characterized via X-ray diffractometry, field emission scanning electron microscopy, field emission transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. These characterizations indicate that a carbon layer was fully coated on the Si particles, and Fe3O4 particles were homogeneously deposited on the carbon-coated Si particles. The Fe3O4/carbon-coated Si electrode exhibited enhanced electrochemical performance, attributed to the high conductivity and stability of carbon layer and pseudocapacitive reaction of Fe3O4. The proposed ternary-hybrid composites may be potentially useful for the fabrication of high-performance electrodes.

  6. Magnetic and rheological properties of monodisperse Fe 3O 4 nanoparticle/organic hybrid

    NASA Astrophysics Data System (ADS)

    Hayashi, Koichiro; Sakamoto, Wataru; Yogo, Toshinobu

    2009-03-01

    Fe 3O 4 nanoparticle/organic hybrids were synthesized via hydrolysis using iron (III) acetylacetonate at ˜80 °C. The synthesis of Fe 3O 4 was confirmed by X-ray diffraction, selected-area diffraction, and X-ray photoelectron spectroscopy. Fe 3O 4 nanoparticles in the organic matrix had diameters ranging from 7 to 13 nm depending on the conditions of hydrolysis. The saturation magnetization of the hybrid increased with an increase in the particle size. When the hybrid contained Fe 3O 4 particles with a size of less than 10 nm, it exhibited superparamagnetic behavior. The blocking temperature of the hybrid containing Fe 3O 4 particles with a size of 7.3 nm was 200 K, and it increased to 310 K as the particle size increased to 9.1 nm. A hybrid containing Fe 3O 4 particles of size greater than 10 nm was ferrimagnetic, and underwent Verwey transition at 130 K. Under a magnetic field, a suspension of the hybrid in silicone oil revealed the magnetorheological effect. The yield stress of the fluid was dependent on the saturation magnetization of Fe 3O 4 nanoparticles in the hybrid, the strength of the magnetic field, and the amount of the hybrid.

  7. Dispersion of Nanocrystalline Fe3O4 within Composite Electrodes: Insights on Battery-Related Electrochemistry.

    PubMed

    Bock, David C; Pelliccione, Christopher J; Zhang, Wei; Wang, Jiajun; Knehr, K W; Wang, Jun; Wang, Feng; West, Alan C; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2016-05-11

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to the aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. This study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes. PMID:27096464

  8. Oxidase-functionalized Fe(3)O(4) nanoparticles for fluorescence sensing of specific substrate.

    PubMed

    Liu, Cheng-Hao; Tseng, Wei-Lung

    2011-10-01

    This study reports the development of a reusable, single-step system for the detection of specific substrates using oxidase-functionalized Fe(3)O(4) nanoparticles (NPs) as a bienzyme system and using amplex ultrared (AU) as a fluorogenic substrate. In the presence of H(2)O(2), the reaction pH between Fe(3)O(4) NPs and AU was similar to the reaction of oxidase and the substrate. The catalytic activity of Fe(3)O(4) NPs with AU was nearly unchanged following modification with poly(diallyldimethylammonium chloride) (PDDA). Based on these features, we prepared a composite of PDDA-modified Fe(3)O(4) NPs and oxidase for the quantification of specific substrates through the H(2)O(2)-mediated oxidation of AU. By monitoring fluorescence intensity at 587 nm of oxidized AU, the minimum detectable concentrations of glucose, galactose, and choline were found to be 3, 2, and 20 μM using glucose oxidase-Fe(3)O(4), galactose oxidase-Fe(3)O(4), and choline oxidase-Fe(3)O(4) composites, respectively. The identification of glucose in blood was selected as the model to validate the applicability of this proposed method. PMID:21843679

  9. Rapid degradation of dyes in water by magnetic Fe(0)/Fe3O4/graphene composites.

    PubMed

    Chong, Shan; Zhang, Guangming; Tian, Huifang; Zhao, He

    2016-06-01

    Magnetic Fe(0)/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption-desorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating-sample magnetometer (VSM) measurements and X-ray photoelectron spectroscopy (XPS). The results indicated that Fe(0)/Fe3O4/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe(0)/Fe3O4/graphene and pollutants. Fe(0)/Fe3O4/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe(0)/Fe3O4/graphene rapidly. After 20min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe(0)/Fe3O4/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe(0)/Fe3O4/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water. PMID:27266311

  10. Dispersion of nanocrystalline Fe3O4 within composite electrodes: Insights on battery-related electrochemistry

    DOE PAGESBeta

    David C. Bock; Takeuchi, Kenneth J.; Pelliccione, Christopher J.; Zhang, Wei; Wang, Jiajun; Knehr, K. W.; Wang, Jun; Wang, Feng; West, Alan C.; Marschilok, Amy C.; et al

    2016-04-20

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to themore » aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. Furthermore, this study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes.« less

  11. Contaminants Induced Onset of Nanostripes and Nanotrenches on the Fe3O4 (001) Surface

    NASA Astrophysics Data System (ADS)

    Ceballos, S. F.; Mariotto, G.; Jordan, K.; Murphy, S.; Seoighe, C.; Shvets, I. V.

    2003-12-01

    We report on the reconstructions induced by the segregation of contaminants at the (001) surface of Fe3O4 (magnetite). Natural and artificial single crystals of magnetite were annealed in ultra high vacuum (UHV) at ˜ 1000 K for periods of time ranging from few hours to several days. This preparation procedure causes impurities to segregate to the surface. Analytical techniques such as Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) were used to study this effect. From previous studies we have determined that a clean surface of magnetite exhibits a (√ × √)R45° reconstruction and, following our preparation procedure, is terminated at the octahedral plane. As impurities (K and Ca) segregate to the surface, the onset of a p(1 × 3) reconstruction was observed by LEED. As the annealing time increased, it was determined by AES that only Ca contaminants were present on the surface leading to a p(1 × 4) surface reconstruction. We propose two models to explain the observed p(1 × 3) and p(1 ×4) reconstructions which are in agreement with our AES, LEED and STM results.

  12. An atomic scale STM study of the Fe 3O 4(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Ceballos, S. F.; Mariotto, G.; Jordan, K.; Murphy, S.; Seoighe, C.; Shvets, I. V.

    2004-01-01

    Despite the intensive investigation into the electronic properties of magnetite, fundamental issues related to the Verwey transition and the electronic transport mechanism are not fully understood. These issues are further complicated at the surface of magnetite crystals, due to the large number of possible surface terminations. The preparation procedure plays a fundamental role in determining the O/Fe ratio, and therefore the electronic properties of a magnetite crystal. We present a detailed investigation of the influence of the preparation conditions on the morphology of Fe 3O 4(0 0 1) single crystal surfaces using AES, LEED, and STM. We show that long anneals of single crystals in UHV cause segregation of contaminants to the surface and that a series of surface reconstructions is induced. A different preparation procedure gives rise to a clean surface exhibiting a ( 2× 2)R 45° reconstruction. This surface is terminated at the octahedral plane and has been imaged down to the atomic scale. This provides a useful test system to study the Verwey transition at the surface.

  13. Hollow superparamagnetic PLGA/Fe 3O 4 composite microspheres for lysozyme adsorption

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Wu, Yao; Lan, Fang; Ma, Shaohua; Xie, Liqin; He, Bin; Gu, Zhongwei

    2014-02-01

    Uniform hollow superparamagnetic poly(lactic-co-glycolic acid) (PLGA)/Fe3O4 composite microspheres composed of an inner cavity, PLGA inner shell and Fe3O4 outer shell have been synthesized by a modified oil-in-water (O/W) emulsion-solvent evaporation method using Fe3O4 nanoparticles as a particulate emulsifier. The obtained composite microspheres with an average diameter of 2.5 μm showed excellent monodispersity and stability in aqueous medium, strong magnetic responsiveness, high magnetite content (>68%), high saturation magnetization (58 emu g-1) and high efficiency in lysozyme adsorption.

  14. Hollow superparamagnetic PLGA/Fe3O4 composite microspheres for lysozyme adsorption.

    PubMed

    Yang, Qi; Wu, Yao; Lan, Fang; Ma, Shaohua; Xie, Liqin; He, Bin; Gu, Zhongwei

    2014-02-28

    Uniform hollow superparamagnetic poly(lactic-co-glycolic acid) (PLGA)/Fe(3)O(4) composite microspheres composed of an inner cavity, PLGA inner shell and Fe(3)O(4) outer shell have been synthesized by a modified oil-in-water (O/W) emulsion-solvent evaporation method using Fe(3)O(4) nanoparticles as a particulate emulsifier. The obtained composite microspheres with an average diameter of 2.5 μm showed excellent monodispersity and stability in aqueous medium, strong magnetic responsiveness, high magnetite content (>68%), high saturation magnetization (58 emu g(-1)) and high efficiency in lysozyme adsorption. PMID:24492410

  15. ortho-Phenylenediamine: an effective spacer to build highly magnetic Fe3O4/Au nanocomposites.

    PubMed

    Zhao, Xinmei; Hosmane, Narayan S; Wu, Aiguo

    2012-12-21

    1,2-Diaminobenzene, popularly known as ortho-phenylenediamine (PDA), is found to be a prototype spacer for the deposition of gold nanoparticles on the surfaces of Fe(3)O(4) microspheres. Upon carbonization with PDA, the morphology of the product changes significantly, and the resulting nanocomposites exhibit enhanced magnetism beyond the saturation value of Fe(3)O(4). The Fe(3)O(4)/Au nanocomposites show good surface-enhanced Raman spectroscopy activity with a detection limit of 10(-15)  M. PMID:23143847

  16. [Detection of Ethoprophos Using SERS Coupled with Magnetic Fe3O4/Ag Composite Materials].

    PubMed

    Yuan, Rong-hui; Liu, Wen-han; Teng, Yuan-jie; Nie, Jing; Ma, Su-zhen

    2015-05-01

    The magnetic Fe3O4/Ag composite materials were synthesized by reducing AgNO3 with sodium citrate in the presence of Fe3O4 which were prepared by co-precipitation firstly. The enrichment and extraction of ethoprophos assembled on Fe3O4/Ag were achieved with the applied magnetic field. The different concentrations of ethoprophos adsorbed on Fe3O4/Ag were analyzed by SERS and it was showed that the trace analysis of ethoprophos had been established, while the enhancement factor of probe molecules on Fe3O4/Ag was 1. 48 X 10(5). The structure and morphology of Fe3O4/Ag were characterized by UV-Vis, EDX and TEM. Compared with Ag, the UV-Vis absorption peak of Fe3O4/Ag shifted from 417 to 369 nm, and the UV-Vis of Fe3O4 almost had no characteristic absorption peak in this region. At the same time, it was showed that the surface properties of Fe3O4/Ag changed with Raman enhancement effect during the aggregation process of Ag around the surface of Fe3O4. Further EDX images of micro area element analysis suggested that the chemical composition of products were Ag, Fe and O while the Cu peak was from the copper mesh. In addition, TEM images indicated that the average particle size of Fe3O4 was between 30 and 60 nm with shape tended to be spherical. And the silver nanoparticles were attached to the Fe3O4 particles and agglomeration occured. Density functional theory calculations which can be applied to qualitative judgment of molecule was carried out to obtain the molecular optimization structure and theoretical Raman spectra. It was found that the stabilized SERS signals were detected under the saturated adsorption equilibrium after 15 min. Finally, Raman response of ethoprophos was achieved with lower than 2 X 10(-8) mol . L-1 , indicatint that the established method had reached the requirements of ethoprophos residues detection and could be used for analysis of sulfur-containing organophosphorus pesticide. PMID:26415443

  17. Comparative Study of Biosafety, DNA, and Chromosome Damage of Different-Materials-Modified Fe3O4 in Rats.

    PubMed

    Xia, Dong-Lin; Chen, Yan-Pei; Chen, Chao; Wang, Yu-Fei; Li, Xiao-dong; He, Hong; Gu, Hai-Ying

    2015-11-01

    The increasing use of modified Fe3O4 magnetic microparticles has raised safety concerns regarding their use and effect on human health. This study assessed the in vivo biosafety, DNA, and chromosome damage of modified Fe3O4 microparticles such as Au@Fe3O4, Ag@Fe3O4, Cs@Fe3O4, Pt@Fe3O4, and CdS@Fe3O4, using spleen-deficient rats. Spleen-deficient rats treated with naked and modified (Au, Cs, Pt) Fe3O4 microparticles (5000 mg/kg) displayed low toxicity. Only treatment with Cds@Fe3O4 resulted in elevated toxicity and death in rats. Au-, Ag-, and Pt-modified Fe3O4 increased the rate of hemolysis in rats relative to treatment with naked Fe3O4. Despite this, Au- and Pt-modified Fe3O4 increased the biocompatibility and reduced DNA and chromosome damage in rats relative to naked Fe3O4. While Cs@Fe3O4 microparticles displayed a higher biocompatibility than naked Fe3O4, they displayed no significant reduction in DNA and chromosome damage. In summary, Au and Pt surface-modified Fe3O4 microparticles display elevated in vivo biosafety compared to unmodified particles. The precious metal material, with good biological compatibility, surface modification of Fe3O4 is an effective strategy to improve the overall safety and potential therapeutic utility of these magnetic materials. PMID:26329888

  18. Adsorption and desorption studies of lysozyme by Fe3O4-polymer nanocomposite via fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Koc, Kenan; Alveroglu, Esra

    2015-06-01

    The work have been undertaken in this study is to synthesis and characterize Fe3O4-polymer nanocomposites which are having different morphological properties. Also, investigation of the adsorption and desorption behaviour of lysozyme onto Fe3O4-polymer nanocomposites have been studied. Fe3O4 nanoparticles, synthesized by in situ in polyacrylamide hydrogels, show super-paramagnetic behaviour and saturation magnetization of composite material have been tuned by changing the hydrogel conformation. Adsorption and desorption studies of lysozyme were followed by using pure water at room temperature via fluorescence measurements. Fluorescence measurements showed that, the composite materials adsorbed lysozyme molecules less than 20 s and higher monomer concentration of composite materials cause faster adsorption. Besides, structure of lysozyme molecules were not changed during the adsorption and desorption. As a result Fe3O4-polymer nanocomposites could be used for drug delivery, protein separation and PAAm gels could be used for synthesis of magnetic composites with varying magnetic properties.

  19. Crystal structures and magnetic properties of magnetite (Fe3O4)/Polyvinyl alcohol (PVA) ribbon

    NASA Astrophysics Data System (ADS)

    Ardiyanti, Harlina; Suharyadi, Edi; Kato, Takeshi; Iwata, Satoshi

    2016-04-01

    Ribbon of magnetite (Fe3O4)/Polyvinyl Alcohol (PVA) nanoparticles have been successfully fabricated with various concentration of PVA synthesized by co-precipitation method. Particle size of nanoparticles Fe3O4 sample and ribbon Fe3O4/PVA 25% sample is about 9.34 nm and 11.29 nm, respectively. The result of Vibrating Sample Magnetometer (VSM) showed that saturation magnetization value decreased from 76.99 emu/g to 15.01 emu/g and coercivity increased from 49.30 Oe to 158.35 Oe as increasing concentration of PVA. Atomic Force Microscopy (AFM) analysis showed that encapsulated PVA given decreasing agglomeration, controlled shape of nanoparticles Fe3O4 more spherical and dispersed. Surface roughness decreased with increasing concentration of PVA.

  20. Magnetically Separable Fe3O4@DOPA-Pd: A Heterogeneous Catalyst for Aqueous Heck Reaction

    EPA Science Inventory

    Magnetically separable Fe3O4@DOPA-Pd catalyst has been synthesized via anchoring of palladium over dopamine-coated magnetite via non-covalent interaction and the catalyst is utilized for expeditious Heck coupling in aqueous media.

  1. Three-dimensional Fe3O4-graphene macroscopic composites for arsenic and arsenate removal.

    PubMed

    Guo, Liangqia; Ye, Peirong; Wang, Jing; Fu, Fengfu; Wu, Zujian

    2015-11-15

    3D graphene macroscopic gel synthesized via self-assembly of GO nanosheets under basic conditions at low temperature is modified with polydopamine and Fe3O4 nanoparticles. The modification of polydopamine can not only strengthen the 3D graphene-based macroscopic architecture but also enhance the loadage and binding ability of Fe3O4 nanoparticles. The synthesized 3D Fe3O4-graphene macroscopic composites are characterized by SEM, XRD, XPS, BET, Raman and magnetic property and used as a versatile adsorbent for sub-ppm concentration of As(III) and As(V) removal from aqueous solutions. The experimental results suggest that the synthesized 3D Fe3O4-graphene macroscopic composites are promising for treating low concentration of arsenic contaminated water. PMID:26001621

  2. TEA controllable preparation of magnetite nanoparticles (Fe3O4 NPs) with excellent magnetic properties

    NASA Astrophysics Data System (ADS)

    Han, Chengliang; Zhu, Dejie; Wu, Hanzhao; Li, Yao; Cheng, Lu; Hu, Kunhong

    2016-06-01

    A fast and controllable synthesis method for superparamagnetic magnetite nanoparticles (Fe3O4 NPs) was developed in Fe(III)-triethanolamine (TEA) solution. The phase structure, morphology and particle size of the as-synthesized samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the magnetic particles were pure Fe3O4 with mean sizes of approximately 10 nm. The used TEA has key effects on the formation of well dispersing Fe3O4 NPs. Vibrating sample magnetometer (VSM) result indicated that the as-obtained Fe3O4 NPs exhibited superparamagnetic behavior and the saturation magnetization (Ms) was about 70 emu/g, which had potential applications in magnetic science and technology.

  3. Polyvinyl Pyrrolidone-Assisted Solvothermal Synthesis of Fe3O4 Vesicular Nanospheres.

    PubMed

    Song, Hongfei; Liu, Meiying; Li, Sainan; Chen, Linlin; Lin, Chunming; Zhang, Liqing

    2015-05-01

    Monodispersed Fe3O4 vesicular nanospheres with a diameter of 160 nm have been fabricated solvothermally in the mixed solution of ethylene glycol (EG) and ethylenediamine (en) with the surfactant polyvinyl pyrrolidone (PVP). The microstructure and magnetic properties of the products were characterized by XRD, Raman, SEM, TEM, HRTEM, N2 adsorption-desorption and SQUID techniques. The HRTEM result shows that spherical Fe3O4 nanoparticles are structurally uniform with a distinct lattice spacing of 2.6 Å, which can be assigned to the (311) crystal facet of cubic Fe3O4. Besides, the as-obtained Fe3O4 vesicular nanospheres are ferromagnetic with a saturation magnetization of 86.9 emu/g as high as its bulk counterpart, demonstrating its promising applications in advanced magnetic materials and biomedicine. PMID:26505038

  4. Exceeding natural resonance frequency limit of monodisperse Fe3O4 nanoparticles via superparamagnetic relaxation

    PubMed Central

    Song, Ning-Ning; Yang, Hai-Tao; Liu, Hao-Liang; Ren, Xiao; Ding, Hao-Feng; Zhang, Xiang-Qun; Cheng, Zhao-Hua

    2013-01-01

    Magnetic nanoparticles have attracted much research interest in the past decades due to their potential applications in microwave devices. Here, we adopted a novel technique to tune cut-off frequency exceeding the natural resonance frequency limit of monodisperse Fe3O4 nanoparticles via superparamagnetic relaxation. We observed that the cut-off frequency can be enhanced from 5.3 GHz for Fe3O4 to 6.9 GHz forFe3O4@SiO2 core-shell structure superparamagnetic nanoparticles, which are much higher than the natural resonance frequency of 1.3 GHz for Fe3O4 bulk material. This finding not only provides us a new approach to enhance the resonance frequency beyond the Snoek's limit, but also extend the application for superparamagnetic nanoparticles to microwave devices. PMID:24196377

  5. An effective way to increase the high-frequency permeability of Fe3O4 nanorods

    NASA Astrophysics Data System (ADS)

    Ren, Xiao; Yang, Haitao; Tang, Jin; Li, Zi-An; Su, Yi Kun; Geng, Sai; Zhou, Jun; Zhang, Xiangqun; Cheng, Zhaohua

    2016-06-01

    Uniform Fe3O4 magnetic nanorods (NRs) were successfully synthesized and oriented in epoxy resin under a rotating magnetic field. Magnetic induction fields within and around a single Fe3O4 nanorod in the remanence state were obtained by off-axis electron holography. The induction fields indicated a single domain state of the highly anisotropic Fe3O4 nanorod due to its strong magnetic shape anisotropy. Quantitative magnetic moment analysis of the obtained phase image yielded an average magnetization of 0.53 T of a single Fe3O4 nanorod. Moreover, the real part of the permeability (μ') of magnetic-oriented Fe3O4 NRs is obviously higher than that of random Fe3O4 NRs in the GHz range. The oriented Fe3O4 NRs exhibit a higher resonance peak at 4.75 GHz compared to the bulk counterpart (1.2 GHz) in the frequency dependence of μ in the range of 1-10 GHz. Moreover, the calculated μ value of the oriented Fe3O4 NRs could be improved to 4.22 with the increased dipolar interaction strength using the OOMMF software. These results could play a guiding significance in the development of an effective method to improve the permeability of magnetic nanomaterials at GHz working frequency.Uniform Fe3O4 magnetic nanorods (NRs) were successfully synthesized and oriented in epoxy resin under a rotating magnetic field. Magnetic induction fields within and around a single Fe3O4 nanorod in the remanence state were obtained by off-axis electron holography. The induction fields indicated a single domain state of the highly anisotropic Fe3O4 nanorod due to its strong magnetic shape anisotropy. Quantitative magnetic moment analysis of the obtained phase image yielded an average magnetization of 0.53 T of a single Fe3O4 nanorod. Moreover, the real part of the permeability (μ') of magnetic-oriented Fe3O4 NRs is obviously higher than that of random Fe3O4 NRs in the GHz range. The oriented Fe3O4 NRs exhibit a higher resonance peak at 4.75 GHz compared to the bulk counterpart (1.2 GHz) in the

  6. Synthesis of Fe3O4 nanoparticles and its antibacterial application

    NASA Astrophysics Data System (ADS)

    Prabhu, Y. T.; Rao, K. Venkateswara; Kumari, B. Siva; Kumar, Vemula Sesha Sai; Pavani, Tambur

    2015-02-01

    The Present work outlines the antibacterial activity of Fe3O4 nanoparticles synthesized through chemical combustion method where ferric nitrate is used as precursor material and urea as fuel with the assistant of Tween 80, a non-ionic surfactant. The obtained Fe3O4 nanoparticles were characterized by X-ray diffraction, differential thermal analysis/thermo gravimetric analysis (DTA/TGA), particle size analyzer, SEM with EDAX and TEM. Various parameters such as dislocation density, micro strain, analysis of weight loss and surface morphological studies were calculated. The particle size was calculated from XRD and it was found to be 33-40 nm. Using well diffusion method antibacterial activity of Fe3O4 nanoparticles was tested against gram-positive and gram-negative Staphylococus aureus, Xanthomonas, Escherichia coli and Proteus vulgaris. Fe3O4 nanoparticles exhibited strong antibacterial activity against bacterial species.

  7. Preparation and electrochemical property of Fe3O4/MWCNT nanocomposite

    NASA Astrophysics Data System (ADS)

    Zhao, Tingkai; Ji, Xianglin; Guo, Xinai; Jin, Wenbo; Dang, Alei; Li, Hao; Li, Tiehu

    2016-06-01

    Ferroferric oxide (Fe3O4)/functionalized multi-walled carbon nanotube (f-MWCNT) nanomaterials were synthesized by chemical deposition & hydrothermal method. Fe3O4/f-MWCNT composites possess the same ferrimagnetism as pure Fe3O4, and the composites will present certain orientation in magnetism. The saturation magnetization (Ms) is about 48.84 emu g-1 and the coercivity (Hc) is 19.19 Oe. The electrochemical analysis displays that the glassy carbon electrode coated with Fe3O4/f-MWCNT composite has a favorable promotion for the electrochemical response of H2O2. This process not only widely improved the redox current of H2O2, but also reduced the overpotential of redox process.

  8. Fe3O4@mesoporous SBA-15: A magnetically recoverable catalyst for photodegradation of malachite green

    NASA Astrophysics Data System (ADS)

    Aliyan, Hamid; Fazaeli, Razieh; Jalilian, Rahil

    2013-07-01

    Surface of mesostructured silica (SBA-15) was modified by immobilizing Fe3O4. This modified-nanosized mesoporous silica Fe3O4@SBA-15 was characterized by FTIR, XRD, BET and SEM. A comparison of the photoefficiency of Fe3O4@SBA-15 toward photodegradation of malachite green (MG) was investigated in a photocatalytic reactor using UV lamp as a light source. The effect of various experimental parameters on the degradation performance of the process was evaluated by examining catalyst dosage, initial dye concentration and pH of the dye solution in the presence of Fe3O4@SBA-15 as photocatalyst. It was found that the photocatalyst exhibited significantly high catalytic stability, and the activity loss is negligible after five MG degradation cycles.

  9. Removal of Microcystis aeruginosa using nano-Fe3O4 particles as a coagulant aid.

    PubMed

    Zhang, Bo; Jiang, Dan; Guo, Xiaochen; He, Yiliang; Ong, Choon Nam; Xu, Yongpeng; Pal, Amrita

    2015-12-01

    Blue-green algae bloom is of great concern globally since they adversely affect the water ecosystem and also drinking water treatment processes. This work investigated the removal of Microcystis aeruginosa (M. aeruginosa) by combining the conventional coagulant polyaluminum chloride (PACl) with nano-Fe3O4 particles as a coagulant aid. The results showed that the addition of nano-Fe3O4 significantly improved the removal efficiency of M. aeruginosa by reducing the amount of PACl dosage and simultaneously hastening the sedimentation. At the M. aeruginosa density of an order of magnitude of 10(7), 10(6), and 10(5) pcs/mL, respectively, the corresponding PACl dose of 200, 20, and 2 mg/L and the mass ratio of PACl to nano-Fe3O4 of 4:1, the removal efficiency of M. aeruginosa could be increased by 33.0, 44.7, and 173.1%, respectively. Compared to PACl, PACl combined with the nano-Fe3O4 as a coagulant aid had higher removal efficiency at a wider pH range. SEM images showed that nano-Fe3O4 first combined with PACl to form clusters and further generated the flocs with algae. Results from the laser particle analyzer further suggested that the floc size increased with the addition of nano-Fe3O4. It was noted that the addition of nano-Fe3O4 led to aluminum species change after PACl hydrolyzed in the algae solution, from Ala to Alb and Alc subsequently. As a coagulant aid, the nano-Fe3O4, in conjunction with PACl, apparently provided nucleation sites for larger flocs to integrate with M. aeruginosa. In addition, increased floc density improved the removal of M. aeruginosa. PMID:26194241

  10. A DNA-Assembled Fe3O4@Ag Nanorod in Silica Matrix for Cholesterol Biosensing

    NASA Astrophysics Data System (ADS)

    Satvekar, R. K.; Tiwari, A. P.; Rohiwal, S. S.; Tiwale, B. M.; Pawar, S. H.

    2015-12-01

    A novel nanocomposite having DNA-assembled Fe3O4@Ag nanorods in silica matrix has been proposed for fabrication of bienzymatic cholesterol nanobiosensor. Cholesterol oxidase and horseradish peroxidase have been co-encapsulated in Silica/Fe3O4@Ag-DNA nanocomposite deposited on the indium tin oxide electrode. Cyclic voltammetry was employed for the electrochemical behavior of proposed biosensor and used to estimate cholesterol with a linear range of 5-195 mg/dL.

  11. Spin transport in molecules studied by Fe3O4/molecule nanoparticles

    NASA Astrophysics Data System (ADS)

    Yue, F. J.; Wang, S.; Wu, D.

    2013-05-01

    In this work, we synthesize single molecular layer coated Fe3O4 nanoparticles to form the network of the molecular junction spin valves. The Fe3O4 nanoparticles chemically bond with molecules without any physically absorbed molecules, leading to one monolayer molecule coated on nanoparticles. The magnetoresistance (MR) of cold-pressed Fe3O4/oleic acid nanoparticles is more than two times larger than bare Fe3O4 nanoparticles, indicating weaker spin scattering in molecules. Furthermore, the MR ratio is as high as ˜21 % at room temperature for Fe3O4/alkane molecule nanoparticles. Interestingly, even though the resistance spans about two decades as the alkane molecular length varies from 0.7 to 2.5 nm, the MR ratio stays approximately constant. This molecular length independent spin valve MR, originated from the weaker hyperfine interaction strength of the σ-electrons in alkane molecules, entails room-temperature spin-conserving transport in molecular materials. Using the size of ˜500 nm Fe3O4 nanoparticles, a large MR is achieved in a relatively low magnetic field. This feature opens a door for the development of future spin-based molecular electronics. Moreover, spin injection at the interface of Fe3O4/stearic acid molecule is investigated in a comparative study between Fe3O4 nanoparticles chemically bonded (ChemNPs) and physically absorbed (PhyNPs) molecules. A MR of 12 % at room temperature is observed in ChemNPs, in sharp contrast to the zero MR ratio in PhyNPs, reflecting that the chemical bonding is crucial for spin injection. These results show that the hybrid nanoparticles provide a simple approach to study the spin transport in molecules.

  12. Synthesis and magnetic properties of highly crystalline Fe3O4 nanorods

    NASA Astrophysics Data System (ADS)

    Das, R.; Stojak Repa, K.; Kalappattil, V.; Alonso, J.; Phan, Mh; Srikanth, H.

    Anisotropic one-dimensional magnetic nanostructures have drawn considerable attention due to their high surface to volume ratio, which drastically influences physical and chemical properties. In the past decade, most attention has been paid to the synthesis of Fe3O4 nanoparticles (NPs), mainly focusing on a spherical morphology. In this work, we report the first systematic study of the magnetic properties of highly crystalline Fe3O4 nanorods (NRs), which were synthesized by the hydrothermal method. XRD and TEM confirm the formation of highly crystalline Fe3O4 NRs with narrow size distribution. For high aspect ratio NRs (65×6nm), room temperature saturation magnetization is close to that of bulk Fe3O4 (~90emu/g) and much larger than that of spherical NPs of the same volume (60-70emu/g). DC magnetization vs. temperature data display a sharp change in the magnetization at 120K, which is attributed to the Verway transition, whose presence affirms the excellent crystallinity of Fe3O4 NRs. Owing to their high effective anisotropy and saturation magnetization, the Fe3O4 NRs show enhanced heating efficiency relative to their spherical NP counterparts when tested in a standard hyperthermia set-up.

  13. Facile synthesis of monodisperse superparamagnetic Fe3O4/PMMA composite nanospheres with high magnetization.

    PubMed

    Lan, Fang; Liu, Ke-Xia; Jiang, Wen; Zeng, Xiao-Bo; Wu, Yao; Gu, Zhong-Wei

    2011-06-01

    Monodisperse superparamagnetic Fe(3)O(4)/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe(3)O(4)/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe(3)O(4)/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe(3)O(4) nanoparticles. VSM and TGA showed that the Fe(3)O(4)/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g(-1) (total mass), which was only decreased by 17% compared with the initial bare Fe(3)O(4) nanoparticles. PMID:21454944

  14. Facile synthesis of monodisperse superparamagnetic Fe3O4/PMMA composite nanospheres with high magnetization

    NASA Astrophysics Data System (ADS)

    Lan, Fang; Liu, Ke-Xia; Jiang, Wen; Zeng, Xiao-Bo; Wu, Yao; Gu, Zhong-Wei

    2011-06-01

    Monodisperse superparamagnetic Fe3O4/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe3O4/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe3O4/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe3O4 nanoparticles. VSM and TGA showed that the Fe3O4/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g - 1 (total mass), which was only decreased by 17% compared with the initial bare Fe3O4 nanoparticles.

  15. Intercalating graphene with clusters of Fe3O4 nanocrystals for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Ke, Qingqing; Tang, Chunhua; Liu, Yanqiong; Liu, Huajun; Wang, John

    2014-04-01

    A hierarchical nanostructure consisting of graphene sheets intercalated by clusters of Fe3O4 nanocystals is developed for high-performance supercapacitor electrode. Here we show that the negatively charged graphene oxide (GO) and positively charged Fe3O4 clusters enable a strong electrostatic interaction, generating a hierarchical 3D nanostructure, which gives rise to the intercalated composites through a rational hydrothermal process. The electrocapacitive behavior of the resultant composites is systematically investigated by cyclic voltammeter and galvanostatic charge-discharge techniques, where a positive synergistic effect between graphene and Fe3O4 clusters is identified. A maximum specific capacitance of 169 F g-1 is achieved in the Fe3O4 clusters decorated with effectively reduced graphene oxide (Fe3O4-rGO-12h), which is much higher than those of rGO (101 F g-1) and Fe3O4 (68 F g-1) at the current density of 1 Ag-1. Moreover, this intercalated hierarchical nanostructure demonstrates a good capacitance retention, retaining over 88% of the initial capacity after 1000 cycles.

  16. The MIL-88A-Derived Fe3O4-Carbon Hierarchical Nanocomposites for Electrochemical Sensing

    NASA Astrophysics Data System (ADS)

    Wang, Li; Zhang, Yayun; Li, Xia; Xie, Yingzhen; He, Juan; Yu, Jie; Song, Yonghai

    2015-09-01

    Metal or metal oxides/carbon nanocomposites with hierarchical superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, novel hierarchical Fe3O4/carbon superstructures have been fabricated based on metal-organic frameworks (MOFs)-derived method. Three kinds of Fe-MOFs (MIL-88A) with different morphologies were prepared beforehand as templates, and then pyrolyzed to fabricate the corresponding novel hierarchical Fe3O4/carbon superstructures. The systematic studies on the thermal decomposition process of the three kinds of MIL-88A and the effect of template morphology on the products were carried out in detail. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermal analysis were employed to investigate the hierarchical Fe3O4/carbon superstructures. Based on these resulted hierarchical Fe3O4/carbon superstructures, a novel and sensitive nonenzymatic N-acetyl cysteine sensor was developed. The porous and hierarchical superstructures and large surface area of the as-formed Fe3O4/carbon superstructures eventually contributed to the good electrocatalytic activity of the prepared sensor towards the oxidation of N-acetyl cysteine. The proposed preparation method of the hierarchical Fe3O4/carbon superstructures is simple, efficient, cheap and easy to mass production. It might open up a new way for hierarchical superstructures preparation.

  17. Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed (Kappaphycus alvarezii) Extract.

    PubMed

    Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

    2016-12-01

    In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii (K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm(-1), which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm. PMID:27251326

  18. Chelerythrine and Fe3O4 Loaded Multi-Walled Carbon Nanotubes for Targeted Cancer Therapy.

    PubMed

    Cao, Liangli; Liang, Yongbo; Zhao, Feijun; Zhao, Xiongjie; Chen, Zhencheng

    2016-06-01

    The work focused on manufacturing improved drug loaded multifunctional magnetic nanoparticles that can overcome the relative non-specificity and potential side-effects of some chemotherapeutic drugs to healthy tissues. A new drug delivery system, Chelerythrine (CHE) and Fe3O4 loaded multi-walled carbon nanotubes (Fe3O4/MWNTs-CHE nanocomposites) that can target hepatocytes when treating malignant tumors, was prepared through a simple adsorption method. The formulation and structure of the Fe3O4/MWNTs-CHE nanocomposites were characterized by vibrating sample magnetometer (VSM), Fourier Transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The cytotoxicity and anti-proliferation effect from the prepared nanocomposites were in vitro tested on human hepatocarcinoma HepG2 and normal liver LO2 cell lines. The results showed the saturated magnetization of Fe3O4/MWNTs-CHE nanocomposites could reach to 45.4O3 emu/g, and the in vitro CHE release behavior exhibited a biphasic release pattern. Moreover, the in vitro cytotoxicity studies revealed that the Fe3O4/MWNTs-CHE nanocomposites showed an efficient inhibition rate to HepG2 cell line and exhibited a lower cytotoxicity to LO2 cell line in comparison to the native CHE. Therefore, the multifunctional Fe3O4/MWNTs-CHE nanocomposites should be a useful and promising candidate for treatment of malignant tumors. PMID:27319224

  19. Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed ( Kappaphycus alvarezii) Extract

    NASA Astrophysics Data System (ADS)

    Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

    2016-06-01

    In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii ( K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm-1, which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

  20. Size-Controllable Synthesis of Fe3O4 Nanospheres for Electromagnetic Wave Absorber

    NASA Astrophysics Data System (ADS)

    Wang, Yanping; Sun, Danping; Liu, Gongzong; Wang, Yujiao; Jiang, Wei

    2015-07-01

    We present a hydrothermal method to control the size of Fe3O4 nanospheres by adjusting the concentration of FeCl3·6H2O in ethylene glycol/diethylene glycol binary solvent mixtures. The electromagnetic wave absorption properties of Fe3O4 nanospheres of different diameters have been investigated using a vector network analyzer. The reflection loss of Fe3O4 nanospheres/paraffin wax composite can reach as high as -30.00 dB at 17.50 GHz and -37.95 dB at 7.67 GHz for Fe3O4 nanospheres with diameter of about 120 nm and 170 nm, respectively. The absorption bandwidth with reflection loss below -10 dB is up to 7.01 GHz when the Fe3O4 diameter is about 220 nm. In contrast, the bandwidth decreased to 4.28 GHz when the size shrank to 70 nm. Therefore, our method can be utilized to precisely control the size of Fe3O4 nanospheres in order to manipulate their electromagnetic wave absorption properties.

  1. The MIL-88A-Derived Fe3O4-Carbon Hierarchical Nanocomposites for Electrochemical Sensing.

    PubMed

    Wang, Li; Zhang, Yayun; Li, Xia; Xie, Yingzhen; He, Juan; Yu, Jie; Song, Yonghai

    2015-01-01

    Metal or metal oxides/carbon nanocomposites with hierarchical superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, novel hierarchical Fe3O4/carbon superstructures have been fabricated based on metal-organic frameworks (MOFs)-derived method. Three kinds of Fe-MOFs (MIL-88A) with different morphologies were prepared beforehand as templates, and then pyrolyzed to fabricate the corresponding novel hierarchical Fe3O4/carbon superstructures. The systematic studies on the thermal decomposition process of the three kinds of MIL-88A and the effect of template morphology on the products were carried out in detail. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermal analysis were employed to investigate the hierarchical Fe3O4/carbon superstructures. Based on these resulted hierarchical Fe3O4/carbon superstructures, a novel and sensitive nonenzymatic N-acetyl cysteine sensor was developed. The porous and hierarchical superstructures and large surface area of the as-formed Fe3O4/carbon superstructures eventually contributed to the good electrocatalytic activity of the prepared sensor towards the oxidation of N-acetyl cysteine. The proposed preparation method of the hierarchical Fe3O4/carbon superstructures is simple, efficient, cheap and easy to mass production. It might open up a new way for hierarchical superstructures preparation. PMID:26387535

  2. The MIL-88A-Derived Fe3O4-Carbon Hierarchical Nanocomposites for Electrochemical Sensing

    PubMed Central

    Wang, Li; Zhang, Yayun; Li, Xia; Xie, Yingzhen; He, Juan; Yu, Jie; Song, Yonghai

    2015-01-01

    Metal or metal oxides/carbon nanocomposites with hierarchical superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, novel hierarchical Fe3O4/carbon superstructures have been fabricated based on metal-organic frameworks (MOFs)-derived method. Three kinds of Fe-MOFs (MIL-88A) with different morphologies were prepared beforehand as templates, and then pyrolyzed to fabricate the corresponding novel hierarchical Fe3O4/carbon superstructures. The systematic studies on the thermal decomposition process of the three kinds of MIL-88A and the effect of template morphology on the products were carried out in detail. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermal analysis were employed to investigate the hierarchical Fe3O4/carbon superstructures. Based on these resulted hierarchical Fe3O4/carbon superstructures, a novel and sensitive nonenzymatic N-acetyl cysteine sensor was developed. The porous and hierarchical superstructures and large surface area of the as-formed Fe3O4/carbon superstructures eventually contributed to the good electrocatalytic activity of the prepared sensor towards the oxidation of N-acetyl cysteine. The proposed preparation method of the hierarchical Fe3O4/carbon superstructures is simple, efficient, cheap and easy to mass production. It might open up a new way for hierarchical superstructures preparation. PMID:26387535

  3. Synthesis and characterization of Fe 3 O 4 @C@Ag nanocomposites and their antibacterial performance

    NASA Astrophysics Data System (ADS)

    Xia, Haiqing; Cui, Bin; Zhou, Junhong; Zhang, Lulu; Zhang, Ji; Guo, Xiaohui; Guo, Huilin

    2011-09-01

    We synthesized Fe 3O 4@C@Ag nanocomposites through a combination of solvothermal, hydrothermal, and chemical redox reactions. Characterization of the resulting samples by X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning and transmission electron microscopy, and magnetic measurement is reported. Compared to Fe 3O 4@Ag nanocomposites, the Fe 3O 4@C@Ag nanocomposites showed enhanced antibacterial activity. The Fe 3O 4@C@Ag nanocomposites were able to almost entirely prevent growth of Escherichia coli when the concentration of Ag nanoparticles was 10 μg/mL. Antibacterial activity of the Fe 3O 4@C@Ag nanocomposites was maintained for more than 40 h at 37 °C. The intermediate carbon layer not only protects magnetic core, but also improves the dispersion and antibacterial activity of the silver nanoparticles. The magnetic core can be used to control the specific location of the antibacterial agent (via external magnetic field) and to recycle the residual silver nanoparticles. The Fe 3O 4@C@Ag nanocomposites will have potential uses in many fields as catalysts, absorbents, and bifunctional magnetic-optical materials.

  4. Biocompatibility of magnetic Fe3O4 nanoparticles and their cytotoxic effect on MCF-7 cells

    PubMed Central

    Chen, Daozhen; Tang, Qiusha; Li, Xiangdong; Zhou, Xiaojin; Zang, Jia; Xue, Wen-qun; Xiang, Jing-ying; Guo, Cai-qin

    2012-01-01

    Background The objective of this study was to evaluate the synthesis and biocompatibility of Fe3O4 nanoparticles and investigate their therapeutic effects when combined with magnetic fluid hyperthermia on cultured MCF-7 cancer cells. Methods Magnetic Fe3O4 nanoparticles were prepared using a coprecipitation method. The appearance, structure, phase composition, functional groups, surface charge, magnetic susceptibility, and release in vitro were characterized by transmission electron microscopy, x-ray diffraction, scanning electron microscopy-energy dispersive x-ray spectroscopy, and a vibrating sample magnetometer. Blood toxicity, in vitro toxicity, and genotoxicity were investigated. Therapeutic effects were evaluated by MTT [3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide] and flow cytometry assays. Results Transmission electron microscopy revealed that the shapes of the Fe3O4 nanoparticles were approximately spherical, with diameters of about 26.1 ± 5.2 nm. Only the spinel phase was indicated in a comparison of the x-ray diffraction data with Joint Corporation of Powder Diffraction Standards (JCPDS) X-ray powder diffraction files. The O-to-Fe ratio of the Fe3O4 was determined by scanning electron microscopy-energy dispersive x-ray spectroscopy elemental analysis, and approximated pure Fe3O4. The vibrating sample magnetometer hysteresis loop suggested that the Fe3O4 nanoparticles were superparamagnetic at room temperature. MTT experiments showed that the toxicity of the material in mouse fibroblast (L-929) cell lines was between Grade 0 to Grade 1, and that the material lacked hemolysis activity. The acute toxicity (LD50) was 8.39 g/kg. Micronucleus testing showed no genotoxic effects. Pathomorphology and blood biochemistry testing demonstrated that the Fe3O4 nanoparticles had no effect on the main organs and blood biochemistry in a rabbit model. MTT and flow cytometry assays revealed that Fe3O4 nano magnetofluid thermotherapy inhibited MCF-7

  5. Thermodynamics of Fe3O4-Co3O4 and Fe3O4-Mn3O4 spinel solid solutions at the bulk and nanoscale.

    PubMed

    Sahu, Sulata K; Huang, Baiyu; Lilova, Kristina; Woodfield, Brian F; Navrotsky, Alexandra

    2015-09-14

    High temperature oxide melt solution calorimetry has been performed to investigate the enthalpies of mixing (ΔmixH) of bulk and nanophase (1 -x)Fe3O4-xM3O4 (M = Co, Mn) spinel solid solutions. The entropies of mixing (ΔmixS) were calculated from the configurational entropies based on cation distributions, and the Gibbs free energies of mixing (ΔmixG) were obtained. The ΔmixH and ΔmixG for the (1 -x)Fe3O4-xCo3O4 system are negative over the complete solid solution range, for both macroscopic and nanoparticulate materials. In (1 -x)Fe3O4-xMn3O4, the formation enthalpies of cubic Fe3O4 (magnetite) and tetragonal Mn3O4 (hausmannite) are negative for Mn3O4 mole fractions less than 0.67 and slightly positive for higher manganese content. Relative to cubic Fe3O4 and cubic Mn3O4 (stable at high temperature), the enthalpies and Gibbs energies of mixing are negative over the entire composition range. A combination of measured mixing enthalpies and reported Gibbs energies in the literature provides experimental entropies of mixing. The experimental entropies of mixing are consistent with those calculated from cation distributions for x > 0.3 but are smaller than those predicted for x < 0.3. This discrepancy may be related to the calculations, having treated Fe(2+) and Fe(3+) as distinguishable species. The measured surface energies of the (1 -x)Fe3O4-xM3O4 solid solutions are in the range of 0.6-0.9 J m(-2), similar to those of many other spinels. Because the surface energies are relatively constant, the thermodynamics of mixing at a given particle size throughout the solid solution can be considered independent of the particular particle size, thus confirming and extending the conclusions of a recent study on iron spinels. PMID:26245233

  6. Synthesis of talc/Fe3O4 magnetic nanocomposites using chemical co-precipitation method

    PubMed Central

    Kalantari, Katayoon; Ahmad, Mansor Bin; Shameli, Kamyar; Khandanlou, Roshanak

    2013-01-01

    The aim of this research was to synthesize and develop a new method for the preparation of iron oxide (Fe3O4) nanoparticles on talc layers using an environmentally friendly process. The Fe3O4 magnetic nanoparticles were synthesized using the chemical co-precipitation method on the exterior surface layer of talc mineral as a solid substrate. Ferric chloride, ferrous chloride, and sodium hydroxide were used as the Fe3O4 precursor and reducing agent in talc. The talc was suspended in deionized water, and then ferrous and ferric ions were added to this solution and stirred. After the absorption of ions on the exterior surface of talc layers, the ions were reduced with sodium hydroxide. The reaction was carried out under a nonoxidizing oxygen-free environment. There were not many changes in the interlamellar space limits (d-spacing = 0.94−0.93 nm); therefore, Fe3O4 nanoparticles formed on the exterior surface of talc, with an average size of 1.95–2.59 nm in diameter. Nanoparticles were characterized using different methods, including powder X-ray diffraction, transmission electron microscopy, emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. These talc/Fe3O4 nanocomposites may have potential applications in the chemical and biological industries. PMID:23696700

  7. Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes.

    PubMed

    Fan, Huailin; Niu, Ruiting; Duan, Jiaqi; Liu, Wei; Shen, Wenzhong

    2016-08-01

    Fe3O4@carbon nanosheet composites were synthesized using ammonium ferric citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, and the utmost utilization of Fe3O4 and resulted in excellent specific capacitance, outstanding rate capability and cycling life as all-solid-state supercapacitor electrodes. PMID:27406686

  8. Thermal decomposition study of Mn doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Malek, Tasmira J.; Chaki, S. H.; Tailor, J. P.; Deshpande, M. P.

    2016-05-01

    Fe3O4 is an excellent magnetic material among iron oxides. It has a cubic inverse spinel structure exhibiting distinguished electric and magnetic properties. In this paper the authors report the synthesis of Mn doped Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its thermal characterization. Ferric chloride hexa-hydrate (FeCl3•6H2O), manganese chloride tetra-hydrate (MnCl2•4H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the as-synthesized Mn doped Fe3O4 nanoparticles were determined by energy dispersive analysis of X-rays (EDAX) technique. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out on the Mn doped Fe3O4 nanoparticles in the temperature range of ambient to 1124 K. The thermo-curves revealed that the particles decompose by four steps. The kinetic parameters were evaluated using non-mechanistic equations for the thermal decomposition.

  9. Functionalized Magnetic Fe3O4-β-Cyclodextran Nanoparticles for Efficient Removal of Bilirubin.

    PubMed

    Han, Lulu; Chu, Simin; Wei, Houliang; Ren, Jun; Xu, Li; Jia, Lingyun

    2016-06-01

    Bilirubin (BR), as a lipophilic toxin, can binds and deposits in various tissues, especially the brain tissue, leading to hepatic coma and even death. Magnetic nanoparticles adsorbent modified by β-cyclodextran (Fe3O4-β-CD) was developed to remove the BR from the plasma. Fe3O4-β-CD nanoparticles was prepared through Schiff base reaction between the polyethylenimine (PEI)-modified Fe3O4 and aldehyde-functionalized β-CD, and characterized by Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and dynamic light scattering (DLS). Under optimized conditions, the Fe3O4-β-CD adsorbent could adsorb 225.6 mg/g free BR in PBS and reach the adsorption equilibrium within 90 min mainly through hydrophobic interaction; Moreover, the adsorbent displayed better adsorption capability in a dialysis system for BSA-bound bilirubin, plasma bilirubin and total bile acid, and the removal rates of those were 66%, 31% and 41% respectively. Because of the advantages of fast separation and purification process, low preparation cost, good adsorption capability for plasma bilirubin, Fe3O4-β-CD may become an economical and promising absorbent of BR for clinical applications. PMID:27427594

  10. Microwave absorption behavior of ZnO whisker modified by nanosized Fe3O4 particles.

    PubMed

    Hu, Shuchun; Wu, Guofeng; Huang, Zhenhao; Chen, Xiaolang

    2010-11-01

    Tetra-needle-like ZnO whisker was magnetic modified through in situ synthesis of nanosized Fe3O4 particles on the surface of the whisker, and the microwave absorption behavior of the as-prepared product was investigated in detail. The result of the comparative microwave absorbing experiment showed that the magnetic modified ZnO whisker appeared more superior property of microwave absorption than that of the original ZnO whisker in 2-18 GHz. Further investigation indicated that the microwave absorption behavior of the product was influenced by ferrite content and Fe3O4 particles' distribution in the product. When the ferrite content of the product changed from 2 wt% to 9 wt%, the microwave absorbing ability of the product was increased; then, the microwave absorbing ability of the product decreased with the further increasing of ferrite content from 9 wt% to 16 wt%. The product with uniform distribution of Fe3O4 particles showed better microwave absorption property than that with irregular distribution of Fe3O4 particles, and this result inferred that the biphase interface between ZnO and Fe3O4 contributed to microwave absorption through interface polarization. PMID:21137989

  11. Magnetic field synthesis of Fe 3O 4 nanoparticles used as a precursor of ferrofluids

    NASA Astrophysics Data System (ADS)

    Hong, R. Y.; Pan, T. T.; Han, Y. P.; Li, H. Z.; Ding, J.; Han, Sijin

    2007-03-01

    Methods to synthesize magnetic Fe 3O 4 nanoparticles and to modify the nanoparticle surface are presented in this paper. In these methods, Fe 3O 4 nanoparticles were prepared by co-precipitation, and the aging of nanoparticles was improved by applied magnetic field. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Thereafter, to enhance the compatibility between nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticle surface. FT-IR, XRD, transmission electron microscopy (TEM), and thermogravimetry (TG) were used to characterize the resultant sample. The testing results indicated that the polyacrylic acid chains have been covalently bonded to the surface of magnetic Fe 3O 4 nanoparticles. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface-modified Fe 3O 4 nanoparticles were investigated. Moreover, the Fe 3O 4-g-PAA hybrid nanoparticles were dispersed in water to form ferrofluids (FFs). The obtained FFs were characterized by UV-vis spectrophotometer, Gouy magnetic balance and laser particle-size analyzer. The testing results showed that the high-concentration FF had excellent stability, with high susceptibility and high saturation magnetization. The rheological properties of the FFs were also investigated using a rotating rheometer.

  12. A plasma protein corona enhances the biocompatibility of Au@Fe3O4 Janus particles.

    PubMed

    Landgraf, Lisa; Christner, Carolin; Storck, Wiebke; Schick, Isabel; Krumbein, Ines; Dähring, Heidi; Haedicke, Katja; Heinz-Herrmann, Karl; Teichgräber, Ulf; Reichenbach, Jürgen R; Tremel, Wolfgang; Tenzer, Stefan; Hilger, Ingrid

    2015-11-01

    Au@Fe3O4 Janus particles (JPs) are heteroparticles with discrete domains defined by different materials. Their tunable composition and morphology confer multimodal and versatile capabilities for use as contrast agents and drug carriers in future medicine. Au@Fe3O4 JPs have colloidal properties and surface characteristics leading to interactions with proteins in biological fluids. The resulting protein adsorption layer ("protein corona") critically affects their interaction with living matter. Although Au@Fe3O4 JPs displayed good biocompatibility in a standardized in vitro situation, an in-depth characterization of the protein corona is of prime importance to unravel underlying mechanisms affecting their pathophysiology and biodistribution in vitro and in vivo. Here, we comparatively analyzed the human plasma corona of Au-thiol@Fe3O4-SiO2-PEG JPs (NH2-functionalized and non-functionalized) and spherical magnetite (Fe3O4-SiO2-PEG) particles and investigated its effects on colloidal stability, biocompatibility and cellular uptake. Label-free quantitative proteomic analyses revealed that complex coronas including almost 180 different proteins were formed within only one minute. Remarkably, in contrast to spherical magnetite particles with surface NH2 groups, the Janus structure prevented aggregation and the adhesion of opsonins. This resulted in an enhanced biocompatibility of corona sheathed JPs compared to spherical magnetite particles and corona-free JPs. PMID:26276693

  13. Studies on the synthesis and microwave absorption properties of Fe3 O4/polyaniline FGM

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Wang, Yuan-Sheng

    2007-12-01

    Electrically conducting polyaniline (PANI)-magnetic oxide (Fe3 O4) composites were synthesized by emulsion polymerization in the presence of dodecyl benzene sulfonic acid (DBSA) as the surfactant and dopant and ammonium persulfate (APS) as the oxidant. Transmission electron microscopy (TEM) indicates that the composite has a magnetic core and an electric shell and the modification has prevented the aggregation of Fe3 O4 nanoparticles effectively. The electromagnetic parameter measurements (ɛ'', ɛ', μ'' and μ') in the range of 2-18 GHz prove that Fe3 O4 in the Fe3 O4/PANI/DBSA is responsible for the electric and ferromagnetic behavior of the composites. As a result, the electromagnetic parameters can be designed by adjusting the content of the Fe3 O4. The microwave absorption of functionally graded material (FGM) was simulated by the computer according to the principle of impedance match and the calculated results agreed quite well with the experimentally measured data (R<-20 dB, Δf>4 GHz).

  14. Synthesis and properties of hybrid hydroxyapatite-ferrite (Fe3O4) particles for hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Tkachenko, M. V.; Kamzin, A. S.

    2016-04-01

    Hybrid ceramics consisting of hydroxyapatite Ca10(PO4)6(OH)2 and ferrite Fe3O4 were synthesized using a two-stage procedure. The first stage included the synthesis of Fe3O4 ferrite particles by co-precipitation and the synthesis of hydroxyapatite. In the second stage, the magnetic hybrid hydroxyapatite-ferrite bioceramics were synthesized by a thorough mixing of the obtained powders of carbonated hydroxyapatite and Fe3O4 ferrite taken in a certain proportion, pressing into tablets, and annealing in a carbon dioxide atmosphere for 30 min at a temperature of 1200°C. The properties of the components and hybrid particles were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Mössbauer spectroscopy. The saturation magnetization of the hybrid ceramic composite containing 20 wt % Fe3O4 was found to be 12 emu/g. The hybrid hydroxyapatite (Ca10(PO4)6(OH)2)-ferrite Fe3O4 ceramics, which are promising for the use in magnetotransport and hyperthermia treatment, were synthesized and investigated for the first time.

  15. Differential Scanning Calorimetry Investigations on Polyvinylidene Fluoride - Fe3O4 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Salinas, Samantha; Jones, Robert; Chipara, Dorina M.; Chipara, Mircea

    2015-03-01

    Nanocomposites of polyvinylidene fluoride (PVDF)-magnetite (Fe3O4) with various weight fractions of nanofiller (0%, 0.2 %, 0.6 %, 1.2%, 2.4 %, 5.8 %, 12 %, 23 %, and 30 %) have been obtained via melt mixing by loading PVDF with Fe3O4 particles (average size 75 nm from Nanostructured & Amorphous Materials, Inc). Thermal stability of PVDF-Fe3O4 has been investigated by TGA in nitrogen. The increase of the thermal stability of PVDF due to the loading with Fe3O4 was quantified by the shift of the temperature at which the (mass) degradation rate is maximum as a function of Fe3O4 content. The effect of the nanofiller on the crystallization of PVDF was investigated by isothermal DSC (TA Instruments, Q500). Non isothermal DSC tests, (at various heating rates ranging from 1 to 25 °C/min) have been used to locate the glass, crystallization, and melting temperatures. The dependence of the glass, crystallization, and melting temperatures on the concentration of nanoparticles is reported and analyzed in detail. The data are critically analyzed within the classical Avrami theory.

  16. In-Situ Preparation and Magnetic Properties of Fe3O4/WOOD Composite

    NASA Astrophysics Data System (ADS)

    Gao, Honglin; Zhang, Genlin; Wu, Guoyuan; Guan, Hongtao

    2011-06-01

    Fe3O4/wood composite, a magnetic material, was prepared by In-situ chemosynthesis method at room temperature. The X-ray diffraction (XRD) shows that the average partical size of Fe3O4 was about 14 nm. The magnetic properties of the resulting composites were investigated by vibrating sample magnetometer (VSM). The composites have saturation magnetization (Ms) values from 4.7 to 25.3 emu/g with the increase of weight percent gains (WPG) of the wood for the composites, but coercive forces (Hc) are invariable, which is different from the magnetic materials reported before. It may be due to the fact that the interaction between wood and Fe3O4 becomes stronger when less of Fe3O4 particles are introduced in the composition, and this also changes the surface anisotropy (Ks) of the magnetism. A structural characterization by Fourier transform infrared (FTIR) proved the interaction between Fe3O4 particles and wood matrix, and it also illustrates that this interaction influences the coercive force of the composite.

  17. Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes.

    PubMed

    Kurtan, U; Amir, Md; Baykal, A; Sözeri, H; Toprak, M S

    2016-03-01

    Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FT-IR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water. PMID:27455668

  18. Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness

    NASA Astrophysics Data System (ADS)

    Gu, Shu-Ying; Jin, Sheng-Peng; Gao, Xie-Feng; Mu, Jian

    2016-05-01

    Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe3O4 nanoparticles in a polymer matrix. A homogeneous distribution of Fe3O4 nanoparticles in the polymer matrix was obtained for nanocomposites with low Fe3O4 loading content. A small agglomeration was observed for nanocomposites with 6 wt% and 9 wt% loading content, leading to a small decline in the mechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites also exhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with an increase in the loading content of Fe3O4 nanoparticles due to an improvement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential application in biomedical areas such as intravascular stent.

  19. Nanoparticle size matters in the formation of plasma protein coronas on Fe3O4 nanoparticles.

    PubMed

    Hu, Zhengyan; Zhang, Hongyan; Zhang, Yi; Wu, Ren'an; Zou, Hanfa

    2014-09-01

    When nanoparticles (NPs) enter into biological systems, proteins would interact with NPs to form the protein corona that can critically impact the biological identity of the nanomaterial. Owing to their fundamental scientific interest and potential applications, Fe3O4 NPs of different sizes have been developed for applications in cell separation and protein separation and as contrast agents in magnetic resonance imaging (MRI), etc. Here, we investigated whether nanoparticle size affects the formation of protein coronas around Fe3O4 NPs. Both the identification and quantification results demonstrated that particle size does play an important role in the formation of plasma protein coronas on Fe3O4 NPs; it not only influenced the protein composition of the formed plasma protein corona but also affected the abundances of the plasma proteins within the coronas. Understanding the different binding profiles of human plasma proteins on Fe3O4 NPs of different sizes would facilitate the exploration of the bio-distributions and biological fates of Fe3O4 NPs in biological systems. PMID:24974013

  20. Polar Spinel-Perovskite Interfaces: an atomistic study of Fe3O4(111)/SrTiO3(111) structure and functionality

    PubMed Central

    Gilks, Daniel; McKenna, Keith P.; Nedelkoski, Zlatko; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Lari, Leonardo; Kepaptsoglou, Demie; Ramasse, Quentin; Tear, Steve; Lazarov, Vlado K.

    2016-01-01

    Atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy combined with ab initio electronic calculations are used to determine the structure and properties of the Fe3O4(111)/SrTiO3(111) polar interface. The interfacial structure and chemical composition are shown to be atomically sharp and of an octahedral Fe/SrO3 nature. Band alignment across the interface pins the Fermi level in the vicinity of the conduction band of SrTiO3. Density functional theory calculations demonstrate very high spin-polarization of Fe3O4 in the interface vicinity which suggests that this system may be an excellent candidate for spintronic applications. PMID:27411576

  1. Polar Spinel-Perovskite Interfaces: an atomistic study of Fe3O4(111)/SrTiO3(111) structure and functionality.

    PubMed

    Gilks, Daniel; McKenna, Keith P; Nedelkoski, Zlatko; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Lari, Leonardo; Kepaptsoglou, Demie; Ramasse, Quentin; Tear, Steve; Lazarov, Vlado K

    2016-01-01

    Atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy combined with ab initio electronic calculations are used to determine the structure and properties of the Fe3O4(111)/SrTiO3(111) polar interface. The interfacial structure and chemical composition are shown to be atomically sharp and of an octahedral Fe/SrO3 nature. Band alignment across the interface pins the Fermi level in the vicinity of the conduction band of SrTiO3. Density functional theory calculations demonstrate very high spin-polarization of Fe3O4 in the interface vicinity which suggests that this system may be an excellent candidate for spintronic applications. PMID:27411576

  2. Polar Spinel-Perovskite Interfaces: an atomistic study of Fe3O4(111)/SrTiO3(111) structure and functionality

    NASA Astrophysics Data System (ADS)

    Gilks, Daniel; McKenna, Keith P.; Nedelkoski, Zlatko; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Lari, Leonardo; Kepaptsoglou, Demie; Ramasse, Quentin; Tear, Steve; Lazarov, Vlado K.

    2016-07-01

    Atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy combined with ab initio electronic calculations are used to determine the structure and properties of the Fe3O4(111)/SrTiO3(111) polar interface. The interfacial structure and chemical composition are shown to be atomically sharp and of an octahedral Fe/SrO3 nature. Band alignment across the interface pins the Fermi level in the vicinity of the conduction band of SrTiO3. Density functional theory calculations demonstrate very high spin-polarization of Fe3O4 in the interface vicinity which suggests that this system may be an excellent candidate for spintronic applications.

  3. Seeded preparation of ultrathin FeS2 nanosheets from Fe3O4 nanoparticles.

    PubMed

    Li, Tingting; Liu, Huiwen; Wu, Zhennan; Liu, Yi; Guo, Zuoxing; Zhang, Hao

    2016-06-01

    FeS2 nanomaterials with two-dimensional features hold great promise for electrochemical and photovoltaic applications. However, the preparation of ultrathin FeS2 nanosheets is still challenging because of the lack of a tailor-made approach. In this work, FeS2 nanosheets with a thickness of 2.1 nm are prepared through a Fe3O4-seeded approach. Uniform Fe3O4 nanoparticles are foremost synthesized via the standard method in organic media. The injection of a S solution leads to the replacement of O in Fe3O4 through anion-exchange, which generates (110) facet-enriched FeS2 nuclei. The subsequent (110) facet-mediated oriented attachment and fusion of FeS2 nuclei produce ultrathin FeS2 nanosheets. As catalysts in the hydrogen evolution reaction, FeS2 nanosheets exhibit good electrochemical activity. PMID:27243138

  4. Analysis of surface potential and magnetic properties of Fe3O4/graphene oxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Mishra, Amodini; Mohanty, Tanuja

    2016-05-01

    Nanocomposite of magnetite/graphene oxide (Fe3O4/GO) has been synthesized by co-precipitation method. The phase formation of the magnetite nanoparticles (Fe3O4 NPs) was confirmed by X-ray diffraction (XRD) analysis. Effect of Fe3O4 NPs on the Raman spectra and on the surface potential of GO has been analyzed. Due to incorporation of NPs, change in the characteristic Raman peaks and also on the surface potential of GO is observed. Transmission electron microscopic (TEM) study has been carried out for surface morphology. Magnetic property measurement was carried out by using physical property measurement system (PPMS) at two different temperatures (30 K and 300K).

  5. Tunable fluorescence enhancement based on bandgap-adjustable 3D Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Fei; Gao, Suning; Zhu, Lili; Liao, Fan; Yang, Lulu; Shao, Mingwang

    2016-06-01

    Great progress has been made in fluorescence-based detection utilizing solid state enhanced substrates in recent years. However, it is still difficult to achieve reliable substrates with tunable enhancement factors. The present work shows liquid fluorescence enhanced substrates consisting of suspensions of Fe3O4 nanoparticles (NPs), which can assemble 3D photonic crystal under the external magnetic field. The photonic bandgap induced by the equilibrium of attractive magnetic force and repulsive electrostatic force between adjacent Fe3O4 NPs is utilized to enhance fluorescence intensity of dye molecules (including R6G, RB, Cy5, DMTPS-DCV) in a reversible and controllable manner. The results show that a maximum of 12.3-fold fluorescence enhancement is realized in the 3D Fe3O4 NP substrates without the utilization of metal particles for PCs/DMTPS-DCV (1.0 × 10‑7 M, water fraction (f w) = 90%).

  6. Finite-size scaling law in single-crystalline Fe3O4 hollow nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoping; Wang, Jun; Gao, Miao

    2016-07-01

    Single-crystalline Fe3O4 hollow nanostructures (nanoring and nanotube) have been successfully synthesized by a hydrothermal method along with a heat treatment process. The temperature dependences of the magnetization of the hollow nanostructures were measured under a high vacuum ( < 9.5 × 10‑6 Torr) from 300K to 900K. The Curie temperatures of the nanoring and nanotube samples were found to decrease with decreasing the mean wall thickness. The Curie temperatures of the hollow magnetite nanostructures follow a finite-size scaling relation with the scaling exponent ν = 1.04 ± 0.03. By comparison with those of the zero-dimensional Fe3O4 particles and two-dimensional Fe3O4 films, we show that the scaling relation for our hollow nanostructures is in better agreement with the quasi-two-dimensional finite-size scaling law.

  7. Robust polymer grafted Fe3O4 nanospheres for benign removal of oil from water

    NASA Astrophysics Data System (ADS)

    Madhusudhana Reddy, P.; Chang, Chi-Jung; Chen, Jem-Kun; Wu, Meng-Ting; Wang, Chih-Feng

    2016-04-01

    Removal of oil from the oil-water mixture (O-W mixture) or oil-in-water emulsions (O/W emulsion) is highly imperative. We have fabricated two series of polymer grafted iron oxide (Fe3O4) nanospheres. The oil removal efficiency of the nanospheres was found to be dependent on the grafted amount of polymers. The polystyrene grafted Fe3O4 nanospheres have shown better oil removal efficiency than the corresponding poly(butyl acrylate) grafted Fe3O4 nanospheres. The higher amount of grafted polystyrene can provide more hydrophobic character to FS series nanospheres. The FS series nanospheres exhibited higher oil-absorption capability than FB series nanospheres. Both the series of nanospheres can be recycled by simple washing method. The present results can pave the way to fabricate the robust materials for efficient absorption of various oils or organic solvents from both the oil-water mixture and oil-water emulsion.

  8. Tunable fluorescence enhancement based on bandgap-adjustable 3D Fe3O4 nanoparticles.

    PubMed

    Hu, Fei; Gao, Suning; Zhu, Lili; Liao, Fan; Yang, Lulu; Shao, Mingwang

    2016-06-17

    Great progress has been made in fluorescence-based detection utilizing solid state enhanced substrates in recent years. However, it is still difficult to achieve reliable substrates with tunable enhancement factors. The present work shows liquid fluorescence enhanced substrates consisting of suspensions of Fe3O4 nanoparticles (NPs), which can assemble 3D photonic crystal under the external magnetic field. The photonic bandgap induced by the equilibrium of attractive magnetic force and repulsive electrostatic force between adjacent Fe3O4 NPs is utilized to enhance fluorescence intensity of dye molecules (including R6G, RB, Cy5, DMTPS-DCV) in a reversible and controllable manner. The results show that a maximum of 12.3-fold fluorescence enhancement is realized in the 3D Fe3O4 NP substrates without the utilization of metal particles for PCs/DMTPS-DCV (1.0 × 10(-7) M, water fraction (f w) = 90%). PMID:27171125

  9. Distinctive uniaxial magnetic anisotropy and positive magnetoresistance in (110)-oriented Fe3O4 films

    NASA Astrophysics Data System (ADS)

    Dho, Joonghoe; Kim, Byeong-geon; Ki, Sanghoon

    2015-04-01

    Magnetite (Fe3O4) films were synthesized on (110)-oriented MgO, MgAl2O4, and SrTiO3 substrates for comparative studies of the substrates' effects on magnetic and magnetoresistance properties of the films. For the [-110] direction, the hysteresis loops of the Fe3O4 film on MgAl2O4 exhibited a good squareness with the largest coercivity of ˜1090 Oe, and the ratio of remanent magnetization to saturation magnetization was ˜0.995. For the [001] direction, positive magnetoresistance in weak magnetic fields was most distinct for the (110) SrTiO3 substrate with the largest lattice mismatch. Positive magnetoresistance in the (110) Fe3O4 films was presumably affected by imperfect atomic arrangements at anti-phase boundaries.

  10. Influence of the uniform electric field on viscosity of magnetic nanofluid (Fe3O4-EG)

    NASA Astrophysics Data System (ADS)

    Monajjemi Rarani, E.; Etesami, N.; Nasr Esfahany, M.

    2012-11-01

    Viscosity of Fe3O4/ethylene glycol nanofluids under electric field (ac and dc) was investigated experimentally. Magnetic nanofluids were prepared by dispersing Fe3O4 nanoparticles in ethylene glycol using a sonicator. Experiments showed that dilute magnetic nanofluids (<0.05 vol. %) as well as base fluid exhibit Newtonian behavior. Viscosity of Fe3O4 / ethylene glycol nanofluids in electric field was measured using capillary tube viscometer. Electric field decreased the viscosity of magnetic nanofluids and base fluid. The viscosity reduction was more profound in higher volume concentrations of nanoparticles. dc electric field caused greater viscosity reduction in magnetic nanofluids relative to ac electric field while ac electric field showed greater reduction effect for base liquid.

  11. Green synthesis and surface properties of Fe3O4@SA core-shell nanocomposites

    NASA Astrophysics Data System (ADS)

    Cao, Huimin; Li, Juchuan; Shen, Yuhua; Li, Shikuo; Huang, Fangzhi; Xie, Anjian

    2014-05-01

    In this paper, a one-step, economic and green approach was explored to prepare Fe3O4 nanoparticles by using L-cysteine as reducer and disperser without any inert gas protection. The Fe3O4 nanoparticles were then modified with stearic acid (SA) to form Fe3O4@SA core-shell nanocomposites. The experiment results indicate that the core-shell nanocomposites prepared could form monolayer on the water surface or films by means of Langmuir-Blodgett (LB) technology due to their hydrophobic and lipophilic properties. Also the composites exhibit paramagnetism, which make product dispersed stably in the oil medium to form magnetic fluid. Moreover, they are developed as sorbents to remove oil from water surface.

  12. Magnetic Fe3O4@chitosan nanoparticle: synthesis, characterization and application as catalyst carrier.

    PubMed

    He, Linghao; Yao, Lu; Liu, Fujun; Qin, Bing; Song, Rul; Huang, Wei

    2010-10-01

    A novel method was developed to prepare Fe3O4@CS beads with core-shell structure using a double-crosslinking process. Before the coating process, an unique crosslinking agent, glutaraldehyde (GA), was adsorbed onto the surface of Fe3O4 in advance, so the subsequent CS can uniformly coat around the magnetic core processed from the strong interaction between GA and CS, forming a perfect core-shell structure. The obtained Fe3O4@CS beads were followed by the Pd deposition through in-situ reduction method, and the prepared composite catalyst was applied exemplarily in synthesizing nabumetone to check its reusing property. The nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and the magnetic hysteresis loop determination method. This novel composite catalyst showed admirable potential in reusable catalysis. PMID:21137729

  13. Tunable dielectric properties and excellent microwave absorbing properties of elliptical Fe3O4 nanorings

    NASA Astrophysics Data System (ADS)

    Tong, Guoxiu; Liu, Yun; Cui, Tingting; Li, Yana; Zhao, Yanting; Guan, Jianguo

    2016-02-01

    Elliptical Fe3O4 nanorings (NRs) with continuously tunable axes that range from 40 nm to 145 nm in length were prepared through a precursor-directed synthetic route to determine the electromagnetic responses generated at 2-18 GHz. The tunability of the dielectric properties of Fe3O4 NRs depends on the long axis rather than on the specific surface area, internal stress, and grain size. Elliptical Fe3O4 NRs exhibit the excellent microwave absorbing properties due to the unique ring-like configuration, which significantly enhances permittivity, multiple scattering, oscillation resonance absorption, microantenna radiation, and interference. These findings indicate that ring-like nanostructures are promising for devising effective microwave absorbers.

  14. Controlled synthesis and size-dependent thermal conductivity of Fe3O4 magnetic nanofluids.

    PubMed

    Wang, Baodui; Wang, Baogang; Wei, Pengfei; Wang, Xiaobo; Lou, Wenjing

    2012-01-21

    The effect of nanoparticle size (4~44 nm) on the thermal conductivities of heat transfer oils has been systematically examined using iron oxide nanoparticles. Such Fe(3)O(4) nanoparticles were synthesized by a simple one-pot pyrolysis method. The size (16~44 nm), shape and assembly patterns of monodisperse Fe(3)O(4) nanoparticles were modulated by only controlling the amount of Fe(acac)(3). After the as-prepared Fe(3)O(4) NPs were dispersed in heat transfer oils, the prepared magnetic nanofluids exhibit higher thermal conductivity than heat transfer oils, and the enhanced values increase with a decrease in particle size. In addition, the viscosities of all nanofliuids are remarkably lower than that of the base fluid, which has been found for the first time in the nanofluid field. The promising features offer potential application in thermal energy engineering. PMID:22086086

  15. Conjugating folate on superparamagnetic Fe3O4@Au nanoparticles using click chemistry

    NASA Astrophysics Data System (ADS)

    Shen, Xiaofang; Ge, Zhaoqiang; Pang, Yuehong

    2015-02-01

    Gold-coated magnetic core@shell nanoparticles, which exhibit magneto-optical properties, not only enhance the chemical stability of core and biocompatibility of surface, but also provide a combination of multimodal imaging and therapeutics. The conjugation of these tiny nanoparticles with specific biomolecules allows researchers to target the desired location. In this paper, superparamagnetic Fe3O4@Au nanoparticles were synthesized and functionalized with the azide group on the surface by formation of self-assembled monolayers. Folate (FA) molecules, non-immunogenic target ligands for cancer cells, are conjugated with alkyne and then immobilized on the azide-terminated Fe3O4@Au nanoparticles through copper(I)-catalyzed azide-alkyne cycloaddition (click reaction). Myelogenous leukemia K562 cells were used as a folate receptor (FR) model, which can be targeted and extracted by magnetic field after interaction with the Fe3O4@Au-FA nanoparticles.

  16. Water dispersible Fe3O4 nanoparticles carrying doxorubicin for cancer therapy.

    PubMed

    Jayakumar, Onattu Damodharan; Ganguly, Rajib; Tyagi, Avesh Kumar; Chandrasekharan, Dhanya K; Nair, Cherupally K Krishnan

    2009-11-01

    Water dispersible Fe3O4 nanoparticles (coated with Poly Vinyl Pyrolidone (PVP) and Poly oxy ethylene 25-propylene glycol stearate (POES)) and complexed with Doxorubicin has been prepared and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The antitumor activity of these particles has been studied by targeting the complex to the tumor site, using an externally applied magnetic field, after oral administration of the magnetic nanoparticle-drug complexes. Our results reveal that the chemotherapy effect of Doxorubicin could be considerably enhanced by combination of the application of the drug-conjugated magnetic Fe3O4 nanoparticles, which are biocompatible and stable, and targeted drug delivery with a magnet. The present report provides the first evidence for the promising application of this novel approach with PVP coated Fe3O4 nanoparticles for cancer therapy using an in vivo murine model. PMID:19908532

  17. Evaluation of the antibacterial activity of Ag/Fe3O4 nanocomposites synthesized using starch.

    PubMed

    Ghaseminezhad, Seyedeh Masumeh; Shojaosadati, Seyed Abbas

    2016-06-25

    Ag/Fe3O4 nanocomposites were successfully synthesized by a facile and cost-effective method using starch. Starch acts as both a biocompatible capping agent for Fe3O4 nanoparticles and a reducing agent for the reduction of silver ions in an alkaline medium. Samples were characterized using several analytical techniques including field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and Fourier-transform infrared (FT-IR) spectroscopy. The vibrating sample magnetometer revealed that the nanocomposites were superparamagnetic. The Ag/Fe3O4 nanocomposites demonstrated a high-antibacterial activity against Escherichia coli as evaluated by means of minimum inhibitory concentration. The characteristics and antibacterial activity of the nanocomposites were significantly influenced by the concentration of silver nitrate and pH. PMID:27083838

  18. Structure determination of (Fe3O4)n+(n = 1 ‑ 3) clusters via DFT

    NASA Astrophysics Data System (ADS)

    Li, Yanhua; Cai, Congzhong; Zhao, Chengjun; Gu, Yonghong

    2016-07-01

    In virtue of the particle swarm optimization (PSO) algorithm, the global minimum candidate structures with the lowest energy for (Fe3O4)n(n = 1 ‑ 3) clusters were obtained by first-principles structural searches. The geometric structures and spin configurations of three cationic (Fe3O4)n+(n = 1 ‑ 3) clusters have been identified for the first time by comparing the experimental IR spectra with the calculated results from density functional theory by using different exchange-correlation functionals. It is found that the lowest energy structures of these clusters are of a shape of hat, boat and tower, respectively, with a ferrimagnetic arrangement of spins, and M06L functional is more suitable for Fe3O4 clusters than other ones.

  19. Biocompatibility of Fe3O4@Au composite magnetic nanoparticles in vitro and in vivo

    PubMed Central

    Li, Yuntao; Liu, Jing; Zhong, Yuejiao; Zhang, Jia; Wang, Ziyu; Wang, Li; An, Yanli; Lin, Mei; Gao, Zhiqiang; Zhang, Dongsheng

    2011-01-01

    Purpose This research was conducted to assess the biocompatibility of the core–shell Fe3O4@ Au composite magnetic nanoparticles (MNPs), which have potential application in tumor hyperthermia. Methods Fe3O4@Au composite MNPs with core–shell structure were synthesized by reduction of Au3+ in the presence of Fe3O4-MNPs prepared by improved co-precipitation. Cytotoxicity assay, hemolysis test, micronucleus (MN) assay, and detection of acute toxicity in mice and beagle dogs were then carried out. Results The result of cytotoxicity assay showed that the toxicity grade of this material on mouse fibroblast cell line (L-929) was classified as grade 1, which belongs to no cytotoxicity. Hemolysis rates showed 0.278%, 0.232%, and 0.197%, far less than 5%, after treatment with different concentrations of Fe3O4@Au composite MNPs. In the MN assay, there was no significant difference in MN formation rates between the experimental groups and negative control (P > 0.05), but there was a significant difference between the experimental groups and the positive control (P < 0.05). The median lethal dose of the Fe3O4@Au composite MNPs after intraperitoneal administration in mice was 8.39 g/kg, and the 95% confidence interval was 6.58–10.72 g/kg, suggesting that these nanoparticles have a wide safety margin. Acute toxicity testing in beagle dogs also showed no significant difference in body weight between the treatment groups at 1, 2, 3, and 4 weeks after liver injection and no behavioral changes. Furthermore, blood parameters, autopsy, and histopathological studies in the experimental group showed no significant difference compared with the control group. Conclusion The results indicate that Fe3O4@Au composite MNPs appear to be highly biocompatible and safe nanoparticles that are suitable for further application in tumor hyperthermia. PMID:22131827

  20. Effect of particle size and relative density on powdery Fe3O4 microwave heating.

    PubMed

    Hayashi, Miyuki; Yokoyama, Yuki; Nagata, Kazuhiro

    2010-01-01

    In recent years, microwave energy is expected to be a heat source of high temperature process aiming for CO2 reduction and energy conservation owing to the possibility of volumetric heating. In order to examine the applicability of microwave heating to ironmaking, it is important to investigate the microwave heating of raw materials of ironmaking such as Fe3O4. In this study, the effect of particle size and relative density on microwave absorptivity of powdery Fe3O4 was elucidated by the heating curves. Powdery Fe3O4 samples having different particle sizes and relative densities and bulk Fe3O4 samples were heated at the positions of the H (magnetic) and E (electric) field maxima in a 2.45 GHz single-mode microwave cavity. Sample temperatures abruptly increase and become constant after a while. At a constant temperature, the energy balance is attained, i.e., the rate of microwave energy absorption is equal to the rate of thermal energy dissipation. Assuming that the thermal energy dissipation rate due to convection and radiation heat fluxes is only a function of the sample temperature, the microwave absorptivity could be evaluated by the temperature at the steady state. It has been found that the microwave absorptivity of Fe3O4 powder decreases with an increase in relative density. On the other hand, the microwave absorptivity hardly depends on the particle size, which may be due to its quite a large penetration depth of Fe3O4 compared to metal. PMID:21721468

  1. Magnetic Fe3O4 nanoparticle catalyzed chemiluminescence for detection of nitric oxide in living cells.

    PubMed

    Wang, Huiliang; Li, Mei; Wang, Bing; Wang, Meng; Kurash, Ibrahim; Zhang, Xiangzhi; Feng, Weiyue

    2016-08-01

    Direct and real-time measurement of nitric oxide (NO) in biological media is very difficult due to its transient nature. Fe3O4 nanoparticles (nanoFe3O4) because of their unique catalytic activities have attracted much attention as catalysts in a variety of organic and inorganic reactions. In this work, we have developed a magnetic Fe3O4 nanoparticle-based rapid-capture system for real-time detection of cellular NO. The basic principle is that the nanoFe3O4 can catalyze the decomposition of H2O2 in the system to generate superoxide anion (O2 (·-)) and the O2 (·-) can serve as an effective NO(·) trapping agent yielding peroxynitrite oxide anion, ONOO(-). Then the concentration of NO in cells can be facilely determined via peroxynitrite-induced luminol chemiluminescence. The linear range of the method is from 10(-4) to 10(-8) mol/L, and the detection of limit (3σ, n = 11) is as low as 3.16 × 10(-9) mol/L. By using this method, the NO concentration in 0.1 and 0.5 mg/L LPS-stimulated BV2 cells was measured as 4.9 and 11.3 μM, respectively. Surface measurements by synchrotron X-ray photoelectron spectroscopy (SRXPS) and scanning transmission X-ray microscopy (STXM) demonstrate the catalytic mechanism of the nanoFe3O4-based system is that the significantly excess Fe(II) exists on the surface of nanoFe3O4 and mediates the rapid heterogeneous electron transfer, thus presenting a new Fe2O3 phase on the surface. PMID:27289465

  2. Controlled assembly of Fe3O4 magnetic nanoparticles on graphene oxide

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Chen, Biao; Zhang, Liming; Huang, Jie; Chen, Fenghua; Yang, Zupei; Yao, Jianlin; Zhang, Zhijun

    2011-04-01

    We describe a facile approach to controllable assembly of monodisperse Fe3O4nanoparticles (NPs) on chemically reduced graphene oxide (rGO). First, reduction and functionalization of GO by polyetheylenimine (PEI) were achieved simultaneously by simply heating the PEI and GO mixture at 60 °C for 12 h. The process is environmentally friendly and convenient compared with previously reported methods. Meso-2,3-dimercaptosuccinnic acid (DMSA)-modified Fe3O4 NPs were then conjugated to the PEI moiety which is located on the periphery of the GO sheets via formation of amide bonds between COOH groups of DMSA molecules bound on the surface of the Fe3O4 NPs and aminegroups of PEI. The magnetic GO composites were characterized by means of TEM, AFM, UV-vis, FTIR, Raman, TGA, and VSM measurements. Finally, preliminary results of using the Fe3O4-rGO composites for efficient removal of tetracycline, an antibiotic that is often found as a contaminant in the environment, are reported.We describe a facile approach to controllable assembly of monodisperse Fe3O4nanoparticles (NPs) on chemically reduced graphene oxide (rGO). First, reduction and functionalization of GO by polyetheylenimine (PEI) were achieved simultaneously by simply heating the PEI and GO mixture at 60 °C for 12 h. The process is environmentally friendly and convenient compared with previously reported methods. Meso-2,3-dimercaptosuccinnic acid (DMSA)-modified Fe3O4 NPs were then conjugated to the PEI moiety which is located on the periphery of the GO sheets via formation of amide bonds between COOH groups of DMSA molecules bound on the surface of the Fe3O4 NPs and aminegroups of PEI. The magnetic GO composites were characterized by means of TEM, AFM, UV-vis, FTIR, Raman, TGA, and VSM measurements. Finally, preliminary results of using the Fe3O4-rGO composites for efficient removal of tetracycline, an antibiotic that is often found as a contaminant in the environment, are reported. Electronic supplementary information

  3. Polymethylmethacrylate/Fe3O4 composite nanofiber membranes with ultra-low dielectric permittivity

    NASA Astrophysics Data System (ADS)

    Zhang, C. C.; Li, X.; Yang, Y.; Wang, C.

    2009-11-01

    Ultra-low dielectric permittivity poly (methyl methacrylate)/Fe3O4 composite fiber membranes have been successfully prepared using electrospinning. The composite membranes were characterized by SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared), XRD (X-ray diffraction) and a radio frequency (RF) impedance/capacitance material analyzer. The magnetic measurement showed that the composite membranes displayed the super-paramagnetic property. The results showed that the dielectric permittivity of the composite fiber membranes was decreasing with increasing Fe3O4 nanoparticle content.

  4. Mössbauer evidence of 57Fe3O4 based ferrofluid biodegradation in the brain

    NASA Astrophysics Data System (ADS)

    Polikarpov, D.; Cherepanov, V.; Chuev, M.; Gabbasov, R.; Mischenko, I.; Nikitin, M.; Vereshagin, Y.; Yurenia, A.; Panchenko, V.

    2014-04-01

    The ferrofluid, based on 57Fe isotope enriched Fe3O4 nanoparticles, was synthesized, investigated by Mössbauer spectroscopy method and injected transcranially in the ventricle of the rat brain. The comparison of the Mössbauer spectra of the initial ferrofluid and the rat brain measured in two hours and one week after the transcranial injection allows us to state that the synthesized magnetic 57Fe3O4 nanoparticles undergo intensive biodegradation in live brain and, therefore, they can be regarded as a promising target for a new method of radionuclide-free Mössbauer brachytherapy.

  5. Inductive heat property of Fe3O4/polymer composite nanoparticles in an ac magnetic field for localized hyperthermia.

    PubMed

    Zhao, Dong-Lin; Zhang, Hai-Long; Zeng, Xian-Wei; Xia, Qi-Sheng; Tang, Jin-Tian

    2006-12-01

    The magnetite (Fe(3)O(4)) nanoparticles were prepared by coprecipitation of Fe(3+) and Fe(2+) with an aqueous NaOH solution. The Fe(3)O(4)/polyaniline (PANI) magnetic composite nanoparticles with a core-shell structure with a diameter of 30-50 nm were prepared via an in situ polymerization of aniline in an aqueous solution containing the Fe(3)O(4) magnetic fluid. The inductive heat property of Fe(3)O(4)/PANI composite nanoparticles in an alternating current (ac) magnetic field was investigated. The potential of Fe(3)O(4)/PANI nanoparticles was evaluated for localized hyperthermia treatment of cancers. The saturation magnetization, M(s), and coercivity, H(c), are 50.05 emu g(-1) and 137 Oe for Fe(3)O(4) nanoparticles and 26.34 emu g(-1) and 0 Oe for Fe(3)O(4)/PANI composite nanoparticles, respectively. Exposed in the ac magnetic field for 29 min, the temperatures of physiological saline suspensions containing Fe(3)O(4) nanoparticles or Fe(3)O(4)/PANI composite nanoparticles are 63.6 degrees C and 52.4 degrees C, respectively. The Fe(3)O(4)/PANI composite nanoparticles would be useful as good thermoseeds for localized hyperthermia treatment of cancers. PMID:18458406

  6. Determination of the Phase Boundary Fe3O4 - h-Fe3O4 at high Temperature and Pressure using in situ Synchroton Radiation

    NASA Astrophysics Data System (ADS)

    Schollenbruch, K.; Woodland, A. B.; Frost, D. J.; Wang, Y.; Sanehira, T.

    2009-12-01

    Magnetite is an important accessory mineral in the Earth’s mantle and its rare occurrence as inclusions in diamonds means that this phase has a direct relevance to geochemical processes in the deep earth. For this reason it is important to define its thermodynamic behaviour at high P and T. Magnetite transforms to an orthorhombic high-pressure phase (h-Fe3O4) at room T and ~25 GPa, however the reaction is very sluggish and h-Fe3O4 is unquenchable, complicating the determination of the exact position of the phase boundary at low T. For this reason the phase transition has been investigated by a combination of a multianvil press and in situ X-ray diffraction measurements performed at the Advanced Photo Source (APS) at Argonne National Laboratory, U.S.A.. With this setup, pressure can be monitored during an experiment, allowing different P-T trajectories to be employed (i.e. pressurisation at high T) compared to conventional methods. Experiments were performed up to 15 GPa and 1400°C. A series of measurements during pressurisation at different temperatures revealed, that diffraction peaks related to h-Fe3O4 appeared at the expense of magnetite peaks at about 10 GPa. At the onset of the phase transition, the pressure decreased slightly due to pressure buffering from the 7% volume reduction attending the transition. However, the strongest magnetite reflections remained even at the highest P and T, underlining the sluggishness of the reaction. Measurements made while tracking down P at high T provided reversals, where the regrowth of magnetite diffraction peaks were observed. Once formed, h-Fe3O4 remains metastable down to nearly ambient conditions. Post-experiment TEM investigation revealed extensive twinning and other microstructures, confirming the interpretation of Frost et al. (2001), that such structures formed during the reconversion to magnetite at low pressure. Our high P-T experiments indicate a nearly isobaric phase boundary over a range of 800-1400

  7. Enhanced UV Photocatalytic Performance of Magnetic Fe3O4/CuO/ZnO/NGP Nanocomposites

    NASA Astrophysics Data System (ADS)

    Tju, Hendry; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    Fe3O4/CuO/ZnO/nanographene platelets (Fe3O4/CuO/ZnO/NGP) with varied ZnO loadings have been synthesized using a sol-gel method followed by hydrothermal method. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) confirmed the formation of the Fe3O4/CuO/ZnO/NGP composites. All of the samples showed the presence of graphene nanoplatelets incorporating Fe3O4, CuO and ZnO structures and exhibited ferromagnetic behavior at room temperature. The composites showed photocatalytic activity under UV irradiation, which was used to affect the degradation of methylene blue. The Fe3O4/CuO/ZnO/NGP composites showed superior photocatalytic activity than the Fe3O4/CuO/ZnO materials.

  8. Mössbauer investigations of Fe and Fe3O4 magnetic nanoparticles for hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Kamzin, A. S.

    2016-03-01

    Magnetic nanoparticles of magnetite Fe3O4 and Fe synthesized by physical vapor deposition with a fast highly effective method using a solar energy have been studied. Targets have been prepared from tablets pressed from Fe3O4 or Fe powders. Relationships between the structure of nanoparticles and their magnetic properties have been investigated in order to understand principles of the control of the parameters of magnetic nanoparticles. Mössbauer investigations have revealed that the nanoparticles synthesized from tablets of both pure iron and Fe3O4 consist of two phases: pure iron and iron oxides (γ-Fe2O3 and Fe3O4). The high iron oxidability suggests that the synthesized nanoparticles have a core/shell structure, where the core is pure iron and the shell is an oxidized iron layer. Magnetite nanoparticles synthesized at a pressure of 80 Torr have the best parameters for hyperthermia due to their core/shell structure and core-to-shell volume ratio.

  9. Magnetic hyperthermia and photothermal effect of functionalized Fe3O4 nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sadat, Md Ehsan; Shi, Donglu; Mast, David B.

    2014-03-01

    The heating of nanoparticle loaded tissue surrogates for potential applications in cancer therapy was achieved when the superparamagnetic Fe3O4 nanoparticles were subjected to either high frequency alternating (AC) magnetic fields or near infra-red (NIR) radiation. Four nanoparticles systems were studied, where each system was distinct in terms of the arrangement, surface modification and physical confinement of the Fe3O4 nanoparticles. It was observed that the thermal response of each nanoparticle system to AC magnetic fields was different and could be described in terms of linear response theory and by taking into account the dipole-dipole interaction for closely packed nanoparticle systems. It was also shown that the same nanoparticle systems could be effectively heated when illuminated with NIR radiation at 785 nm and 808 nm. The measured optical absorption and scattering of the Fe3O4 nanoparticle systems was analyzed in terms of Mie scattering theory. The overall results from this study clearly demonstrate that the temperature increase of Fe3O4 nanoparticle loaded tissue surrogate samples to therapeutic levels could be achieved using AC magnetic fields and NIR radiation.

  10. Strong electron correlation on the Fe3O4(0 0 1) surfaces

    NASA Astrophysics Data System (ADS)

    Pinto, Henry; Elliott, Simon D.; Foster, Adam; Nieminen, R. M.

    2007-03-01

    Magnetite Fe3O4 is a fascinating material that still is not well understood and presents challenges for the state-of-the-art computational methods. This transition metal oxide undergoes a first-order metal-insulator transition at TV=120 K. The ferrimagnetic properties of Fe3O4 makes it a promising material for spintronic applications. We use a plane wave density functional theory in the generalized gradient approximation adding a Hubbard-U parameter to describe properly the strongly correlated Fe--3d electrons. Based on previous results, we compute the surface structure, magnetic properties and electronic structure of several Fe3O4(0 0 1) surfaces with (√2x√2)R45^o reconstruction. The simulated scanning tunneling microscopy images of these surfaces are compared and discussed in the light of available experimental data. Finally, we analyze the possible existence of charge ordering on the Fe3O4(0 0 1) surface and the effect on the surface electronic structure with changing the value of the Hubbard-U parameter on the superficial Fe sites. H. Pinto, S. Elliott, J.Phys.: Condens. Matter 18, 10427 (2006)

  11. Au doping effect on the electrical and magnetic properties of Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahmood, Asif; Ramay, Shahid Mahmood; Al-Zaghayer, Yousef S.; Alhazaa, A. N.; Al Masary, Waheed A.; Atiq, Shahid

    2015-12-01

    Impurities free ferromagnetic Fe3O4 was prepared via sol-gel auto-combustion method and then gold was doped with various concentrations 1, 3 and 5 wt.% using conventional deposition-precipitation method. All samples of Fe3O4 with/without Au doping were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The room temperature magnetic hysteresis loops of all the samples were measured using a physical property measuring system (PPMS), and the results showed a ferromagnetic behavior at room temperature. The results obtained confirmed the fabrication of magnetite-gold composite nanoparticles. The results showed that the resistance and the magnetic behavior of the samples decrease sharply with the increase of Au concentration indicating semiconducting behavior. The saturation magnetization (Ms) of the bare Fe3O4 sample (94.72 emu/g) is much higher than that (66.78 emu/g) of the 5 wt.% Au-doped Fe3O4 sample.

  12. Uniform Superparamagnetic Fe3O4/CMCS Composite Nanospheres for Lysozyme Adsorption.

    PubMed

    Yang, Qi; Lan, Fang; Liu, Ziyao; Ma, Shaohua; Li, Wenliao; Wu, Yao; Gu, Zhongwei

    2016-03-01

    In this study, uniform superparamagnetic Fe3O4/carboxymethyl chitosan composite nanospheres with high saturation magnetization were successfully synthesized via a modified inverse emulsion crosslinking approach, using genipin as a cross-linking agent. These nanospheres were then characterized, and their protein adsorption capacity was further investigated under various conditions. The implementation of a sonication treatment of a mixture containing Fe3O4 nanoparticles and carboxymethyl chitosan before the emulsion process significantly promoted the homogeneity of Fe3O4 nanoparticles in an aqueous phase system. The Fe3O4/carboxymethyl chitosan composite nanospheres were of uniform spherical structure, were approximately 230 nm in size, and possessed superparamagnetic characteristics with a mean saturation magnetization as high as 35 emu g(-1), corresponding to a magnetite content of 43%. Lysozyme was then employed as a model protein to investigate the effects of pH, incubation time and ion strength on the protein adsorption capacity of the as-synthesized composite nanospheres. The as-obtained composite nanospheres could serve as a promising candidate for fast and efficient protein adsorption. PMID:27455623

  13. Functionalized Fe3O4 nanoparticles for detecting zinc ions in living cells and their cytotoxicity.

    PubMed

    Kang, Gyusik; Son, Hyunjong; Lim, Jung Mi; Kweon, Hee-Seek; Lee, In Soo; Kang, Dongmin; Jung, Jong Hwa

    2012-05-01

    The zinc tank: A new fluoro-chromogenic chemosensor based on BODIPY-functionalized Fe(3)O(4) nanoparticles (1) has been prepared. Chemoprobe 1 exhibits high selectivity for Zn(2+) over other competing metal ions tested. Moreover, confocal microscopy experiments established that 1 can be used for detecting Zn(2+) levels in living cells (see figure). PMID:22517629

  14. Characterization and immobilization of trypsin on tannic acid modified Fe3O4 nanoparticles.

    PubMed

    Atacan, Keziban; Özacar, Mahmut

    2015-04-01

    Fe3O4 nanoparticles (NPs) were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. Fe3O4 NPs functionalized with tannic acid were prepared. After functionalization process, trypsin enzyme was immobilized on these Fe3O4 NPs. The influence of pH, temperature, thermal stability, storage time stability and reusability on non-covalent immobilization was studied. The properties of Fe3O4 and its modified forms were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), UV-vis spectrometer (UV) and X-ray diffraction (XRD), magnetization and zeta potential measurements. The immobilized enzyme was slightly more stable than the free enzyme at 45°C. According to the results, the activity of immobilized trypsin was preserved 55% at 45°C after 2 h and 90% after 120 days storage. In addition, the activity of the immobilized trypsin was preserved 40% of its initial activity after eight times of successive reuse. PMID:25686792

  15. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications

    NASA Astrophysics Data System (ADS)

    Muñoz-Noval, Alvaro; Rubio-Zuazo, Juan; Salas-Colera, Eduardo; Serrano, Aida; Rubio-Marcos, Fernando; Castro, Germán R.

    2015-11-01

    The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.

  16. Lightweight, multifunctional polyetherimide/graphene@Fe3O4 composite foams for shielding of electromagnetic pollution.

    PubMed

    Shen, Bin; Zhai, Wentao; Tao, Mimi; Ling, Jianqiang; Zheng, Wenge

    2013-11-13

    Novel high-performance polyetherimide (PEI)/graphene@Fe3O4 (G@Fe3O4) composite foams with flexible character and low density of about 0.28-0.4 g/cm(3) have been developed by using a phase separation method. The obtained PEI/G@Fe3O4 foam with G@Fe3O4 loading of 10 wt % exhibited excellent specific EMI shielding effectiveness (EMI SE) of ~41.5 dB/(g/cm(3)) at 8-12 GHz. Moreover, most the applied microwave was verified to be absorbed rather than being reflected back, resulting from the improved impedance matching, electromagnetic wave attenuation, as well as multiple reflections. Meanwhile, the resulting foams also possessed a superparamagnetic behavior and low thermal conductiviy of 0.042-0.071 W/(m K). This technique is fast, highly reproducible, and scalable, which may facilitate the commercialization of such composite foams and generalize the use of them as EMI shielding materials in the fields of spacecraft and aircraft. PMID:24134429

  17. Controlled assembly of Fe3O4 magnetic nanoparticles on graphene oxide.

    PubMed

    Zhang, Yi; Chen, Biao; Zhang, Liming; Huang, Jie; Chen, Fenghua; Yang, Zupei; Yao, Jianlin; Zhang, Zhijun

    2011-04-01

    We describe a facile approach to controllable assembly of monodisperse Fe(3)O(4) nanoparticles (NPs) on chemically reduced graphene oxide (rGO). First, reduction and functionalization of GO by polyetheylenimine (PEI) were achieved simultaneously by simply heating the PEI and GO mixture at 60 °C for 12 h. The process is environmentally friendly and convenient compared with previously reported methods. Meso-2,3-dimercaptosuccinnic acid (DMSA)-modified Fe(3)O(4) NPs were then conjugated to the PEI moiety which is located on the periphery of the GO sheets via formation of amide bonds between COOH groups of DMSA molecules bound on the surface of the Fe(3)O(4) NPs and amine groups of PEI. The magnetic GO composites were characterized by means of TEM, AFM, UV-vis, FTIR, Raman, TGA, and VSM measurements. Finally, preliminary results of using the Fe(3)O(4)-rGO composites for efficient removal of tetracycline, an antibiotic that is often found as a contaminant in the environment, are reported. PMID:21301708

  18. The investigation of giant magnetic moment in ultrathin Fe3O4 films

    NASA Astrophysics Data System (ADS)

    Guan, Xiaofen; Zhou, Guowei; Xue, Wuhong; Quan, Zhiyong; Xu, Xiaohong

    2016-03-01

    The magnetic and transport properties of Fe3O4 films with a series of thicknesses are investigated. For the films with thickness below 15 nm, the saturation magnetization (Ms) increases and the coercivity decreases with the decrease in films' thickness. The Ms of 3 nm Fe3O4 film is dramatically increased to 1017 emu/cm3. As for films' thickness more than 15 nm, Ms is tending to be close to the Fe3O4 bulk value. Furthermore, the Verwey transition temperature (Tv) is visible for all the films, but suppressed for 3 nm film. We also find that the ρ of 3 nm film is the highest of all the films. The suppressed Tv and high ρ may be related to the islands morphology in 3 nm film. To study the structure, magnetic, and transport properties of the Fe3O4 films, we propose that the giant magnetic moment most likely comes from the spin of Fe ions in the tetrahedron site switching parallel to the Fe ions in the octahedron site at the surface, interface, and grain boundaries. The above results are of great significance and also provide a promising future for either device applications or fundamental research.

  19. Intracellular distribution of Fe3O4 nanoparticles in both human and mouse cells

    NASA Astrophysics Data System (ADS)

    Palihawadana Arachchige, Maheshika; Laha, Suvra; Rajagopal, Amulya; Kulkarni, Sanjana; Wang, Shuo; Flack, Amanda; Li, Chunying; Jena, Bhanu; Lawes, Gavin

    2014-03-01

    In recent years there has been an increasing interest in developing Fe3O4 nanoparticles for biomedical applications including targeted drug delivery and magnetic resonance imaging. Understanding of the intracellular distribution of these nanoparticles is crucial when considering these nanoparticles for specific applications. We have synthesized Fe3O4 nanoparticles having average size of 14 nm using a co-precipitation technique, which were coated with dextran. We studied the structural and morphological characteristics of the nanoparticles using x-ray diffraction, electron microscopy, dynamic light scattering, and zeta potential measurements. We also characterized the magnetic properties of the nanoparticles. In order to investigate the intracellular distribution of these Fe3O4 nanoparticles, we functionalized the dextran coated Fe3O4 nanoparticles with a fluorescent dye, Fluorescein isothiocyanate (FITC), and cultured them with both mouse insulinoma MIN 6 cells and human pancreatic MIA PaCa 2 cells. Using optical microscope we investigated the intracellular distribution of the nanoparticles and the effects on cell growth.

  20. Adsorption mechanism of magnetically separable Fe3O4/graphene oxide hybrids

    NASA Astrophysics Data System (ADS)

    Ouyang, Ke; Zhu, Chuanhe; Zhao, Ya; Wang, Leichao; Xie, Shan; Wang, Qun

    2015-11-01

    A reclaimable Fe3O4/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polyol approach and employed as a recyclable adsorbent for Bisphenol A (BPA) in aqueous solutions. The maximum adsorption capacity (qm) of the Fe3O4/GO hybrid for BPA was 72.80 mg/g at 273 K. The kinetics of the adsorption process and the adsorption isotherm data were fitted using the Freundlich equation and a pseudo-second-order kinetic model. The results of the thermodynamic parameters ΔH°, ΔS° and ΔG° showed that the adsorption process was exothermic and spontaneous. Furthermore, the reusability of the samples was investigated, and the results indicated that the samples exhibited high stability. The magnetic characterization demonstrated that hybrids were superparamagnetic and could be recovered conveniently by magnetic separation. The strong π-π interaction was determined to be the predominant driving force behind the adsorption of BPA onto the Fe3O4/GO hybrid. Therefore, the Fe3O4/GO hybrid could be regarded as a potential adsorbent for wastewater treatment and purification processes.

  1. One-pot synthesis of a rose-like Pd-Fe3O4 nanocatalyst for Sonogashira coupling reactions

    NASA Astrophysics Data System (ADS)

    Woo, Hyunje; Lee, Kyoungho; Park, Ji Chan; Park, Kang Hyun

    2016-03-01

    A one-pot synthesis of rose-like Pd-Fe3O4 nanocomposites via the controlled thermal decomposition of Fe(CO)5 and reduction of Pd(OAc)2 is reported. This rose-like Pd-Fe3O4 composite structure has a high surface area owing to the individual Pd-Fe3O4 nanosheets, which imparted a high catalytic activity for Sonogashira coupling reactions. Moreover, the catalyst also demonstrated magnetic recyclability.

  2. Competing reactions of selected atmospheric gases on Fe3O4 nanoparticles surfaces.

    PubMed

    Eltouny, N; Ariya, Parisa A

    2014-11-14

    Heterogeneous reactions on atmospheric aerosol surfaces are increasingly considered important in understanding aerosol-cloud nucleation and climate change. To understand potential reactions in polluted atmospheres, the co-adsorption of NO2 and toluene to magnetite (Fe3O4i.e. FeO·Fe2O3) nanoparticles at ambient conditions was investigated for the first time. The surface area, size distribution, and morphology of Fe3O4 nanoparticles were characterized by BET method and high-resolution transmission electron microscopy. Adsorption isotherms, collected by gas chromatography with flame ionization detection, showed that the presence of NO2 decreased the adsorption of toluene. The analyses of the surface chemical composition of Fe3O4 by X-ray photoelectron spectroscopy (XPS) reveal that, upon the addition of NO2, the surface is oxidized and a contribution at 532.5 ± 0.4 eV in the O1s spectrum appears, showing that NO2 likely competes with toluene by dissociating on Fe(2+) sites and forming NO3(-). Different competing effects were observed for oxidized Fe3O4; oxidation occurred when exposed solely to NO2, whereas, the mixture of toluene and NO2 resulted in a reduction of the surface i.e. increased Fe(2+)/Fe(3+). Analyses by time of flight secondary ion mass spectrometry further suggest toluene reacts with Fe(3+) sites forming oxygenated organics. Our results indicate that on reduced magnetite, NO2 is more reactive and competes with toluene; in contrast, on oxidized Fe3O4, toluene is more reactive. Because magnetite can assume a range of oxidation ratios in the environment, different competing interactions between pollutants like NO2 and toluene could influence atmospheric processes, namely, the formation of Fe(2+) and the formation of atmospheric oxidants. PMID:25247461

  3. Synthesis of Fe3O4/Polyacrylonitrile Composite Electrospun Nanofiber Mat for Effective Adsorption of Tetracycline.

    PubMed

    Liu, Qing; Zhong, Lu-Bin; Zhao, Quan-Bao; Frear, Craig; Zheng, Yu-Ming

    2015-07-15

    Novel Fe3O4/polyacrylonitrile (PAN) composite nanofibers (NFs) were prepared by a simple two-step process, an electrospinning and solvothermal method. Characterization by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) demonstrated formation of a uniform nanoparticles coating (about 20 nm in thickness) on the PAN nanofiber backbone. The coating was constructed by well-crystallized cubic phase Fe3O4 nanoparticles as examined by X-ray diffraction spectroscopy (XRD). The coating doubled the specific surface area of NFs, from 8.4 to 17.8 m2 g(-1), as confirmed by nitrogen sorption isotherm analysis. To evaluate the feasibility of Fe3O4/PAN composite NFs as a potential adsorbent for antibiotic removal, batch adsorption experiments were conducted using tetracycline (TC) as the model antibiotic molecule. The results showed that Fe3O4/PAN composite NFs were effective in removing TC with no impactful loss of Fe in the pH regime of environmental interest (5-8). The adsorption of TC onto Fe3O4/PAN composite NFs better fitted the pseudo-second-order kinetics model, and the maximum adsorption capacity calculated from Langmuir isotherm model was 257.07 mg g(-1) at pH 6. The composite NFs also exhibited good regenerability over repeated adsorption/desorption cycles. Surface complexation between TC and the composite NFs contributed most to the adsorption as elucidated by X-ray photoelectron spectroscopy (XPS). This highly effective and novel adsorbent can be easily modularized and separated, promising its huge potential in drinking and wastewater treatment for antibiotic removal. PMID:26079116

  4. Efficient removal of crystal violet using Fe3O4-coated biochar: the role of the Fe3O4 nanoparticles and modeling study their adsorption behavior

    NASA Astrophysics Data System (ADS)

    Sun, Pengfei; Hui, Cai; Azim Khan, Rashid; Du, Jingting; Zhang, Qichun; Zhao, Yu-Hua

    2015-07-01

    Biochar shows great promise for use in adsorbing pollutants. However, a process for enhancing its adsorption capacity and re-collection efficiency is yet to be further developed. Hence, in this study, we developed a type of biochar coated with magnetic Fe3O4 nanoparticles (i.e., magnetic biochar (MBC)) and assessed its use for crystal violet (CV) adsorption as well as its recycling potential. The coating of Fe3O4 nanoparticles, which was not only on the surface, but also in the interior of biochar, performed two functions. Firstly, it produced a saturation magnetization of 61.48 emu/g, which enabled the biochar being efficiently re-collected using a magnet. Secondly, it significantly enhanced the adsorption capacity of the biochar (from 80.36 to 99.19 mg/g). The adsorption capacity of the MBC was determined to be the largest by so far (349.40 mg/g) for an initial CV concentration of 400 mg/L, pH of 6.0, and temperature of 40 °C, and the adsorption capacity of re-collected MBC was 73.31 mg/g. The adsorption of CV by the MBC was found to be a spontaneous and endothermic physical process in which the intraparticle diffusion was the limiting step. These findings inspire us to use other similar materials to tackle the menace of pollutions.

  5. Efficient removal of crystal violet using Fe3O4-coated biochar: the role of the Fe3O4 nanoparticles and modeling study their adsorption behavior

    PubMed Central

    Sun, Pengfei; Hui, Cai; Azim Khan, Rashid; Du, Jingting; Zhang, Qichun; Zhao, Yu-Hua

    2015-01-01

    Biochar shows great promise for use in adsorbing pollutants. However, a process for enhancing its adsorption capacity and re-collection efficiency is yet to be further developed. Hence, in this study, we developed a type of biochar coated with magnetic Fe3O4 nanoparticles (i.e., magnetic biochar (MBC)) and assessed its use for crystal violet (CV) adsorption as well as its recycling potential. The coating of Fe3O4 nanoparticles, which was not only on the surface, but also in the interior of biochar, performed two functions. Firstly, it produced a saturation magnetization of 61.48 emu/g, which enabled the biochar being efficiently re-collected using a magnet. Secondly, it significantly enhanced the adsorption capacity of the biochar (from 80.36 to 99.19 mg/g). The adsorption capacity of the MBC was determined to be the largest by so far (349.40 mg/g) for an initial CV concentration of 400 mg/L, pH of 6.0, and temperature of 40 °C, and the adsorption capacity of re-collected MBC was 73.31 mg/g. The adsorption of CV by the MBC was found to be a spontaneous and endothermic physical process in which the intraparticle diffusion was the limiting step. These findings inspire us to use other similar materials to tackle the menace of pollutions. PMID:26220603

  6. Coating Fe3O4 magnetic nanoparticles with humic acid for high efficient removal of heavy metals in water.

    PubMed

    Liu, Jing-fu; Zhao, Zong-shan; Jiang, Gui-bin

    2008-09-15

    Humic acid (HA) coated Fe3O4 nanoparticles (Fe3O4/HA) were developed for the removal of toxic Hg(II), Pb(II), Cd(II), and Cu(II) from water. Fe3O4/HA were prepared by a coprecipitation procedure with cheap and environmentally friendly iron salts and HA. TOC and XPS analysis showed the as-prepared Fe3O4/HA contains approximately 11% (w/w) of HA which are fractions abundant in O and N-based functional groups. TEM images and laser particle size analysis revealed the Fe3O4/HA (with approximately 10 nm Fe3O4 cores) aggregated in aqueous suspensions to form aggregates with an average hydrodynamic size of approximately 140 nm. With a saturation magnetization of 79.6 emu/g, the Fe3O4/HA can be simply recovered from water with magnetic separations at low magnetic field gradients within a few minutes. Sorption of the heavy metals to Fe3O4/HA reached equilibrium in less than 15 min, and agreed well to the Langmuir adsorption model with maximum adsorption capacities from 46.3 to 97.7 mg/g. The Fe3O4/HA was stable in tap water, natural waters, and acidic/ basic solutions ranging from 0.1 M HCl to 2 M NaOH with low leaching of Fe (< or = 3.7%) and HA (< or = 5.3%). The Fe3O4/HA was able to remove over 99% of Hg(ll) and Pb(ll) and over 95% of Cu(II) and Cd(II) in natural and tap water at optimized pH. Leaching back of the Fe3O4/HA sorbed heavy metals in water was found to be negligible. PMID:18853814

  7. Seeded preparation of ultrathin FeS2 nanosheets from Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Tingting; Liu, Huiwen; Wu, Zhennan; Liu, Yi; Guo, Zuoxing; Zhang, Hao

    2016-06-01

    FeS2 nanomaterials with two-dimensional features hold great promise for electrochemical and photovoltaic applications. However, the preparation of ultrathin FeS2 nanosheets is still challenging because of the lack of a tailor-made approach. In this work, FeS2 nanosheets with a thickness of 2.1 nm are prepared through a Fe3O4-seeded approach. Uniform Fe3O4 nanoparticles are foremost synthesized via the standard method in organic media. The injection of a S solution leads to the replacement of O in Fe3O4 through anion-exchange, which generates (110) facet-enriched FeS2 nuclei. The subsequent (110) facet-mediated oriented attachment and fusion of FeS2 nuclei produce ultrathin FeS2 nanosheets. As catalysts in the hydrogen evolution reaction, FeS2 nanosheets exhibit good electrochemical activity.FeS2 nanomaterials with two-dimensional features hold great promise for electrochemical and photovoltaic applications. However, the preparation of ultrathin FeS2 nanosheets is still challenging because of the lack of a tailor-made approach. In this work, FeS2 nanosheets with a thickness of 2.1 nm are prepared through a Fe3O4-seeded approach. Uniform Fe3O4 nanoparticles are foremost synthesized via the standard method in organic media. The injection of a S solution leads to the replacement of O in Fe3O4 through anion-exchange, which generates (110) facet-enriched FeS2 nuclei. The subsequent (110) facet-mediated oriented attachment and fusion of FeS2 nuclei produce ultrathin FeS2 nanosheets. As catalysts in the hydrogen evolution reaction, FeS2 nanosheets exhibit good electrochemical activity. Electronic supplementary information (ESI) available: EDX, AFM images, small-angle XRD pattern, SAED pattern, and TEM images of FeS2 nanosheets. See DOI: 10.1039/c6nr02211a

  8. Low-temperature hydrothermal synthesis of α-Fe/Fe3O4 nanocomposite for fast Congo red removal.

    PubMed

    Wang, Lixia; Li, Jianchen; Wang, Zhitao; Zhao, Lijun; Jiang, Qing

    2013-02-21

    A facile low-temperature hydrothermal process to synthesize α-Fe/Fe(3)O(4) nanocomposite is reported. TEM and HRTEM revealed that the α-Fe/Fe(3)O(4) nanocomposite was composed of catenulate α-Fe and lamellar structured Fe(3)O(4). The weight ratio of α-Fe in the α-Fe/Fe(3)O(4) nanocomposite is 35.6%. The α-Fe/Fe(3)O(4) nanocomposite demonstrates an extremely high Congo red (CR) removal efficiency from waste water showing almost complete removal within 3 min. For 100 mg L(-1) of CR aqueous solution, the maximum CR removal can reach 1297.06 mg g(-1). The large saturation magnetization (80.5 emu g(-1)) of the nanocomposite allows fast separation of α-Fe/Fe(3)O(4) nanoparticles loaded with CR from the liquid suspension. The synergistic effect of the nanocomposite may contribute to the enhanced CR removal ability, because the CR can be removed by reduction reaction and adsorption at the same time. Based on the degradation products identified by UV-Vis spectra, XRD and FTIR spectra, a possible degradation mechanism of CR on the α-Fe/Fe(3)O(4) composite was proposed. The significantly reduced treatment time required to remove the CR and the simple, low-cost and pollution-free preparation method make α-Fe/Fe(3)O(4) nanocomposite promising for highly efficient removal of dyes from waste water. PMID:23223415

  9. Hybrid nanostructured C-dot decorated Fe3O4 electrode materials for superior electrochemical energy storage performance.

    PubMed

    Bhattacharya, K; Deb, P

    2015-05-21

    Research on energy storage devices has created a niche owing to the ever increasing demand for alternative energy production and its efficient utilisation. Here, a novel composite of Fe3O4 nanospheres and carbon quantum dots (C-dots) have been synthesized by a two step chemical route. Hybrids of C-dots with metal oxides can contribute to charge storage capacity through the combined effect of Faradaic pseudocapacitance from the Fe3O4 and the excellent electrical properties of the C-dots, which are a promising new member of the carbon family. The structural and morphological properties of the obtained Fe3O4-C hybrid nanocomposite were extensively studied. Detailed electrochemical studies show that the high performance of the magnetically responsive Fe3O4-C hybrid nanocomposite makes it an efficient supercapacitor electrode material. The remarkable improvement in the electrochemical performance of the Fe3O4-C hybrid nanocomposite is attributed to the Faradaic pseudocapacitance of Fe3O4 coupled with the high electrical conductivity of the C-dot which aided in fast transport and ionic motion during the charge-discharge cycles. Cyclic voltammetry and galvanostatic charge-discharge studies of Fe3O4-C hybrid nanocomposite show that the nanosystem delivers a maximum specific capacitance of ∼208 F g(-1). These results demonstrate that the novel Fe3O4-C hybrid nanocomposite has great potential as a high performance electrode material for supercapacitors. PMID:25909760

  10. Properties of poly(1-naphthylamine)/Fe3O4 composites and arsenic adsorption capacity in wastewater

    NASA Astrophysics Data System (ADS)

    Tran, Minh Thi; Nguyen, Thi Huyen Trang; Vu, Quoc Trung; Nguyen, Minh Vuong

    2016-03-01

    The research results of poly(1-naphthylamine)/Fe3O4 (PNA/Fe3O4) nanocomposites synthesized by a chemical method for As(III) wastewater treatment are presented in this paper. XRD patterns and TEM images showed that the Fe3O4 grain size varied from 13 to 20 nm. The results of Raman spectral analysis showed that PNA participated in part of the PNA/Fe3O4 composite samples. The grain size of PNA/Fe3O4 composite samples is about 25-30 nm measured by SEM. The results of vibrating sample magnetometer measurements at room temperature showed that the saturation magnetic moment of PNA/Fe3O4 samples decreased from 63.13 to 43.43 emu/g, while the PNA concentration increased from 5% to 15%. The nitrogen adsorption-desorption isotherm of samples at 77 K at a relative pressure P/ P 0 of about 1 was studied in order to investigate the surface and porous structure of nanoparticles by the BET method. Although the saturation magnetic moments of samples decreased with the polymer concentration increase, the arsenic adsorption capacity of the PNA/Fe3O4 sample with the PNA concentration of 5% is better than that of Fe3O4 in a solution with pH = 7. In the solution with pH > 14, the arsenic adsorption of magnetic nanoparticles is insignificant.

  11. Micro-optical coherence tomography tracking of magnetic gene transfection via Au-Fe3O4 dumbbell nanoparticles

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Liu, Xinyu; Wei, Chao; Xu, Zhichuan J.; Sim, Stanley Siong Wei; Liu, Linbo; Xu, Chenjie

    2015-10-01

    Heterogeneous Au-Fe3O4 dumbbell nanoparticles (NPs) are composed of Au NPs and Fe3O4 NPs that bring in optical and magnetic properties respectively. This article reports the engineering of Au-Fe3O4 NPs as gene carriers for magnetic gene transfection as well as contrast agents for micro-optical coherence tomography (μOCT). As a proof-of-concept, Au-Fe3O4 NPs are used to deliver the green fluorescent protein to HEK 293T cells and their entrance into the cells is monitored through μOCT.Heterogeneous Au-Fe3O4 dumbbell nanoparticles (NPs) are composed of Au NPs and Fe3O4 NPs that bring in optical and magnetic properties respectively. This article reports the engineering of Au-Fe3O4 NPs as gene carriers for magnetic gene transfection as well as contrast agents for micro-optical coherence tomography (μOCT). As a proof-of-concept, Au-Fe3O4 NPs are used to deliver the green fluorescent protein to HEK 293T cells and their entrance into the cells is monitored through μOCT. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05459a

  12. Amperometric carbon paste enzyme electrodes with Fe(3)O(4) nanoparticles and 1,4-benzoquinone for glucose determination.

    PubMed

    Erden, Pınar Esra; Zeybek, Bülent; Pekyardımcı, Şule; Kılıç, Esma

    2013-06-01

    Two new amperometric carbon paste enzyme electrodes including Fe(3)O(4) nanoparticles with and without 1,4-benzoquinone were developed for glucose determination. Electron transfer properties of unmodified and Fe(3)O(4) nanoparticles and/or 1,4-benzoquinone modified carbon paste electrodes were investigated in 0.1 M KCl support electrolyte containing Fe(CN)6(3-/4-) as redox probe by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. Fe(3)O(4) nanoparticles increased electron transfer at solution/electrode interface. The parameters affecting the analytical performance of the enzyme electrode have been investigated in detail and optimized for Fe(3)O(4) nanoparticle modified enzyme electrode (Fe(3)O(4)-CPEE). Fe(3)O(4) nanoparticles and 1,4-benzoquinone modified enzyme electrode (BQ-Fe(3)O(4)-CPEE) exhibited linear response from 1.9 × 10(-7) M to 3.7 × 10(-6) M, from 7.2 × 10(-6) M to 1.5 × 10(-4) M and from 1.3 × 10(-3) M to 1.2 × 10(-2) M with an excellent detection limit of 1.9 × 10(-8) M. BQ-Fe(3)O(4)-CPEE was used for determination of glucose in serum samples and results were in good agreement with those obtained by spectrophotometric method. PMID:22889252

  13. Reversed ageing of Fe3O4 nanoparticles by hydrogen plasma

    PubMed Central

    Schmitz-Antoniak, Carolin; Schmitz, Detlef; Warland, Anne; Svechkina, Nataliya; Salamon, Soma; Piamonteze, Cinthia; Wende, Heiko

    2016-01-01

    Magnetite (Fe3O4) nanoparticles suffer from severe ageing effects when exposed to air even when they are dispersed in a solvent limiting their applications. In this work, we show that this ageing can be fully reversed by a hydrogen plasma treatment. By x-ray absorption spectroscopy and its associated magnetic circular dichroism, the electronic structure and magnetic properties were studied before and after the plasma treatment and compared to results of freshly prepared magnetite nanoparticles. While aged magnetite nanoparticles exhibit a more γ-Fe2O3 like behaviour, the hydrogen plasma yields pure Fe3O4 nanoparticles. Monitoring the temperature dependence of the intra-atomic spin dipole contribution to the dichroic spectra gives evidence that the structural, electronic and magnetic properties of plasma treated magnetite nanoparticles can outperform the ones of the freshly prepared batch. PMID:26902789

  14. Fabrication, characterization and measurement of thermal conductivity of Fe 3O 4 nanofluids

    NASA Astrophysics Data System (ADS)

    Abareshi, Maryam; Goharshadi, Elaheh K.; Mojtaba Zebarjad, Seyed; Khandan Fadafan, Hassan; Youssefi, Abbas

    2010-12-01

    Magnetite Fe 3O 4 nanoparticles were synthesized by a co-precipitation method at different pH values. The products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electronic microscopy. Their magnetic properties were evaluated on a vibrating sample magnetometer. The results show that the shape of the particles is cubic and they are superparamagnetic at room temperature. Magnetic nanofluids were prepared by dispersing the Fe 3O 4 nanoparticles in water as a base fluid in the presence of tetramethyl ammonium hydroxide as a dispersant. The thermal conductivity of the nanofluids was measured as a function of volume fraction and temperature. The results show that the thermal conductivity ratio of the nanofluids increases with increase in temperature and volume fraction. The highest enhancement of thermal conductivity was 11.5% in the nanofluid of 3 vol% of nanoparticles at 40 °C. The experimental results were also compared with the theoretical models.

  15. Thermodynamics of Fe(II)Fe(III) oxide systems I. Hydrothermal Fe3O4

    USGS Publications Warehouse

    Bartel, J.J.; Westrum, E.F., Jr.; Haas, J.L., Jr.

    1976-01-01

    The heat capacity of a hydrothermally-prepared polycrystalline sample of Fe3O4 was measured from 53 to 350 K, primarily to study the thermophysics of the Verwey transitions. Although the bifurcation of the transition was confirmed, the sample was found to contain traces of manganese. The observed transition temperatures of 117.0 and 123.0 K are 3.7 and 4.2 K higher respectively than those found in pure Fe3O4. Ancillary analytical results are consistent and indicate a stoichiometry of Mn0.008Fe2.992O4 for this material. Characteristics in the transition region are ascribed to dopant effects. ?? 1976.

  16. Facile synthesis of pectin coated Fe3O4 nanospheres by the sonochemical method

    NASA Astrophysics Data System (ADS)

    Dai, Junjun; Wu, Shixi; Jiang, Wei; Li, Pingyun; Chen, Xiaolong; Liu, Li; Liu, Jie; Sun, Danping; Chen, Wei; Chen, Binhua; Li, Fengsheng

    2013-04-01

    Pectin coated Fe3O4 magnetic nanospheres (PCMNs) were synthesized by the sonochemical method. The Fe3O4 nanoparticles were prepared by chemical precipitation as reported in the previous articles, and the PCMNs were characterized by transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, Fourier-transform infrared spectroscopy, a vibrating sample magnetometer and energy dispersive X-ray spectrum. The results indicated that the magnetic nanoparticles have been coated by pectin, magnetite content of which was up to 63%, with the saturation magnetization being 32.69 emu/g. The formation mechanism and further application of PCMNs have also been discussed. The results show that the PCMNs can be applied to biomedical applications.

  17. Synthesis, characterization and magnetic properties of Fe3O4 doped chitosan polymer

    NASA Astrophysics Data System (ADS)

    Karaca, E.; Şatır, M.; Kazan, S.; Açıkgöz, M.; Öztürk, E.; Gürdağ, G.; Ulutaş, D.

    2015-01-01

    Fe3O4 nanoparticles doped into chitosan films were prepared by the solution casting technique. Various samples were synthesized in atmospheric medium and in vacuum. The morphological properties of the samples were characterized by high resolution transmission electron microscopy (HR-TEM) and Scanning Electron Microscopy (SEM). The structural, magnetic, and microwave absorption properties of magnetic chitosan films have been carried out using the Vibrating Sample Magnetometer (VSM) and Ferromagnetic Resonance (FMR). It is shown that the composite polymer behaves like a superparamagnetic material with high blocking temperature. The effective magnetization shows gradual increments with the concentration of dopant Fe3O4 nanoparticles. The microwave absorption characteristic of superparamagnetic composite polymer shows low reflection loss.

  18. Doping of inorganic materials in microreactors - preparation of Zn doped Fe3O4 nanoparticles.

    PubMed

    Simmons, M D; Jones, N; Evans, D J; Wiles, C; Watts, P; Salamon, S; Escobar Castillo, M; Wende, H; Lupascu, D C; Francesconi, M G

    2015-08-01

    Microreactor systems are now used more and more for the continuous production of metal nanoparticles and metal oxide nanoparticles owing to the controllability of the particle size, an important property in many applications. Here, for the first time, we used microreactors to prepare metal oxide nanoparticles with controlled and varying metal stoichiometry. We prepared and characterised Zn-substituted Fe3O4 nanoparticles with linear increase of Zn content (ZnxFe3-xO4 with 0 ≤ x ≤ 0.48), which causes linear increases in properties such as the saturation magnetization, relative to pure Fe3O4. The methodology is simple and low cost and has great potential to be adapted to the targeted doping of a vast array of other inorganic materials, allowing greater control on the chemical stoichiometry for nanoparticles prepared in microreactors. PMID:26099495

  19. Synthesis and characterization of Fe3O4: Porous carbon nanocomposites for biosensor application

    NASA Astrophysics Data System (ADS)

    Arora, Manju; Zargar, R. A.

    2015-08-01

    Fe3O4:Porous carbon (Fe3O4:PC) nano-magnetic composites were prepared by using different weight fractions of acid treated PC by the chemical co-precipitation route and annealed at 573 K, 773 K and 973 K temperatures in inert N2 gas atmosphere for 2 hrs to obtain desired stoichiometry of nanocomposites. The structural, morphological and magnetic properties of these composites were characterized by powder XRD, TEM, EPR and VSM analytical techniques. The crystallinity of the composites, g-value and spin concentration increases with increasing annealing temperature. TEM images confirmed the formation of nanosized ferrite nanoprticles whose size increases from 23 nm to 54 nm on increasing annealing temperature. Porous carbon increases porosity, coercivity and reduces saturation magnetization of these prepared nanocomposites.

  20. Reactions of Deuterated Methanol (CD3OD) on Fe3O4(111)

    SciTech Connect

    Li, Zhisheng; Potapenko, Denis V.; Rim, Kwang T.; Flytzani-Stephanopoulos, Maria; Flynn, George; Osgood, Richard; Wen, Xiaodong; Batista, Enrique R.

    2015-01-15

    We report an experimental and theoretical investigation of the decomposition (partial oxidation) of deuterated methanol (CD3OD) on a single-crystal Fe3O4(111) surface. The crystal surface contains majority areas of a Fe-terminated Fe3O4(111) surface as well as smaller regions of O-terminated FeO(111) or biphase surface reconstruction. Our investigation uses a combination of scanning tunneling microscopy, temperature-programmed desorption, and density functional theory calculations to examine the surface reactions and adsorbates as a function of coverage. Our studies show that the reaction of methanol on this iron–oxide surface is highly sensitive to atomic-level surface reconstructions

  1. Design of porous C@Fe3O4 hybrid nanotubes with excellent microwave absorption.

    PubMed

    Meng, Fanbin; Wei, Wei; Chen, Xiangnan; Xu, Xiaoling; Jiang, Man; Jun, Lu; Wang, Yong; Zhou, Zuowan

    2016-01-28

    An efficient method was developed to fabricate a porous hybridizing nanotubes structure of amorphous carbon interspersed among Fe3O4 (C@Fe3O4) with a ∼200 nm diameter and ∼70 nm wall thickness. The as-structured porous nanotubes with ferromagnetic behaviour exhibited excellent microwave absorption properties, including a strong ability to attenuate the electromagnetic (EM) wave, and they are also lightweight. Adding only 10 wt% of the as-prepared sample into paraffin can show a maximum reflection loss of -45.0 dB at 6.18 GHz with a sample thickness of 3.4 mm. The absorption mechanism, which results from its porous nanotubes structure, multi-interfaces, dielectric-magnetic integration and geometric effect, is proposed to explain the excellent EM absorption performance. Furthermore, the synthesis strategy presented herein can be expended as a facile approach to synthesizing related carbon-based nanostructures for functional design and applications. PMID:26698330

  2. Fe3O4-nanoparticles within porous silicon: Magnetic and cytotoxicity characterization

    NASA Astrophysics Data System (ADS)

    Granitzer, P.; Rumpf, K.; Tian, Y.; Akkaraju, G.; Coffer, J.; Poelt, P.; Reissner, M.

    2013-05-01

    The magnetic properties of porous silicon/Fe3O4 composites are investigated with respect to the adjustability of the blocking temperature along with an evaluation of any size-dependent changes in cytocompatibility. Fe3O4-nanoparticles have been infiltrated within mesoporous silicon, resulting in a system with tunable magnetic properties due to the matrix-morphology, the loading of the nanoparticles, and their size. In order to provide basic information regarding its suitability as a therapeutic platform, the cytotoxicity of these composites have been investigated by a trypan blue exclusion assay with respect to human embryonic kidney 293 cells, and the results compared with cell-only and known cytotoxic controls.

  3. Preparation and Microwave Absorption Properties of Novel Carbon Nanofiber/Fe3O4 Composites.

    PubMed

    Ren, Yong; Dai, Bo; Wang, Gai-Hua; Zhang, Xiao-Wei; Zhu, Pei; Li, Shi-Rong

    2015-04-01

    Novel, carbonized bacterial cellulose (CBC)/Fe3O4 nanocomposites were synthesized using vacuum filtration and annealing (VFA) methods. The as-synthesized products were characterized by scanning electron microscopy, vibrating sample magnetometry, and transmission electron microscopy. The complex permittivity and permeability of Fe3O4-CBC (5 wt.% CBC)/paraffin wax composites were measured by vector network analysis. To study the microwave absorption (MA) performances, we compared the VFA products with the vacuum filtration (VF) products. The VFA products exhibited better absorption performances because of their larger dielectric loss. When the matching thickness was 2.4 mm, the calculated reflection loss reached a minimum value of -27 dB when VFA was used and a value of -11 dB when VF was used. The wide-range MA properties of these materials lead to potential applications in MA fields. PMID:26353503

  4. Water-soluble rhamnose-coated Fe3O4 nanoparticles.

    PubMed

    Lartigue, Lenaic; Oumzil, Khalid; Guari, Yannick; Larionova, Joulia; Guérin, Christian; Montero, Jean-Louis; Barragan-Montero, Veronique; Sangregorio, Claudio; Caneschi, Andrea; Innocenti, Claudia; Kalaivani, T; Arosio, P; Lascialfari, A

    2009-07-16

    Water-soluble biocompatible rhamnose-coated Fe(3)O(4) nanoparticles of 4.0 nm are obtained by covalent anchorage of rhamnose on the nanoparticles surface via a phosphate linker. These nanoparticles present superparamagnetic behavior and nuclear relaxivities in the same order of magnitude as Endorem that make them potential magnetic resonance imaging (MRI) contrast agents of a second generation, where the saccharides represent also specific ligands able to target lectins on skin cells. PMID:19545163

  5. Structural And Magnetic Properties Of Mn And Zn Doped Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Varshney, Dinesh; Verma, Kavita; Yogi, A.

    2011-07-01

    Mn and Zn doped Fe3O4 nanoparticles of size 7.36 and 12.52 nm were prepared by co precipitation method. X-ray diffraction (XRD) pattern infers that both the samples are in single phase with Fd3m space group, which was further confirmed by Rietveld refinement. Transmission Mössbauer spectra reveals ferrimagnetic nature for Mn doping concentration while into that for Zn doping concentration it shows diamagnetic behaviour. Zn doped nanoparticles shows the superparamagnetic property.

  6. One-pot preparation of superparamagnetic attapulgite/Fe3O4/polydopamine nanocomposites for adsorption of methylene blue

    NASA Astrophysics Data System (ADS)

    Mu, Bin; Kang, Yuru; Zheng, Maosong; Wang, Aiqin

    2016-05-01

    Superparamagnetic attapulgite/Fe3O4/polydopamine nanocomposites have been facilely prepared by a one-pot process without the nitrogen protection, in which Fe(III) was served as both of the oxidant for dopamine and the precursor of Fe3O4 in the presence of attapulgite. The introduction of attapulgite can effectively induce the uniform encapsulation of polydopamine and Fe3O4 nanoparticles on the surface of attapulgite, preventing from the formation of the free aggregates of Fe3O4 nanoparticles. The as-prepared APT/Fe3O4/PANI nanocomposites can be used as an adsorbent for the removal of methylene blue, and the adsorption ratio toward 100 ppm of methylene blue could reach 95.8%.

  7. Preparation of Fe3O4 encapsulated-silica sulfonic acid nanoparticles and study of their in vitro antimicrobial activity.

    PubMed

    Naeimi, Hossein; Nazifi, Zahra Sadat; Amininezhad, Seyedeh Matin

    2015-08-01

    A simple and efficient method for the functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acid is described. The prepared compounds were screened for antibacterial activity against Escherichia coli (E. coli ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923) under UV-light and dark conditions. It was found that the Fe3O4@SiO2-SO3H was significantly indicated the higher photocatalytic inactivation than both Fe3O4 and Fe3O4@SiO2 against E. coli in compared with S. aureus. Furthermore, the inactivation efficiency against both organisms under light conditions has been higher than this efficiency under dark conditions. PMID:26092181

  8. Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

    NASA Astrophysics Data System (ADS)

    Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

    2013-06-01

    Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

  9. Magnetic fluid with high dispersion and heating performance using nano-sized Fe3O4 platelets

    NASA Astrophysics Data System (ADS)

    Kishimoto, Mikio; Miyamoto, Ryoichi; Oda, Tatsuya; Yanagihara, Hideto; Ohkohchi, Nobuhiro; Kita, Eiji

    2016-01-01

    Magnetic fluid with high dispersion and heating performance was developed using 30 to 50 nm platelet Fe3O4 particles. This fluid was prepared by mechanical dispersion in ethyl alcohol with a silane coupling agent, bonding with polyethylene glycol (PEG), and removal of aggregates formed by precipitation. The peak diameter of the resulting Fe3O4 particles, measured by dynamic light scattering, was approximately 150 nm. The fluid exhibited a 300 W/g specific loss power (measured at 114 kHz by a 50.9 kA/m magnetic field). Distribution of the Fe3O4 particles in tissues was observed by intravenously administrating the fluid in mice. The Fe3O4 particles passed through the lungs, and were uniformly distributed throughout the liver and spleen. High dispersion and high heating performance were simultaneously achieved in the magnetic fluid using platelet Fe3O4 particles surface modified with PEG.

  10. Growth mechanism of ZnO nanorod/Fe3O4 nanoparticle composites and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Wenda; Yu, Leiming; Yang, Hanjia; Hong, Kunquan; Qiao, Zhenfang; Wang, Hai

    2015-11-01

    ZnO nanorods/Fe3O4 nanocomposites as the recyclable photocatalyst were synthesized by a co-precipitation method, with microwave assistant by dropping alkaline solution with Fe3O4 nanoparticles into the aqueous of zinc salt. These Fe3O4 nanoparticles were the nucleated centers for the ZnO nanorods growth so that these nanorods ended with aggregated Fe3O4 nanoparticles. The growth processes and mechanism are explained as those insoluble zinc hydroxides prefer to nucleate on the surface of Fe3O4 nanoparticles (heterogeneous nucleation) rather than nucleated as isolated ZnO nanostructures (homogeneous nucleation). These nanocomposites have strong photocatalytic ability to reduce RhB and moderate magnetization, which make them being good recyclable photocatalysts.

  11. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-02-01

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future.Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the

  12. Synthesis and characterization of Ag/Fe3O4 electromagnetic shielding particles

    NASA Astrophysics Data System (ADS)

    Li, Shichuan; Zhou, Zunning; Zhang, Tonglai; Jiang, Guotao; Su, Ruyi

    2014-05-01

    Ag/Fe3O4 nano-composites are synthesized by electroless silver plating technique and characterized by X-ray diffraction, scanning/transmission electron microscope, magnetic measurement equipment and vector network analyzer. They show the silver layer coated on the surface of the particles successfully, and which can enhance the dielectricity and permeability properties of the ferromagnetic particles. The dielectric loss values of the composites are more than 1.0 in the almost whole test frequency range and the imaginary part of permeability of Ag/Fe3O4 is higher than real part in 2-5 GHz. The value of Hc is increased to 165.2 Oe due to the extended relaxation time of magnetic domain deflection of the magnetic powders which covered by silver layer. And the calculated microwave loss is more than 20 dB in the whole frequency range. As a result, the Ag/Fe3O4 nano-composites are expected to be used as electromagnetic shielding particle material in multiband smoke agent.

  13. Adsorption studies of cationic, anionic and azo-dyes via monodispersed Fe3O4 nanoparticles.

    PubMed

    Chaudhary, Ganga Ram; Saharan, Priya; Kumar, Arun; Mehta, S K; Mor, Suman; Umar, Ahmad

    2013-05-01

    The present paper reports the applicability of magnetite (Fe3O4) nanoparticles as an adsorbent for the removal of three dyes viz. Acridine orange (cationic dye), Comassie Brilliant Blue R-250 (anionic dye) and Congo red (azo dye) from their aqueous solution. The Fe3O4 nanoparticles were synthesized via simple chemical precipitation method using CTAB, as surfactant. The as-prepared nanoparticles were characterized in terms of their morphological, structural and optical properties by using transmission electron microscopy X-ray diffraction and UV-visible spectroscopic measurements. The dye removal efficiency of Fe3O4 NPs have been determined by investigating several factors such as effect of pH, amount of adsorbent dose and effect of contact time on different dye concentrations. Langmuir and Freundlich adsorption isotherms have also been studied to explain the interaction of dyes. The experimental data indicate that the adsorption rate follows pseudo- second-order kinetics for the removal of all the three dyes. Moreover, the nanoparticles and the adsorbed dyes were desorbed. The identities of recovered nanoparticles as well as the three dyes have been found, as same and were reused. PMID:23858837

  14. Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

    NASA Astrophysics Data System (ADS)

    Lv, Yuzhen; Wang, Qi; Zhou, You; Li, Chengrong; Ge, Yang; Qi, Bo

    2016-03-01

    Fe3O4 nanoparticles with an average diameter of 10 nm were prepared and used to modify streamer characteristic of transformer oil. It was found that positive streamer propagation velocity in transformer oil-based Fe3O4 nanofluid is greatly reduced by 51% in comparison with that in pure oil. The evolution of streamer shape is also dramatically affected by the presence of nanoparticles, changing from a tree-like shape with sharp branches in pure oil to a bush-like structure with thicker and denser branches in nanofluid. The TSC results reveal that the modification of Fe3O4 nanoparticle can greatly increase the density of shallow trap and change space charge distribution in nanofluid by converting fast electrons into slow electrons via trapping and de-trapping process in shallow traps. These negative space charges induced by nanoparticles greatly alleviate the electric field distortion in front of the positive streamer tip and significantly hinder the propagation of positive streamer.

  15. Enhanced high-frequency absorption of anisotropic Fe3O4/graphene nanocomposites.

    PubMed

    Yin, Yichao; Zeng, Min; Liu, Jue; Tang, Wukui; Dong, Hangrong; Xia, Ruozhou; Yu, Ronghai

    2016-01-01

    Anisotropic Fe3O4 nanoparticle and a series of its graphene composites have been successfully prepared as high-frequency absorbers. The crystal structure, morphology and magnetic property of the samples were detailed characterized through X-ray diffractometer (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The high-frequency absorbing performance of the composites is evaluated within 2.0-18.0 GHz. Combining reduced graphene oxide (RGO) to Fe3O4 helps to adjust the permittivity and permeability of the composite, balance the dielectric loss and magnetic loss, consequently improve the absorbing performance in view of the impedance matching characteristic. The optimal reflection loss of the pure Fe3O4 sample reaches -38.1 dB with a thickness of 1.7 mm, and it increases to -65.1 dB for the sample grafted with 3 wt.% RGO. The addition of proper content of RGO both improves the reflection loss and expands the absorbing bandwidth. This work not only opens a new method and an idea for tuning the electromagnetic properties and enhancing the capacity of high-efficient absorbers, but also broadens the application of such kinds of lightweight absorbing materials frameworks. PMID:27142260

  16. Magnetic quenching of photonic activity in Fe3O4-elastomer composite

    NASA Astrophysics Data System (ADS)

    Ma, Danhao; Hess, Dustin T.; Shetty, Pralav P.; Adu, Kofi W.; Bell, Richard C.; Terrones, Mauricio

    2016-01-01

    We report a quenching phenomenon within the visible region of the electromagnetic spectrum in the photonic response of a passive Fe3O4-silicone elastomer composite film due to magnetically aligned Fe3O4 nanoparticles. We performed systematic studies of the polarization dependence, the effect of particle size, and an in- and out-of-plane particle alignment on the optical response of the Fe3O4-silicone elastomer composites using a UV/vis/NIR spectrometer. We observed systematic redshifts in the response of the out-of-plane composite films with increasing particle alignment and weight that are attributed to dipole-induced effects. There were no observable shifts in the spectra of the in-plane films, suggesting the orientation of the magnetic dipole and the induced electric dipole play a crucial role in the optical response. A dramatic suppression to near quenching of the photonic response occurred in films containing moderate concentrations of the aligned nanoparticles. This is attributed to the interplay between the intra- and the interparticle dipoles. This occurred even when low magnetic fields were used during the curing process, suggesting that particle alignment and particle size limitation are critical in the manipulation of the photonic properties. A dipole approximation model is used to explain the quenching phenomenon. An active system of such a composite has a potential application in magneto-optic switches.

  17. Ultrafast Preparation of Monodisperse Fe3 O4 Nanoparticles by Microwave-Assisted Thermal Decomposition.

    PubMed

    Liang, Yi-Jun; Zhang, Yu; Guo, Zhirui; Xie, Jun; Bai, Tingting; Zou, Jiemeng; Gu, Ning

    2016-08-01

    Thermal decomposition, as the main synthetic procedure for the synthesis of magnetic nanoparticles (NPs), is facing several problems, such as high reaction temperatures and time consumption. An improved a microwave-assisted thermal decomposition procedure has been developed by which monodisperse Fe3 O4 NPs could be rapidly produced at a low aging temperature with high yield (90.1 %). The as-synthesized NPs show excellent inductive heating and MRI properties in vitro. In contrast, Fe3 O4 NPs synthesized by classical thermal decomposition were obtained in very low yield (20.3 %) with an overall poor quality. It was found for the first time that, besides precursors and solvents, magnetic NPs themselves could be heated by microwave irradiation during the synthetic process. These findings were demonstrated by a series of microwave-heating experiments, Raman spectroscopy and vector-network analysis, indicating that the initially formed magnetic Fe3 O4 particles were able to transform microwave energy into heat directly and, thus, contribute to the nanoparticle growth. PMID:27381301

  18. Low temperature glassy relaxation in rare earth doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Laha, Suvra; Lawes, Gavin

    2012-10-01

    Magnetic nanoparticles typically exhibit glassy relaxation at low temperature, which can be affected by doping. Gadolinium and Lanthanum doped Fe3O4 nanoparticles were synthesized using a chemical co-precipitation method. The structural and optical properties of these nanoparticles were characterized by using Transmission Electron Microscope (TEM) and the Raman spectroscopy. The TEM images show the formation of nanoparticles of size ranging between 12-14 nm and Raman spectra are consistent with the formation of Fe3O4. AC magnetic measurements were also conducted on these nanoparticles. From the ac out-of-phase susceptibility (χ//) vs temperature (T) graphs, it is observed that the doped nanoparticles show larger amplitude relaxation peaks at low temperature as compared to the undoped particles. These magnetic relaxation features develop roughly between 25K to 35K and show frequency dependence. The increased magnetic relaxation at low temperatures can be attributed to structural defects which may arise due to the doping of lanthanides in Fe3O4 nanoparticles.

  19. Effects of impurity states on exchange coupling in Fe/Fe3O4 junctions

    NASA Astrophysics Data System (ADS)

    Inoue, J.; Honda, S.; Itoh, H.; Mibu, K.; Yanagihara, H.; Kita, E.

    2012-05-01

    Exchange coupling (EC) in Fe/Fe3O4 junctions containing magnetic impurities and in-gap states at the interface is calculated using a formula obtained by a cleaved layer method. The model for EC is constructed by performing first-principles calculations of the electronic and magnetic states of Co, Mn, and Cr impurities on the Fe surface and those of in-gap states in a bulk γ-Fe2O3, which has the same lattice structure as Fe3O4 but contains Fe defects. We show that the effect of Co impurities on EC is opposite to that of Cr and Mn impurities and that in-gap states tend to cause parallel magnetization alignment of two ferromagnets. These results are attributed to the change in electronic states caused by the presence of impurities. Further, we compare calculated results with experimental ones obtained in Fe/Fe3O4 junctions and suggest that doping magnetic impurities at the interface could be a useful way to control the magnitude and sign of the EC.

  20. Magnetic properties of In2O3 containing Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Alshammari, Marzook S.; Alqahtani, Mohammed S.; Albargi, Hasan B.; Alfihed, Salman A.; Alshetwi, Yaser A.; Alghihab, Abdulrahman A.; Alsamrah, Abdullah M.; Alshammari, Nawaf M.; Aldosari, Mohammed A.; Alyamani, Ahmed; Hakimi, Ali M. H. R.; Heald, Steve M.; Blythe, Harry J.; Blamire, Mark G.; Fox, A. Mark; Gehring, Gillian A.

    2014-10-01

    Films of Fe-doped In2O3 that were deliberately fabricated so they contained Fe3O4 nanoparticles were deposited on sapphire substrates by pulsed laser deposition at low oxygen pressure. The concentration of Fe was varied between 1% and 5%, and the effect of including 5% of Sn and vacuum annealing were also investigated. Structural analysis indicated a high concentration of Fe3O4 nanoparticles that caused substantial values of the coercive field at room temperature. Transport measurements indicated that the films were metallic, and an anomalous Hall effect was observed for the sample with 5% of Fe. The concentration of nanoparticles was reduced dramatically by the inclusion of 5% of Sn. Magnetic circular dichroism spectra taken in field and at remanence were analyzed to show that the samples had a magnetically polarized defect band located below the conduction band as well as magnetic Fe3O4 nanoparticles. The signal from the defect states near the band edge was enhanced by increasing the number of carriers by either including Sn or by annealing in vacuum.

  1. Synthesis and characterization of Fe3O4-TiO2 core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Stefan, M.; Pana, O.; Leostean, C.; Bele, C.; Silipas, D.; Senila, M.; Gautron, E.

    2014-09-01

    Composite core-shell nanoparticles may have morpho-structural, magnetic, and optical (photoluminescence (PL)) properties different from each of the components considered separately. The properties of Fe3O4-TiO2 nanoparticles can be controlled by adjusting the titania amount (shell thinness). Core-shell nanoparticles were prepared by seed mediated growth of semiconductor (TiO2) through a modified sol-gel process onto preformed magnetite (Fe3O4) cores resulted from the co-precipitation method. The structure and morphology of samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), and high resolution-TEM respectively. X-ray photoelectron spectroscopy was correlated with ICP-AES. Magnetic measurements, optical absorption spectra, as well as PL spectroscopy indicate the presence of a charge/spin transfer from the conduction band of magnetite into the band gap of titania nanocrystals. The process modifies both Fe3O4 and TiO2 magnetic and optical properties, respectively.

  2. The Magnetorheological Finishing (MRF) of Potassium Dihydrogen Phosphate (KDP) Crystal with Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ji, Fang; Xu, Min; Wang, Chao; Li, Xiaoyuan; Gao, Wei; Zhang, Yunfei; Wang, Baorui; Tang, Guangping; Yue, Xiaobin

    2016-02-01

    The cubic Fe3O4 nanoparticles with sharp horns that display the size distribution between 100 and 200 nm are utilized to substitute the magnetic sensitive medium (carbonyl iron powders, CIPs) and abrasives (CeO2/diamond) simultaneously which are widely employed in conventional magnetorheological finishing fluid. The removal rate of this novel fluid is extremely low compared with the value of conventional one even though the spot of the former is much bigger. This surprising phenomenon is generated due to the small size and low saturation magnetization ( M s) of Fe3O4 and corresponding weak shear stress under external magnetic field according to material removal rate model of magnetorheological finishing (MRF). Different from conventional D-shaped finishing spot, the low M s also results in a shuttle-like spot because the magnetic controllability is weak and particles in the fringe of spot are loose. The surface texture as well as figure accuracy and PSD1 (power spectrum density) of potassium dihydrogen phosphate (KDP) is greatly improved after MRF, which clearly prove the feasibility of substituting CIP and abrasive with Fe3O4 in our novel MRF design.

  3. Experimental study of natural convection enhancement using a Fe3O4-water based magnetic nanofluid.

    PubMed

    Stoian, Floriana D; Holotescu, Sorin

    2012-10-01

    The effect of nanoparticles dispersed in a carrier fluid on the natural convection heat transfer is still raising controversies. While the reported experimental results show no improvement or even worsening of the heat transfer performance of nanofluids, the numerical simulations show an increase of the heat transfer coefficient, at least for certain ranges of Ra number. We report an experimental investigation regarding the natural convection heat transfer performance of a Fe3O4-water based nanofluid, in a cylindrical enclosure. The fluid was heated linearly from the bottom wall using an electric heater and cooled from the upper wall by a constant flow of water, such that a constant temperature difference between the upper and bottom walls was obtained at steady-state. The experiment was also carried out using water, in order to observe the effect of the addition of Fe3O4 nanoparticles on the heat transfer coefficient. Several regimes were tested, both for water and nanofluid. The experimental results showed that values obtained for the heat transfer coefficient for Fe3O4-water nanofluid were higher than those for water, at the same temperature difference. The present experimental results are also compared with our previous work and the reference literature. PMID:23421199

  4. The Magnetorheological Finishing (MRF) of Potassium Dihydrogen Phosphate (KDP) Crystal with Fe3O4 Nanoparticles.

    PubMed

    Ji, Fang; Xu, Min; Wang, Chao; Li, Xiaoyuan; Gao, Wei; Zhang, Yunfei; Wang, Baorui; Tang, Guangping; Yue, Xiaobin

    2016-12-01

    The cubic Fe3O4 nanoparticles with sharp horns that display the size distribution between 100 and 200 nm are utilized to substitute the magnetic sensitive medium (carbonyl iron powders, CIPs) and abrasives (CeO2/diamond) simultaneously which are widely employed in conventional magnetorheological finishing fluid. The removal rate of this novel fluid is extremely low compared with the value of conventional one even though the spot of the former is much bigger. This surprising phenomenon is generated due to the small size and low saturation magnetization (M s) of Fe3O4 and corresponding weak shear stress under external magnetic field according to material removal rate model of magnetorheological finishing (MRF). Different from conventional D-shaped finishing spot, the low M s also results in a shuttle-like spot because the magnetic controllability is weak and particles in the fringe of spot are loose. The surface texture as well as figure accuracy and PSD1 (power spectrum density) of potassium dihydrogen phosphate (KDP) is greatly improved after MRF, which clearly prove the feasibility of substituting CIP and abrasive with Fe3O4 in our novel MRF design. PMID:26858161

  5. Fe3O4@Nico-Ag magnetically recyclable nanocatalyst for azo dyes reduction

    NASA Astrophysics Data System (ADS)

    Kurtan, U.; Amir, Md.; Baykal, A.

    2016-02-01

    In this study, we report the successful synthesis of Fe3O4@Nico-Ag nanocomposite as magnetically recyclable nanocatalyst (MRCs) via reflux process at 80 °C for 5 h followed by reduction of Ag+. FeCl3·6H2O, FeCl2·4H2O, AgNO3 as starting reactants and nicotinic acid as linker. The structure, morphology, thermal behaviour and magnetic properties of the product were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDX), thermal gravimetry (TG) and vibrating sample magnetometry (VSM), respectively. The catalytic activity of product for various azo dyes such as methylene blue (MB), methyl orange (MO), Rhodamine B (RhB) and eosin Y (EY) and their double mixtures were studied. It was found that Fe3O4@Nico-Ag MRCs is an efficient catalyst and can also rapidly separated from the reaction medium using magnet without considerable loss in its catalytic activity and used several times. Fe3O4@Nico-Ag MRCs has potential for the treatment of industrial dye pollutants.

  6. Effective PEGylation of Fe3O4 Nanomicelles for In Vivo MR Imaging.

    PubMed

    Song, Lina; Zang, Fengchao; Song, Mengjie; Chen, Gong; Zhang, Yu; Gu, Ning

    2015-06-01

    A practical and effective strategy for synthesizing PEGylated Fe3O4 nanomicelles is established. In this strategy, a magnetic fluid of the Fe3O4 nanomicelles was synthesized with amphiphilic PEGylated phospholipid as surfactant and soybean oil as stabilizer under simple mechanical stirring and subsequent ultrasonication. Transmission electron microscope (TEM) measurement indicated that the sample is monodisperse spherical Fe3O4 nanoparticles with internal core size of 9 nm and external nanomicelle shell thickness of 1.5 nm. The final hydrodynamic size of the sample is 19.5 nm and its zeta potential is - 38.5 mV, suggesting good stability of the magnetic nanomicelles in water. To assess the ability of magnetic nanomicelles to escape reticuloendothelial system (RES) uptake, in vitro cell phagocytosis experiments were conducted using murine macrophages (RAW264.7). The results indicated that the PEGylation can effectively prevent the uptake of the nanomicelles by the macrophages. Using a mouse model of 4T1 breast cancer, the nanomicelles provided a good magnetic resonance imaging (MRI) capability to sensitively detect tumor by enhanced permeability and retention (EPR) effect. The PEGylated monodisperse magnetic nanomicelles would become a potential contrast agent for passive targeting diagnosis of tumor by MR imaging. PMID:26369019

  7. Potentiometric glucose biosensor based on core-shell Fe3O4-enzyme-polypyrrole nanoparticles.

    PubMed

    Yang, Zhengpeng; Zhang, Chunjing; Zhang, Jianxin; Bai, Wanbei

    2014-01-15

    Core-shell Fe3O4-enzyme-polypyrrole (Ppy) nanoparticles with excellent magnetism and conductivity were successfully prepared via the surface modification and enzyme self-encapsulation within Ppy. A novel potentiometric glucose biosensor has been constructed by effectively attaching the proposed Fe3O4-enzyme-Ppy nanoparticles to the surface of the magnetic glassy carbon electrode (MGCE). The optimum biosensing conditions could be provided with polymerization time of pyrrole for 6h and 0.42 mg immobilization amount of Fe3O4-enzyme-Ppy nanoparticles on MGCE. The performance of the developed glucose biosensor was evaluated and the results indicated that a sensitive glucose biosensor could be fabricated. The obtained glucose biosensor presents shorter response time (6 s), wider linear range (0.5 μM to 34 mM), lower limit of detection (LOD, 0.3 μM), high-selectivity monitoring of glucose and good stability (with about 98.1% of the initial response signal retained after 20 days). The analytical application of the glucose biosensor confirms the feasibility of glucose detection in serum sample. PMID:23974157

  8. Enhanced high-frequency absorption of anisotropic Fe3O4/graphene nanocomposites

    NASA Astrophysics Data System (ADS)

    Yin, Yichao; Zeng, Min; Liu, Jue; Tang, Wukui; Dong, Hangrong; Xia, Ruozhou; Yu, Ronghai

    2016-05-01

    Anisotropic Fe3O4 nanoparticle and a series of its graphene composites have been successfully prepared as high-frequency absorbers. The crystal structure, morphology and magnetic property of the samples were detailed characterized through X-ray diffractometer (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The high-frequency absorbing performance of the composites is evaluated within 2.0–18.0 GHz. Combining reduced graphene oxide (RGO) to Fe3O4 helps to adjust the permittivity and permeability of the composite, balance the dielectric loss and magnetic loss, consequently improve the absorbing performance in view of the impedance matching characteristic. The optimal reflection loss of the pure Fe3O4 sample reaches ‑38.1 dB with a thickness of 1.7 mm, and it increases to ‑65.1 dB for the sample grafted with 3 wt.% RGO. The addition of proper content of RGO both improves the reflection loss and expands the absorbing bandwidth. This work not only opens a new method and an idea for tuning the electromagnetic properties and enhancing the capacity of high-efficient absorbers, but also broadens the application of such kinds of lightweight absorbing materials frameworks.

  9. Electrical transport, magnetic properties of the half-metallic Fe 3O 4-based Schottky diode

    NASA Astrophysics Data System (ADS)

    Yan, Hong; Zhang, Ming; Yan, Hui

    2009-08-01

    Fe 3O 4 thin films were prepared successfully by using the rf-sputtering technique with Fe 2O 3 target. The inverse spinel structure of the film was determined by X-ray diffraction (XRD) and the single phase of the Fe 3O 4 was confirmed by the XPS measurements. The surface roughness increases with the increase of the partial pressure of hydrogen. A high saturated magnetic field, 5000 Oe, implies that there exist the antiphase boundaries (APBs) in the film. The higher coercive filed below T V is ascribed to the lower symmetry of the monoclinic structure. The temperature dependence of resistance shows a very clear Verwey transition and it is implied that the electrical transport behavior follows the variable-range hopping (VRH) mechanism from 40 to 300 K. The current vs. voltage curves of Fe 3O 4/Si Schottky heterojunction exhibits good rectifying property. The ideality factor and Schottky barrier height were obtained from the fitting curves calculated by the standard thermionic emission/diffusion model.

  10. Synthesis and characterization of Fe3O4-SiO2-AgCl photocatalyst

    NASA Astrophysics Data System (ADS)

    Husni, H. N.; Mahmed, N.; Ngee, H. L.

    2016-07-01

    Magnetite-silica-silver chloride (Fe3O4-SiO2-AgCl) coreshell particles with AgCl crystallite size of 117 nm was prepared by a wet chemistry method at ambient temperature. The magnetite-core was synthesized by using iron (II) sulfate heptahydrate (FeSO4•7H2O) and iron (III) sulfate hydrate (Fe2(SO4)3) with ammonium hydroxide (NH4OH) as the precipitating agent. The silica-shell was synthesized by using a modified Stöber process. The silver ions (Ag+) was adsorbed onto the silica surface after Söber process, followed by the addition of Cl- and polyvinylpyrrolidone (PVP) for the formation of Fe3O4-SiO2-AgCl coreshell particles. The effectiveness of the synthesized photocatalyst was investigated by monitoring the degradation of the methylene blue (MB) under sunlight for five cycles. About 90 % of the MB solution can be degraded after 2 hours. The degradation of MB solution by the Fe3O4-SiO2-AgCl particles is highly efficient for first three cycles according to the MB concentration recorded by the UV-Visible spectroscopy (UV-Vis). Nevertheless, the synthesized particles could be a promising material for photocatalytic applications.

  11. Electrostatic self-assembly of Fe 3O 4 nanoparticles on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Jiang, Wei; Li, Song; Li, Fengsheng

    2009-06-01

    Carbon nanotubes (CNTs)-based magnetic nanocomposites can find numerous applications in nanotechnology, integrated functional system, and in medicine owing to their great potentialities. Herein, densely distributed magnetic Fe 3O 4 nanoparticles were successfully attached onto the convex surfaces of carbon nanotubes (CNTs) by an in situ polyol-medium solvothermal method via non-covalent functionalization of CNTs with cationic surfactant, cetyltrimethylammonium bromide (CTAB), and anionic polyelectrolyte, poly(sodium 4-styrenesulfonate) (PSS), through the polymer-wrapping technique, in which the negatively charged PSS-grafted CNTs can be used as primer for efficiently adsorption of positively metal ions on the basis of electrostatic attraction. X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis have been used to study the formation of Fe 3O 4/CNTs. The Fe 3O 4/CNTs nanocomposites were proved to be superparamagnetic with saturation magnetization of 43.5 emu g -1. A mechanism scheme was proposed to illustrate the formation process of the magnetic nanocomposites.

  12. Synthesis and characterization of core-shell Fe3O4-gold-chitosan nanostructure

    PubMed Central

    2012-01-01

    Background Fe3O4-gold-chitosan core-shell nanostructure can be used in biotechnological and biomedical applications such as magnetic bioseparation, water and wastewater treatment, biodetection and bioimaging, drug delivery, and cancer treatment. Results Magnetite nanoparticles with an average size of 9.8 nm in diameter were synthesized using the chemical co-precipitation method. A gold-coated Fe3O4 monotonous core-shell nanostructure was produced with an average size of 15 nm in diameter by glucose reduction of Au3+ which is then stabilized with a chitosan cross linked by formaldehyde. The results of analyses with X-ray diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and Atomic Force Microscopy (AFM) indicated that the nanoparticles were regularly shaped, and agglomerate-free, with a narrow size distribution. Conclusions A rapid, mild method for synthesizing Fe3O4-gold nanoparticles using chitosan was investigated. A magnetic core-shell-chitosan nanocomposite, including both the supermagnetic properties of iron oxide and the optical characteristics of colloidal gold nanoparticles, was synthesized. PMID:22221555

  13. Enhanced high-frequency absorption of anisotropic Fe3O4/graphene nanocomposites

    PubMed Central

    Yin, Yichao; Zeng, Min; Liu, Jue; Tang, Wukui; Dong, Hangrong; Xia, Ruozhou; Yu, Ronghai

    2016-01-01

    Anisotropic Fe3O4 nanoparticle and a series of its graphene composites have been successfully prepared as high-frequency absorbers. The crystal structure, morphology and magnetic property of the samples were detailed characterized through X-ray diffractometer (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The high-frequency absorbing performance of the composites is evaluated within 2.0–18.0 GHz. Combining reduced graphene oxide (RGO) to Fe3O4 helps to adjust the permittivity and permeability of the composite, balance the dielectric loss and magnetic loss, consequently improve the absorbing performance in view of the impedance matching characteristic. The optimal reflection loss of the pure Fe3O4 sample reaches −38.1 dB with a thickness of 1.7 mm, and it increases to −65.1 dB for the sample grafted with 3 wt.% RGO. The addition of proper content of RGO both improves the reflection loss and expands the absorbing bandwidth. This work not only opens a new method and an idea for tuning the electromagnetic properties and enhancing the capacity of high-efficient absorbers, but also broadens the application of such kinds of lightweight absorbing materials frameworks. PMID:27142260

  14. Sustained magnetization oscillations in polyaniline-Fe3O4 nanocomposites.

    PubMed

    de Araújo, A C V; Rodrigues, A R; de Azevedo, W M; Machado, F L A; Rezende, S M

    2015-09-28

    We report experiments with polyaniline-Fe3O4 (PANI-Fe3O4) nanocomposites synthesized under several different conditions. With a reaction carried out at room temperature and assisted by intense ultra-violet (UV) irradiation, we observe sustained oscillations in the magnetization with a period of about 25 min. The oscillations are interpreted as the result of an oscillatory chemical reaction in which part of the Fe(+2) ions of magnetite, Fe3O4, are oxidized by the UV irradiation to form Fe(+3) so that a fraction of the magnetite content transforms into maghemite, γ-Fe2O3. Then, Fe(+3) ions at the nanoparticle surfaces are reduced and transformed back into Fe(+2), when acting as an oxidizing agent for polyaniline in the polymerization process. Since maghemite has smaller magnetization than magnetite, the oscillating chemical reaction results in the oscillatory magnetization. The observations are interpreted with the Lotka-Volterra nonlinear coupled equations with parameters that can be adjusted to fit very well the experimental data. PMID:26429031

  15. Sustained magnetization oscillations in polyaniline-Fe3O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    de Araújo, A. C. V.; Rodrigues, A. R.; de Azevedo, W. M.; Machado, F. L. A.; Rezende, S. M.

    2015-09-01

    We report experiments with polyaniline-Fe3O4 (PANI-Fe3O4) nanocomposites synthesized under several different conditions. With a reaction carried out at room temperature and assisted by intense ultra-violet (UV) irradiation, we observe sustained oscillations in the magnetization with a period of about 25 min. The oscillations are interpreted as the result of an oscillatory chemical reaction in which part of the Fe+2 ions of magnetite, Fe3O4, are oxidized by the UV irradiation to form Fe+3 so that a fraction of the magnetite content transforms into maghemite, γ-Fe2O3. Then, Fe+3 ions at the nanoparticle surfaces are reduced and transformed back into Fe+2, when acting as an oxidizing agent for polyaniline in the polymerization process. Since maghemite has smaller magnetization than magnetite, the oscillating chemical reaction results in the oscillatory magnetization. The observations are interpreted with the Lotka-Volterra nonlinear coupled equations with parameters that can be adjusted to fit very well the experimental data.

  16. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites.

    PubMed

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-03-01

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future. PMID:26884248

  17. Fe3O4/carbon core-shell nanotubes as promising anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Xia, Hui; Wan, Yunhai; Yuan, Guoliang; Fu, Yongsheng; Wang, Xin

    2013-11-01

    Magnetite (Fe3O4)/carbon core-shell nanotubes have been successfully synthesized by partial reduction of monodispersed hematite (Fe2O3) nanotubes with carbon coating. Fe2O3 is completely converted to Fe3O4 during the reduction process and a thin carbon layer is continuously coated on the surface of Fe3O4 with the nanotube morphology reserved. The Fe3O4/carbon core-shell nanotubes exhibit superior electrochemical properties as anode material for lithium-ion batteries compared with the Fe2O3 and Fe3O4 nanotubes. The Fe3O4/carbon core-shell nanotubes electrode shows a large reversible capacity up to 938 mAh g-1 as well as improved cycling stability and excellent rate capability. The promising anode performance of the Fe3O4/carbon core-shell nanotubes can be attributed to their tubular morphology and continuous carbon coating, which provide improved structural stability and fast charge transport.

  18. Magnetically separable and recyclable Fe3O4-polydopamine hybrid hollow microsphere for highly efficient peroxidase mimetic catalysts.

    PubMed

    Liu, Shujun; Fu, Jianwei; Wang, Minghuan; Yan, Ya; Xin, Qianqian; Cai, Lu; Xu, Qun

    2016-05-01

    Magnetic Fe3O4-polydopamine (PDA) hybrid hollow microspheres, in which Fe3O4 nanoparticles were firmly incorporated in the cross-linked PDA shell, have been prepared through the formation of core/shell PS/Fe3O4-PDA composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property and magnetic property of the magnetic hybrid hollow microspheres were characterized by SEM, TEM, FT-IR, XRD, TGA, and vibrating sample magnetometer, respectively. Results revealed that the magnetic hybrid hollow microspheres had about 380 nm of inner diameter and about 30 nm of shell thickness, and 13.6 emu g(-1) of magnetization saturation. More importantly, the Fe3O4-PDA hybrid hollow microspheres exhibited intrinsic peroxidase-like activity, as they could quickly catalyze the oxidation of typical substrates 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. Compared with PDA/Fe3O4 composites where Fe3O4 nanoparticles were loaded on the surface of PDA microspheres, the stability of Fe3O4-PDA hybrid hollow microspheres was greatly improved. As-prepared magnetic hollow microspheres might open up a new application field in biodetection, biocatalysis, and environmental monitoring. PMID:26871276

  19. Ferroic ordering and charge-spin-lattice order coupling in Gd doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Laha, Suvra; Abdelhamid, Ehab; Palihawadana Arachchige, Maheshika; Dixit, Ambesh; Lawes, Gavin; Naik, Vaman; Naik, Ratna

    Rare earth doped spinels have been extensively studied for their potential applications in magneto-optical recording and as MRI contrast agents. In the present study, we have investigated the effect of gadolinium doping (1-5 at.%) on the magnetic and dielectric properties of Fe3O4nanoparticles synthesized by the chemical co-precipitation method. The structure and morphology of the as-synthesized gadolinium doped Fe3O4(Gd-Fe3O4) nanoparticles were characterized by XRD, SEM and TEM, and the magnetic properties were measured by a Quantum Design physical property measurement system. We find that the penetration of excess Gd3+ ions into Fe3O4 spinel matrix significantly influences the average crystallite size and saturation magnetization in Gd-Fe3O4. The average crystallite size, estimated from XRD using Scherrer equation, increases with increasing Gd doping percentage and the saturation magnetization drops monotonically with excess Gd3+ ions. Interestingly, Gd- Fe3O4develops enhanced ferroelectric ordering at low temperatures. The details of the temperature dependent dielectric, ferroelectric and magnetocapacitance measurements to understand the onset of charge-spin-lattice coupling in Gd-Fe3O4 system will be presented.

  20. Valence band structure and magnetic properties of Co-doped Fe3O4(100) films

    NASA Astrophysics Data System (ADS)

    Ran, F. Y.; Tsunemaru, Y.; Hasegawa, T.; Takeichi, Y.; Harasawa, A.; Yaji, K.; Kim, S.; Kakizaki, A.

    2011-06-01

    Structural and magnetic properties, and the valence band structure of pure and Co-doped (up to 33%) Fe3O4(100) films were investigated. Reconstruction of the Fe3O4(100) surface is found to be blocked by Co doping. Doped Co ions in Fe3O4 are in a charge state of 2 + and substitute the Fe2+ in the B site of Fe3O4. All the films exhibit room temperature ferromagnetism. Co doping changes the coercivity and reduces saturation magnetization. The density of states near the Fermi level is reduced by Co doping due to the decrease of Fe2+ in the B site, which might responsible for the decrease in conductivity and magnetoresistance of Co-doped Fe3O4. The Verwey transition in the range of 100-120 K is observed for the pure Fe3O4 film, while no transition could be detected for Co-doped Fe3O4 films.

  1. Preparation of stable magnetic nanofluids containing Fe3O4@PPy nanoparticles by a novel one-pot route

    PubMed Central

    2011-01-01

    Stable magnetic nanofluids containing Fe3O4@Polypyrrole (PPy) nanoparticles (NPs) were prepared by using a facile and novel method, in which one-pot route was used. FeCl3·6H2O was applied as the iron source, and the oxidizing agent to produce PPy. Trisodium citrate (Na3cit) was used as the reducing reagent to form Fe3O4 NPs. The as-prepared nanofluid can keep long-term stability. The Fe3O4@PPy NPs can still keep dispersing well after the nanofluid has been standing for 1 month and no sedimentation is found. The polymerization reaction of the pyrrole monomers took place with Fe3+ ions as the initiator, in which these Fe3+ ions remained in the solution adsorbed on the surface of the Fe3O4 NPs. Thus, the core-shell NPs of Fe3O4@PPy were obtained. The particle size of the as-prepared Fe3O4@PPy can be easily controlled from 7 to 30 nm by the polymerization reaction of the pyrrole monomers. The steric stabilization and weight of the NPs affect the stability of the nanofluids. The as-prepared Fe3O4@PPy NPs exhibit superparamagnetic behavior. PMID:21711771

  2. Facile synthesis of FeCo/Fe3O4 nanocomposite with high wave-absorbing properties.

    PubMed

    Gu, Yu; Cao, Yang; Chi, Huijuan; Liang, Qing; Zhang, Yongji; Sun, Youyi

    2013-01-01

    The FeCo/Fe3O4 nanocomposite was synthesized using the hydrothermal approach, in which the FeCo alloy and Fe3O4 are formed by one step. The structure of the FeCo/Fe3O4 nanocomposite was characterized by means of Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy-dispersive spectrometer spectroscopy (EDX). They show that the mass ratio of FeCo/Fe3O4 strongly depends on the reaction temperature. Such various architectures follow a stepwise growth mechanism of the composites prepared in various reaction temperatures were also discussed. It indicates that this strategy is facile, effective and controllable for the synthesis of FeCo/Fe3O4 by the one-step method. Furthermore, the magnetic and wave-absorbing properties of the nanocomposites with various structures were investigated in detail. The results show that the FeCo/Fe3O4 with higher mass ratio has higher magnetic properties. Moreover, the FeCo/Fe3O4 nanocomposite shows high wave-absorbing properties (e.g., -37.9 dB), which are expected to apply in microwave absorbing materials. PMID:23839091

  3. Facile Synthesis of FeCo/Fe3O4 Nanocomposite with High Wave-Absorbing Properties

    PubMed Central

    Gu, Yu; Cao, Yang; Chi, Huijuan; Liang, Qing; Zhang, Yongji; Sun, Youyi

    2013-01-01

    The FeCo/Fe3O4 nanocomposite was synthesized using the hydrothermal approach, in which the FeCo alloy and Fe3O4 are formed by one step. The structure of the FeCo/Fe3O4 nanocomposite was characterized by means of Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy-dispersive spectrometer spectroscopy (EDX). They show that the mass ratio of FeCo/Fe3O4 strongly depends on the reaction temperature. Such various architectures follow a stepwise growth mechanism of the composites prepared in various reaction temperatures were also discussed. It indicates that this strategy is facile, effective and controllable for the synthesis of FeCo/Fe3O4 by the one-step method. Furthermore, the magnetic and wave-absorbing properties of the nanocomposites with various structures were investigated in detail. The results show that the FeCo/Fe3O4 with higher mass ratio has higher magnetic properties. Moreover, the FeCo/Fe3O4 nanocomposite shows high wave-absorbing properties (e.g., −37.9 dB), which are expected to apply in microwave absorbing materials. PMID:23839091

  4. In situ anchor of magnetic Fe3O4 nanoparticles onto natural maifanite as efficient heterogeneous Fenton-like catalyst

    NASA Astrophysics Data System (ADS)

    Zhao, Hang; Weng, Ling; Cui, Wei-Wei; Zhang, Xiao-Rui; Xu, Huan-Yan; Liu, Li-Zhu

    2016-06-01

    In situ anchor of magnetic Fe3O4 nanoparticles (NPs) onto the surface of natural maifanite was realized by chemical oxidation coprecipitation in hot alkaline solution. The Fe3O4/maifanite composites were characterized by XRD, FTIR, SEM, and TEM. These results indicated that polycrystalline Fe3O4 NPs with inverse spinel structure were formed and tightly dispersed on maifanite surface. Based on the measurement of surface Zeta potential of maifanite at different medium pHs, the possible combination mechanism between natural maifanite and Fe3O4 NPs was proposed. Then, the asobtained composites were developed as highly efficient heterogeneous Fenton-like catalyst for the discoloration of an azo dye, Methyl Orange (MO). The comparative tests on MO discoloration in different systems revealed that Fe3O4/maifanite composite exhibited much higher Fenton-like catalytic activity than Fe3O4 NPs and the heterogeneous Fentonlike reaction governed the discoloration of MO. Kinetic results clearly showed that MO discoloration process followed the second-order kinetic model. Fe3O4/maifanite composites exhibited the typical ferromagnetic property detected by VSM and could be easily separated from solution by an external magnetic field.

  5. In situ anchor of magnetic Fe3O4 nanoparticles onto natural maifanite as efficient heterogeneous Fenton-like catalyst

    NASA Astrophysics Data System (ADS)

    Zhao, Hang; Weng, Ling; Cui, Wei-Wei; Zhang, Xiao-Rui; Xu, Huan-Yan; Liu, Li-Zhu

    2016-09-01

    In situ anchor of magnetic Fe3O4 nanoparticles (NPs) onto the surface of natural maifanite was realized by chemical oxidation coprecipitation in hot alkaline solution. The Fe3O4/maifanite composites were characterized by XRD, FTIR, SEM, and TEM. These results indicated that polycrystalline Fe3O4 NPs with inverse spinel structure were formed and tightly dispersed on maifanite surface. Based on the measurement of surface Zeta potential of maifanite at different medium pHs, the possible combination mechanism between natural maifanite and Fe3O4 NPs was proposed. Then, the asobtained composites were developed as highly efficient heterogeneous Fenton-like catalyst for the discoloration of an azo dye, Methyl Orange (MO). The comparative tests on MO discoloration in different systems revealed that Fe3O4/maifanite composite exhibited much higher Fenton-like catalytic activity than Fe3O4 NPs and the heterogeneous Fentonlike reaction governed the discoloration of MO. Kinetic results clearly showed that MO discoloration process followed the second-order kinetic model. Fe3O4/maifanite composites exhibited the typical ferromagnetic property detected by VSM and could be easily separated from solution by an external magnetic field.

  6. One-step solvothermal synthesis of magnetic Fe3O4-graphite composite for Fenton-like degradation of levofloxacin.

    PubMed

    Wang, Long; Zhao, Qi; Hou, Juan; Yan, Jin; Zhang, Fengshuang; Zhao, Jiahui; Ding, Hong; Li, Yi; Ding, Lan

    2016-01-01

    A novel Fe3O4-graphite composite was prepared, characterized, and investigated as a heterogeneous Fenton-like catalyst for the degradation of levofloxacin (LEV) in an aqueous solution. The results revealed that the Fe3O4-graphite composite exhibited excellent properties for the degradation and mineralization of LEV, achieving a nearly complete degradation of 50 mg L(-1) LEV in 15 min and 48% of total organic carbon removal in 60 min under optimal conditions. A large electronic conjugation structure exists in graphite, which may lead to the fast production of •OH radical species because of the easy reduction of Fe(III) to Fe(II). In addition, we observed that the graphite can degrade LEV in the presence of H2O2. Therefore, the synergistic results of the graphite structure and Fe3O4 magnetic nanoparticles (MNPs) may contribute to the high catalytic activity of the Fe3O4-graphite composite. Compared with pure Fe3O4 MNPs, lesser iron leaching of the Fe3O4-graphite composite was observed during the degradation of LEV. The degradation efficiency of LEV remained approximately 80% at the fifth recycling run, which indicates that the Fe3O4-graphite composite has potential applications in water treatment for removing organic pollutants. PMID:26513011

  7. Graphene-encapsulated Fe3O4 nanoparticles with 3D laminated structure as superior anode in lithium ion batteries.

    PubMed

    Wang, Jia-Zhao; Zhong, Chao; Wexler, David; Idris, Nurul Hayati; Wang, Zhao-Xiang; Chen, Li-Quan; Liu, Hua-Kun

    2011-01-10

    Fe(3)O(4)-graphene composites with three-dimensional laminated structures have been synthesised by a simple in situ hydrothermal method. From field-emission and transmission electron microscopy results, the Fe(3)O(4) nanoparticles, around 3-15 nm in size, are highly encapsulated in a graphene nanosheet matrix. The reversible Li-cycling properties of Fe(3)O(4)-graphene have been evaluated by galvanostatic discharge-charge cycling, cyclic voltammetry and impedance spectroscopy. Results show that the Fe(3)O(4)-graphene nanocomposite with a graphene content of 38.0 wt % exhibits a stable capacity of about 650 mAh  g(-1) with no noticeable fading for up to 100 cycles in the voltage range of 0.0-3.0 V. The superior performance of Fe(3)O(4)-graphene is clearly established by comparison of the results with those from bare Fe(3)O(4). The graphene nanosheets in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe(3)O(4). PMID:21207587

  8. Gel-limited synthesis of dumbbell-like Fe3O4-Ag composite microspheres and their SERS applications.

    PubMed

    Zhang, Xiaoli; Niu, Chunyu; Wang, Yongqiang; Zhou, Shaomin; Liu, Jin

    2014-11-01

    A novel gel-limited strategy was developed to synthesize dumbbell-like Fe3O4-Ag composite microspheres through a simple one-pot solvothermal method. In such a reaction system, a special precursor solution containing oleic, water, ethanol and silver ions was used and transformed into a bulk gel under heating at the very beginning of the reaction, thus all the subsequent reactions proceeded in the interior of the gel. The gel-limited reactions had two advantages, on the one hand, the magnetic Fe3O4 microspheres were fixed in the gel which avoided them aggregating together, whereas on the other hand, the silver ions stored in the gel could be gradually released and tended to diffuse towards the nearest Fe3O4 microsphere, which favored the generation of a dumbbell-like Fe3O4-Ag structure. From the time-dependent experiments under optimal conditions, the typical growth process of dumbbell-like structures clearly demonstrated that a silver seed first appeared on the surface of a single Fe3O4 microsphere, which then grew bigger slowly and finally formed a dumbbell-like Fe3O4-Ag structure. Moreover, the formation of the gel was found to be strongly affected by the ratio of water and ethanol in the precursor solution, which further influenced the morphologies of the Fe3O4-Ag microspheres. Furthermore, the effect of lattice match between Fe3O4 and Ag on the final products was also proven from the control experiments by using a template with a different surface crystalline structure. When used as SERS substrates, the final dumbbell-like Fe3O4-Ag microspheres show fast magnetic separation and the selective detection of thiram for the surface capped oleic chain during the growth process. PMID:25188029

  9. The investigation of the electrical properties of Fe3O4/n-Si heterojunctions in a wide temperature range.

    PubMed

    Deniz, Ali Rıza; Çaldıran, Zakir; Metin, Önder; Meral, Kadem; Aydoğan, Şakir

    2016-07-01

    Monodisperse 8nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16eV. Au circle contacts with 7.85×10(-3)cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5)Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature-dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of Au/Fe3O4/n-Si/Al device was calculated to be 2.17A/K(2)cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction. PMID:27078739

  10. Self-assembly of Fe 3 O 4 nanocrystal-clusters into cauliflower-like architectures: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Zhu, Lu-Ping; Liao, Gui-Hong; Bing, Nai-Ci; Wang, Lin-Lin; Xie, Hong-Yong

    2011-09-01

    Large-scale cauliflower-like Fe 3O 4 architectures consist of well-assembled magnetite nanocrystal clusters have been synthesized by a simple solvothermal process. The as-synthesized Fe 3O 4 samples were characterized by XRD, XPS, FT-IR, SEM, TEM, etc. The results show that the samples exhibit cauliflower-like hierarchical microstructures. The influences of synthesis parameters on the morphology of the samples were experimentally investigated. Magnetic properties of the Fe 3O 4 cauliflower-like hierarchical microstructures have been detected by VSM at room temperature, showing a relatively low saturation magnetization of 65 emu/g and an enhanced coercive force of 247 Oe.

  11. Biosurfactant assisted synthesis of Fe3O4@rhamnolipid@BiOBr and its behaviour in plasma discharge system

    NASA Astrophysics Data System (ADS)

    Wang, Li; Yu, Zebin; Hou, Yanping; Peng, Zhenbo; Zhang, Li; Meng, Zhengcheng; Li, Fengyuan; He, Jun; Huang, Junlin

    2016-06-01

    A novel Fe3O4@rhamnolipid@BiOBr (FRB) was synthesized via a modified precipitation method and applied in the plasma discharge system. Rhamnolipid was used as biosurfactant to modify Fe3O4 by interacting with Fe3O4 via its aliphatic chain. The results show that the prepared FRB magnetic photocatalyst exhibited excellent photocatalytic activity and Fenton reaction behavior in the plasma discharge system. Meanwhile, the addition of FRB could improve energy efficiency of defluorination by 21.29 mg kW‑1 h‑1.

  12. Fe3O4/CuO/ZnO/Nano graphene platelets (Fe3O4/CuO/ZnO/NGP) composites prepared by sol-gel method with enhanced sonocatalytic activity for the removal of dye

    NASA Astrophysics Data System (ADS)

    Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    In this study, an attempt has been made to synthesize nanographene platelets coupled with Fe3O4/CuO/ZnO (Fe3O4/CuO/ZnO/NGP) with various ZnO loadings using a two step methods, sol-gel followed by hydrothermal method. Characterization was carried out by X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer. The sonocatalytic performance was evaluated by degradation of methylene blue under ultrasonic irradiation.The Fe3O4/CuO/ZnO/NGP showed superior sonocatalytic activity than the Fe3O4/CuO/ZnO materials. They also showed high stability and can be easily separated from the reaction system for recycling process.

  13. Effect of annealing temperature on magnetic phase transition in Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Jafari, A.; Farjami Shayesteh, S.; Salouti, M.; Boustani, K.

    2015-04-01

    Fe3O4 (magnetite) nanoparticles (NPs) were synthesized using a co-precipitation method, and then annealed at various temperatures between 50 and 850 °C for 1 h in air. After annealing, the NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM). The FTIR and XRD results indicated that Fe3O4 NPs were converted to γ-Fe2O3 (maghemite) by annealing at 250 °C for 1 h and then to α-Fe2O3 (hematite) on annealing in the range of 550-650 °C. The average crystallite size of the NPs estimated by the Debye-Scherrer equation increased from 6.6 to 37.6 nm by increasing annealing temperature from 50 to 850 °C. According to VSM results, the magnetite NPs were superparamagnetic and converted to the maghemite with superparamagnetic phase by annealing up to 550 °C. A phase transition from soft to hard ferromagnetic was occurred at annealing temperature 650 and 850 °C, respectively °C. This phase transition was attributed to the conversion of magnetite to hematite. The VSM analysis confirmed the XRD and FTIR results. The saturation magnetization (Ms) of Fe3O4 NPs was increased from 41.69 to 53.61 emu/g by increasing annealing temperature from 50 to 550 °C, and then decreased intensively to 0.49 emu/g after annealing at 850 °C. By increasing annealing temperature from 50 to 550, the crystallite size of NPs was increased from 6.6 to 12.7 and the coercive force (Hc) was reached to 4.20 Oe after annealing at 550 °C and then intensively increased to 1459.02 Oe for any further increasing of particle size up to 850 °C.

  14. Preparation of multi-functionalized Fe3O4/Au nanoparticles for medical purposes.

    PubMed

    del Mar Ramos-Tejada, María; Viota, Julian L; Rudzka, Katarzyna; Delgado, Angel V

    2015-04-01

    In this work, we investigate a route towards the synthesis of multi-functionalized nanoparticles for medical purposes. The aim is to produce magnetite/gold (Fe3O4/Au) nanoparticles combining several complementary properties, specifically, being able to carry simultaneously an antitumor drug and a selected antibody chosen so as to improve specificity of the drug vehicle. The procedure included, firstly, the preparation of Fe3O4 cores coated with Au nanoparticles: this was achieved by using initially the layer-by-layer technique in order to coat the magnetite particles with a three polyelectrolyte (cationic-anionic-cationic) layer. With this, the particles became a good substrate for the growth of the gold layer in a well-defined core-shell structure. The resulting nanoparticles benefit from the magnetic properties of the magnetite and the robust chemistry and the biostability of gold surfaces. Subsequently, the Fe3O4/Au nanoparticles were functionalized with a humanized monoclonal antibody, bevacizumab, and a chemotherapy drug, doxorubicin. Taken together, bevacizumab enhances the therapeutic effect of chemotherapy agents on some kinds of tumors. In this work we first discuss the morphology of the particles and the electrical characteristics of their surface in the successive synthesis stages. Special attention is paid to the chemical stability of the final coating, and the physical stability of the suspensions of the nanoparticles in aqueous solutions and phosphate buffer. We describe how optical absorbance and electrokinetic data provide a follow up of the progress of the nanostructure formation. Additionally, the same techniques are employed to demonstrate that the composite nanoparticles are capable of loading/releasing doxorubicin and/or bevacizumab. PMID:25710633

  15. High coverage hydrogen adsorption on the Fe3O4(1 1 0) surface

    NASA Astrophysics Data System (ADS)

    Yu, Xiaohu; Zhang, Xuemei; Wang, Shengguang

    2015-10-01

    Hydrogen adsorption on the A and B termination layers of the Fe3O4(1 1 0) surface at different coverage has been systematically studied by density functional theory calculations including an on-site Hubbard term (GGA + U). The adsorption of hydrogen prefers surface oxygen atoms on both layers. The more stable A layer has stronger adsorption energy than the less stable B layer. The saturation coverage has two dissociatively adsorbed H2 on the A layer, and one dissociatively adsorbed H2 on the B layer. The adsorption mechanism has been analyzed on the basis of projected density of states (PDOS).

  16. Fe3O4(110)-(1 × 3) revisited: Periodic (111) nanofacets

    NASA Astrophysics Data System (ADS)

    Parkinson, Gareth S.; Lackner, Peter; Gamba, Oscar; Maaß, Sebastian; Gerhold, Stefan; Riva, Michele; Bliem, Roland; Diebold, Ulrike; Schmid, Michael

    2016-07-01

    The structure of the Fe3O4(110)-(1 × 3) surface was studied with scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and reflection high-energy electron diffraction (RHEED). The so-called one-dimensional reconstruction is characterized by bright rows that extend hundreds of nanometers in the [ 1 bar10] direction and have a periodicity of 2.52 nm in [001] in STM. It is concluded that this reconstruction is the result of a periodic faceting to expose {111}-type planes with a lower surface energy.

  17. Exchange spring magnetic behavior in BaFe12O19/Fe3O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Remya, K. P.; Prabhu, D.; Amirthapandian, S.; Viswanathan, C.; Ponpandian, N.

    2016-05-01

    We report the investigation on exchange spring coupling behavior of BaFe12O19/Fe3O4 nanocomposite synthesized by simple mixing followed by heat treatment of individual ferrites. Morphologically tuned, well crystalline hard and soft ferrites were synthesized by simple chemical method and the phase composition, crystallinity, surface morphology and magnetic properties of the as prepared ferrites as well as the nanocomposites were studied by using XRD, FESEM and VSM respectively. Exchange coupling behavior is observed in the nanocomposite samples heated at 600 °C with simultaneous enhancements of (BH)max and remanence.

  18. Folate-conjugated luminescent Fe3O4 nanoparticles for magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

    Barick, K. C.; Rana, Suman; Hassan, P. A.

    2014-04-01

    We demonstrate a facile approach for the synthesis of folate-conjugated luminescent iron oxide nanoparticles (FLIONs). XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. The conjugation of folate receptor (folic acid, FA) and luminescent molecule (fluorescein isothiocyanate, FITC) onto the surface of nanoparticles was evident from FTIR and UV-visible spectroscopy. These FLIONs show good colloidal stability, high magnetic field responsivity and excellent self-heating efficacy. Specifically, a new class of magnetic nanoparticles has been fabricated, which can be used as an effective heating source for hyperthermia.

  19. Magnetic hyperthermia in brick-like Ag@Fe3O4 core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Brollo, M. E. F.; Orozco-Henao, J. M.; López-Ruiz, R.; Muraca, D.; Dias, C. S. B.; Pirota, K. R.; Knobel, M.

    2016-01-01

    Heating efficiency of multifunctional Ag@Fe3O4 brick-like nanoparticles under alternating magnetic field was investigated by means of specific absorption rate (SAR) measurements, and compared with equivalent measurements for plain magnetite and dimer heteroparticles. The samples were synthesized by thermal decomposition reactions and present narrow size polydispersity and high degree of crystallinity. The SAR values are analyzed using the superparamagnetic theory, in which the basic morphology, size and dispersion of sizes play key roles. The results suggest that these novel brick-like nanoparticles are good candidates for hyperthermia applications, displaying heating efficiencies comparable with the most efficient plain nanoparticles.

  20. Recent advances in the synthesis of Fe3O4@AU core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Salihov, Sergei V.; Ivanenkov, Yan A.; Krechetov, Sergei P.; Veselov, Mark S.; Sviridenkova, Natalia V.; Savchenko, Alexander G.; Klyachko, Natalya L.; Golovin, Yury I.; Chufarova, Nina V.; Beloglazkina, Elena K.; Majouga, Alexander G.

    2015-11-01

    Fe3O4@Au core/shell nanoparticles have unique magnetic and optical properties. These nanoparticles are used for biomedical applications, such as magnetic resonance imaging, photothermal therapy, controlled drug delivery, protein separation, biosensors, DNA detection, and immunosensors. In this review, recent methods for the synthesis of core/shell nanoparticles are discussed. We divided all of the synthetic methods in two groups: methods of synthesis of bi-layer structures and methods of synthesis of multilayer composite structures. The latter methods have a layer of "glue" material between the core and the shell.

  1. Grape-Like Fe3O4 Agglomerates Grown on Graphene Nanosheets for Ultrafast and Stable Lithium Storage.

    PubMed

    Qi, Liya; Xin, Yuelong; Zuo, Zicheng; Yang, Chengkai; Wu, Kai; Wu, Bin; Zhou, Henghui

    2016-07-13

    An in situ simple and effective synthesis method is effectively exploited to construct MOF-derived grape-like architecture anchoring on nitrogen-doped graphene, in which ultrafine Fe3O4 nanoparticles are uniformly dispersed (Fe3O4@C/NG). In this hybrid hierarchical structure, new synergistic features are accessed. The graphene oxide plane with functional groups is expected to alleviate the aggregation problem in the MOFs' growth. Moreover, the morphology and size of iron-based MOFs and carbon content are conveniently controlled by controlling the solution concentration of precursor. Through making use of in situ carbonization of the organic ligands in MOFs, Fe3O4 subunits are effectively protected by 3D interconnected conductive carbon at microscale. Consequently, when applied as anode materials, even as high as 10 A g(-1) after 1000 cycles, Fe3O4@C/NG still maintains as high as 458 mA h g(-1). PMID:27311737

  2. The role of Fe3O4 nanocrystal film in bilayer-heterojunction CuPc/C60 solar cells.

    PubMed

    Meng, Fanxu; Tao, Chen; Wang, Yongfan; Shen, Liang; Guo, Wenbin; Chen, Yu; Ruan, Shengping

    2014-05-01

    The CuPc/C60 thin-film bilayer-heterojunction solar cells are fabricated by vacuum deposition with bathocuproine (BCP) as the exciton-blocking layer. Ferroferric oxide (Fe3O4) nanocrystal film is inserted between the copper phthalocaynine (CuPc) layer and indium tin oxide (ITO) anode. The device performances dependent on the thickness of Fe3O4 are investigated and compared. The results show that both the short-circuit current density and fill factor are enhanced by introducing a 1 nm Fe3O4 buffer layer, leading to an increase of power conversion efficiency. The role of Fe3O4 as a buffer layer in the improvement of the device performances is studied in detail by ultraviolet photoemission spectroscopy (UPS). PMID:24734601

  3. Sonocatalytic Methylene Blue in The Presence of Fe3O4-CuO-TiO2 Nanocomposites Heterostructure

    NASA Astrophysics Data System (ADS)

    Fauzian, Malleo; Jalaludin, Shofianina; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    In this work, the emphasis was mainly placed on investigating the sonocatalytic activity of Fe3O4-CuO-TiO2 nanocomposites heterostructure. The prepared samples were characterized by X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM), Brunauer-Emmett-Teller (BET) Surface Area Analysis. Methylene blue dye was selected to examine the sonocatalytic activity of Fe3O4-CuO-TiO2 nanocomposites heterostructure. The degradation reaction processes were monitored by UV-vis spectrophotometer. The influence on the activity of the Fe3O4-CuO-TiO2 nanocomposites heterostructure such as TiO2 loading was studied. The sonocatalyst Fe3O4-CuO-TiO2 with molar ratio of 1:1:5 showed the highest sonocatalytic activity. At last, the experiment also indicated that holes are the main reactive species in the photodegradation mechanism in methylene blue.

  4. Synthesis and electromagnetic, microwave absorbing properties of core-shell Fe3O4-poly(3, 4-ethylenedioxythiophene) microspheres.

    PubMed

    Zhou, Wencai; Hu, Xiujie; Bai, Xiaoxia; Zhou, Shuyun; Sun, Chenghua; Yan, Jun; Chen, Ping

    2011-10-01

    Highly regulated core-shell Fe(3)O(4)-poly(3, 4-ethylenedioxythiophene) (PEDOT) microspheres were successfully synthesized by a two-step method in the presence of polyvinyl alcohol (PVA) and p-toluenesulfonic acid (p-TSA). And their morphology, microstructure, electromagnetic and microwave absorbing properties were subsequently characterized. By simply adjusting the molar ratio of 3, 4-ethylenedioxythiophene (EDOT) to Fe(3)O(4) (represented by (EDOT)/(Fe(3)O(4))), the thickness of the polymer shell can be tuned from tens to hundreds of nanometers. Moreover, it was found that the composite exhibited excellent microwave absorbing property with a minimum reflection loss (RL) of about -30 dB at 9.5 GHz with a (EDOT)/(Fe(3)O(4)) ratio of 20. PMID:21913665

  5. Synthesis of Fe3O4-graphene-TiO2 ternary composite networks for enhanced capture of phosphopeptides.

    PubMed

    Min, Qianhao; Zhang, Xiaoxia; Zhang, Hongyi; Zhou, Fang; Zhu, Jun-Jie

    2011-11-14

    Fe(3)O(4)-graphene-TiO(2) ternary composite networks were first synthesized, which exhibited high selectivity and capacity in the capture of phosphopeptides, due to the enhanced contact to phosphopeptides given by the graphene scaffold. PMID:21952172

  6. Effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles.

    PubMed

    Larumbe, S; Gómez-Polo, C; Pérez-Landazábal, J I; Pastor, J M

    2012-07-01

    In this work the effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles obtained by the sol-gel method is analyzed. Two sets of samples were prepared: Fe3O4 nanoparticles and Fe3O4@SiO2 core-shell composites. The samples display the characteristic spinel structure associated with the magnetite Fe3O4 phase, with the majority of grain sizes around 5-10 nm. At room temperature the nanoparticles show the characteristic superparamagnetic behavior with mean blocking temperatures around 160 and 120 K for Fe3O4 and Fe3O4@SiO2, respectively. The main effect of the SiO2 coating is reflected in the temperature dependence of the high field magnetization (μ(0)H = 6 T), i.e. deviations from the Bloch law at low temperatures (T < 20 K). Such deviations, enhanced by the introduction of the SiO2 coating, are associated with the occurrence of surface spin disordered effects. The induction heating effects (magnetic hyperthermia) are analyzed under the application of an AC magnetic field. Maximum specific absorption rate (SAR) values around 1.5 W g(-1) were achieved for the Fe3O4 nanoparticles. A significant decrease (around 26%) is found in the SAR values of the SiO2 coated nanocomposite. The different heating response is analyzed in terms of the decrease of the effective nanoparticle magnetization in the Fe3O4@SiO2 core-shell composites at room temperature. PMID:22700683

  7. Colorimetric aptasensing of ochratoxin A using Au@Fe3O4 nanoparticles as signal indicator and magnetic separator.

    PubMed

    Wang, Chengquan; Qian, Jing; Wang, Kun; Yang, Xingwang; Liu, Qian; Hao, Nan; Wang, Chengke; Dong, Xiaoya; Huang, Xingyi

    2016-03-15

    Gold nanoparticles (Au NPs) doped Fe3O4 (Au@Fe3O4) NPs have been synthesized by a facile one-step solvothermal method. The peroxidase-like activity of Au@Fe3O4 NPs was effectively enhanced due to the synergistic effect between the Fe3O4 NPs and Au NPs. On this basis, an efficient colorimetric aptasensor has been developed using the intrinsic dual functionality of the Au@Fe3O4 NPs as signal indicator and magnetic separator. Initially, the amino-modified aptamer specific for a typical mycotoxin, ochratoxin A (OTA), was surface confined on the amino-terminated glass beads surafce using glutaraldehyde as a linker. Subsequently, the amino-modified capture DNA (cDNA) was labeled with the amino-functionalized Au@Fe3O4 NPs and the aptasensor was thus fabricated through the hybridization reaction between cDNA and the aptamers. While upon OTA addition, aptamers preferred to form the OTA-aptamer complex and the Au@Fe3O4 NPs linked on the cDNA were released into the bulk solution. Through a simple magnetic separation, the collected Au@Fe3O4 NPs can produce a blue colored solution in the presence of 3,3',5,5'-tetramethylbenzidine and H2O2. When the reaction was terminated by addition of H(+) ions, the blue product could be changed into a yellow one with higher absorption intensity. This colorimetric aptasensor can detect as low as 30 pgmL(-1) OTA with high specificity. To the best of our knowledge, the present colorimetric aptasensor is the first attempt to use the peroxidase-like activity of nanomaterial for OTA detection, which may provide an acttractive path toward routine quality control of food safety. PMID:26583358

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

    PubMed

    Liu, Yue-Wen; Guan, Meng-Xue; Feng, Lan; Deng, Shun-Liu; Bao, Jian-Feng; Xie, Su-Yuan; Chen, Zhong; Huang, Rong-Bin; Zheng, Lan-Sun

    2013-01-18

    A superparamagnetic reduced graphene oxide-Fe(3)O(4) hybrid composite (rGO-Fe(3)O(4)) 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 Fe(3)O(4) nanoparticles (NPs) can be achieved in one step. The Fe(3)O(4) NPs are firmly deposited on the surfaces of rGO, avoiding their reassembly to graphite. The rGO sheets prevent the agglomeration of Fe(3)O(4) NPs and enable a uniform dispersion of these metal oxide particles. The size distribution and coverage density of Fe(3)O(4) 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 Fe(3)O(4) NPs with an average size of 19.9 nm. The magnetic-functionalized rGO hybrid exhibits a good magnetic property and the specific saturation magnetization (M(s)) is 13.2 emu g(-1). The adsorption test of methylene blue from aqueous solution demonstrates the potential application of this rGO-Fe(3)O(4) hybrid composite in removing organic dyes from polluted water. PMID:23220906

  9. Beta-cyclodextrins conjugated magnetic Fe3O4 colloidal nanoclusters for the loading and release of hydrophobic molecule

    NASA Astrophysics Data System (ADS)

    Lv, Shaonan; Song, Yubei; Song, Yaya; Zhao, Zhigang; Cheng, Changjing

    2014-06-01

    Herein, we report a facile method to prepare beta-cyclodextrin (β-CD)-conjugated magnetic Fe3O4 colloidal nanocrystal clusters (Fe3O4@GLY-CD) using (3-glycidyloxypropyl) trimethoxysilane (GLY) as the intermediate linker. The resulting Fe3O4@GLY-CD was characterized by several methods including Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). In addition, the loading and release properties of the synthesized Fe3O4@GLY-CD for the hydrophobic molecule 8-anilino-1-naphthalenesulfonic acid ammonium salt (ANS) were also investigated. The results show that the Fe3O4@GLY-CD has a spherical structure with an average diameter of 186 nm and high saturated magnetism of 51.2 emu/g. The grafting of β-CD onto Fe3O4 colloidal nanocrystal clusters can markedly increase the loading capacity of ANS because of β-CD/ANS inclusion complex formation. The in vitro delivery profile shows that the release of ANS from the Fe3O4@GLY-CD nanosystem exhibits an initial burst followed by a slow and steady release. Moreover, Fe3O4@GLY-CD also demonstrates a temperature-dependent release behavior for ANS owing to the effect of temperature on the association constants of β-CD/ANS inclusion complexes. The developed magnetic hybrid nanomaterial is expected to find potential applications in several fields including separation science and biomedicine.

  10. 2, 2'-(phenylazanediyl) diacetic acid modified Fe3O4@PEI for selective removal of cadmium ions from blood

    NASA Astrophysics Data System (ADS)

    Jin, Jun; Yang, Fang; Zhang, Fengwei; Hu, Wuquan; Sun, Shao-Bo; Ma, Jiantai

    2012-01-01

    A water-dispersible and supermagnetic nanocomposite (PAD-PEG-Fe3O4@PEI) has been successfully synthesized using polyethylenimine (PEI, Mol MW = 10000) coated supermagnetic Fe3O4-NH2 which was modified with 2, 2'-(phenylazanediyl) diacetic acid (PAD) through the bridge of poly(ethylene glycol) (PEG, Mol MW = 2000). The average particle size of PAD-PEG-Fe3O4@PEI was determined by TEM, and was about 50 nm. From magnetic hysteresis cycles for PAD-PEG-Fe3O4@PEI at room temperature, the saturation magnetization (Ms) was shown to be 58.14 emu g-1. Inductively coupled plasma spectrometry (ICP) analysis showed that the designed magnetic nanocomposite can remove 98% and 80% of Cd2+ from water and blood, respectively.A water-dispersible and supermagnetic nanocomposite (PAD-PEG-Fe3O4@PEI) has been successfully synthesized using polyethylenimine (PEI, Mol MW = 10000) coated supermagnetic Fe3O4-NH2 which was modified with 2, 2'-(phenylazanediyl) diacetic acid (PAD) through the bridge of poly(ethylene glycol) (PEG, Mol MW = 2000). The average particle size of PAD-PEG-Fe3O4@PEI was determined by TEM, and was about 50 nm. From magnetic hysteresis cycles for PAD-PEG-Fe3O4@PEI at room temperature, the saturation magnetization (Ms) was shown to be 58.14 emu g-1. Inductively coupled plasma spectrometry (ICP) analysis showed that the designed magnetic nanocomposite can remove 98% and 80% of Cd2+ from water and blood, respectively. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11481j

  11. Electron Localization in Fe3 O4 : an Ab Initio Wannier Study

    NASA Astrophysics Data System (ADS)

    Sakkaris, Perry; Boekema, Carel

    2014-03-01

    Magnetite, Fe3O4 , is an unusual ferrimagnetic oxide with emergent physical properties that are not yet fully understood. Among these are the metal-insulator transition at the Verwey Temperature TV (123K) and a spin-glass-like transition at about twice TV. The ``extra'' fully spin-polarized 3d electrons that span the t2 g bands of the B sublattice show strong electron correlation effects and are mainly responsible for conduction above TV. We perform a DFT+U calculation to obtain a set of Bloch orbitals describing the t2 g bands. We then use the gauge invariance of Wannier functions to transform the Bloch orbitals into a set of Maximally Localized Wannier Functions (MLWFs). The MLWFs are a real space description of the ``extra'' 3d electrons allowing us to describe their spatial localization and determine the mechanism of conduction above TV. Wannier studies of Fe3O4 may also allow us to determine the extent of electronic coupling to lattice vibrations, which may provide us substantial quantitative clues on the physical mechanism of the Verwey Transition. Research is supported by AFC San Jose.

  12. Core-shell-corona doxorubicin-loaded superparamagnetic Fe3O4 nanoparticles for cancer theranostics.

    PubMed

    Semkina, A; Abakumov, M; Grinenko, N; Abakumov, A; Skorikov, A; Mironova, E; Davydova, G; Majouga, A G; Nukolova, N; Kabanov, A; Chekhonin, V

    2015-12-01

    Superparamagnetic iron oxide magnetic nanoparticles (MNPs) are successfully used as contrast agents in magnetic-resonance imaging. They can be easily functionalized for drug delivery functions, demonstrating great potential for both imaging and therapeutic applications. Here we developed new pH-responsive theranostic core-shell-corona nanoparticles consisting of superparamagentic Fe3O4 core that displays high T2 relaxivity, bovine serum albumin (BSA) shell that binds anticancer drug, doxorubicin (Dox) and poly(ethylene glycol) (PEG) corona that increases stability and biocompatibility. The nanoparticles were produced by adsorption of the BSA shell onto the Fe3O4 core followed by crosslinking of the protein layer and subsequent grafting of the PEG corona using monoamino-terminated PEG via carbodiimide chemistry. The hydrodynamic diameter, zeta-potential, composition and T2 relaxivity of the resulting nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, thermogravimetric analysis and T2-relaxometry. Nanoparticles were shown to absorb Dox molecules, possibly through a combination of electrostatic and hydrophobic interactions. The loading capacity (LC) of the nanoparticles was 8 wt.%. The Dox loaded nanoparticles release the drug at a higher rate at pH 5.5 compared to pH 7.4 and display similar cytotoxicity against C6 and HEK293 cells as the free Dox. PMID:26595387

  13. Interface composition between Fe3O4 nanoparticles and GaAs for spintronic applications

    NASA Astrophysics Data System (ADS)

    Hihath, Sahar; Kiehl, Richard A.; Benthem, Klaus van

    2014-08-01

    Recent interest in spintronic applications has necessitated the study of magnetic materials in contact with semiconductor substrates; importantly, the structure and composition of these interfaces can influence both device functionality and the magnetic properties. Nanoscale ferromagnet/semiconductor structures are of particular interest. In this study, the interface structure between a monolayer of ferromagnetic magnetite (Fe3O4) nanoparticles and a GaAs substrate was studied using cross-sectional transmission electron microscopy techniques. It was found that a continuous amorphous oxide interface layer separates the nanoparticles from the GaAs substrate, and that iron diffused into the interface layer forming a compositional gradient. Electron energy-loss near-edge fine structures of the O K absorption edge revealed that the amorphous oxide is composed of γ-Fe2O3 directly underneath the Fe3O4 nanoparticles, followed by a solid solution of Ga2O3 and FeO and mostly Ga2O3 when approaching the buckled oxide/substrate interface. Real-space density functional theory calculations of the dynamical form factor confirmed the experimental observations. The implication of the findings on the optimization of these structures for spin injection is discussed.

  14. Thermodynamic Properties of α-Fe2O3 and Fe3O4 Nanoparticles

    DOE PAGESBeta

    Spencer, Elinor C.; Ross, Nancy L.; Olsen, Rebecca E.; Huang, Baiyu; Kolesnikov, Alexander I.; Woodfield, Brian F.

    2015-04-21

    Here we comprehansively assessed the thermodynamic properties of hydrated α-Fe2O3 (hematite) and Fe3O4 (magnetite) nanoparticles. In addition to 9 nm Fe3O4, three α-e2O3nanoparticles samples of different sizes (11, 14, and 25 nm) and bulk α-e2O3 have been evaluated by inelastic neutron scattering methods. The contribution of the two-level magnetic spin flip transition to the heat capacity of the α-e2O3 particles has been determined. The isochoric heat capacity of the water confined on the surface of these two types of iron oxide particles have been calculated from their INS spectra, and is affected by the chemical composition of the underlying particle.more » Furthermore, the heat capacity and dynamics of the particle hydration layers appear to be influenced by a complex array of factors including particle size, water coverage, and possibly the magnetic state of the particle itself.« less

  15. Preparation of Fe3O4 magnetic nanoparticles coated with gallic acid for drug delivery

    PubMed Central

    Dorniani, Dena; Hussein, Mohd Zobir Bin; Kura, Aminu Umar; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

    2012-01-01

    Background and methods Magnetic iron oxide nanoparticles were prepared using a sonochemical method under atmospheric conditions at a Fe2+ to Fe3+ molar ratio of 1:2. The iron oxide nanoparticles were subsequently coated with chitosan and gallic acid to produce a core-shell structure. Results X-ray diffraction demonstrated that the magnetic nanoparticles were pure Fe3O4 with a cubic inverse spinel structure. Transmission electron microscopy showed that the Fe3O4 nanoparticles were of spherical shape with a mean diameter of 11 nm, compared with 13 nm for the iron oxide-chitosan-gallic acid (FCG) nanocarriers. Conclusion The magnetic nanocarrier enhanced the thermal stability of the drug, gallic acid. Release of the active drug from the FCG nanocarrier was found to occur in a controlled manner. The gallic acid and FCG nanoparticles were not toxic in a normal human fibroblast (3T3) line, and anticancer activity was higher in HT29 than MCF7 cell lines. PMID:23166439

  16. Water dispersible oleic acid-coated Fe3O4 nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Shete, P. B.; Patil, R. M.; Tiwale, B. M.; Pawar, S. H.

    2015-03-01

    Fe3O4 magnetic nanoparticles (MNPs) have proved their tremendous potential to be used for various biomedical applications. Oleic acid (OA) is widely used in ferrite nanoparticle synthesis because it can form a dense protective monolayer, thereby producing highly uniform and monodispersed particles. Capping agents such as oleic acid are often used because they form a protective monolayer, which is strongly bonded to the surface of nanoparticles. This is necessary for making monodisperse and highly uniform MNPs. Coating of Fe3O4 MNPs with OA makes the particles dispersible only in organic solvents and consequently limits their use for biomedical applications. Hence, in this work, the OA coated MNPs were again functionalized with chitosan (CS), in order to impart hydrophilicity on their surface. All the morphological, magnetic, colloidal and cytotoxic characteristics of the resulting core-shells were studied thoroughly. Their heating induction ability was studied to predict their possible use in hyperthermia therapy of cancer. Specific absorption rate was found to be increased than that of bare MNPs.

  17. Synthesis and characterizations of Fe3O4-acid fuchsin tagged poly(ɛ-caprolactone) nanocomposites

    NASA Astrophysics Data System (ADS)

    Meenarathi, Balakrishnan; Kannammal, Lingasamy; Palanikumar, Shanmugavel; Anbarasan, Ramasamy

    2014-04-01

    Ring opening polymerization (ROP) of caprolactone (CL) was carried out at different experimental conditions such as variation in [M], [M/I] and temperature under N2 atmosphere at 160 °C for 2 h with mild stirring condition by using acid fuchsin (AF) decorated Fe3O4 as a novel chemical initiator with the aid of stannous octoate as an effective catalyst. Thus, prepared polymer nano composite samples were characterised by various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), vibrating sample measurement (VSM), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). Presence of Fe2p and Fe3p was confirmed by x-ray photoelectron spectroscopy (XPS) analysis. It was found that while increasing the [M/I] the melt transition values were increased. The surface catalytic effect of Fe3O4/AF hybrid system towards the ROP of CL was also studied.

  18. Preparation Fe3O4@chitosan magnetic particles for covalent immobilization of lipase from Thermomyces lanuginosus.

    PubMed

    Wang, Xiang-Yu; Jiang, Xiao-Ping; Li, Yue; Zeng, Sha; Zhang, Ye-Wang

    2015-04-01

    Magnetic Fe3O4@chitosan nanoparticles were prepared by a simple in situ co-precipitation method and characterized by transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The prepared Fe3O4@chitosan nanoparticles were used for covalent immobilization of lipase from Thermomyces lanuginosus by chemical conjugation after electrostatic entrapment (CCEE). The optimal immobilization conditions were obtained as follows: enzyme/support 19.8 mg/g, pH 5.0, time 4h and temperature 30 °C. Under these conditions, a high immobilization efficiency of 75% and a protein loading of 16.8 mg/g-support were obtained. Broad pH tolerance and high thermostability could be achieved by immobilization. The immobilized lipase retained 70% initial activity after ten cycles. Kinetic parameters Vmax and Km of free and immobilized lipase were determined as 5.72 mM/min, 2.26 mM/min and 21.25 mM, 28.73 mM, respectively. Ascorbyl palmitate synthesis with immobilized lipase was carried out in tert-butanol at 50 °C, and the conversion of ascorbic acid was obtained higher than 50%. These results showed that the immobilization of lipase onto magnetic chitosan nanoparticles by the method of CCEE is an efficient and simple way for preparation of stable lipase. PMID:25603148

  19. Fractal Structures on Fe3O4 Ferrofluid: A Small-Angle Neutron Scattering Study

    NASA Astrophysics Data System (ADS)

    Giri Rachman Putra, Edy; Seong, Baek Seok; Shin, Eunjoo; Ikram, Abarrul; Ani, Sistin Ari; Darminto

    2010-10-01

    A small-angle neutron scattering (SANS) which is a powerful technique to reveal the large scale structures was applied to investigate the fractal structures of water-based Fe3O4ferrofluid, magnetic fluid. The natural magnetite Fe3O4 from iron sand of several rivers in East Java Province of Indonesia was extracted and purified using magnetic separator. Four different ferrofluid concentrations, i.e. 0.5, 1.0, 2.0 and 3.0 Molar (M) were synthesized through a co-precipitation method and then dispersed in tetramethyl ammonium hydroxide (TMAH) as surfactant. The fractal aggregates in ferrofluid samples were observed from their SANS scattering distributions confirming the correlations to their concentrations. The mass fractal dimension changed from about 3 to 2 as ferrofluid concentration increased showing a deviation slope at intermediate scattering vector q range. The size of primary magnetic particle as a building block was determined by fitting the scattering profiles with a log-normal sphere model calculation. The mean average size of those magnetic particles is about 60 - 100 Å in diameter with a particle size distribution σ = 0.5.

  20. Fluorescence and magnetic properties of hydrogels containing Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Alveroğlu, E.; Sözeri, H.; Baykal, A.; Kurtan, U.; Şenel, M.

    2013-04-01

    In this study, Fe3O4 (magnetite) nanoparticles were synthesized by in situ in polyacrylamide (PAAm) gels. Structural and magnetic properties of magnetite nanoparticles were investigated by X-Ray diffractometry (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) methods. Interaction of pyranine molecules with Fe3O4 nanoparticles was investigated by fluorescence spectroscopy measurements in which pyranine (POH) molecules were used as a flouroprobe. It was observed that magnetite nanoparticles have single domain structure with average grain size of 12 nm which was also supported by magnetization measurements. M-H hysteresis curves revealed the superparamagnetic nature of magnetite nanoparticles synthesized in PAAm gels. Fluorescence measurements depicted that there is an interaction between POH and magnetite nanoparticles which was deduced from the presence of two new peaks at 380 nm and 405 nm in emission spectrum. Besides, it was observed that POH molecules could not diffuse into the gel when it consists of magnetite nanoparticles which also make the gel more homogeneous. As swelling ratio increases from 1 to 13, magnetization of the gel does not change which reveals that magnetic nanoparticles do not diffuse out of the gel during water-intake. This feature makes the gel suitable for applications as waste water treatments.

  1. Linear birefringence and dichroism measurement in oil-based Fe3O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Jing-Fung; Wang, Chia-Hung; Lee, Meng-Zhe

    2013-04-01

    To prepare dispersed Fe3O4 magnetic nanoparticles (MNPs), we adopt a co-precipitation method and consider surfactant amount, stirring speed, dispersion mode, and molar ratio of Fe3+/Fe2+. Via transmission electronic microscopy and X-ray diffractometry, we characterize the dispersibility and size of the products and determine the appropriate values of experimental parameters. The stirring speed is 1000 rpm in titration. There is simultaneous ultrasonic vibration and mechanical stirring in the titration and surface coating processes. The surfactant amount of oleic acid is 1.2 ml for molar ratios of Fe3+/Fe2+ as 1.7:1, 1.8:1, and 1.9:1. The average diameters of these Fe3O4 MNPs are 11 nm, and the ratios of saturation magnetization for these MNPs to that of bulk magnetite range from 45% to 65%, with remanent magnetization close to zero and low coercivity. Above all, the linear birefringence and dichroism measurements of the kerosene-based ferrofluid (FF) samples are investigated by a Stokes polarimeter. The influences of particle size distribution and magnetization in the birefringence and dichroism measurements of FFs are discussed.

  2. Linear birefringence and dichroism in citric acid coated Fe3O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Jing-Fung; Tsai, Chun-Chin; Lee, Meng-Zhe

    2014-12-01

    To prepare highly dispersed water-based Fe3O4 magnetic nanoparticles (MNPs), we adopted the co-precipitation method and used citric acid (CA) as the surfactant. Via transmission electronic microscopy, dynamic light scattering, and X-ray diffractometry, we characterized the dispersibility and size of the products. Through two single-parameter experiments, including the pH value of suspension and the action of double centrifugations, the appropriate parameters' values were determined. Further, to produce CA coated MNPs with good magneto-optical properties as high retardance and low dichroism, the orthogonal design method was used to find the optimal parameters' values, including pH value of suspension after coating was 5, molar ratio of CA to Fe3O4 MNPs was 0.06, volume of CA was 40 ml, and coating temperature was 70 °C. Above all, the linear birefringence and dichroism of the best CA coated ferrofluid we produced were measured by a Stokes polarimeter as 23.6294° and 0.3411 under 64.5 mT, respectively. Thus, the biomedical applications could be performed hereafter.

  3. Investigation of the Magnetic Behavior in Fe3O4 Ferrofluid Functionalized by Carapa Guianensis Oil

    NASA Astrophysics Data System (ADS)

    López, Jorge Luis; Rodriguez, Anselmo Fortunato Ruiz; de Jesus Nascimento Pontes, Maria; de Morais, Paulo Cesar; de Azevedo, Ricardo Bentes; Pfannes, Hans Dieter; Dias Filho, José Higino

    2010-12-01

    A ferrofluid based on Fe3O4 has been synthesized using the condensation method by coprecipitating aqueous solutions of FeSO4 and FeCl3 mixtures in NH4OH and treated further in order to obtain colloidal sols by creating a charge density on their surface and functionalized by carapa guianensis (andiroba oil). Aqueous sample with an average particle diameter ˜7 nm were studied by Mössbauer spectroscopy and dc magnetization measurements in the range of 4.2-250 K. The saturation magnetization (Ms) at 4.2 K was determined from M vs 1/H plots by extrapolating the value of magnetizations to infinite fields, to 5.6 emu/g and coercivity to 344 Oe. The low saturation magnetization value was attributed to spin noncollinearity predominantly at the surface. From the magnetization measurements a magnetic anisotropy energy constant (K) of 1×104 J/m3 was calculated. Fe3O4 spectra at room temperature showed a singlet due to superparamagnetic relaxation and a sextet at low temperature.

  4. MAPLE fabricated Fe3O4@Cinnamomum verum antimicrobial surfaces for improved gastrostomy tubes.

    PubMed

    Anghel, Alina Georgiana; Grumezescu, Alexandru Mihai; Chirea, Mariana; Grumezescu, Valentina; Socol, Gabriel; Iordache, Florin; Oprea, Alexandra Elena; Anghel, Ion; Holban, Alina Maria

    2014-01-01

    Cinnamomum verum-functionalized Fe3O4 nanoparticles of 9.4 nm in size were laser transferred by matrix assisted pulsed laser evaporation (MAPLE) technique onto gastrostomy tubes (G-tubes) for antibacterial activity evaluation toward Gram positive and Gram negative microbial colonization. X-ray diffraction analysis of the nanoparticle powder showed a polycrystalline magnetite structure, whereas infrared mapping confirmed the integrity of C. verum (CV) functional groups after the laser transfer. The specific topography of the deposited films involved a uniform thin coating together with several aggregates of bio-functionalized magnetite particles covering the G-tubes. Cytotoxicity assays showed an increase of the G-tube surface biocompatibility after Fe3O4@CV treatment, allowing a normal development of endothelial cells up to five days of incubation. Microbiological assays on nanoparticle-modified G-tube surfaces have proved an improvement of anti-adherent properties, significantly reducing both Gram negative and Gram positive bacteria colonization. PMID:24979402

  5. Facile Synthesis of Fe3O4/GCs Composites and Their Enhanced Microwave Absorption Properties.

    PubMed

    Jian, Xian; Wu, Biao; Wei, Yufeng; Dou, Shi Xue; Wang, Xiaolin; He, Weidong; Mahmood, Nasir

    2016-03-01

    Graphene has good stability and adjustable dielectric properties along with tunable morphologies, and hence can be used to design novel and high-performance functional materials. Here, we have reported a facile synthesis method of nanoscale Fe3O4/graphene capsules (GCs) composites using the combination of catalytic chemical vapor deposition (CCVD) and hydrothermal process. The resulting composite has the advantage of unique morphology that offers better synergism among the Fe3O4 particles as well as particles and GCs. The microwave-absorbing characteristics of developed composites were investigated through experimentally measured electromagnetic properties and simulation studies based on the transmission line theory, explained on the basis of eddy current, natural and exchange resonance, as well as dielectric relaxation processes. The composites bear minimum RL value of -32 dB at 8.76 GHz along with the absorption bandwidth range from 5.4 to 17 GHz for RL lower than -10 dB. The better performance of the composite based on the reasonable impedance characteristic, existence of interfaces around the composites, and the polarization of free carriers in 3D GCs that make the as-prepared composites capable of absorbing microwave more effectively. These results offer an effective way to design high-performance functional materials to facilitate the research in electromagnetic shielding and microwave absorption. PMID:26890224

  6. Arsenic (V) adsorption on Fe3O4 nanoparticle-coated boron nitride nanotubes.

    PubMed

    Chen, Rongzhi; Zhi, Chunyi; Yang, Huang; Bando, Yoshio; Zhang, Zhenya; Sugiur, Norio; Golberg, Dmitri

    2011-07-01

    Multiwalled boron nitride nanotubes (BNNTs) functionalized with Fe(3)O(4) nanoparticles (NPs) were used for arsenic removal from water solutions. Sonication followed by a heating process was developed to in situ functionalize Fe(3)O(4) NPs onto a tube surface. A batch of adsorption experiments conducted at neutral pH (6.9) and room temperature (25 °C) and using the developed nanocomposites revealed effective arsenic (V) removal. The Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms were measured for a range of As(V) initial concentrations from 1 to 40 mg/L under the same conditions. The equilibrium data well fitted all isotherms, indicating that the mechanism for As(V) adsorption was a combination of chemical complexation and physical electrostatic attraction with a slight preference for chemisorption. The magnetite NPs functionalized on BNNTs led to a simple and rapid separation of magnetic metal-loaded adsorbents from the treated water under an external magnetic field. PMID:21507418

  7. Fe3O4/carbon hybrid nanoparticle electrodes for high-capacity electrochemical capacitors.

    PubMed

    Lee, Jun Seop; Shin, Dong Hoon; Jun, Jaemoon; Lee, Choonghyeon; Jang, Jyongsik

    2014-06-01

    Fe3O4/carbon hybrid nanoparticles (FeCHNPs) were fabricated using dual-nozzle electrospraying, vapor deposition polymerization (VDP), and carbonization. FeOOH nanoneedles decorated with polypyrrole (PPy) nanoparticles (FePNPs) were fabricated by electrospraying pristine PPy mixed with FeCl3 solution, followed by heating stirring reaction. A PPy coating was then formed on the FeOOH nanoneedles through a VDP process. FeCHNPs were produced through carbonization of PPy and FeOOH phase transitions. These hybrid carbon nanoparticles (NPs) were used to build electrodes of electrochemical capacitors. The specific capacitance of the FeCHNPs was 455 F g(-1), which is larger than that of pristine PPy NPs (105 F g(-1)) or other hybrid PPy NPs. Furthermore, the FeCHNP-based capacitors exhibited better cycle stability during charge-discharge cycling than other hybrid NP capacitors. This is because the carbon layer on the Fe3 O4 surface formed a protective coating, preventing damage to the electrode materials during the charge-discharge processes. This fabrication technique is an effective approach for forming stable carbon/metal oxide nanostructures for energy storage applications. PMID:24706636

  8. Preparation and Characterization of Graphene/Fe3O4 Composites by Solvothermal Method.

    PubMed

    Zhou, Lin; Peng, Xiaoling; Wang, Xinqing; Jin, Dingfeng; Jin, Hongxiao; Ge, Hongliang

    2015-06-01

    In the present study, graphene/Fe3O4 nanocomposites were prepared by solvothermal method using graphite oxide (GO) and FeCl3 x 6H2O as starting materials and the products were characterized by X-ray Diffraction (XRD), Scanning Electronic Microscope (SEM) and Vibrating Sample Magnetometer (VSM). Effects of Fe ion concentration, temperature and time of solvothermal reaction on the magnetic properties, microstructures and morphologies of graphene/Fe3O4 nanocomposites were investigated. The results showed that with the raising of Fe ion, particle size of the products became bigger, and saturation magnetization of the products got higher. The saturation magnetization and particle size of the products can be enhanced by increasing the reaction time and temperature, but the change of saturation magnetization and particle size were not obvious after the time got 8 h and temperature was at 200 degrees C, which demonstrated that the products became stable under this condition. The morphologies, microstructures and properties of products can be controlled by adjusting synthesis conditions. PMID:26369052

  9. Porous Hollow Fe3O4 Nanoparticles for Targeted Delivery and Controlled Release of Cisplatin

    PubMed Central

    Cheng, Kai; Peng, Sheng; Xu, Chenjie; Sun, Shouheng

    2009-01-01

    We report a new approach to cisplatin storage and release using porous hollow nanoparticles (PHNPs) of Fe3O4. We prepared the PHNPs by controlled oxidation of Fe NPs at 250°C followed by acid etching. The opening pores (~2–4 nm) facilitated the cisplatin diffusion into the cavity of the hollow structure. The porous shell was stable in neutral or basic physiological conditions and cisplatin escape from the cavity through the same pores was diffusion-controlled slow process with t1/2 = 16 hrs. But in low pH (< 6) conditions, the pores were subject to acidic etching, resulting in wider pore gaps and faster release of cisplatin with t1/2 < 4 hrs. Once coupled with Herceptin to the surface, the cisplatin-loaded hollow NPs could target to breast cancer SK-BR-3 cells with IC50 reaching 2.9 μM, much lower than 6.8 μM needed for free cisplatin. Our model experiments indicate that the low pH-responsive PHNPs of Fe3O4 can be exploited as a cisplatin delivery vehicle for target-specific therapeutic applications. PMID:19722635

  10. Magnetoelectric properties of epitaxial Fe3O4 thin films on (011) PMN-PT piezosubstrates

    NASA Astrophysics Data System (ADS)

    Tkach, Alexander; Baghaie Yazdi, Mehrdad; Foerster, Michael; Büttner, Felix; Vafaee, Mehran; Fries, Maximilian; Kläui, Mathias

    2015-01-01

    We determine the magnetic and magnetotransport properties of 33 nm thick Fe3O4 films epitaxially deposited by rf-magnetron sputtering on unpoled (011) [PbMg1/3Nb2/3O3] 0.68-[PbTiO3]0.32 (PMN-PT) substrates. The magnetoresistance (MR), as well as the magnetization reversal, strongly depend on the in-plane crystallographic direction of the epitaxial (011) Fe3O4 film and strain. When the magnetic field is applied along [100], the magnetization loops are slanted and the sign of the longitudinal MR changes from positive to negative around the Verwey transition at 125 K on cooling. Along the [01 1 ¯] direction, the loops are square shaped and the MR is negative above the switching field across the whole temperature range, just increasing in absolute value when cooling from 300 K to 150 K. The value of the MR is found to be strongly affected by poling the PMN-PT substrate, decreasing in the [100] direction and slightly increasing in the [01 1 ¯] direction upon poling, which results in a strained film.