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Sample records for silica-coated fe3o4 nanoparticles

  1. Electrochemical sensing behaviour of Ni doped Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    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

  2. Electrochemical sensing behaviour of Ni doped Fe3O4 nanoparticles

    Science.gov (United States)

    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. Electrochemical sensing property of Mn doped Fe3O4 nanoparticles

    Science.gov (United States)

    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.

  4. Polyethyleneimine-modified superparamagnetic Fe3O4 nanoparticles for lipase immobilization: Characterization and application

    International Nuclear Information System (INIS)

    Magnetically separable nanospheres consisting of polyethyleneimine (PEI) and succinated PEI grafted on silica coated magnetite (Fe3O4) were prepared and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy. The prepared magnetic nanoparticles were then applied for physical adsorption or covalent attachment of Thermomyces lanuginosa lipase (TLL) via glutaraldehyde or hexamethylene diisocyanate. The reusability, storage, pH and thermal stabilities of the immobilized enzymes compared to that of free lipase were examined. The obtained results showed that the immobilized lipase on MNPs@PEI-GLU was the best biocatalyst which retained 80% of its initial activity after 12 cycles of application. The immobilized lipase on the selected support (MNPs@PEI-GLU) was also applied for the synthesis of ethyl valerate. Following 24 h incubation of the immobilized lipase on the selected support in n-hexane and solvent free media, the esterification percentages were 72.9% and 28.9%, respectively. - Graphical abstract: A schematic of the preparation of PEI- and succinated PEI-grafted Fe3O4 MNPs (MNPs@PEI) and the immobilization of lipase by covalent bonding and adsorption. - Highlights: • Functionalized polyethylenimine-grafted magnetic nanoparticles were synthesized. • The prepared supports were fully characterized by various analysis methods. • Lipase was immobilized on the nanostructures by adsorption and covalent attachment. • Immobilized lipase produced ethyl valerate in solvent free medium

  5. Purification and magnetic interrogation of hybrid Au-Fe3O4 and FePt-Fe3O4 nanoparticles.

    Science.gov (United States)

    Beveridge, Jacob S; Buck, Matthew R; Bondi, James F; Misra, Rajiv; Schiffer, Peter; Schaak, Raymond E; Williams, Mary Elizabeth

    2011-10-10

    Purifying heterodimers: differential magnetic catch and release separation is used to purify two important hybrid nanocrystal systems, Au-Fe(3)O(4) and FePt-Fe(3)O(4). The purified samples have substantially different magnetic properties compared to the as-synthesized materials: the magnetization values are more accurate and magnetic polydispersity is identified in morphologically similar hybrid nanoparticles. PMID:21898742

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Influence of carbon nanotubes support on the morphology of Fe3O4 nanoparticles

    Science.gov (United States)

    Zabihi, F.; Taleshi, F.; Salmani, A.; Pahlavan, A.; Dehghan-niarostami, N.; Vadadi, M. M.

    2015-03-01

    In this paper, the effects of carbon nanotubes as a support to the morphology and size of Fe3O4 magnetic nanoparticles have been investigated. The synthesis of Fe3O4/CNTs nanocomposite powder was performed by the direct precipitation method through ferric chloride (II) and (III) at room temperature. The prepared samples were analyzed by X-ray diffraction spectra, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The results demonstrated considerable changes in the Fe3O4 nanoparticle size, also the morphology of Fe3O4/CNTs nanocomposite powder from agglomerative into rode shape.

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

    Science.gov (United States)

    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.

  10. Green fabrication of agar-conjugated Fe3O4 magnetic nanoparticles

    International Nuclear Information System (INIS)

    Magnetic nanoparticles are of great interest both for fundamental research and emerging applications. In the biomedical field, magnetite (Fe3O4) has shown promise as a hyperthermia-based tumor therapeutic. However, preparing suitable solubilized magnetite nanoparticles is challenging, primarily due to aggregation and poor biocompatibility. Thus methods for coating Fe3O4 NPs with biocompatible stabilizers are required. We report a new method for preparing Fe3O4 nanoparticles by co-precipitation within the pores of agar gel samples. Permeated agar gels were then dried and ground into a powder, yielding agar-conjugated Fe3O4 nanoparticles. Samples were characterized using XRD, FTIR, TGA, TEM and SQUID. This method for preparing agar-coated Fe3O4 nanoparticles is environmentally friendly, inexpensive and scalable.

  11. Photoluminescence and photothermal effect of Fe3O4 nanoparticles for medical imaging and therapy

    International Nuclear Information System (INIS)

    Photoluminescence (PL) of Fe3O4 nanoparticle was observed from the visible to near-infrared (NIR) range by laser irradiation at 407?nm. PL spectra of ?10?nm diameter Fe3O4 nanoparticles organized in different spatial configuration, showed characteristic emissions with a major peak near 560?nm, and two weak peaks near 690?nm and 840?nm. Different band gap energies were determined for these Fe3O4 nanoparticle samples corresponding to, respectively, the electron band structures of the octahedral site (2.2?eV) and the tetrahedral site (0.9?eV). Photothermal effect of Fe3O4 nanoparticles was found to be associated with the photoluminescence emissions in the NIR range. Also discussed is the mechanism responsible for the photothermal effect of Fe3O4 nanoparticles in medical therapy.

  12. Hydrothermal synthesis of superparamagnetic Fe3O4 nanoparticles with ionic liquids as stabilizer

    International Nuclear Information System (INIS)

    Highlights: • Superparamagnetic Fe3O4 nanoparticles with good dispersity have been synthesized via hydrothermal method. • Ionic liquid [C16mim]Cl acts as stabilizer for the Fe3O4 nanoparticles. • Fe3O4 nanoparticles have a saturation magnetization of 67.69 emu/g at 300 K. - Abstract: Superparamagnetic Fe3O4 nanoparticles have been successfully synthesized under hydrothermal condition with the assistant of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). The structure and morphology of the sample have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), and the results indicate that the as-synthesized inverse spinel Fe3O4 nanoparticles have an average diameter of about 10 nm and exhibit relatively good dispersity. More importantly, it is found that [C16mim]Cl acts as stabilizer for the Fe3O4 nanoparticles by adsorbing on the particles surfaces to prevent the agglomeration. In addition, the obtained superparamagnetic Fe3O4 nanoparticles have a saturation magnetization of 67.69 emu/g at 300 K

  13. Preparation and antibacterial activity of Fe3O4-Ag nanoparticles

    International Nuclear Information System (INIS)

    Bifunctional Fe3O4-Ag nanoparticles with both superparamagnetic and antibacterial properties were prepared by reducing silver nitrate on the surface of Fe3O4 nanoparticles using the water-in-oil microemulsion method. Formation of well-dispersed nanoparticles with sizes of 60 ± 20 nm was confirmed by transmission electron microscopy and dynamic light scattering. X-ray diffraction patterns and UV-visible spectroscopy indicated that both Fe3O4 and silver are present in the same particle. The superparamagnetism of Fe3O4-Ag nanoparticles was confirmed with a vibrating sample magnetometer. Their antibacterial activity was evaluated by means of minimum inhibitory concentration value, flow cytometry, and antibacterial rate assays. The results showed that Fe3O4-Ag nanoparticles presented good antibacterial performance against Escherichia coli (gram-negative bacteria), Staphylococcus epidermidis (gram-positive bacteria) and Bacillus subtilis (spore bacteria). Furthermore, Fe3O4-Ag nanoparticles can be easily removed from water by using a magnetic field to avoid contamination of surroundings. Reclaimed Fe3O4-Ag nanoparticles can still have antibacterial capability and can be reused

  14. 99mTc radiolabelling of Fe3O4-Au core-shell and Au-Fe3O4 dumbbell-like nanoparticles

    Science.gov (United States)

    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 DOI: 10.1039/c5nr00269a

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

    OpenAIRE

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

    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 ...

  16. Preparation and enhanced properties of Fe3O4 nanoparticles reinforced polyimide nanocomposites

    Science.gov (United States)

    Ding, Daowei; Yan, Xingru; Zhang, Xi; He, Qingliang; Qiu, Bin; Jiang, Dawei; Wei, Huige; Guo, Jiang; Umar, Ahmad; Sun, Luyi; Wang, Qiang; Khan, Mojammel A.; Young, David P.; Zhang, Xin; Weeks, Brandon; Ho, Thomas C.; Guo, Zhanhu; Wei, Suying

    2015-09-01

    Polyimide (PI) nanocomposite reinforced with Fe3O4 nanoparticles (NPs) at various NPs loadings levels of 5.0, 10.0, 15.0, and 20.0 wt% were prepared. The chemical interactions of the Fe3O4 NPs/PI nanocomposites were characterized using Fourier Transform Infrared (FT-IR) spectroscopy. X-ray Diffraction (XRD) results revealed that the addition of NPs had a significant effect on the crystallization of PI. Scanning electron microscope (SEM) and the atomic force microscope (AFM) were used to characterize the dispersion and surface morphology of the Fe3O4 NPs and the PI nanocomposites. The obtained optical band gap of the nanocomposites characterized using Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS) was decreased with increasing the Fe3O4 loading. Differential scanning calorimetry (DSC) results showed a continuous increase of Tg with increasing the Fe3O4 NPs loading. Some differences were observed in the onset decomposition temperature between the pure PI and nanocomposites since the NPs and the PI matrix were physically entangled together to form the nanocomposites. The contact angle of pure PI was larger than that of Fe3O4/PI nanocomposites films, and increased with increasing the loading of Fe3O4. The degree of swelling was increased with increasing the Fe3O4 loading and the swelling time. The dielectric properties of the nanocomposite were strongly related to the Fe3O4 loading levels. The Fe3O4/PI magnetic property also had been improved with increasing the loading of the magnetic nanoparticles.

  17. Versatile functionalization of Fe3O4 nanoparticles via RAFT polymerization and click chemistry

    International Nuclear Information System (INIS)

    Azide-functionalized chain transfer agent (CTA) was synthesized and subsequently employed to mediate the reversible addition fragmentation transfer (RAFT) polymerization of poly(ethylene glycol) monomethacrylate (PEGMA) on the alkyne-functionalized Fe3O4 nanoparticles surface together with click chemistry. In a single pot procedure, azide-functionalized CTA, alkyne-functionalized Fe3O4 and PEGMA were combined to produce the desired product. Fourier transformed infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) results showed that PEGMA chains were grafted to Fe3O4 nanoparticles using RAFT polymerization and click chemistry.

  18. A Facile Solvothermal Synthesis of Octahedral Fe3O4 Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Sonochemical synthesis, structure and magnetic properties of air-stable Fe3O4/Au nanoparticles

    International Nuclear Information System (INIS)

    Air-stable nanoparticles of Fe3O4/Au were prepared via sonolysis of a solution mixture of hydrogen tetrachloroaureate(III) trihydrate (HAuCl4) and (3-aminopropyl)triethoxysilane (APTES)-coated Fe3O4 nanoparticles with further drop-addition of sodium citrate. The Fe3O4/Au nanoparticles were characterized by x-ray powder diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID) magnetometry. Nanoparticles of Fe3O4/Au obtained under appropriate conditions possess a very high saturation magnetization of about 63 emu g-1 and their average diameter is about 30 nm

  20. Temperature dependence of magnetic property and photocatalytic activity of Fe3O4/hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Fe3O4/hydroxyapatite (HAP) nanoparticles have been developed as a novel photocatalyst support, based on the embedment of magnetic Fe3O4 particles into HAP shell via homogeneous precipitation method. The resultant nanoparticles were characterized by transmission electron microscope (TEM) and X-ray diffraction (XRD). These particles were almost spherical in shape, rather monodisperse and have a unique size of about 25 nm in diameter. The effect of calcination temperature on magnetic property and photocatalytic activity of Fe3O4/HAP nanoparticles was investigated in detail. The obtained results showed that the Fe3O4/HAP nanoparticles calcined at 400 oC possessed good magnetism and photocatalytic activity in comparison with that calcined at other temperatures.

  1. Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

    Indian Academy of Sciences (India)

    K C Barick; D Bahadur

    2006-11-01

    The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 spheres have been prepared by an in situ reaction using different molar ratios of Fe3+/Fe2+ (50–200%). It has been observed that morphology of the assembly and properties of these hybrid materials composed of SiO2 as core and Fe3O4 nanoparticles as shell depend on the molar ratio of Fe3+/Fe2+.

  2. High-temperature magnetic properties of noninteracting single-domain Fe3O4 nanoparticles

    OpenAIRE

    Wang, Jun; Beeli, Pieder; Meng, L. H.; Zhao, Guo-meng

    2010-01-01

    Magnetic measurements have been performed on 40-nm sphere-like Fe3O4 nanoparticles using a Quantum Design vibrating sample magnetometer. Coating Fe3O4 nanoparticles with SiO2 effectively eliminates magnetic interparticle interactions so that the coercive field HC in the hightemperature range between 300 K and the Curie temperature (855 K) can be well fitted by an expression for noninteracting randomly oriented single-domain particles. From the fitting parameters, the effecti...

  3. Effect of silica capping on the oxidation of Fe3O4 nanoparticles in dispersion revealed by x-ray absorption spectroscopy

    Science.gov (United States)

    Warland, A.; Antoniak, C.; Darbandi, M.; Weis, C.; Landers, J.; Keune, W.; Wende, H.

    2012-06-01

    Fe3O4 nanoparticles have been investigated as they are biocompatible and their surface can be functionalized. We synthesized iron oxide nanoparticles using a water-in-oil microemulsion method. Bare and silica-coated iron oxide nanoparticles of a core size of 6 nm dispersed in ethanol have been investigated by means of x-ray absorption spectroscopy (XAS). Due to a dedicated experimental setup the particles can be measured directly in dispersion. XAS allows us to disentangle the contributions of the Fe2+ and Fe3+ ions and therefore to estimate the amount of Fe3O4 in the particles. In case of the silica coated particles a high amount of magnetite was obtained. In contrast, the bare nanoparticles showed indications of a further oxidation into ?-Fe2O3 even in dispersion.

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

    Science.gov (United States)

    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 nanoparticles showed no significant cytotoxicity to the CHO cells up to 48 h even at concentrations of 1 mg ml-1 making them suitable for biomedical applications such as local heat generators (hyperthermia) for cancer treatment and drug delivery vehicles.

  5. ESR on Superparamagnetic Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    In this study we have investigated temperature and frequency dependence of magnetic properties of superparamagnetic iron oxide particles (SPION) having a size of 1.1 nm. The polycrystalline powders placed in nonmagnetic paraffin just above its melting temperature, have been tried to orient in the presence of strong magnetic field (15 kg) and cooled down to melting temperature of paraffin. A sample with dimensions 1.5x2x2.5 mm was cut from this ingot and ESR measurements have been carried out in a temperature range of 10-300 K. A single, relatively broad and temperature dependent ESR signal was observed at all measurement temperatures. The linewidth slightly increases with decreasing temperature down to 100 K, then it sharply increases down to 60 K. Below 60 K the trend is reversed and the linewidth start to decrease. The resonance field remains almost constant down to 100 K and decreases sharply as the temperature is decreased further. The ESR spectra of Fe3O4 shows a linear dependence on microwave frequency. By using experimental results, the effective g-value and internal field are deduced as 1.9846 and 40 G, respectively

  6. Synthesis and characterization of surface-modified Fe3O4 super-paramagnetic nanoparticles.

    Science.gov (United States)

    Zhang, Zhan-jie; Ma, Jia; Xu, Shuang-bing; Ren, Jing-hua; Qin, You; Huang, Jing; Yang, Kun-yu; Zhang, Zhi-ping; Wu, Gang

    2014-04-01

    Aqueous dispersion and stability of Fe3O4 nanoparticles remain an issue unresolved since aggregation of naked iron nanoparticles in water. In this study, we successfully synthesized different Fe3O4 super-paramagnetic nanoparticles which were modified by three kinds of materials [DSPE-MPEG2000, TiO2 and poly acrylic acid (PAA)] and further detected their characteristics. Transmission electron microscopy (TEM) clearly showed sizes and morphology of the four kinds of nanoparticles. X-ray diffraction (XRD) proved successfully coating of the three kinds of nanoparticles and their structures were maintained. Vibrating sample magnetometer (VSM) verified that their magnetic properties fitted for the super-paramagnetic function. More importantly, the particle size analysis indicated that Fe3O4@PAA had a better size distribution, biocompatibility, stability and dispersion than the other two kinds of nanoparticles. In addition, using CNE2 cells as a model, we found that all nanoparticles were nontoxic. Taken together, our data suggest that Fe3O4@PAA nanoaparticles are superior in the application of biomedical field among the four kinds of Fe3O4 nanoparticles in the future. PMID:24710944

  7. Synthesis and characterization of Fe3O4@ZnS and Fe3O4@Au@ZnS core-shell nanoparticles

    Science.gov (United States)

    Stefan, M.; Leostean, C.; Pana, O.; Soran, M.-L.; Suciu, R. C.; Gautron, E.; Chauvet, O.

    2014-01-01

    In the present work we report new assets on the synthesis and characterization of magnetite based core-shell nanoparticles such as Fe3O4@ZnS and Fe3O4@Au@ZnS. The composites were prepared by seed mediated growth which consist in a sequential growth of a second or third component on a preformed magnetite seeds in the presence of sodium laurylsulphate additives with essential role in growth and aggregation of nanoparticles. Evolved gas analysis (EGA) coupled with FT-IR was used in order to evidence the stages of ZnS shell formation. XRD studies were used for the structural characterization while high resolution transmission electron microscopy gave information concerning morphology and size distributions of nanoparticles. Qualitative and quantitative compositional analysis of samples was made by X-ray photoelectron spectroscopy (XPS). All the samples showed magnetic response due to the superparamagnetic behavior of magnetite cores. Increased saturation magnetization was determined for Fe3O4@ZnS samples. A significant photoluminescence (PL) enhancement was also observed as a result of Fe3O4:Zn2+ molar ratio decrease. Additional PL increased response was realized by inserting a gold shell between the magnetite core and ZnS outer shell. Considerations regarding both PL and magnetization enhancements are also presented.

  8. Synthesis and characterization of Fe3O4@ZnS and Fe3O4@Au@ZnS core–shell nanoparticles

    International Nuclear Information System (INIS)

    In the present work we report new assets on the synthesis and characterization of magnetite based core–shell nanoparticles such as Fe3O4@ZnS and Fe3O4@Au@ZnS. The composites were prepared by seed mediated growth which consist in a sequential growth of a second or third component on a preformed magnetite seeds in the presence of sodium laurylsulphate additives with essential role in growth and aggregation of nanoparticles. Evolved gas analysis (EGA) coupled with FT-IR was used in order to evidence the stages of ZnS shell formation. XRD studies were used for the structural characterization while high resolution transmission electron microscopy gave information concerning morphology and size distributions of nanoparticles. Qualitative and quantitative compositional analysis of samples was made by X-ray photoelectron spectroscopy (XPS). All the samples showed magnetic response due to the superparamagnetic behavior of magnetite cores. Increased saturation magnetization was determined for Fe3O4@ZnS samples. A significant photoluminescence (PL) enhancement was also observed as a result of Fe3O4:Zn2+ molar ratio decrease. Additional PL increased response was realized by inserting a gold shell between the magnetite core and ZnS outer shell. Considerations regarding both PL and magnetization enhancements are also presented.

  9. Catalytic performance of Fe3O4 nanoparticles for cyclocondensation synthesis of thiacrown ethers

    Science.gov (United States)

    Lin, Shangxin; Chen, Yajie; Tan, Xiepeng; Song, Feng; Yue-Bun Pun, Edwin; He, Zhubing; Pu, Jixiong

    2015-01-01

    The catalytic function of nanoparticles is one the most successful applications of nanotechnologies so far. A novel and mild one-pot cyclocondensation reaction catalyzed by Fe3O4 nanoparticles is achieved for the first time in this work. By the function of those nanoparticles, the thiacrown ethers, including both 1,4-dithiane and 1,4,7-trithiacyclononane were obtained with considerable yield and turnover in a milder condition than that of the conventional routes. The excellent dehydrating ability and acid sensitivity of Fe3O4 nanoparticles were discovered in a series of experiments of esterification of DL-malic acid. The catalytic reaction mechanism of Fe3O4 nanoparticles was explored through the investigation of morphology evolution of those nanoparticles by transmission electron microscopy. Interestingly, the as-prepared big nanoparticles were decomposed into hollow or loose bounded aggregates of smaller nanoparticles after catalytic cycles. The result shown in this work claims promising utilization of Fe3O4 nanoparticles with big potential in catalytic synthesis.

  10. Fabrication of Fe3O4@mSiO2 Core-Shell Composite Nanoparticles for Drug Delivery Applications

    Science.gov (United States)

    Uribe Madrid, Sergio I.; Pal, Umapada; Kang, Young Soo; Kim, Junghoon; Kwon, Hyungjin; Kim, Jungho

    2015-05-01

    We report the synthesis of Fe3O4@mSiO2 nanostructures of different meso-silica (mSiO2) shell thickness, their biocompatibility and behaviors for loading and release of a model drug ibuprofen. The composite nanostructures have superparamagnetic magnetite cores of 208 nm average size and meso-silica shells of 15 to 40 nm thickness. A modified Stöber method was used to grow the meso-silica shells over the hydrothermally grown monodispersed magnetite particles. The composite nanoparticles show very promising drug holding and releasing behaviors, which depend on the thickness of meso-silica shell. The biocompatibility of the meso-silica-coated and uncoated magnetite nanoparticles was tested through cytotoxicity assay on breast cancer (MCF-7), ovarian cancer (SKOV3), normal human lung fibroblasts MRC-5, and IMR-90 cells. The high drug holding capacity and reasonable biocompatibility of the nanostructures make them ideal agents for targeted drug delivery applications in human body.

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

    Science.gov (United States)

    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.

  12. Synthesis and characterization of Fe3O4 nanoparticles coated with fucan polysaccharides

    International Nuclear Information System (INIS)

    In this work we report the preparation of fucan-coated magnetite (Fe3O4) nanoparticles by the co-precipitation method. These nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Mössbauer spectroscopy and magnetic measurements. The nanoparticles showed quasi-spherical morphology with mean sizes around 10 nm. XRD and FT-IR confirmed the functionalization of the Fe3O4 nanoparticles with the fucan polysaccharide. Room temperature magnetization measurements and Mössbauer spectroscopy showed that the nanoparticles exhibited superparamagnetic behavior at 300 K and the magnetic properties of the Fe3O4 are partly screened by the coating preventing aggregation. - Highlights: • Syntheses of fucan-coated Fe3O4 nanoparticles were made by co-precipitation method. • The efficiency of polysaccharide coated was analyzed by XRD and FT-IR. • The magnetic nanoparticles mean size was 10–20 nm. • The fucan-coated magnetite nanoparticles showed superparamagnetic behavior

  13. Green synthesis and characterization of superparamagnetic Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    In this paper, we have first demonstrated a facile and green synthetic approach for preparing superparamagnetic Fe3O4 nanoparticles using ?-D-glucose as the reducing agent and gluconic acid (the oxidative product of glucose) as stabilizer and dispersant. The X-ray powder diffraction (XRD), X-ray photoelectron spectrometry (XPS), and selected area electron diffraction (SAED) results showed that the inverse spinel structure pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results exhibited that Fe3O4 nanoparticles were roughly spherical shape and its average size was about 12.5 nm. The high-resolution TEM (HRTEM) result proved that the nanoparticles were structurally uniform with a lattice fringe spacing about 0.25 nm, which corresponded well with the values of 0.253 nm of the (3 1 1) lattice plane of the inverse spinel Fe3O4 obtained from the JCPDS database. The superconducting quantum interference device (SQUID) results revealed that the blocking temperature (Tb) was 190 K, and that the magnetic hysteresis loop at 300 K showed a saturation magnetization of 60.5 emu/g, and the absence of coercivity and remanence indicated that the as-synthesized Fe3O4 nanoparticles had superparamagnetic properties. Fourier transform infrared spectroscopy (FT-IR) spectrum displayed that the characteristic band of Fe-O at 569 cm-1 was indicative of Fe3O4. This method might provide a new, mild, green, and economical concept for the synthesis of other nanomaterials.

  14. Removal of Lignin from aqueous solution using Fe3O4 Nanoparticles as an effective adsorbent

    Directory of Open Access Journals (Sweden)

    Harajyoti Mazumdar

    2015-06-01

    Full Text Available The study was carried out to find out the adsorption efficiency of lignin from paper mill waste water by using Fe3O4 magnetic nanoparticles. The physico-chemical analysis of paper mill effluent results high B.O.D value. Separations of lignin from black liquor were done by acid precipitation method and removal of lignin was done with nanoparticles. Synthesis of nanoparticles was done by co-precipitation method by mixing and stirring of FeCl3.6H2O and FeCl2.4H2O solution at 2:1 molar ratio. The nanoparticles were characterized by using U.V-Vis spectrophotometer and X-Ray Diffraction. U.V-Vis spectra show absorbance spectra at around 585 nm while XRD revealed around 10 nm sizes of Fe3O4 MNPs. The removal efficiency of lignin by Fe3O4 MNPs was investigated at different pH and contact time. Maximum adsorption of lignin onto the surface of Fe3O4 MNPs took place at pH 2.5 and 10 mins of contact time. Desorption of lignin by nanoparticles was studies by using different organic solvents.

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

    Directory of Open Access Journals (Sweden)

    Chen DZ

    2012-09-01

    Full Text Available Daozhen Chen,1,3,* Qiusha Tang,2,* Xiangdong Li,3,* Xiaojin Zhou,1 Jia Zang,1 Wen-qun Xue,1 Jing-ying Xiang,1 Cai-qin Guo11Central Laboratory, Wuxi Hospital for Matemaland Child Health Care Affiliated Medical School of Nanjing, Jiangsu Province; 2Department of Pathology and Pathophysiology, Medical College, Southeast University, Jiangsu Province; 3The People’s Hospital of Aheqi County, Xinjiang, China *These authors contributed equally to this workBackground: 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 cell proliferation, and its inhibitory effect was dose-dependent according to the Fe3O4 nano magnetofluid concentration.Conclusion: The Fe3O4 nanoparticles prepared in this study have good biocompatibility and are suitable for further application in tumor hyperthermia.Keywords: characterization, biocompatibility, Fe3O4, magnetic nanoparticles, hyperthermia

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Fe3O4 nanoparticles synthesized FeCl2 as the sole source by alkaline precipitation. • Hydrophilicity imparted to OA-Fe3O4 MNPs. • Improved heating induction ability. • Highly stabilized colloidal suspension. • Improved biocompatiblity

  17. Magneto capacitance in Fe3O4 and NiFe2O4 nanoparticles

    International Nuclear Information System (INIS)

    We have synthesized NiFe2O4 (? ?6 nm) and Fe3O4 (??30 nm) magnetic nanoparticles by solvothermal synthesis; furthermore the Fe3O4 nanoparticles have been coated with a SiO2 shell of approximately 5 nm of thickness by the Stober method. In the study of the dielectric properties as a function of the frequency, temperature and applied magnetic field, we observe a magnetocapacitive behavior (MC) at room temperature and under a moderate magnetic field (H=0.5T), that is specially important in the case of the Fe3O4, nanoparticles (MC 6%). On the other hand, the NiFe2O4 and Fe3O4atSiO2 samples present smaller magnetocapacitive effects: MC? 2% y MC? 1%, respectively. These MC values, that are higher than those reported in the literature for other related magnetic nanoparticles, corroborate the theoretical model proposed by Catalan in which the combination of Maxwell-Wagner effects and magnetoresistance promote the appearance of stronger magnetocapacitive effects. (Author)

  18. A comprehensive study on the synthesis and paramagnetic properties of PEG-coated Fe3O4 nanoparticles

    Science.gov (United States)

    Yang, Jinghai; Zou, Ping; Yang, Lili; Cao, Jian; Sun, Yunfei; Han, Donglai; Yang, Shuo; Wang, Zhe; Chen, Gang; Wang, Bingji; Kong, Xiangwang

    2014-06-01

    The PEG-coated Fe3O4 (PEG-Fe3O4) nanoparticles had been fabricated through chemical coprecipitation method. We comprehensively investigated the influence of different reaction conditions, such as vapor pressures with opening or sealing the beaker, molecular weights and amounts of PEG, on the structural and paramagnetic properties of PEG-Fe3O4 nanoparticles. The well-dispersed magnetic PEG-Fe3O4 nanoparticles with better size distribution can be obtained with adding 4 g PEG1000 while sealing the beaker. The possible growth mechanism was also discussed in detail.

  19. Simple polyol route to synthesize heptanoic acid coated magnetite (Fe3O4) nanoparticles

    International Nuclear Information System (INIS)

    Highlights: ? Heptanoic acid@Fe3O4 nanocomposite has been prepared via simple polyol. ? Heptanoic acid used as both surfactant and solvents. ? Magneto polymer composite with adjustable Ea has a potential usage as functional composites. - Abstract: Magnetite (Fe3O4) nanoparticles were prepared via polyol method by using FeCl2 as only source of iron. As-prepared samples were characterized by powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analyzer (TGA) and vibrating sample magnetometer (VSM). Crystalline phase was identified as Fe3O4 and the crystallite sizes were calculated as 19.1 ± 1.1 and 22 ± 1.3 nm for uncalcinated and calcinated products from X-ray line profile fitting. The capping of heptanoic acid around Fe3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygen's of the carboxylate and the nanoparticle surface and also by TG analysis. VSM measurements showed that both samples exhibited typical superparamagnetic behavior at room temperature with different Ms values. The ?? decreases with increasing frequency for both composites and permeability has almost same values for all temperatures at higher frequencies. As synthesized and calcinated samples conductivity increase linearly with the temperature

  20. Fabrication of Fe3O4 nanoparticle arrays via patterned template assisted self-assembly

    International Nuclear Information System (INIS)

    Magnetic nanoparticle arrays have been fabricated by combining chemically synthesized Fe3O4 nanoparticles with a diblock copolymer template substrate consisting of self-assembled polystyrene (PS) dots in a polymethylmethacrylate (PMMA) matrix. The influence of the volume fraction of the Fe3O4 suspending solution and the withdrawal speed of the template on the formation of array structures was investigated. A small volume fraction of the nanoparticles and low withdrawal speed play an important role in the fabrication of the patterned arrays of nanoparticles via template assisted self-assembly. Below a withdrawal speed of 0.5 mm s-1 and a nanoparticle volume fraction below 0.05 vol% (in particular, at extremely high dilutions of less than 0.01 vol%), the selective deposition of one to several nanoparticles on every single PS dot becomes possible

  1. DBT degradation enhancement by decorating Rhodococcus erythropolis IGST8 with magnetic Fe3O4 nanoparticles

    OpenAIRE

    Ansari, Farahnaz; Grigoriev, P.; LIBOR, S; Tothill, Ibtisam E.; Ramsden, Jeremy J.

    2009-01-01

    Biodesulfurization (BDS) of dibenzothiophene (DBT) was carried out by Rhodococcus erythropolis IGST8 decorated with magnetic Fe3O4 nanoparticles, synthesized in-house by a chemical method, with an average size of 45-50 nm, in order to facilitate the post-reaction separation of the bacteria from the reaction mixture. Scanning electron microscopy (SEM) showed that the magnetic nanoparticles substantially coated the surfaces of the bacteria. It was found that the decorated cells had a 56% higher...

  2. Synthesis and characterization of multifunctional Fe3O4/poly(fluorescein O-methacrylate) core/shell nanoparticles.

    Science.gov (United States)

    Govindaiah, Patakamuri; Hwang, Taewon; Yoo, Hyunhee; Kim, Yong Seok; Lee, Sun Jong; Choi, Sung Wook; Kim, Jung Hyun

    2012-08-01

    Multifunctional fluorescent and superparamagnetic Fe(3)O(4)/poly(fluorescein O-methacrylate) [Fe(3)O(4)/poly(FMA)] nanoparticles with core/shell structure were synthesized via surface-initiated polymerization. First, polymerizable double bonds were introduced onto the surface of Fe(3)O(4) nanoparticles via ligand exchange and a condensation reaction. A fluorescent monomer, FMA, was then polymerized to the double bonds at the surface via free-radical polymerization, leading to form a fluorescent polymer shell around the superparamagnetic Fe(3)O(4) core. The resultant Fe(3)O(4)/poly(FMA) nanoparticles were characterized by Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy to confirm the reactions. Transmission electron microscopy images showed that the Fe(3)O(4)/poly(FMA) nanoparticles have a spherical and monodisperse core/shell morphology. Photoluminescence spectroscopy and superconducting quantum interference device magnetometer analyses confirmed that the Fe(3)O(4)/poly(FMA) nanoparticles exhibited fluorescent and superparamagnetic properties, respectively. In addition, we demonstrated the potential bioimaging application of the Fe(3)O(4)/poly(FMA) nanoparticles by visualizing the cellular uptake of the nanoparticles into A549 lung cancer cells. PMID:22613627

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

    Science.gov (United States)

    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.

  4. Interactions in ?-Fe2O3 and Fe3O4 nanoparticle systems

    International Nuclear Information System (INIS)

    We have investigated interaction effects in two different systems of iron oxide nanoparticles. Samples of ?-Fe2O3 and Fe3O4 nanoparticles were synthesized using a matrix-mediated precipitation reaction and a chemical co-precipitation technique respectively. The structural properties of these nanoparticles were studied using x-ray diffraction and transmission electron microscopy. We also used temperature dependent ac magnetic susceptibility measurements to carefully investigate the interactions among these nanoparticles. Our analysis showed that the characteristic interaction energy does not depend simply on the average spacing between the nanoparticles but is likely to be strongly influenced by the fluctuations in the nanoparticle distribution

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. A facile strategy to synthesize monodisperse superparamagnetic OA-modified Fe3O4 nanoparticles with PEG assistant

    International Nuclear Information System (INIS)

    A facile strategy was reported to synthesize monodisperse super-paramagnetic oleic acid (OA) modified Fe3O4 nanoparticles, which the poly ethylene glycol (PEG) was used as the assistant. The influence of the molecular weight and concentration of PEG was investigated in the process of OA-modification. In addition, the mechanism of PEG action in the reaction system was discussed. The morphology and properties of the as-synthesized Fe3O4 magnetic nanoparticles were characterized by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and superconducting quantum interference device (SQUID). The size (12 nm) of the as-prepared Fe3O4 nanoparticles is smaller than the superparamagnetic critical size (25 nm) of Fe3O4 nanoparticles, which endows the OA-modified Fe3O4 nanoparticles with superparamagnetic property. Furthermore, the dispersibility and stability of as-synthesized OA-modified Fe3O4 magnetic nanoparticles were very good. As the stabilizer and dispersant, PEG played a very important role and did not encapsulate the OA-modified Fe3O4 nanoparticles. The condition for OA-modified Fe3O4 nanoparticles preparation was optimized. - Highlights: • A facile strategy with PEG assistant was adopted to synthesize OA-modified Fe3O4. • As-prepared OA-modified Fe3O4 is super-paramagnetic, monodisperse and stable. • The surface-modified method has good merits of celerity, simplicity and green. • The molecular and concentration of PEG as the assistant were optimized

  8. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings

    International Nuclear Information System (INIS)

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25?nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

  9. Magnetodielectric study in SiO2-coated Fe3O4 nanoparticle compacts

    OpenAIRE

    Chang, C. -C.; Zhao, L; Wu, M. -K.

    2011-01-01

    The dielectric properties of Fe$_{3}$O$_{4}$ magnetic nanoparticles with an insulating coating layer of SiO$_{2}$ were investigated. At high temperatures, the changes of the dielectric constant and loss induced by the magnetic field are opposite in sign and strongly frequency-dependent, which originates from extrinsic magnetodielectric coupling-the Maxwell-Wagner effect combined with magnetoresistance. And the interface defects leads to the obvious hysteresis phenomena obser...

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

    Science.gov (United States)

    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.

  11. The double-effect mechanism between Fe3O4 nanoparticles and MSA-capped CdTe QDs

    International Nuclear Information System (INIS)

    Water-soluble mercaptosuccinic acid (MSA)-capped CdTe quantum dots (QDs) of two sizes and superparamagnetic Fe3O4 nanoparticles have been synthesized and used to investigate the effect of the mechanism of Fe3O4 nanoparticles on the fluorescence intensity of QDs. In the presence of a low concentration of Fe3O4 nanoparticles, the CdTe QDs with smaller particle size exhibit fluorescence quenching while fluorescence enhancement of CdTe QDs with larger particle size was observed, and the fluorescence intensity changes with the excitation wavelength and the concentration of Fe3O4 nanoparticles. The mechanism study shows that there is a double-effect between the Fe3O4 and CdTe QDs: one is the fluorescence quenching effect due to Fe3O4 strong absorption of excitation and emission light, the other is the fluorescence enhancement effect resulting from a localized electromagnetic field caused by the absorption of exciting light. The fluorescence of CdTe QDs with lower concentration of Fe3O4 nanoparticles was determined via the synergy of the double-effect. To our best knowledge, this is the first systematic study on the interaction between Fe3O4 nanoparticles and CdTe QDs, which finds the fluorescence enhancement effect in the presence of low concentration of Fe3O4. - Highlights: ? Interaction of Fe3O4 nanoparticles of CdTe QDs. ? Fluorescence intensity of different size QDs shows quenching or enhancement. ? Double-effect mechanism of fluorescence enhancement and fluorescence quenching.

  12. A selective nanocatalyst for an efficient Ugi reaction: Magnetically recoverable Cu(acac)2/NH2-T/SiO2@Fe3O4 nanoparticles

    Indian Academy of Sciences (India)

    Monireh Ghavami; Maryam Koohi; Mohammad Zaman Kassaee

    2013-11-01

    A novel, magnetically recoverable nanocatalyst is fabricated through simple immobilization of copper(II) acetylacetonate on the surface of amine-terminated silica-coated Fe3O4 nanoparticles: Cu(acac)2/NH2-T/SiO2@Fe3O4NPs. Unambiguous bonding of Cu to the terminal amine is indicated by Xray photoelectron spectroscopy (XPS). Further characterizations are carried out by different techniques. Selectivity of this catalyst is demonstrated through one-pot synthesis of fourteen ?-aminoacyl amides using Ugi four-component reaction of cyclohexyl isocyanide, acetic acid, amines and various aldehydes. Interestingly, all aromatic aldehydes react with short reaction times and high yields, but heteroaromatic aldehydes do not yield any product. Catalyst efficiency remains unaltered through three consecutive experiments.

  13. Bi-functional properties of Fe3O4@YPO4:Eu hybrid nanoparticles: hyperthermia application.

    Science.gov (United States)

    Prasad, A I; Parchur, A K; Juluri, R R; Jadhav, N; Pandey, B N; Ningthoujam, R S; Vatsa, R K

    2013-04-14

    Magnetic nanoparticles based hyperthermia therapy is a possible low cost and effective technique for killing cancer tissues in the human body. Fe3O4 and Fe3O4@YPO4:5Eu hybrid magnetic nanoparticles are prepared by co-precipitation method and their average particle sizes are found to be ?10 and 25 nm, respectively. The particles are spherical, non-agglomerated and highly dispersible in water. The crystallinity of as-prepared YPO4:5Eu sample is more than Fe3O4@YPO4:5Eu hybrid magnetic nanoparticles. The chemical bonds interaction between Fe3O4 and YPO4:5Eu is confirmed through FeO-P. The magnetization of hybrid nanocomposite shows magnetization Ms = 11.1 emu g(-1) with zero coercivity (measured at 2 × 10(-4) Oe) at room temperature indicating superparamagnetic behaviour. They attain hyperthermia temperature (~42 °C) under AC magnetic field showing characteristic induction heating of the prepared nanohybrid and they will be potential material for biological application. Samples produce the red emission peaks at 618 nm and 695 nm, which are in range of biological window. The quantum yield of YPO4:5Eu sample is found to be 12%. Eu(3+) present on surface and core could be distinguished from luminescence decay study. Very high specific absorption rate up to 100 W g(-1) could be achieved. The intracellular uptake of nanocomposites is found in mouse fibrosarcoma (Wehi 164) tumor cells by Prussian blue staining. PMID:23370409

  14. Study on the Synthesis and Properties of Superparamagnetic Monodisperse Fe3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    JIANG Wen,WEN Xian-Tao,WANG Wei,WU Yao,GU Zhong-Wei

    2009-07-01

    Full Text Available There are extensive applications for superparamagnetic Fe3O4 nanoparticles in the field of biomaterials. Superparamagnetic magnetite nanoparticles coated with oleic acid were prepared in the refluxing mixed system of water, ethanol alcohol and toluene at 74¡?The effect of the OH- concentration on the surface properties, size, dispersion and magnetic properties of magnetite nanoparticles was studied systematically. The properties of magnetite nanoparticles were tested by X-ray diffraction (XRD, fourier transform infrared (FTIR, dynamic light scattering (DLS, transmission electron microscopy (TEM and vibrating sample magnetometer (VSM. The results show that when the molar ratio of NaOH to Fe(¢

  15. Spin Disorder and Magnetic Anisotropy in Fe3O4 Nanoparticles

    CERN Document Server

    Lima, E; Arelaro, A D; Goya, G F

    2006-01-01

    We have studied the magnetic behavior of dextran-coated Fe3O4 nanoparticles with median particle size = 8 nm. The magnetic anisotropy Ea of the particles was calculated from magnetization and ac susceptibility data. The resulting values correspond to the magnetocrystalline contribution of the high-temperature cubic phase with easy magnetic direction [111], without any additional contributions from particle surface, shape or exchange origin. The resulting values are incompatible with the uniaxial anisotropy of the low-temperature crystal structure of Fe3O4, suggesting that the high-temperature cubic structure is preserved below the Verwey transition in nanometric particles. Accordingly, fully oriented particles showed a continuous decrease of the M(T) curves, without discontinuities at TV . The thermal dependence of the hyperfine field B_hyp(T) was fitted by a simple model of collective magnetic excitations to calculate the single-particle magnetic anisotropy energy Ea. The resulting values give further suppo...

  16. Magnetodielectric study in SiO2-coated Fe3O4 nanoparticle compacts

    Science.gov (United States)

    Chang, Chung-Chieh; Zhao, Li; Wu, Maw-Kuen

    2010-11-01

    The dielectric properties of Fe3O4 magnetic nanoparticles with an insulating coating layer of SiO2 were investigated. At high temperatures, the changes in the dielectric constant and loss induced by the magnetic field are opposite in sign and strongly frequency-dependent, which originates from extrinsic magnetodielectric coupling-the Maxwell-Wagner effect combined with magnetoresistance. And the interface defects leads to the obvious hysteresis phenomena observed in the measurements. On the other hand, the strong coupling of dielectric and magnetic properties at low temperatures contradicts the Maxwell-Wagner model, suggesting the intrinsic magnetodielectric coupling. Our observations are consistent with the recent polarization switching measurements, which confirm the low-temperature multiferroic state existing in highly lossy Fe3O4. And the core/shell nanostructure may provide a new route to achieve applicable magnetoelectric materials with low loss.

  17. Polyethyleneimine-modified superparamagnetic Fe3O4 nanoparticles: An efficient, reusable and water tolerance nanocatalyst

    International Nuclear Information System (INIS)

    A novel magnetically separable catalyst was prepared based on surface modification of Fe3O4 magnetic nanoparticle (MNPs) with polyethyleneimine (PEI) via covalent bonding. [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane (EPO) was used as cross linker to bond PEI on the surface of MNPs with permanent stability in contrast to PEI coating via electrostatic interactions. The synthesized catalyst was characterized by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The catalyst show high efficiency for one-pot synthesis of 2-amino-3-cyano-4H-pyran derivatives via multi-component reaction (MCR). This procedure offers the advantages of green reaction media, high yield, short reaction time, easy purification of the products and simple recovery and reuse of the catalyst by simple magnetic decantation without significant loss of catalytic activity. - Graphical abstract: Covalently grafted polyethyleneimine on Fe3O4 magnetic nanoparticles as easily reusable catalyst for the synthesis of various 4H-pyrans. - Highlights: • Polyethyleneimine modified Fe3O4 via covalent bonding as a novel water tolerance catalyst. • The catalyst showed high efficiency for one-pot synthesis of 2-amino-3-cyano-4H-pyrans in water. • Catalysts could be easily recovered and reused for several times without a significant loss in their catalytic activity

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

    Science.gov (United States)

    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.

  19. Umbelliprenin-coated Fe3O4 magnetite nanoparticles: Antiproliferation evaluation on human Fibrosarcoma cell line (HT-1080)

    International Nuclear Information System (INIS)

    The potential applications of Fe3O4 magnetite nanoparticles (MNPs) in nanomedicine as drug delivery systems are well known. In this study we prepared umbelliprenin-coated Fe3O4 MNPs and evaluated the antiproliferative effect of combination in vitro. After synthesis of Fe3O4 MNPs, particles were characterized by transmission electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction spectroscopy techniques. The natural candidate compound - umbelliprenin- was isolated and identified and umbelliprenin-coated Fe3O4 MNPs were prepared, using precipitation method. The surface chemistry of umbelliprenin-coated Fe3O4 MNPs as well as their thermal decomposition characteristics was examined using Fourier transform infrared spectroscopy and Thermogravimetric Analyzer equipment, respectively. HT-1080 cells were cultured until the logarithmic phase of growth, and MTT assay was successfully carried out to evaluate the possible cytotoxic effects of umbelliprenin-coated Fe3O4 MNPs in viable cells in vitro. The results demonstrated that umbelliprenin has moderate antiproliferative effects with IC50 value of 50 ?g/mL. However, the combination of umbelliprenin and Fe3O4 MNPs showed the IC50 value of 9 ?g/mL. In other words, cell proliferation decreased to the remarkably-low proportion of 45% after treating cells with umbelliprenin-coated Fe3O4 MNPs. This suggests that with the aid of nanoparticles as carriers, natural products may have even broader range of medical applications in future.

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

    Science.gov (United States)

    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 (?OCT). 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 ?OCT.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 (?OCT). 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 ?OCT. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05459a

  1. Synthesis and characterization of Fe3O4 nanoparticles with perspectives in biomedical applications

    Scientific Electronic Library Online (English)

    Javier Bustamante, Mamani; Lionel Fernel, Gamarra; Giancarlo Espósito de Souza, Brito.

    2014-06-01

    Full Text Available Nowadays the use of magnetic nanoparticles (MNP) in medical applications has exceeded expectations. In molecular imaging, MNP based on iron oxide coated with appropriated materials have several applications in vitro and in vivo studies. For applications in nanobiotechnology these MNP must present so [...] me characteristics such as size smaller than 100 nanometers, high magnetization values, among others. Therefore the MNP have physical and chemical properties that are specific to certain studies which must be characterized for quality control of the nanostructured material. This study presents the synthesis and characterization of MNP of magnetite (Fe3O4) dispersible in water with perspectives in a wide range of biomedical applications. The characterization of the colloidal suspension based on MNP stated that the average diameter is (12.6±0.2) nm determined by Transmission Electron Microscopy where the MNP have the crystalline phase of magnetite (Fe3O4) that was identified by Diffraction X-ray and confirmed by Mössbauer Spectroscopy. The blocking temperature of (89±1) K, Fe3O4 MNP property, was determined from magnetic measurements based on the Zero Field Cooled and Field Cooled methods. The hysteresis loops were measured at different temperatures below and above blocking temperature. The magnetometry determined that the MNP showed superparamagnetic behavior confirmed by ferromagnetic resonance.

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

    Directory of Open Access Journals (Sweden)

    Dorniani D

    2012-11-01

    Full Text Available Dena Dorniani,1 Mohd Zobir Bin Hussein,1,2 Aminu Umar Kura,3 Sharida Fakurazi,3 Abdul Halim Shaari,4 Zalinah Ahmad51Chemistry Department, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 3Vaccines and Immunotherapeutics Laboratory, 4Physics Department, Faculty of Science, 5Chemical Pathology Unit, Department of Pathology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, MalaysiaBackground 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.Keywords: magnetic nanoparticles, chitosan, superparamagnetic, controlled-release, gallic acid, drug delivery

  3. Gum arabic modified Fe3O4 nanoparticles cross linked with collagen for isolation of bacteria

    Directory of Open Access Journals (Sweden)

    Chittor Raghuraman

    2010-12-01

    Full Text Available Abstract Background Multifunctional magnetic nanoparticles are important class of materials in the field of nanobiotechnology, as it is an emerging area of research for material science and molecular biology researchers. One of the various methods to obtain multifunctional nanomaterials, molecular functionalization by attaching organic functional groups to nanomagnetic materials is an important technique. Recently, functionalized magnetic nanoparticles have been demonstrated to be useful in isolation/detection of dangerous pathogens (bacteria/viruses for human life. Iron (Fe based material especially FePt is used in the isolation of ultralow concentrations (2 cfu/ml of bacteria in less time and it has been demonstrated that van-FePt may be used as an alternative fast detection technique with respect to conventional polymerase chain reaction (PCR method. However, still further improved demonstrations are necessary with interest to biocompatibility and green chemistry. Herein, we report the synthesis of Fe3O4 nanoparticles by template medication and its application for the detection/isolation of S. aureus bacteria. Results The reduction of anhydrous Iron chloride (FeCl3 in presence of sodium borohydride and water soluble polyelectrolyte (polydiallyldimethyl ammonium chloride, PDADMAC produces black precipitates. The X-ray diffraction (XRD, XPS and TEM analysis of the precipitates dried at 373 K demonstrated the formation of nanocrystalline Fe3O4. Moreover, scanning electron microscopy (SEM showed isolated staphylococcous aureus (S. aureus bacteria at ultralow concentrations using collagen coated gum arabic modified iron oxide nanoparticles (CCGAMION. Conclusion We are able to synthesize nanocrystalline Fe3O4 and CCGAMION was able to isolate S. aureus bacteria at 8-10 cfu (colony forming units/ml within ~3 minutes.

  4. Heat dissipation and magnetic properties of surface-coated Fe3O4 nanoparticles for biomedical applications

    Science.gov (United States)

    Tomitaka, Asahi; Ueda, Koji; Yamada, Tsutomu; Takemura, Yasushi

    2012-10-01

    In this study, the influence of surface coating on the magnetic and heat dissipation properties of Fe3O4 nanoparticles was investigated. Fe3O4 nanoparticles that ranged in size between (particle sizes of 20 and 30 nm) were coated with polyethylenimine (PEI), oleic acid, and Pluronic F-127. Surface coatings that were composed of thick layers of oleic acid and Pluronic F-127 reduced dipole interactions between the particles, and resulted in reduced coercivity and decreased Néel relaxation times. The ac magnetization measurements revealed that the heat dissipation of the PEI-coated Fe3O4 nanoparticles was induced by hysteresis loss and Brownian relaxation loss and that of the oleic-acid-coated Fe3O4 nanoparticles was mainly induced by hysteresis loss and Néel relaxation loss.

  5. Multifunctional polypyrrole@fe3o4 nanoparticles for dual-modal imaging and in vivo photothermal cancer therapy

    KAUST Repository

    Tian, Qiwei

    2013-11-27

    Magnetic Fe3O4 crystals are produced in situ on preformed polypyrrole (PPY) nanoparticles by rationally converting the residual Fe species in the synthetic system. The obtained PPY@Fe3O4 composite nanoparticles exhibit good photostability and biocompatibility, and they can be used as multifunctional probes for MRI, thermal imaging, and photothermal ablation of cancer cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Hydrothermal synthesis, off-axis electron holography and magnetic properties of Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (< 50 nm) from mixed FeCl3 / FeCl2 precursor solution at pH ? 12 has been confirmed using complementary characterisation techniques of transmission electron microscopy and X-ray diffractometry. Off-axis electron holography allowed for visualisation of their single domain (SD) nature, as well as inter-particle interactions, with the latter attributed to explain the pseudo-SD/multi-domain behaviour demonstrated by bulk magnetic measurements

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

    OpenAIRE

    Zhao, Baobao; Nan, Zhaodong

    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 sediment...

  8. Study on the adsorption of DNA on Fe3O4 nanoparticles and on ionic liquid-modified Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    We have investigated the adsorption of herring sperm DNA on Fe3O4 magnetic nanoparticles (NPs) before and after modification with the ionic liquid 1-hexyl-3-methylimidazolium bromide. Experiments were performed in a batch mode, and the effects of DNA concentration, pH of the sample solution, ionic strength, temperature, and contact time between reagents were optimized. An evaluation of the adsorption isotherm revealed that the Langmuir model better fits the equilibrium data than the Freundlich model. The maximum adsorption capacities of the unmodified and modified NPs, respectively, were found to be 11.8 and 19.8 mg DNA per gram of adsorbent. The adsorption of DNA onto the modified NPs was endothermic, while it was exothermic in the case of the unmodified NPs. The DNA can be desorbed from the modified surfaces of the NPs by using EDTA as the eluent. The NPs were able to adsorb about 90?±?1.5 % of DNA after being recycled for three times. The method is simple, fast, robust, and does not require organic solvents or sophisticated equipment. (author)

  9. Fabrication of docetaxel surfaced Fe3O4 magnetite nanoparticles and their cytotoxicity on 4?T1 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Yazdi MH

    2012-08-01

    Full Text Available Abstract Background In the recent years, there is an increasing attention to the using of Fe3O4 magnetite nanoparticles (MNPs as drug delivery systems. Application of this nanoparticles could profit advantages of nanomedicine to enhance biological activity of pharmaceutical ingredients. Methods Fe3O4 MNPs were synthesised by a chemical method and characterized by transmission electron microscopy and energy-dispersive spectroscopy techniques. In the next step, docetaxel-coated Fe3O4 MNPs were prepared, using percipitation method. The surface chemistry of docetaxel-coated Fe3O4 MNPs as well as their thermal decomposition characteristics were examined using fourier transform infrared spectroscopy and thermogravimetric analyzer equipment, respectively. The cytotoxicity assay was conducted on 4?T1 breast cancer carsinoma by MTT assay to evaluate the possible in vitro antiproliferative effects of docetaxel-coated Fe3O4 MNPs. Results During precipitation process, docetaxel molecules were precipitated on the surface of Fe3O4 MNPs by the ratio of 3:100 w/w which indicates that each milligram of coated Fe3O4 MNPs averagely contained 30??g pure docetaxel compound. Docetaxel showed aniproliferative effects against mentioned cell line. The higestest concentartion of docetaxel (80??g/ml caused about 80% cell death. However, the results demostarted that much lower amounts of docetaxel will be needed in combination of Fe3O4 MNPs to produce the potent antiproliferative effect compared to docetaxel alone. Dose response cytotoxicity assay of docetaxel-coated Fe3O4 MNPs against 4?T1 breast cancer cells showed that lower amount of docetaxel (0.6??g/ml can exhibit higher cytotoxic effect against this cancer cell line (90% cell death.

  10. Fabrication of Docetaxel Surfaced Fe3O4 Magnetite Nanoparticles and their Cytotoxicity on 4 T1 Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    MH Yazdi

    2012-08-01

    Full Text Available Background:In the recent years, there is an increasing attention to the using of Fe3O4 magnetite nanoparticles (MNPs as drug delivery systems. Application of this nanoparticles could profit advantages of nanomedicine to enhance biological activity of pharmaceutical ingredients. Methods:Fe3O4 MNPs were synthesised by a chemical method and characterized by transmission electron microscopy and energy-dispersive spectroscopy techniques. In the next step, docetaxel-coated Fe3O4 MNPs were prepared, using percipitation method. The surface chemistry of docetaxel-coated Fe3O4 MNPs as well as their thermal decomposition characteristics were examined using fourier transform infrared spectroscopy and thermogravimetric analyzer equipment, respectively. The cytotoxicity assay was conducted on 4 T1 breast cancer carsinoma by MTT assay to evaluate the possible in vitro antiproliferative effects of docetaxel-coated Fe3O4 MNPs. Results:During precipitation process, docetaxel molecules were precipitated on the surface of Fe3O4 MNPs by the ratio of 3:100 w/w which indicates that each milligram of coated Fe3O4 MNPs averagely contained 30 mug pure docetaxel compound. Docetaxel showed aniproliferative effects against mentioned cell line. The higestest concentartion of docetaxel (80 mug/ml caused about 80% cell death. However, the results demostarted that much lower amounts of docetaxel will be needed in combination of Fe3O4 MNPs to produce the potent antiproliferative effect compared to docetaxel alone. Dose response cytotoxicity assay of docetaxel-coated Fe3O4 MNPs against 4 T1 breast cancer cells showed that lower amount of docetaxel (0.6 mug/ml can exhibit higher cytotoxic effect against this cancer cell line (90% cell death.

  11. Characterization of the magnetic Fe3O4 nanoparticles prepared by gamma irradiation

    International Nuclear Information System (INIS)

    In this study, gamma irradiation treatment has been applied for preparation of the magnetic nanoparticles from iron(III) chloride (FeCl3). Structure of the resulting black powders were characterized with X-ray diffraction (XRD). The results revealed that the products prepared by gamma irradiation were mainly magnetite (Fe3O4) instead of maghemite (Fe2O3). The basic characteristics of the magnetite nanoparticles such as their particle size and magnetic properties were investigated using scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The nanoparticles showed superparamagnetism with the saturated magnetization of about 48.6 emu/g. Influences of radiation conditions on radiation preparation of magnetite nanoparticles and their properties were also discussed. Reaction yield increased, while average diameter of the obtained nanoparticles reduced from 46 to 17 nm depended on the absorbed dose. (author)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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 ?-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. Ethylene glycol methacrylate phosphate coated Fe3O4 nanoparticles for selective separation of plutonium

    International Nuclear Information System (INIS)

    Recovery of lanthanides and actinides from high level nuclear waste is an area of world-wide concern. Recently, interest has been focused on magnetic fluidized bed separation technology and the development of magnetically assisted chemical separation (MACS) systems for nuclear waste remediation. The magnetic-sorbent have larger surface area, can be quickly recovered from the medium using external magnetic field, and secondary waste is not generated. However, sorption selectivity and efficiency of these materials towards targeted radionuclides have still scope for improvement. Ethylene glycol methacrylate phosphate takes up actinides. Yudhisthira Sahoo and co-workers demonstrates that alkyl phosphonates and phosphates bind efficiently to iron oxide particle surfaces and can serve, in general, as potential alternatives to fatty acids as coating agents for oxide nanoparticles. In the present work, 0.1 g of Fe3O4 nanoparticles (20-30 nm) were dispersed in 10 mL 0.1 M Ethylene glycol methacrylate phosphate (EGMP) solution in methanol at room temperature under shaking condition for 24 h. Organic layer is then removed and the particles were washed 3 times with 1 mL methanol. It was the dried in air at room temperature overnight. Weighed amount of EGMP coated Fe3O4 nanoparticles were equilibrated with 241Am, 233U or 239Pu activity spiked in feed having acid concentration varying from 0.01-3.0 M HNO3

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

    Directory of Open Access Journals (Sweden)

    Zhao Baobao

    2011-01-01

    Full Text Available Abstract 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.

  16. Contribution of Fe3O4 nanoparticles to the fouling of ultrafiltration with coagulation pre-treatment

    Science.gov (United States)

    Yu, Wenzheng; Xu, Lei; Graham, Nigel; Qu, Jiuhui

    2015-08-01

    A coagulation (FeCl3)-ultrafiltration process was used to treat two different raw waters with/without the presence of Fe3O4 nanoparticle contaminants. The existence of Fe3O4 nanoparticles in the raw water was found to increase both irreversible and reversible membrane fouling. The trans-membrane pressure (TMP) increase was similar in the early stages of the membrane runs for both raw waters, while it increased rapidly after about 15 days in the raw water with Fe3O4 nanoparticles, suggesting the involvement of biological effects. Enhanced microbial activity with the presence of Fe3O4 nanoparticles was evident from the measured concentrations of extracellular polymeric substances (EPS) and deoxyribonucleic acid (DNA), and fluorescence intensities. It is speculated that Fe3O4 nanoparticles accumulated in the cake layer and increased bacterial growth. Associated with the bacterial growth is the production of EPS which enhances the bonding with, and between, the coagulant flocs; EPS together with smaller sizes of the nano-scale primary particles of the Fe3O4-CUF cake layer, led to the formation of a lower porosity, more resilient cake layer and membrane pore blockage.

  17. Facile deposition of gold nanoparticles on core-shell Fe3O4@polydopamine as recyclable nanocatalyst

    Science.gov (United States)

    Zhao, Yan; Yeh, Yaowen; Liu, Rui; You, Jinmao; Qu, Fengli

    2015-07-01

    A simple and green method for the controllable synthesis of core-shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs) with tunable shell thickness and their application as a recyclable nanocatalyst support is presented. Magnetite Fe3O4 NPs formed in a one-pot process by the hydrothermal approach with a diameter of ?240 nm were coated with a polydopamine shell layer with a tunable thickness of 15-45 nm. The facile deposition of Au NPs atop Fe3O4@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The satellite nanocatalysts exhibited high catalytic performance for the reduction of p-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 8 times without detectible loss in activity. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core-shell NPs as a versatile platform for potential applications.

  18. Alpha chymotrypsin coated clusters of Fe3O4 nanoparticles for biocatalysis in low water media

    Directory of Open Access Journals (Sweden)

    Mukherjee Joyeeta

    2012-11-01

    Full Text Available Abstract Background Enzymes in low water containing non aqueous media are useful for organic synthesis. For example, hydrolases in such media can be used for synthetic purposes. Initial work in this area was carried out with lyophilized powders of enzymes. These were found to have poor activity. Drying (removing bulk water by precipitation turned out to be a better approach. As enzymes in such media are heterogeneous catalysts, spreading these precipitates over a large surface gave even better results. In this context, nanoparticles with their better surface to volume ratio provide obvious advantage. Magnetic nanoparticles have an added advantage of easy separation after the reaction. Keeping this in view, alpha chymotrypsin solution in water was precipitated over a stirred population of Fe3O4 nanoparticles in n-propanol. This led to alpha chymotrypsin activity coated over clusters of Fe3O4 nanoparticles. These preparations were found to have quite high transesterification activity in low water containing n-octane. Results Precipitation of alpha chymotrypsin over a stirred suspension of Fe3O4 nanoparticles (3.6 nm diameter led to the formation of enzyme coated clusters of nanoparticles (ECCNs. These clusters were also magnetic and their hydrodynamic diameter ranged from 1.2- 2.6 microns (as measured by dynamic light scattering. Transmission electron microscopy (TEM, showed that these clusters had highly irregular shapes. Transesterification assay of various clusters in anhydrous n-octane led to optimization of concentration of nanoparticles in suspension during precipitation. Optimized design of enzyme coated magnetic clusters of nanoparticles (ECCN 3 showed the highest initial rate of 465 nmol min-1 mg-1protein which was about 9 times higher as compared to the simple precipitates with an initial rate of 52 nmol min-1 mg-1 protein. Circular Dichroism (CD(with a spinning cell accessory showed that secondary structure content of the alpha Chymotrypsin in ECCN 3 [15% ?-helix, 37% ?-sheet and 48% random coil] was identical to the simple precipitates of alpha chymotrypsin. Conclusion A strategy for obtaining a high activity preparation of alpha chymotrypsin for application in low water media is described. Such high activity biocatalysts are useful in organic synthesis.

  19. DBT degradation enhancement by decorating Rhodococcus erythropolis IGST8 with magnetic Fe3O4 nanoparticles.

    Science.gov (United States)

    Ansari, F; Grigoriev, P; Libor, S; Tothill, I E; Ramsden, J J

    2009-04-01

    Biodesulfurization (BDS) of dibenzothiophene (DBT) was carried out by Rhodococcus erythropolis IGST8 decorated with magnetic Fe3O4 nanoparticles, synthesized in-house by a chemical method, with an average size of 45-50 nm, in order to facilitate the post-reaction separation of the bacteria from the reaction mixture. Scanning electron microscopy (SEM) showed that the magnetic nanoparticles substantially coated the surfaces of the bacteria. It was found that the decorated cells had a 56% higher DBT desulfurization activity in basic salt medium (BSM) compared to the nondecorated cells. We propose that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product, respectively. Model experiments with black lipid membranes (BLM) demonstrated that the nanoparticles indeed enhance membrane permeability. PMID:19012265

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

    Science.gov (United States)

    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.

  1. Graphene oxide-Fe3O4 nanoparticle composite with high transverse proton relaxivity value for magnetic resonance imaging

    International Nuclear Information System (INIS)

    The potential of graphene oxide–Fe3O4 nanoparticle (GO-Fe3O4) composite as an image contrast enhancing material in magnetic resonance imaging has been investigated. Proton relaxivity values were obtained in three different homogeneous dispersions of GO-Fe3O4 composites synthesized by precipitating Fe3O4 nanoparticles in three different reaction mixtures containing 0.01?g, 0.1?g, and 0.2?g of graphene oxide. A noticeable difference in proton relaxivity values was observed between the three cases. A comprehensive structural and magnetic characterization revealed discrete differences in the extent of reduction of the graphene oxide and spacing between the graphene oxide sheets in the three composites. The GO-Fe3O4 composite framework that contained graphene oxide with least extent of reduction of the carboxyl groups and largest spacing between the graphene oxide sheets provided the optimum structure for yielding a very high transverse proton relaxivity value. It was found that the GO-Fe3O4 composites possessed good biocompatibility with normal cell lines, whereas they exhibited considerable toxicity towards breast cancer cells

  2. The effect of Fe3O4 nanoparticles on the thermal conductivities of various base fluids.

    Science.gov (United States)

    Altan, Cem L; Bucak, Seyda

    2011-07-15

    Conventional heat transfer fluids have intrinsically poor heat transfer properties compared to solids. Enhancing the efficiency of heat transfer is of great interest for various industrial applications. Suspending solid particles in a fluid increases the thermal conductivity of the resulting suspension and enhances the heat transfer properties. In this work, changes in thermal conductivities of fluids upon the addition of magnetic nanoparticles have been investigated. Fe(3)O(4) nanoparticles are synthesized using different synthesis methods and are suspended in various oils. The effect of the base fluid and the type of magnetic particle on the thermal conductivity is investigated in detail. Up to 28% increase in the thermal conductivity is obtained with 2.5 wt% magnetic particles in hexane. The thermal conductivity enhancement is found to depend on the particle concentration, method of preparation and base fluid. The enhancements obtained are higher than those estimated using any theoretical model present in the literature. PMID:21659690

  3. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    Science.gov (United States)

    Feygenson, Mikhail; Bauer, John C.; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S.; Beyer, Kevin A.; Dai, Sheng

    2015-08-01

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron-scattering, synchrotron x-ray diffraction, and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wüstite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatch between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into the FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed, presumably across the interface to accommodate an excess of oxygen released during the reduction of magnetite.

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

    Science.gov (United States)

    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 30pgmL(-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

  5. Uniform PEGylated PLGA Microcapsules with Embedded Fe3O4 Nanoparticles for US/MR Dual-Modality Imaging.

    Science.gov (United States)

    Xu, Sijia; Yang, Fei; Zhou, Xiao; Zhuang, Yaping; Liu, Baoxia; Mu, Yang; Wang, Xing; Shen, Hong; Zhi, Guang; Wu, Decheng

    2015-09-16

    Well-designed agents for enhanced multimodal imaging have attracted great interests in recent years. In this work, we adopted a premix membrane emulsification (PME) method to prepare uniform PEGylated poly(lactic-co-glycolic acid) (PLGA) microcapsules (MCs) with superparamagnetic Fe3O4 nanoparticles (NPs) embedded in the shell (Fe3O4@PEG-PLGA MCs) for ultrasound (US)/magnetic resonance (MR) bimodal imaging. Compared to Fe3O4@PLGA MCs without PEGylation, Fe3O4@PEG-PLGA MCs could more stably and homogeneously disperse in physiological solutions. In vitro and in vivo trials demonstrated that Fe3O4@PEG-PLGA MCs (?3.7 ?m) with very narrow size distribution (PDI=0.03) could function as efficient dual-modality contrast agents to simultaneously enhance US and MR imaging performance greatly. In vitro cell toxicity and careful histological examinations illustrated no appreciable cytotoxicity and embolism of Fe3O4@PEG-PLGA MCs to mice even at high dose. The uniform composite MCs developed here can act as clinical bimodal contrast agents to improve hybrid US/MR imaging contrast, which is promising for accurate diagnosis and real-time monitoring of difficult and complicated diseases. PMID:26327472

  6. UCST-like hybrid PAAm-AA/Fe3O4 microgels. Effect of Fe3O4 nanoparticles on morphology, thermosensitivity and elasticity.

    Science.gov (United States)

    Echeverria, Coro; Mijangos, Carmen

    2011-07-01

    The incorporation of metal oxide nanoparticles into microgels forming hybrid systems gives additional functionalities to the system and widens the field of potential application in biomedicine, biotechnology, and other fields. In particular, there have been very few investigations regarding UCST-like hybrid microgels. In connection with this, we report the preparation of UCST-like hybrid microgels of magnetite nanoparticles (Fe(3)O(4)) encapsulated in poly(acrylamide-acrylic acid) microgel matrix via an inverse emulsion polymerization method. The key factor in the preparation of hybrid microgels is the need to divide in two the aqueous phase of the emulsion and feed them separately in order to avoid the aggregation of magnetic nanoparticles prior to polymerization reaction. The morphology, size, and spherical shape of hybrid microgels are determined by scanning electron microscopy. The encapsulation of magnetite nanoparticles within the polymer matrix is confirmed by transmission electron microscopy. Dynamic light scattering is employed to study both the swelling UCST-like behavior and the surface charge of the hybrid microgels. Swelling measurements confirm that the incorporation of magnetite does not affect the thermosensitivity of the system. In order to highlight the rheological behavior that can affect the final potential applications of these hybrid systems, a deep study of the viscoelastic properties is carried out by means of an oscillatory rheometer. The dependence of G' and G'' of the microgel dispersions with the frequency suggests a gel-like behavior and hence the occurrence of structural organization. In order to understand this structure formation and the influence of the magnetite in the interaction between hybrid microgels, scaling theory was applied. In terms of rheology, the addition of magnetite leads to a change in the interaction between hybrid microgels giving rise to an increase in the elasticity of the system. PMID:21630668

  7. Mechanism and controlled growth of shape and size variant core/shell FeO/Fe3O4 nanoparticles

    Science.gov (United States)

    Khurshid, Hafsa; Li, Wanfeng; Chandra, Sayan; Phan, Manh-Huong; Hadjipanayis, George C.; Mukherjee, Pritish; Srikanth, Hariharan

    2013-08-01

    We report a novel synthesis approach for the growth of core/shell FeO/Fe3O4 nanoparticles with controlled shape and size. FeO particles were partially oxidized to form core/shell FeO/Fe3O4 structures, as evidenced from transmission electron microscopy, X-ray diffraction, and magnetometry analysis. We find that the molar ratios and concentrations of surfactants are the key parameters in controlling the particle size. The particles can grow in either isotropic or anisotropic shapes, depending upon a chemical reaction scheme that is controlled kinetically or thermodynamically. The competitive growth rates of {111} and {100} facets can be used to tune the final shape of nanoparticles to spherical, cubic, octahedral, octopod, and cuboctahedral geometries. FeO particles can also be oxidized chemically or thermally to form Fe3O4 nanoparticles. By following the same synthesis technique, it is possible to synthesize rods and triangles of Fe3O4 by introducing twinnings and defects into the crystal structure of the seed. The thermally activated first-order Verwey transition at ~120 K has been observed in all the synthesized FeO/Fe3O4 nanoparticles, indicating its independence from the particle shape. These core/shell nanoparticles exhibit a strong shift in field-cooled hysteresis loops accompanied by an increase in coercivity (the so-called exchange bias effect), but the low field-switching behavior appears to vary with the particle shape.

  8. The synthesis and application of Au/Fe3O4 nanoparticles as catalysts in PEM fuel cell

    Science.gov (United States)

    Yuan, Muzhaozi

    As an alternative energy source, PEM fuel cell has low operating temperatures, low carbon dioxide emission and high power densities. However the high price of platinum electrodes restrains it from being widely used in industry. The sintering of platinum nanoparticles is another serious problem which acts as a barrier of PEM fuel cell popularization. Current research regarding PEM fuel cell is mainly focused on the design of catalyst used to improve the power output while reduce the cost. Our research brings out a new strategy to design a new type of catalyst of this kind by introducing the metal oxide into the gold nanostructure. In this thesis, the gold nanoparticles, Fe 3O4 nanoparticles as well as the nanoparticles (Au/ Fe 3O4) with Fe3O4 as core and gold as shell were synthesized at first. Then Langmuir-Blodgett (LB) trough technique was used to coat different nanoparticles onto the Nafion membranes. Membranes with coating and without coating were tested in PEM fuel cell device. The voltage and current were recorded to calculate the power output enhanced by each type of corresponding nanoparticles. It is shown in the test that the Au/ Fe3O4 catalyst boosted the performance of PEM fuel cell by increasing the power output to 117% of the control sample. The costs to the same level of power output when using different nanoparticles were analyzed and compared as well. The results show the Au/ Fe3O 4 nanoparticles have the best performance-cost ratio compared with pure gold nanoparticles and Fe3O4 nanoparticles.

  9. Polyethyleneimine-modified superparamagnetic Fe3O4 nanoparticles: An efficient, reusable and water tolerance nanocatalyst

    Science.gov (United States)

    Khoobi, Mehdi; Delshad, Tayebeh Modiri; Vosooghi, Mohsen; Alipour, Masoumeh; Hamadi, Hosein; Alipour, Eskandar; Hamedani, Majid Pirali; Sadat ebrahimi, Seyed Esmaeil; Safaei, Zahra; Foroumadi, Alireza; Shafiee, Abbas

    2015-02-01

    A novel magnetically separable catalyst was prepared based on surface modification of Fe3O4 magnetic nanoparticle (MNPs) with polyethyleneimine (PEI) via covalent bonding. [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane (EPO) was used as cross linker to bond PEI on the surface of MNPs with permanent stability in contrast to PEI coating via electrostatic interactions. The synthesized catalyst was characterized by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The catalyst show high efficiency for one-pot synthesis of 2-amino-3-cyano-4H-pyran derivatives via multi-component reaction (MCR). This procedure offers the advantages of green reaction media, high yield, short reaction time, easy purification of the products and simple recovery and reuse of the catalyst by simple magnetic decantation without significant loss of catalytic activity.

  10. Differential response of macrophages to core-shell Fe3O4@Au nanoparticles and nanostars

    Science.gov (United States)

    Xia, Wei; Song, Hyon-Min; Wei, Qingshan; Wei, Alexander

    2012-10-01

    Murine RAW 264.7 cells were exposed to spheroidal core-shell Fe3O4@Au nanoparticles (SCS-NPs, ca. 34 nm) or nanostars (NSTs, ca. 100 nm) in the presence of bovine serum albumin, with variable effects observed after macrophagocytosis. Uptake of SCS-NPs caused macrophages to adopt a rounded, amoeboid form, accompanied by an increase in surface detachment. In contrast, the uptake of multibranched NSTs did not induce gross changes in macrophage shape or adhesion, but correlated instead with cell enlargement and signatures of macrophage activation such as TNF-? and ROS. MTT assays indicate a low cytotoxic response to either SCS-NPs or NSTs despite differences in macrophage behavior. These observations show that differences in NP size and shape are sufficient to produce diverse responses in macrophages following uptake.Murine RAW 264.7 cells were exposed to spheroidal core-shell Fe3O4@Au nanoparticles (SCS-NPs, ca. 34 nm) or nanostars (NSTs, ca. 100 nm) in the presence of bovine serum albumin, with variable effects observed after macrophagocytosis. Uptake of SCS-NPs caused macrophages to adopt a rounded, amoeboid form, accompanied by an increase in surface detachment. In contrast, the uptake of multibranched NSTs did not induce gross changes in macrophage shape or adhesion, but correlated instead with cell enlargement and signatures of macrophage activation such as TNF-? and ROS. MTT assays indicate a low cytotoxic response to either SCS-NPs or NSTs despite differences in macrophage behavior. These observations show that differences in NP size and shape are sufficient to produce diverse responses in macrophages following uptake. Electronic supplementary information (ESI) available: Synthetic details, additional TEM images, absorbance spectra, and DLS analysis of SCS-NPs and NSTs, negative and positive control images of ROS imaging, and the effect of magnetic field gradient on ROS production. See DOI: 10.1039/c2nr32070c

  11. Correlation of structural and magnetic properties of Fe3O4 nanoparticles with their calorimetric and magnetorheological performance

    International Nuclear Information System (INIS)

    Magnetic particles based on Fe3O4 were prepared by means of the microwave solvothermal method under different reaction conditions with the intention of their utilization as a mediator in magnetic hyperthermia and material for reducing blood flow in the tumor area. The synthesized particles were characterized in terms of their structure, size, shape, and magnetic properties with an emphasis on the correlation between particle morphology and magnetic properties. Most importantly, their heat development when exposed to an alternating magnetic field was determined, as well as the rheological behavior of their suspensions under static magnetic field. Reasonable heat development and substantial flow resistance under the effect of magnetic field indicate their potential for applications such as hyperthermia mediators or substances for temporary embolization. - Highlights: ? Fe3O4 nanoparticles were obtained by microwave-assisted synthesis ? Nucleation agents affect morphological and magnetic properties of nanoparticles. ? Aqueous ammonia nucleated Fe3O4 nanoparticles show high heating ability in AC magnetic field due to Neel relaxation. ? Suspension of Fe3O4 in silicone oil demonstrates flow resistance under DC magnetic field caused by chain formation. ? Fe3O4 nanoparticles has potential as a hyperthermia mediator and substance for temporary embolization.

  12. Fe3O4/Salicylic acid nanoparticles behavior on chick CAM vasculature

    International Nuclear Information System (INIS)

    A modified ferrite co-precipitation synthesis was used to obtain core–shell Fe3O4/salicylic acid magnetic nanoparticles (Sa-MNP) with well-dispersed aqueous solution properties. The newly developed iron oxide nanoparticles properties were investigated with X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, and laser light scattering for their characteristic establishment. The resulting Sa-MNPs have spherical morphology, homogenous size distribution around 60 nm (35 nm FWHM), and a 67 mV Zeta potential value (15.5 mV STDV). In vivo biocompatibility and intravascular behavior of the 60 nm diameter size range synthesized nanoparticles were evaluated on chick chorioallantoic membrane model. The results show a reversible and good controlled intravascular accumulation under static magnetic field, a low risk of embolisation with nanoparticle aggregates detached from venous intravascular nanoblocked areas, a persistent blocking of the arterioles and dependent capillaries network, a good circulating life time and biocompatibility. The beneficial effects of salicylic acid (SA) and in vivo demonstrated capacity of Sa-MNPs to cutoff regional vascular supply under static magnetic field control suggest a possible biomedical application of these MNPs in targeted cancer therapy through magnetic controlled blood flow nanoblocking mechanism

  13. Investigation of magnetic properties of Fe3O4 nanoparticles using temperature dependent magnetic hyperthermia in ferrofluids

    International Nuclear Information System (INIS)

    Rate of heat generated by magnetic nanoparticles in a ferrofluid is affected by their magnetic properties, temperature, and viscosity of the carrier liquid. We have investigated temperature dependent magnetic hyperthermia in ferrofluids, consisting of dextran coated superparamagnetic Fe3O4 nanoparticles, subjected to external magnetic fields of various frequencies (188–375 kHz) and amplitudes (140–235 Oe). Transmission electron microscopy measurements show that the nanoparticles are polydispersed with a mean diameter of 13.8?±?3.1?nm. The fitting of experimental dc magnetization data to a standard Langevin function incorporating particle size distribution yields a mean diameter of 10.6?±?1.2?nm, and a reduced saturation magnetization (?65?emu/g) compared to the bulk value of Fe3O4 (?95?emu/g). This is due to the presence of a finite surface layer (?1?nm thickness) of non-aligned spins surrounding the ferromagnetically aligned Fe3O4 core. We found the specific absorption rate, measured as power absorbed per gram of iron oxide nanoparticles, decreases monotonically with increasing temperature for all values of magnetic field and frequency. Using the size distribution of magnetic nanoparticles estimated from the magnetization measurements, we have fitted the specific absorption rate versus temperature data using a linear response theory and relaxation dissipation mechanisms to determine the value of magnetic anisotropy constant (28?±?2?kJ/m3) of Fe3O4 nanoparticles.

  14. Optically transparent magnetic nanocomposites based on encapsulated Fe3O4 nanoparticles in a sol-gel silica network

    International Nuclear Information System (INIS)

    Composite Fe3O4-SiO2 materials were prepared by the sol-gel method with tetraethoxysilane and aqueous-based Fe3O4 ferrofluids as precursors. The monoliths obtained were crack free and showed both optical and magnetic properties. The structural properties were determined by infrared spectroscopy, x-ray diffractometry and transmission electron microscopy. Fe3O4 particles of 20 nm size lie within the pores of the matrix without any strong Si-O-Fe bonding. The well established silica network provides effective confinement to these nanoparticles. The composites were transparent in the 600-800 nm regime and the field dependent magnetization curves suggest that the composite exhibits superparamagnetic characteristics

  15. Synthesis of M–Nd doped Fe3O4 nanoparticles (M = Co, Ce, Cr, Ni with tunable magnetic properties

    Directory of Open Access Journals (Sweden)

    P. Alimard

    2013-04-01

    Full Text Available Magnetic nanoparticles were prepared by the aqueous co-precipitation method. The magnetic nanoparticles obtained were characterized systematically through the use of an X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDS, scanning electron microscope (SEM, transmission electron microscope (TEM, Fourier transform infrared spectroscopy (FT-IR and a vibrating sampling magnetometer (VSM. The results revealed that the magnetic nanoparticles were spherical shaped with inverse spinel structure. The size of Fe3O4 and Nd-Co doped Fe3O4 magnetic nanoparticles were approximately 15 nm. Magnetic measurement revealed that the nanoparticles were super paramagnetic at room temperature. It was found that the magnetic response of the Fe3O4 increased when it was doped with Nd3+ and Co2+. However, the magnetic response of the Fe3O4 decreased when it was doped with Nd3+ or Ce3+ or Cr3+or Ni2+.DOI: http://dx.doi.org/10.4314/bcse.v27i1.5

  16. Investigation on transformation of spindle-like Fe3O4 nanoparticles from self-assembling ?-Fe2O3

    Science.gov (United States)

    Huang, Zhaocong; Meng, Hong; Yuan, Shijun; Zhang, Wen; Liu, Er; Zhang, Dong; Kou, Zhaoxia; Zhai, Ya; Wang, Baoping; Zhai, Hongru

    2015-05-01

    Porous monodisperse spindle-like ?-Fe2O3 nanomaterials are first synthesized successfully by a hydrothermal method, and then the as-prepared nanoparticles are annealed at different temperatures under various atmospheres to achieve the spindle-like Fe3O4 nanoparticles. The evolution of the features of nanoparticles, including the changes of the structures and microstructures as well as the magnetic properties, during the reduction process has been investigated by using the Raman spectrum and Mössbauer spectrum. Our research reveals that the ?-Fe2O3 nanoparticles annealed by covering of the C powder become a mixture of ?-Fe2O3 and Fe3O4 in the range of annealing temperature from 300 °C to 800 °C. With reduced atmospheric H2, spindle-like ?-Fe2O3 nanoparticles are transferred to mixture of ?-Fe2O3, Fe3O4 and Fe as temperature increases. They are also converted from a typical rhombohedral structure to a cubic ?-Fe phase at 500 °C. Finally, with the atmosphere of H2/Ar (5%/95%), a pure Fe3O4 phase, and its excellent magnetic properties are achieved at 450 °C.

  17. Synthesis and characterization of polyethylene glycol (PEG) coated Fe3O4 nanoparticles by chemical co-precipitation method for biomedical applications

    Science.gov (United States)

    Anbarasu, M.; Anandan, M.; Chinnasamy, E.; Gopinath, V.; Balamurugan, K.

    2015-01-01

    Polyethylene glycol (PEG) coated Fe3O4 nanoparticles were synthesized by chemical co-precipitation method. With polyethylene glycol (PEG) as a stabilizer and dispersant. The X-ray diffraction and selected area electron diffraction (SAED) results show that the cubic inverse spinel structure of pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FT-IR) results suggested that PEG indicated with Fe3O4 via its carbonyl groups. Results of vibrating sample magnetometer (VSM) indicated that the prepared Fe3O4 nanoparticles exhibit superparamagnetic behavior and high saturation magnetization at room temperature. Such Fe3O4 nanoparticles with favorable size and tunable magnetic properties are promising biomedical applications.

  18. Synergistic effect of magnetic nanoparticles of Fe3O4 with gambogic acid on apoptosis of K562 leukemia cells

    Directory of Open Access Journals (Sweden)

    Baoan Chen

    2009-11-01

    Full Text Available Baoan Chen1,*, Yiqiong Liang1,*, Weiwei Wu1, Jian Cheng1, Guohua Xia1, Feng Gao1, Jiahua Ding1, Chong Gao1, Zeye Shao1, Guohong Li1, Wenji Chen1, Wenlin Xu2, Xinchen Sun3, Lijie Liu4, Xiaomao Li5, Xuemei Wang61Department of Hematology; 3Department of Oncology, The Affiliated Zhongda Hospital, Clinical Medical School, Southeast University, Nanjing, People’s Republic of China; 2Department of Hematology, The Affiliated People’s Hospital, Jiangsu University, Zhenjiang, People’s Republic of China; 4Institution of Physiology, Southeast University, Nanjing, People’s Republic of China; 5Department of Physics, University of Saarland, Saarbruechen, Germany; 6State Key Lab of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, Peoples Republic of China; *These authors have contributed equally to this workAbstract: Gambogic acid (GA has a significant anticancer effect on a wide variety of solid tumors. Recently, many nanoparticles have been introduced as drug-delivery systems to enhance the efficiency of anticancer drug delivery. The aim of this study was to investigate the potential benefit of combination therapy with GA and magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4. The proliferation of K562 cells and their cytotoxicity were evaluated by MTT assay. Cell apoptosis was observed and analyzed by microscope and flow cytometry, respectively. Furthermore, realtime polymerase chain reaction and Western blotting analyses were performed to examine gene transcription and protein expression, respectively. The results showed that MNPs-Fe3O4 dramatically enhanced GA-induced cytotoxicity and apoptosis in K562 cells. The typical morphological features of apoptosis treated with GA and MNPs-Fe3O4 were observed under an optical microscope and a fluorescence microscope, respectively. The transcription of caspase-3 and bax gene in the group treated with GA and MNPs-Fe3O4 was higher than that in the GA-alone group or MNPs-Fe3O4-alone group, but the transcription of bcl-2, nuclear factor-?B, and survivin degraded as did the expression of corresponding proteins in K562 cells. Our data suggests a potential clinical application of a combination of GA and MNPs-Fe3O4 in leukemia therapy.Keywords: gambogic acid, magnetic nanoparticles of Fe3O4, traditional Chinese medicine, K562 leukemia cells, apoptosis

  19. Magnetic properties of Cr doped Fe3O4 porous nanoparticles prepared through a co-precipitation method using surfactant

    International Nuclear Information System (INIS)

    Magnetic Cr3+xFe3+2 ? xFe2+O4 (0 ? x  ?  0.1) porous nanoparticles were prepared by the aqueous co-precipitation method. The resulting magnetic nanoparticles were characterized by using an x-ray diffraction (XRD), field enhanced scanning electron microscope (FESEM), transmission electron microscope (TEM), and vibrating sampling magnetometer (VSM). The nitrogen gas adsorption/desorption isotherm showed a microporous structure of the obtained magnetic materials. A rod and round shape of Fe3O4 was observed as using polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) surfactant, respectively. The Fe3O4 nanoparticles exhibited superparamagnetic properties with easy separation and re-dispersion in solution by using an external magnet. More remarkably, the saturation magnetization (Ms) was enhanced up to 1.2 times for doping Cr3+ into the Fe3O4 lattice. The effect of surfactants and Cr3+ doping concentrations on size and the magnetic properties of Fe3O4 nanoparticles are studied. (paper)

  20. Sulphamic acid-functionalized magnetic Fe3O4 nanoparticles as recyclable catalyst for synthesis of imidazoles under microwave irradiation

    Indian Academy of Sciences (India)

    Javad Safari; Zohre Zarnegar

    2013-07-01

    Trisubstituted imidazoles have been synthesized in high yield in the presence of sulphamic acidfunctionalized magnetic Fe3O4 nanoparticles (SA-MNPs) as a novel solid acid catalyst under solvent-free classical heating conditions or using microwave irradiation. The heterogeneous catalyst could be recovered easily and reused many times without significant loss of catalytic activity.

  1. Particle speciation during PEG–Fe3O4 hybrid nanoparticle self-assembly on Si(Ti)O2

    International Nuclear Information System (INIS)

    The kinetics of assembly of polyethylene glycol (PEG)-coated superparamagnetic Fe3O4 nanoparticles in aqueous suspension on planar Si(Ti)O2 surfaces have been determined using high-resolution optical waveguide lightmode spectroscopy (OWLS). Analysis of the results revealed that the initially uniform population was spontaneously transformed into two types of particles with significantly different adsorption behaviour.

  2. Magnetic iron oxide (Fe3O4) nanoparticles from tea waste for arsenic removal

    International Nuclear Information System (INIS)

    Magnetic iron oxide nanoparticles (MION-Tea) successfully synthesized using tea waste template. MION-Tea exhibit super magnetic properties under external magnetic field with saturation magnetization value of 6.9 emu/g at room temperature. SEM of MION-Tea shows cuboid/pyramid shaped crystals structure of Fe3O4 (magnetite). TEM of MION-Tea shows the particle size in the range of 5–25 nm. XRD pattern of MION-Tea is identical to magnetite. Magnetic nanoparticles are tested for removal of As(III) and As(V) from aqueous solution. The adsorption data obeyed the Langmuir equation with high adsorption capacity of 188.69 mg/g for arsenic (III), and 153.8 mg/g for arsenic (V). The mean sorption energy (E) calculated from D–R model, indicated physico-chemical sorption process. A pseudo-second-order kinetic model fitted best for As(III) adsorption on MION-Tea and the derived activation energy was 64.27 kJ/mol. Thermodynamics revealed the endothermic nature of adsorption. The effects of solution pH, interfering anions and initial As(III) concentration have been investigated. MION-Tea was very low cost (Rs. 136 per kg). MION-Tea can be reused up to 5 adsorption cycles and regenerated using NaOH. Cost of As(III) removal from water of was estimated to be Rs. 14 for 100 L. Comparison with reported adsorbents proved MION-Tea a potential adsorbent for As(III) and As(V) adsorption. - Highlights: • Used tea has been used to prepare magnetic nanoparticles. • Nanoparticles have particle size of 2-25nm and cuboid/pyramid structure. • Magnetic nanoparticles show high adsorption capacity for arsenic

  3. Preparation and characterization of poly(glycidyl methacrylate)-grafted magnetic nanoparticles: Effects of the precursor concentration on polyol synthesis of Fe3O4 and [PMDETA]0/[CuBr2]0 ratios on SI-AGET ATRP

    Science.gov (United States)

    Jiang, Liping; Zhou, Xuyang; Wei, Guyun; Lu, Xiaoduo; Wei, Weiping; Qiu, Jianhua

    2015-12-01

    Polymer brushes based on poly(glycidyl methacrylate) (PGMA) have been successfully grafted from the surface of silica coated iron oxide (Fe3O4@SiO2) nanoparticles via surface-initiated activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The size of the nanoparticles could be adjusted from 7.3 to 9.6 nm by varying the precursor concentration of iron(III) acetylacetonate. The Fe3O4 nanoparticles possessed a highly crystalline structure, and the saturation magnetization of the as-prepared magnetite was strongly related to the particle size. Furthermore, the grafted PGMA content on the magnetic nanoparticles could be controlled by varying the ligand to transition metal ratio in a N,N,N?,N?,N?-pentamethyldiethylenetriamine (PMDETA)/CuBr2 catalyst system. The maximum grafted content was 23.1% at a ratio of [PMDETA]0/[CuBr2]0 = 2:1.

  4. The changes of T lymphocytes and cytokines in ICR mice fed with Fe3O4 magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Wang J

    2011-04-01

    Full Text Available Jun Wang1, Baoan Chen1, Nan Jin1, Guohua Xia2, Yue Chen1, Ying Zhou1, Xiaohui Cai1,2, Jiahua Ding1, Xiaomao Li3, Xuemei Wang41Department of Hematology, Zhongda Hospital, 2Department of Medical Laboratory, Medical School, Southeast University, Nanjing, People's Republic of China; 3Department of Physics, University of Saarland, Saarbruecken, Germany; 4National Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, People’s Republic of ChinaAbstract: The aim of this article is to study the changes inhibited T lymphocytes and cytokines related to the cellular immunity in ICR (imprinting control region mice fed with Fe3O4 magnetic nanoparticles (Fe3O4-MNPs. The Fe3O4-MNPs were synthesized, and their characteristics such as particle size, zeta potential, and X-ray diffraction patterns were measured and determined. All ICR mice were sacrificed after being exposed to 0, 300, 600, and 1200 mg/kg of Fe3O4-MNPs by single gastric administration for 14 days. Splenocytes proliferation was indicated with stimulate index by MTT assay; release of cytokines in the serum of ICR mice was detected by enzyme-linked immunosorbent assay, and the phenotypic analyses of T-lymphocyte subsets were performed using flow cytometry. Our results indicated that there were no significant differences in splenocyte proliferation and release of cytokines between exposed and control groups. Furthermore, there was no significant difference in the proportions of T-lymphocyte subsets in the low-dose Fe3O4-MNPs group when compared to the control group, but the proportions of CD3+CD4+ and CD3+CD8+ T-lymphocyte subsets both in the medium- and high-dose Fe3O4-MNPs groups were higher than those in the control group. It is concluded that a high dose of Fe3O4-MNPs, to some extent, could influence in vivo immune function of normal ICR mice.Keywords: Fe3O4, magnetic nanoparticles, splenocyte proliferation, release of cytokines, T-lymphocyte subsets, ICR mice

  5. Passively Q-switched EDFL using Fe3O4-nanoparticle saturable absorber

    CERN Document Server

    Bai, Xuekun; Xu, Luxi; Huang, Sujuan; Wang, Tingyun; Pu, Shengli; Zeng, Xianglong

    2015-01-01

    We experimentally demonstrate a passively Q-switched erbium-doped fiber laser (EDFL) operation by using a saturable absorber based on Fe3O4 nanoparticles (FONP) in magnetic fluid (MF). As a kind of transition metal oxide, the FONP has a large nonlinear optical response with a fast response time for saturable absorber. By depositing MF at the end of optical fiber ferrule, we fabricated a FONP-based saturable absorber, which enables a strong light-matter interaction owing to the confined transmitted optical field within the single mode fiber. Because of large third-order optical nonlinearities of FONP-based saturable absorber, large modulation depth of 8.2% and non saturable absorption of 56.6% are demonstrated. As a result, stable passively Q-switched EDFL pulses with maximum output pulse energy of 23.76 nJ, repetition rate of 33.3 kHz, and pulse width of 3.2 {\\mu}s are achieved when the input pump power is 110 mW at the wavelength of 980 nm. The laser features a low threshold pump power of ~15 mW.

  6. Observation of superspin-glass behavior in Fe3O4 nanoparticles

    Science.gov (United States)

    Suzuki, Masatsugu; Fullem, Sharbani I.; Suzuki, Itsuko S.; Wang, Lingyan; Zhong, Chuan-Jian

    2009-01-01

    The aging and memory effects of Fe3O4 nanoparticles have been studied using a series of zero-field-cooled (ZFC) and field-cooled magnetization measurements at various aging protocols. The genuine ZFC magnetization after the ZFC procedure with a single stop and wait process shows an aging dip at the stop temperature on reheating. The depth of the aging dip is dependent on the wait time. The frequency dependence of the ac magnetic susceptibility is indicative of critical slowing down at a freezing temperature Tf (=30.6±1.6K) . The relaxation time ? is described by a power-law form with a dynamic critical exponent x (=8.2±1.0) and a microscopic relaxation time ?0 [=(1.33±0.05)×10-9s] . The ZFC-peak temperature decreases with increasing magnetic field (H) , forming a critical line with an exponent p=1.78±0.26 , close to the de Almeida-Thouless exponent (p=3/2) . These results indicate that the superspin-glass phase occurs below Tf .

  7. Multifunctional glucose biosensors from Fe3O4 nanoparticles modified chitosan/graphene nanocomposites

    Science.gov (United States)

    Zhang, Wenjing; Li, Xiaojian; Zou, Ruitao; Wu, Huizi; Shi, Haiyan; Yu, Shanshan; Liu, Yong

    2015-06-01

    Novel water-dispersible and biocompatible chitosan-functionalized graphene (CG) has been prepared by a one-step ball milling of carboxylic chitosan and graphite. Presence of nitrogen (from chitosan) at the surface of graphene enables the CG to be an outstanding catalyst for the electrochemical biosensors. The resulting CG shows lower ID/IG ratio in the Raman spectrum than other nitrogen-containing graphene prepared using different techniques. Magnetic Fe3O4 nanoparticles (MNP) are further introduced into the as-synthesized CG for multifunctional applications beyond biosensors such as magnetic resonance imaging (MRI). Carboxyl groups from CG is used to directly immobilize glucose oxidase (GOx) via covalent linkage while incorporation of MNP further facilitated enzyme loading and other unique properties. The resulting biosensor exhibits a good glucose detection response with a detection limit of 16??M, a sensitivity of 5.658?mA/cm2/M, and a linear detection range up to 26?mM glucose. Formation of the multifunctional MNP/CG nanocomposites provides additional advantages for applications in more clinical areas such as in vivo biosensors and MRI agents.

  8. Hybrid composites made of multiwalled carbon nanotubes functionalized with Fe3O4 nanoparticles for tissue engineering applications

    International Nuclear Information System (INIS)

    A straightforward technique for functionalization of multiwalled carbon nanotubes (MWCNTs) with magnetite (Fe3O4) nanoparticles was developed. Iron oxide nanoparticles were deposited on MWCNT surfaces by a deposition–precipitation method using Fe3+/Fe2+ salts precursors in basic solution. The characterizations by HRTEM, XRD, SEM/EDX, AAS and TPR analyses confirmed the successful formation of magnetic iron oxide nanoparticles on the MWCNT surface. Fe3O4/MWCNT hybrid composites were analysed in vitro by incubation with mesenchymal stem cells for 1, 3 and 7 days, either in the presence or absence of a static magnetic field. Analysis of cell proliferation was performed by the MTT assay, quantification of cellular stress was performed by the Lactate Dehydrogenase assay and analysis of cell morphology was performed by actin immunofluorescence and scanning electron microscopy. Results demonstrate that the introduction of magnetite into the MWCNT structure increases biocompatibility of oxidized MWCNTs. In addition, the presence of a static magnetic field further increases Fe3O4/MWCNT influence on cell behaviour. These results demonstrate this novel Fe3O4/MWCNT hybrid composite has good potential for tissue engineering applications. (paper)

  9. Electrostatic Self-Assembly of Fe3O4 Nanoparticles on Graphene Oxides for High Capacity Lithium-Ion Battery Anodes

    Directory of Open Access Journals (Sweden)

    Jung Kyoo Lee

    2013-09-01

    Full Text Available Magnetite, Fe3O4, is a promising anode material for lithium ion batteries due to its high theoretical capacity (924 mA h g?1, high density, low cost and low toxicity. However, its application as high capacity anodes is still hampered by poor cycling performance. To stabilize the cycling performance of Fe3O4 nanoparticles, composites comprising Fe3O4 nanoparticles and graphene sheets (GS were fabricated. The Fe3O4/GS composite disks of mm dimensions were prepared by electrostatic self-assembly between negatively charged graphene oxide (GO sheets and positively charged Fe3O4-APTMS [Fe3O4 grafted with (3-aminopropyltrimethoxysilane (APTMS] in an acidic solution (pH = 2 followed by in situ chemical reduction. Thus prepared Fe3O4/GS composite showed an excellent rate capability as well as much enhanced cycling stability compared with Fe3O4 electrode. The superior electrochemical responses of Fe3O4/GS composite disks assure the advantages of: (1 electrostatic self-assembly between high storage-capacity materials with GO; and (2 incorporation of GS in the Fe3O4/GS composite for high capacity lithium-ion battery application.

  10. Preparation and characterization of biofunctionalized chitosan/Fe3O4 magnetic nanoparticles for application in liver magnetic resonance imaging

    Science.gov (United States)

    Song, Xiaoli; Luo, Xiadan; Zhang, Qingqing; Zhu, Aiping; Ji, Lijun; Yan, Caifeng

    2015-08-01

    Biofunctionalized chitosan@Fe3O4 nanoparticles are synthesized by combining Fe3O4 and CS chemically modified with PEG and lactobionic acid in one step. The biofunctionalized nanoparticles are characterized by TEM, X-ray, DLS, zeta-potential and magnetic measurements. The in vitro and in vivo behaviors of the biofunctionalized nanoparticles, especially, the cytotoxicity, the protein resistance, metabolism and iron toxicity are assessed. The functional groups, PEG enable the nanoparticles more biocompatible and the lactobionic acid groups enable liver targeting. The potential applications of the nanoparticles in liver magnetic resonance imaging are confirmed. The results demonstrated that the nanoparticles are suspension stability, non-cytotoxicity, non-tissue toxicity and sensitive in liver magnetic resonance imaging, representing potential tools for applications in the biomedical field.

  11. Green Biosynthesis and Characterization of Magnetic Iron Oxide (Fe3O4) Nanoparticles Using Seaweed (Sargassum muticum) Aqueous Extract

    OpenAIRE

    Rosfarizan Mohamad; Mansor Bin Ahmad; Mahnaz Mahdavi; Farideh Namvar

    2013-01-01

    The synthesis of nanoparticles has become a matter of great interest in recent times due to their various advantageous properties and applications in a variety of fields. The exploitation of different plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. In this study, iron oxide nanoparticles (Fe3O4-NPs) were synthesized using a rapid, single step and completely green biosynthetic method by reduction of ferri...

  12. Synthesis of Magnetic Fe3O4-Chitosan Nanoparticles by Ionic Gelation and Their Dye Removal Ability.

    Science.gov (United States)

    Akin, Deniz; Yakar, Arzu; Gündüz, Ufuk

    2015-05-01

    The aim of this study was to synthesize magnetic Fe3O4 chitosan nanoparticles (m-Fe3O4-CNs) by ionic gelation method and use them as adsorbent for the removal of Bromothymol Blue (BB) from aqueous solutions. Also, the effect of various parameters on the preparation of m-Fe3O4-CNs was investigated in this study. The nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometry (VSM). Adsorption of BB on m-Fe3O4-CNs was studied in a batch reactor at different experimental conditions such as adsorbent dosage, pH, contact time, initial BB concentration and temperature. Kinetic behaviors, equilibrium isotherms and thermodynamics of the adsorption process were investigated in detail. The Langmuir adsorption isotherm model and pseudo-second-order kinetic model well fitted the adsorption experimental results. The thermodynamic parameters showed that the adsorption was a spontaneous, favorable and exothermic process in nature. PMID:26460462

  13. Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sadat, M E [University of Cincinnati; Patel, Ronak [University of Cincinnati; Sookoor, Jason [University of Cincinnati; Bud' ko, Sergey L [Ames Laboratory; Ewing, Rodney C [Stanford University; Zhang, Jiaming [Stanford University; Xu, Hong [Shanghai Jiao Tong University; Wang, Yilong [Tongji University School of Medicine; Pauletti, Giovanni M [University of Cincinnati; Mast, David B [University of Cincinnati; Shi, Donglu [University of Cincinnati

    2014-09-01

    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems.

  14. Magnetic solid phase extraction of brominated flame retardants and pentachlorophenol from environmental waters with carbon doped Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Magnetic Fe3O4/C nanospheres were used in MSPE of BFRs and PCP from water samples. • The method shows merits of simpleness, reliableness and environmental friendliness. • The bonding between Fe3O4 and coated organic carbon has been demonstrated in Fe3O4/C. • The straight influences of synthesis conditions of Fe3O4/C on MSPE were investigated. • The extraction characteristics of Fe3O4/C nanoparticles were further elucidated. - Abstract: Carbon doped Fe3O4 nanoparticles (Fe3O4/C) prepared by a facile hydrothermal reaction of glucose with iron resource have been applied as magnetic solid-phase extraction (MSPE) sorbent, for the first time, to extract trace brominated flame retardants (BFRs) and pentachlorophenol (PCP) from environmental waters. Various MSPE parameters were optimized including amount of Fe3O4/C nanoparticles, pH of sample solution, enrichment factor of analytes and reusability of Fe3O4/C sorbent. The reliability of the MSPE method was evaluated by the recoveries of BFRs and PCP in spiked water samples. Good recoveries (80.0–110.0%) were achieved with the relative standard deviations range from 0.3% to 6.8%. In this paper, the extraction characteristics of Fe3O4/C sorbent were further elucidated. It is found that the adsorption process of Fe3O4/C to analytes predominates the MSPE efficiency. There is hybrid hydrophobic interaction and hydrogen bonding or dipole–dipole attraction between Fe3O4/C and analytes. Notably, the chemical components of carbon layer on the surface of Fe3O4 nanoparticles were identified by X-ray photoelectron spectroscopy and thermogravimetry-mass spectrometry, and in consequence the covalent bonds between Fe3O4 and the coated carbon have been observed. In addition, the straight influence of synthesis condition of Fe3O4/C nanoparticles including glucose concentration and hydrothermal reaction time on extraction performance for BFRs and PCP has been investigated. It is confirmed that the existence of organic carbon containing functional groups over Fe3O4/C sorbent is responsible for the MSPE extraction

  15. The reversal effect of magnetic Fe3O4 nanoparticles loaded with cisplatin on SKOV3/DDP ovarian carcinoma cells

    Directory of Open Access Journals (Sweden)

    Zhi Jiang

    2009-04-01

    Full Text Available Zhi Jiang1,6, Bao-An Chen1,6, Guo-Hua Xia1, Qiang Wu2, Yu Zhang1, Tie-Yan Hong1, Wei Zhang1, Jian Cheng1, Feng Gao1, Li-Jie Liu3, Xiao-Mao Li4, Xue-Mei Wang51Department of Hematology, the Affiliated Zhongda Hospital of Southeast University, Nanjing, China; 2The Jiangsu Province Cancer Hospital, Nanjing, China; 3Institutions of Physiology, Southeast University, Nanjing, China; 4Department of Physics, University of Saarland, Saarbruechen, Germany; 5National Key Lab of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, China; 6These authors have contributed equally to this workAbstract: To explore whether the magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4 loaded with cisplatin can reverse the diaminedichloro platinum (DDP resistance to multidrug resistance of ovarian carcinoma cells and to investigate its mechanisms. The SKOV3/DDP cells were divided into DDP treatment (DDP group, MNPs-Fe3O4 treatment (MNPs-Fe3O4 group, DDP + MNPs-Fe3O4 treatment (DDP + MNPs-Fe3O4 group, and control group. After incubation with those conjugates for 48 h, the cytotoxic effects were measured by MTT assay. Apoptosis and the intracellular DDP concentration were investigated by flow cytometry and inductively coupled plasma atomic emission spectroscopy, respectively. The expression of apoptosis associated gene Bcl-2 mRNA was detected by reverse transcription polymerase chain reaction and the expressions of MDR1, lung resistance-related protein (LRP, and P-glycoprotein (P-gp genes were studied by Western blot. Our results indicated that the 50% inhibition concentration (IC50 of the MNPs-Fe3O4 loaded with DDP was 17.4 µmol/ l, while the IC50 was 39.31 µmol/l in DDP groups (p < 0.05; Apoptosis rates of SKOV3/DDP cells increased more than those of DDP groups. Accumulation of intracellular cisplatin in DDP + MNPs-Fe3O4 groups was higher than those in DDP groups (p < 0.05. Moreover, the expression of Bcl-2 mRNA and the protein expressions of MDR1, LRP, and P-gp were decreased when compared with those of DDP groups, respectively. Our results suggest that MNPs-Fe3O4 can reverse the DDP resistance to the ovarian carcinoma cell. The effects may be associated with over-expression of MDR1, LRP, P-gp, and Bcl-2, which can increase the intracellular platinum accumulation and induce the cell apoptosis.Keywords: magnetic nanoparticles of Fe3O4 , multidrug resistance reversal, SKOV3/DDP, MDR1, LRP, P-gp, Bcl-2

  16. Bio-inspired green synthesis of Fe3O4 spherical magnetic nanoparticles using Syzygium cumini seed extract

    International Nuclear Information System (INIS)

    A novel and bio-inspired Fe3O4 spherical magnetic nanoparticles (SMNPs) were synthesized using Syzygium cumini (S. cumini) seed extract, which is a non-toxic ecofriendly fruit waste material. S. cumini seed extract acts as a green solvent, reducing and capping agent in which sodium acetate acts as electrostatic stabilizing agent. The green synthesized nanoparticles were characterized with the help of various techniques such as X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Energy-dispersive spectroscopy (EDS), Vibrating sample magnetometer (VSM), FTIR spectroscopy and nitrogen adsorption and desorption analysis techniques. The XRD study divulged that the synthesized SMNPs have inverse spinel cubic structure. The hysteresis loop of Fe3O4 nanoparticles shows an excellent ferromagnetic behavior with saturation magnetization value of 13.6 emu/g

  17. A novel approach for the synthesis of ultrathin silica-coated iron oxide nanocubes decorated with silver nanodots (Fe3O4/SiO2/Ag) and their superior catalytic reduction of 4-nitroaniline

    Science.gov (United States)

    Abbas, Mohamed; Torati, Sri Ramulu; Kim, Cheolgi

    2015-07-01

    A novel sonochemical approach was developed for the synthesis of different core/shell structures of Fe3O4/SiO2/Ag nanocubes and SiO2/Ag nanospheres. The total reaction time of the three sonochemical steps for the synthesis of Fe3O4/SiO2/Ag nanocubes is shorter than that of the previously reported methods. A proposed reaction mechanism for the sonochemical functionalization of the silica and the silver on the surface of magnetic nanocubes was discussed in detail. Transmission electron microscopy revealed that the surface of Fe3O4/SiO2 nanocubes was decorated with small Ag nanoparticles of approximately 10-20 nm in size, and the energy dispersive spectroscopy mapping analysis confirmed the morphology of the structure. Additionally, X-ray diffraction data were used to confirm the formation of both phases of a cubic inverse spinel structure for Fe3O4 and bcc structures for Ag in the core/shell structure of the Fe3O4/SiO2/Ag nanocubes. The as-synthesized Fe3O4/SiO2/Ag nanocubes showed a high efficiency in the catalytic reduction reaction of 4-nitroaniline to 4-phenylenediamine and a better performance than both Ag and SiO2/Ag nanoparticles. The grafted silver catalyst was recycled and reused at least fifteen times without a significant loss of catalytic efficiency.A novel sonochemical approach was developed for the synthesis of different core/shell structures of Fe3O4/SiO2/Ag nanocubes and SiO2/Ag nanospheres. The total reaction time of the three sonochemical steps for the synthesis of Fe3O4/SiO2/Ag nanocubes is shorter than that of the previously reported methods. A proposed reaction mechanism for the sonochemical functionalization of the silica and the silver on the surface of magnetic nanocubes was discussed in detail. Transmission electron microscopy revealed that the surface of Fe3O4/SiO2 nanocubes was decorated with small Ag nanoparticles of approximately 10-20 nm in size, and the energy dispersive spectroscopy mapping analysis confirmed the morphology of the structure. Additionally, X-ray diffraction data were used to confirm the formation of both phases of a cubic inverse spinel structure for Fe3O4 and bcc structures for Ag in the core/shell structure of the Fe3O4/SiO2/Ag nanocubes. The as-synthesized Fe3O4/SiO2/Ag nanocubes showed a high efficiency in the catalytic reduction reaction of 4-nitroaniline to 4-phenylenediamine and a better performance than both Ag and SiO2/Ag nanoparticles. The grafted silver catalyst was recycled and reused at least fifteen times without a significant loss of catalytic efficiency. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02680f

  18. Aqueous nickel-nitrilotriacetate modified Fe3O4-NH3+ nanoparticles for protein purification and cell targeting

    International Nuclear Information System (INIS)

    A comprehensive totally aqueous phase synthesis of nickel-nitrilotriacetate (Ni-NTA) modified superparamagnetic Fe3O4 nanoparticles is presented. The Fe3O4-NTA-Ni nanoparticles are able to perform efficient and specific purification of 6-His tagged proteins from crude cell lysates, as evidenced by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. The average binding capacity, as demonstrated by streptopain (MW 42 kDa), is 0.23 mg/mg (protein/Fe3O4-NTA-Ni). Considering the high affinity and specificity of the binding between hexahistidine motif and Ni-NTA, Ni-NTA modified nanoparticles could act as a module to carry 6-His tagged proteins on the particle surface with molecular orientation control, since only the 6-His domain could be attached. These modularly designed functional nanoparticles enhance cancer cell targeting, as supported by the in vitro receptor mediated targeting assay using RGD-4C-6-His fusion peptide. The nanoparticles show no significant hemolysis for human blood and could be investigated further for their in vivo functional imaging applications

  19. Photoelectron diffraction of Rh nanoparticles growth on Fe3O4/Pd(111) ultra thin film

    International Nuclear Information System (INIS)

    Full text: Heterogeneous catalysis is a highly complex process. Usually, a catalyst is formed by transition metal nanoparticles (for example, Pd, Pt, Rh, Ni, Au) supported by an oxide such as alumina, silica, titania among others [1-4]. The performance of the catalyst in terms of macroscopic chemical parameters such as the temperature for reaction activation, selectivity and efficiency can be strongly influenced by different characteristics of the catalyst at the atomic level, for instance, its electronic and atomic structure, particle size and shape, crystallographic structure [5-6] and support material effects[1]. Metal-oxide-based catalysts are used for many important synthesis reactions in the chemical industry, such as selective oxidation, dehydrogenation, isomerization and other chemical processes [7]. Rhodium nanoparticles have been used, for example, in the studies of propionaldehyde decomposition under ultra-high vacuum (UHV) conditions. The aim of this work is to prepare rhodium nanoparticles on magnetite (Fe3O4) (111) growth on Pd(111). The rhodium clusters and iron oxide ultra-thin films (thickness <10ML) were prepared in UHV conditions by Molecular Beam Epitaxy (MBE) and keeping the substrate at 450 deg C. The system was characterized by X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED) and photoelectron diffraction (PED) performed at the SGM beam line at the Brazilian Synchrotron Light Source (LNLS). Our results shows the formation of small Rh an island with the same atomic structure of fcc Rh at bulk, and thickness lower then 5MLs. The islands cover approximately 15% of the iron surface. These findings were determined mainly with the PED experiments supported by a comprehensive simulation approach based on multiple scattering calculations. References: [1] J. Libuda, H.-J. Freund, Surf. Sci. Rep. 57, 157 (2005). [2] C. R. Henry, Surf. Sci. Rep. 31, 231 (1998). [3] N. Nilius, A. Corper, G. Bozdech, N. Ernst , H.-J. Freund, Prog. Surf. Sci. 67, 99 (2001). [4] C. T. Campbell, Surf. Sci. Rep. 27, 1 (1997). [5] M. Frank, S. Andersson, J. Libuda, S. Stempel, A. Sandell, B. Brena, A. Giertz, P. A. Bruhwiler, M. Baumer, N. Martensson, H.-J. Freund, Chem. Phys. Lett. 279 92 (1997). [6] S. Andersson, M. Frank, A. Sandell, A. Giertz, B. Brena, P. A. Bruhwiler, N. Martensson, J. Libuda, M. Baumer, H.-J. Freund, J. Chem. Phys. 108 2967 (1998). [7] G. Ertl, H. Knozinger, J. Weitkamp, Handbook of Heterogeneous Catalysis, Wiley-VCH, Weinheim, 1997. (author)

  20. Magnetic solid phase extraction of brominated flame retardants and pentachlorophenol from environmental waters with carbon doped Fe3O4 nanoparticles

    Science.gov (United States)

    Yang, Jing; Li, Jia-yuan; Qiao, Jun-qin; Cui, Shi-hai; Lian, Hong-zhen; Chen, Hong-yuan

    2014-12-01

    Carbon doped Fe3O4 nanoparticles (Fe3O4/C) prepared by a facile hydrothermal reaction of glucose with iron resource have been applied as magnetic solid-phase extraction (MSPE) sorbent, for the first time, to extract trace brominated flame retardants (BFRs) and pentachlorophenol (PCP) from environmental waters. Various MSPE parameters were optimized including amount of Fe3O4/C nanoparticles, pH of sample solution, enrichment factor of analytes and reusability of Fe3O4/C sorbent. The reliability of the MSPE method was evaluated by the recoveries of BFRs and PCP in spiked water samples. Good recoveries (80.0-110.0%) were achieved with the relative standard deviations range from 0.3% to 6.8%. In this paper, the extraction characteristics of Fe3O4/C sorbent were further elucidated. It is found that the adsorption process of Fe3O4/C to analytes predominates the MSPE efficiency. There is hybrid hydrophobic interaction and hydrogen bonding or dipole-dipole attraction between Fe3O4/C and analytes. Notably, the chemical components of carbon layer on the surface of Fe3O4 nanoparticles were identified by X-ray photoelectron spectroscopy and thermogravimetry-mass spectrometry, and in consequence the covalent bonds between Fe3O4 and the coated carbon have been observed. In addition, the straight influence of synthesis condition of Fe3O4/C nanoparticles including glucose concentration and hydrothermal reaction time on extraction performance for BFRs and PCP has been investigated. It is confirmed that the existence of organic carbon containing functional groups over Fe3O4/C sorbent is responsible for the MSPE extraction.

  1. Magnetic nanoparticle (Fe3O4) impregnated onto tea waste for the removal of nickel(II) from aqueous solution

    International Nuclear Information System (INIS)

    The removal of Ni(II) from aqueous solution by magnetic nanoparticles prepared and impregnated onto tea waste (Fe3O4-TW) from agriculture biomass was investigated. Magnetic nanoparticles (Fe3O4) were prepared by chemical precipitation of a Fe2+ and Fe3+ salts from aqueous solution by ammonia solution. These magnetic nanoparticles of the adsorbent Fe3O4 were characterized by surface area (BET), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). The effects of various parameters, such as contact time, pH, concentration, adsorbent dosage and temperature were studied. The kinetics followed is first order in nature, and the value of rate constant was found to be 1.90 x 10-2 min-1 at 100 mg L-1 and 303 K. Removal efficiency decreases from 99 to 87% by increasing the concentration of Ni(II) in solution from 50 to 100 mg L-1. It was found that the adsorption of Ni(II) increases by increasing temperature from 303 to 323 K and the process is endothermic in nature. The adsorption isotherm data were fitted to Langmuir and Freundlich equation, and the Langmuir adsorption capacity, Qo, was found to be (38.3) mg g-1. The results also revealed that nanoparticle impregnated onto tea waste from agriculture biomass, can be an attractive option for metal removal from industrial effluent.

  2. Intraperitoneal injection of magnetic Fe3O4-nanoparticle induces hepatic and renal tissue injury via oxidative stress in mice

    Directory of Open Access Journals (Sweden)

    Ma P

    2012-09-01

    Full Text Available Ping Ma,1,2,* Qing Luo,2,* Jiaoe Chen,1 Yaping Gan,1 Juan Du,2 Shumao Ding,2 Zhuge Xi,3 Xu Yang2 1College of Basic Medical Sciences, Hubei University of Science and Technology, Xianning, People's Republic of China; 2Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan, People's Republic of China; 3Tianjin Institute of Health and Environmental Medicine, Tianjin, People's Republic of China*These authors contributed equally to this workAbstract: Because of its unique magnetic properties, the iron oxide (Fe3O4 nanoparticle has been widely exploited and its application in various fields has promised immense benefits. However, doubts exist over the use of Fe3O4-nanoparticles in human beings. Thus, the aim of the current study was to find out the potential safety range of medical use. Twenty-five Kunming mice were exposed to Fe3O4-nanoparticles via intraperitoneal injection daily for 1 week at doses of 0, 5, 10, 20, and 40 mg/kg. Hepatic and renal tissues were sliced for physiological observation. Injuries were observed in the high-dose groups (20 and 40 mg/kg compared with the control group (0 mg/kg. Biomarkers of reactive oxygen species, glutathione, malondialdehyde, DNA-protein crosslinks, and 8-hydroxy-2'-deoxyguanosine in the hepatic and renal tissues were detected. Injury to tissues and oxidative damage to cells at the molecular level was found. The safest dose recommended from the results of this study is 5 mg/kg, as we believe this to be an upper limit balancing the benefits and risks for sub-long-term exposure.Keywords: Fe3O4-nanoparticles, reactive oxygen species, glutathione, malondialdehyde, DNA-protein crosslinks, 8-hydroxy-2'-deoxyguanosine

  3. Enhanced superconducting properties in epitaxial FeSe thin films with self-assembled Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Epitaxial tetragonal FeSe thin films were deposited by pulsed laser deposition. Deposition temperature and annealing process are critical for achieving the optimum superconducting properties of the films. The optimum deposition temperatures are ?500 deg. C and 550 deg/ C for samples on STO and MgO substrates, respectively. The self-assembled Fe3O4 nanoparticles were found to have a direct correlation with the optimum superconducting properties of the films. In this paper we report epitaxial tetragonal iron selenide thin films grown on single crystal SrTiO3 (STO) (0 0 1) and MgO (0 0 1) substrates by a pulsed laser deposition (PLD) technique. Deposition temperature and annealing process are found to be critical for achieving the tetragonal phase and the optimum superconducting properties of the films. The critical transition temperature of the thin films ranges from 2 K to 11.5 K depending on the deposition temperature and annealing condition. The samples with higher critical transition temperatures show better film crystallinity along with self-assembled Fe3O4 nanoparticles (?15 nm in average particle size) in the films according to both X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. Besides the better crystallinity achieved in the films, the formation of Fe3O4 nanoparticles could assist the formation of the tetragonal FeSe phase and thus lead to the enhanced superconducting properties.

  4. Biocompatibility of Fe3O4 nanoparticles evaluated by in vitro cytotoxicity assays using normal, glia and breast cancer cells

    International Nuclear Information System (INIS)

    In order to reveal the biocompatibility of Fe3O4 nanoparticles and bipolar surfactant tetramethylammonium 11-aminoundecanoate cytotoxicity tests were performed as a function of concentration from low (0.1 ?g ml-1) to higher concentration (100 ?g ml-1) using various human glia, human breast cancer and normal cell lines. Cytotoxicity tests for human glia (D54MG, G9T, SF126, U87, U251, U373), human breast cancer (MB157, SKBR3, T47D) and normal (H184B5F5/M10, WI-38, SVGp12) cell lines exhibited almost nontoxicity and reveal biocompatibility of Fe3O4 nanoparticles in the concentration range of 0.1-10 ?g ml-1, while accountable cytotoxicity can be seen at 100 ?g ml-1. The results of our studies suggest that Fe3O4 nanoparticles coated with bipolar surfactant tetramethylammonium 11-aminoundecanoate are biocompatible and promising for bio-applications such as drug delivery, magnetic resonance imaging and magnetic hyperthermia.

  5. ?-Cyclodextrin coated Fe3O4 nanoparticles: a simple preparation and application for selective oxidation of alcohols in water

    Scientific Electronic Library Online (English)

    Jie, Zhu; Peng-cheng, Wang; Ming, Lu.

    2013-01-01

    Full Text Available Um catalisador magnético foi sintetizado via proceso de ativação da carboimida em ?-ciclodextrina funcionalizada com nanopartículas core-shell (Fe3O4/SiO2/CM-?-CD). O catalisador apresenta elevada atividade na oxidação seletiva de vários álcoois usando NaOCl como oxidante e água como solvente. Foi o [...] btido um processo seletivo na ausência de metal de transição e de fácil separação do catalisador. Abstract in english A magnetically separable catalyst was synthesized via a carbodiimide activation process with ?-cyclodextrin functionalized by core-shell nanoparticles (Fe3O4/SiO2/CM-?-CD). The catalyst presented high activity for selective oxidation of various alcohols with NaOCl as oxidant and water only as the so [...] lvent. A substrate-selective and transition metal-free process was achieved with easy separation of the catalyst.

  6. Electrochemical detection of short HIV sequences on chitosan/Fe3O4 nanoparticle based screen printed electrodes

    International Nuclear Information System (INIS)

    In this study, a novel CS/Fe3O4 nanobiocomposite-based platform for electrochemical detection of HIV-1 was developed. The most attractive feature of this system is a suitable microenvironment (Fe3O4 nanoparticles) which could contribute to electron transfer and thus sensitivity enhancement when using methylene blue (MB) as an external mediator and Square Wave Voltammetry (SWV), Electrochemical Impedance Spectroscopy (EIS) techniques. The proposed screen printed electrode (SPE) had a low detection limit (as low as 50 pM), acceptable stability and good reproducibility, which would be valuable for clinical diagnosis. In addition, this sensing interface may be feasibly adapted for multiplexed detection of other species of bacterial pathogens.

  7. Fe3O4/PS magnetic nanoparticles: Synthesis, characterization and their application as sorbents of oil from waste water

    Science.gov (United States)

    Yu, Liuhua; Hao, Gazi; Gu, Junjun; Zhou, Shuai; Zhang, Ning; Jiang, Wei

    2015-11-01

    In this work, Fe3O4/PS composites with a rough surface and different coating rates were successfully designed and synthesized by emulsion polymerization. We carried out some comparative experiments to compare magnetic properties and oil absorption properties of the nano-magnetic materials. It had been found that several prepared groups of magnetic nanocomposites have a core-shell structure and good coating rates. These nanoparticles combined with unsinked, highly hydrophobic and superoleophilic properties. The absorption capacity of Fe3O4/PS composites for organic solvents and the composites could absorb diesel oil up to 2.492 times of its own weight. It is more important that the oil could be readily removed from the surfaces of nanoparticles by a simple ultrasonic treatment whereas the nanocomposites particles still kept highly hydrophobic and superoleophilic characteristics. With a combination of simple synthesis process, low density, magnetic responsibility and excellent hydrophobicity, Fe3O4/PS nanocomposites as a promising absorbent have great potential in the application of spilled oil recovery and environmental protection.

  8. Scalable synthesis of Fe3O4 nanoparticles anchored on graphene as a high-performance anode for lithium ion batteries

    International Nuclear Information System (INIS)

    We report a scalable strategy to synthesize Fe3O4/graphene nanocomposites as a high-performance anode material for lithium ion batteries. In this study, ferric citrate is used as precursor to prepare Fe3O4 nanoparticles without introducing additional reducing agent; furthermore and show that such Fe3O4 nanoparticles can be anchored on graphene sheets which attributed to multifunctional group effect of citrate. Electrochemical characterization of the Fe3O4/graphene nanocomposites exhibit large reversible capacity (?1347 mA h g?1 at a current density of 0.2 C up to 100 cycles, and subsequent capacity of ?619 mA h g?1 at a current density of 2 C up to 200 cycles), as well as high coulombic efficiency (?97%), excellent rate capability, and good cyclic stability. High resolution transmission electron microscopy confirms that Fe3O4 nanoparticles, with a size of ?4–16 nm are densely anchored on thin graphene sheets, resulting in large synergetic effects between Fe3O4 nanoparticles and graphene sheets with high electrochemical performance. - Graphical abstract: The reduction of Fe3+ to Fe2+ and the deposition of Fe3O4 on graphene sheets occur simultaneously using citrate function as reductant and anchor agent in this reaction process. Highlights: ? Fe3O4/graphene composites are synthesized directly from graphene and C6H5FeO7. ? The citrate function as reductant and anchor agent in this reaction process. ? The resulting Fe3O4 particles (?4–16 nm) are densely anchored on graphene sheets. ? The prepared Fe3O4/graphene composites exhibit excellent electrochemical performance

  9. Preparation and characterization of 18-crown-ether-6/LA/Fe3O4 magnetic nanoparticles

    International Nuclear Information System (INIS)

    Fe3O4 Magnetic nanoparticles (MNPs) have the advantages of large specific surface area, high adsorption capacity, and conveniently magnetic separation. Crown ether display good selectivity of coordination with uranyl ion, thorium ion and so on. To combine the feature and advantage, this study prepared for 18-Crown-ether-6/LA/Fe3O4 magnetic particles which with high adsorption and selectivity properties and easy to separate from wastewater with magnet. The structure was characterized with IR, SEM, VSM, DGA and so on. The results reveal that: 18-Crown-ether-6/LA/ Fe3O4 magnetic particles was size of (12-23) nm, saturation magnetization was 56.338 emu/g with superparamagnetism and strong antioxidant properties. A test for the adsorption of the magnetic particles with uranyl ion and thorium ion has been carried out. The results indicated that the magnetic particles had good adsorption capacity, quick efficient and conveniently magnetic separation. It can be used repeatedly, with a good reproducibility. (authors)

  10. Thermal annealing synthesis of Fe4N/Fe nanocomposites from iron oxide (Fe3O4) nanoparticles

    International Nuclear Information System (INIS)

    A facile sono-thermal approach using inexpensive and non-toxic chemicals was applied for the large-scale synthesis of iron nitride/iron (Fe4N/Fe) nanocomposite. The as-synthesized iron oxide (Fe3O4) nanoparticles by sonochemical method were treated in a thermal annealing chamber in presence of hydrogen (H2) and ammonia (NH3) gases to obtain Fe4N/Fe nanocomposite. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses revealed that the Fe4N/Fe nanocomposite had been successfully synthesized using this simple method. Transmission electron microscopy (TEM) data demonstrated that the sizes of the as-synthesized Fe4N/Fe nanocomposite were larger compared to the sizes for the initial Fe3O4 NPs. The magnetization curve obtained using vibrating sample magnetometer (VSM) measurements showed that the magnetization had been significantly increased in the synthesized Fe4N/Fe nanocomposite compared to that in the freshly-prepared Fe3O4 magnetic NPs.

  11. The Effect of Emulation Formulation to Encapsulation of Fe3O4 Magnetic nanoparticle with Poly (Lactic Acid)

    International Nuclear Information System (INIS)

    The research to study the effect of emulsion formulation to encapsulation Fe3O4 magnetic nanoparticle with Poly(Lactic Acid) (PLA) has been done. Microemulsion by ultrasonic probe is used in encapsulation process and continued by solvent evaporation. Emulsion formulation has been varied by changing oil phase volume in the oil in water (o/w) emulsion system from 6 mL, 8 mL, 10 mL, 12 mL and 14 mL, whereas water phase volume is constant (55 mL). Sample characterization is carried on by Scanning Electron Microscope (SEM) to know the morphology and sample size. X-Ray Diffractometer (XRD) is used to identify the phase, Vibrating Sample Magnetometer (VSM) is used to measure magnetic saturation while Neutron Activation Analysis (NAA) is used to measure encapsulation percentage of Fe3O4 with PLA. The smallest nanosphere is resulted by emulsion formulation (o/w) of 14/55 with the main sample size 382 nm. The maximum magnetic saturation of Fe3O4 + PLA nanosphere is 2.556 emu/g and encapsulation percentage is 24.94 %. (author)

  12. Preparation and characterization of core-shell structure Fe3O4/C nanoparticles with unique stability and high electrochemical performance for lithium-ion battery anode material

    International Nuclear Information System (INIS)

    Core-shell structure carbon coating Fe3O4 nanoparticles are prepared by a two-step method. The crystalline structure and the electrochemical performance of the prepared samples are investigated. The results indicate that a uniform and continuous carbon layer is formed on the surface of Fe3O4 nanoparticles. The core-shell structure Fe3O4/C nanoparticles show a high initial discharge capacity of 1546 mAh g-1 and a specific stable discharge capacity of about 800 mAh g-1 at 0.5 C with no noticeable capacity fading up to 100 cycles.

  13. One step grafting of iron phthalocyanine containing flexible chains on Fe3O4 nanoparticles towards high performance polymer magnetic composites

    Science.gov (United States)

    Pu, Zejun; Zhou, Xuefei; Yang, Xulin; Jia, Kun; Liu, Xiaobo

    2015-07-01

    To develop high-performance inorganic particles/polymer composites, the interfacial interaction and dispersion of inorganic particles are the two essential issues to be considered. Herein, we report an effective approach to graft iron phthalocyanine containing flexible chains (NP-ph) on Fe3O4 nanoparticles (NP-ph@Fe3O4). The hybrids were monodispersed solid nanoparticles with the average diameter of about 250 nm. About 16.8% of the phthalocyanine oligomer was incorporated into the resulting NP-ph@Fe3O4 nanoparticles. The NP-ph@Fe3O4 nanoparticles were subsequently used as the novel filler for preparation of high performance poly(arylene ether nitrile)s (PAEN) composites. The scanning electron microscopy (SEM) investigation showed that the NP-ph@Fe3O4 nanoparticles present better dispersion and interfacial compatibility with PAEN matrix than that of raw Fe3O4, which was further confirmed by rheological study. Consequently, the improved thermal stability and enhanced mechanical properties were obtained from composites using NP-ph@Fe3O4. Vibrating sample magnetometer (VSM) results showed that the prepared PAEN composites exhibited higher saturation magnetization and soft magnetic properties. Meanwhile, the saturation magnetization (Ms) of the PAEN/NP-ph@Fe3O4 composite films increased with the increase of the hybrid nanoparticles loading. Thus, the PAEN/NP-ph@Fe3O4 composite would find potential applications in organic magnetic films fields due to their high thermal stability, excellent flexibility and tunable magnetic properties

  14. FMR study of carbon nanotubes filled with Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Ordered arrays of carbon nanotubes were produced using a non-catalytic chemical vapour deposition. The multiwall nanotubes with an inner diameter of 120 nm were grown inside porous alumina templates and then filled with a magnetic colloid of 7.5 nm Fe3O4 particles. X-ray diffraction, electron microscopy and ferromagnetic resonance (FMR) were used to characterize structural and magnetic properties of the grown samples. To estimate the filling factor from the angular dependence of the FMR resonance field, we have derived an effective demagnetization factor for our system using the formalism proposed by Skomsky and Dubowik. Angular dependence of the FMR line width allows one to conclude about the non-uniform filling, while temperature dependent measurements reflect typical features of a superparamagnetic resonance. - Highlights: • Synthesis of CNTs inside of alumina membrane and filling it with Fe3O4 particles. • X-ray diffraction and electron microscopy study of the samples. • Magnetic properties of the samples studied by FMR. • Filling factor has been determined from the angular dependences of FMR. • Resulted magnetic CNTs are attractive for production of magnetic nanofluids

  15. Tuning Fe3O4 nanoparticle dispersion through pH in PVA/guar gum/electrospun membranes.

    Science.gov (United States)

    Lubambo, A F; Ono, L; Drago, V; Mattoso, N; Varalda, J; Sierakowski, M-R; Sakakibara, C N; Freitas, R A; Saul, C K

    2015-12-10

    Polyvinyl Alcohol (PVA)/guar gum (GG) membranes with different loads of paramagnetic iron oxide Fe3O4 nanoparticles were successfully electrospun using both non-alkaline and alkaline stock solutions. The nanoparticle homogeneity distribution was clearly enhanced in fibers obtained from alkaline stock solutions. This is mainly due to the interaction between GG and the metallic ion, which also leads to further dispersion of remained uncoated nanoparticles in the mixture. It was also noticed that GG favors nanoparticle stability in the mixture and contributes to nanoparticle encapsulation. X-ray results showed that all membranes were semi-crystalline. FTIR-ATR spectra showed that FeO absorption band intensity improved with increasing nanoparticle load, reaching saturation at 3.5mg/ml Fe3O4 concentration under alkaline conditions. VSM analyses showed that the nanoparticles are paramagnetic and were successfully incorporated by the fibers. In vitro biocompatibility tests using L929 cells indicates adequate levels of cytotoxicity and cell adhesion/proliferation assays for both membranes obtained from non-alkaline and alkaline stock solutions. Therefore, they have potential for biomedical applications as biodegradable wound dressing. PMID:26428185

  16. Surfactant-enhanced spectrofluorimetric determination of total aflatoxins from wheat samples after magnetic solid-phase extraction using modified Fe3O4 nanoparticles

    Science.gov (United States)

    Manafi, Mohammad Hanif; Allahyari, Mehdi; Pourghazi, Kamyar; Amoli-Diva, Mitra; Taherimaslak, Zohreh

    2015-07-01

    The extraction and preconcentration of total aflatoxins (including aflatoxin B1, B2, G1, and G2) using magnetic nanoparticles based solid phase extraction (MSPE) followed by surfactant-enhanced spectrofluorimetric detection was proposed. Ethylene glycol bis-mercaptoacetate modified silica coated Fe3O4 nanoparticles as an efficient antibody-free adsorbent was successfully applied to extract aflatoxins from wheat samples. High surface area and strong magnetization properties of magnetic nanoparticles were utilized to achieve high enrichment factor (97), and satisfactory recoveries (92-105%) using only 100 mg of the adsorbent. Furthermore, the fast separation time (less than 10 min) avoids many time-consuming cartridge loading or column-passing procedures accompany with the conventional SPE. In determination step, signal enhancement was performed by formation of Triton X-100 micelles around the analytes in 15% (v/v) acetonitrile-water which dramatically increase the sensitivity of the method. Main factors affecting the extraction efficiency and signal enhancement of the analytes including pH of sample solution, desorption conditions, extraction time, sample volume, adsorbent amount, surfactant concentration and volume and time of micelle formation were evaluated and optimized. Under the optimum conditions, wide linear range of 0.1-50 ng mL-1 with low detection limit of 0.03 ng mL-1 were obtained. The developed method was successfully applied to the extraction and preconcentration of aflatoxins in three commercially available wheat samples and the results were compared with the official AOAC method.

  17. Removal of heavy metals from aqueous solutions using Fe3O4, ZnO, and CuO nanoparticles

    International Nuclear Information System (INIS)

    This study investigated the removal of Cd2+, Cu2+, Ni2+, and Pb2+ from aqueous solutions with novel nanoparticle sorbents (Fe3O4, ZnO, and CuO) using a range of experimental approaches, including, pH, competing ions, sorbent masses, contact time, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The images showed that Fe3O4, ZnO, and CuO particles had mean diameters of about 50 nm (spheroid), 25 nm (rod shape), and 75 nm (spheroid), respectively. Tests were performed under batch conditions to determine the adsorption rate and uptake at equilibrium from single and multiple component solutions. The maximum uptake values (sum of four metals) in multiple component solutions were 360.6, 114.5, and 73.0 mg g?1, for ZnO, CuO, and Fe3O4, respectively. Based on the average metal removal by the three nanoparticles, the following order was determined for single component solutions: Cd2+ > Pb2+ > Cu2+ > Ni2+, while the following order was determined in multiple component solutions: Pb2+ > Cu2+ > Cd2+ > Ni2+. Sorption equilibrium isotherms could be described using the Freundlich model in some cases, whereas other isotherms did not follow this model. Furthermore, a pseudo-second order kinetic model was found to correctly describe the experimental data for all nanoparticles. Scanning electron microscopy, energy dispersive X-ray before and after metal sorption, and soil solution saturation indices showed that the main mechanism of sorption for Cd2+ and Pb2+ was adsorption, whereas both Cu2+ and Ni2+ sorption were due to adsorption and precipitation. These nanoparticles have potential for use as efficient sorbents for the removal of heavy metals from aqueous solutions and ZnO nanoparticles were identified as the most promising sorbent due to their high metal uptake.

  18. Direct Electrochemistry and Electrocatalysis of Horseradish Peroxidase Immobilized in a DNA/Chitosan-Fe3O4 Magnetic Nanoparticle Bio-Complex Film

    OpenAIRE

    Tingting Gu; Jianli Wang; Hongqi Xia; Si Wang; Xiaoting Yu

    2014-01-01

    A DNA/chitosan-Fe3O4 magnetic nanoparticle bio-complex film was constructed for the immobilization of horseradish peroxidase (HRP) on a glassy carbon electrode. HRP was simply mixed with DNA, chitosan and Fe3O4 nanoparticles, and then applied to the electrode surface to form an enzyme-incorporated polyion complex film. Scanning electron microscopy (SEM) was used to study the surface features of DNA/chitosan/Fe3O4/HRP layer. The results of electrochemical impedance spectroscopy (EIS) show that...

  19. Monodisperse magnetizable silica composite particles from heteroaggregate of carboxylic polystyrene latex and Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Monodisperse magnetizable silica composite particles were prepared from heteroaggregates of carboxylic polystyrene latex and Fe3O4 nanoparticles. It was found that the heteroaggregation of the carboxylic latex and Fe3O4 nanoparticles is dependent on the pH of the solution. At low pH value (pH 2-4), the aggregation proceeds effectively due to opposite charges on the surfaces of the latex and the magnetic nanoparticles. At high pH value (pH>8), no aggregation was observed due to the negative charge on both the surface of the latex and the magnetic nanoparticles. The heteroaggregate of the latex and magnetic nanoparticles was found to be stable in a wide range of pH values, due to the existence of coordination interactions at the interface of the latex and magnetic nanoparticles. After silica layer coating on the heteroaggregate by the Stoeber process and removal of the latex by calcination, hollow monodisperse magnetizable silica composite particles are obtained

  20. Green Biosynthesis and Characterization of Magnetic Iron Oxide (Fe3O4 Nanoparticles Using Seaweed (Sargassum muticum Aqueous Extract

    Directory of Open Access Journals (Sweden)

    Rosfarizan Mohamad

    2013-05-01

    Full Text Available The synthesis of nanoparticles has become a matter of great interest in recent times due to their various advantageous properties and applications in a variety of fields. The exploitation of different plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. In this study, iron oxide nanoparticles (Fe3O4-NPs were synthesized using a rapid, single step and completely green biosynthetic method by reduction of ferric chloride solution with brown seaweed (BS, Sargassum muticum water extract containing sulphated polysaccharides as a main factor which acts as reducing agent and efficient stabilizer. The structural and properties of the Fe3O4-NPs were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM, energy dispersive X-ray fluorescence spectrometry (EDXRF, vibrating sample magnetometry (VSM and transmission electron microscopy. The average particle diameter as determined by TEM was found to be 18 ± 4 nm. X-ray diffraction showed that the nanoparticles are crystalline in nature, with a cubic shape. The nanoparticles synthesized through this biosynthesis method can potentially useful in various applications.

  1. Molecular imprinting and immobilization of cellulase onto magnetic Fe3O4@SiO2 nanoparticles.

    Science.gov (United States)

    Li, Yue; Wang, Xiang-Yu; Zhang, Rui-Zhuo; Zhang, Xiao-Yun; Liu, Wei; Xu, Xi-Ming; Zhang, Ye-Wang

    2014-04-01

    Supermagnetic Fe3O4@SiO2 nanoparticles were molecular-imprinted prepared with cellulase as the template. The molecular imprinted nanoparticles were used as support to immobilization of cellulase. The transmission electron microscopy confirmed the core-shell structure and revealed that the size of the nanoparticles was around 10 nm. It was observed that cellulase was immobilized on the nanoparticles successfully from the Fourier transform infrared spectra. The adsorption of cellulase on the nanoparticles was specific and rapid. A high immobilization efficiency of 95% was achieved after the optimization. At 70 degrees C, the half-life of the immobilized cellulase was 3.3-fold of the free enzyme. Compared with the free enzyme, the immobilized cellulase has the same optimal pH, higher optimal temperature, better thermal stability and higher catalytic efficiency. The results strongly suggest that the immobilized cellulase on molecular imprinted Fe3O4@SiO2 has the potential applications in the production of bioethanol, paper and pulp industry, and pharmaceutical industry. PMID:24734713

  2. Bio-inspired green synthesis of Fe3O4 magnetic nanoparticles using watermelon rinds and their catalytic activity

    Science.gov (United States)

    Prasad, Ch.; Gangadhara, S.; Venkateswarlu, P.

    2015-08-01

    Novel and bio-inspired magnetic nanoparticles were synthesized using watermelon rinds (WR) which are nontoxic and biodegradable. Watermelon rind extract was used as a solvent and capping and reducing agent in the synthesis. The Fe3o4 MNPs were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer techniques (VSM). XRD studies revealed a high degree of crystalline and monophasic Fe nanoparticles of face-centered cubic stricture. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process in an excellent candidate for the synthesis of iron nanoparticles that is simple, easy to execute, pollutant free and inexpensive. A practical and convenient method for the synthesis of highly stable and small-sized iron nanoparticles with a narrow distribution from 2 to 20 nm is reported. Also, the MNPs present in higher saturation magnetization (Ms) of 14.2 emu/g demonstrate tremendous magnetic response behavior. However, the synthesized iron nanoparticles were used as a catalyst for the preparation of biologically interesting 2-oxo-1,2,3,4-tetrahydropyrimidine derivatives in high yields. These results exhibited that the synthesized Fe3O4 MNPs could be used as a catalyst in organic synthesis.

  3. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties

    KAUST Repository

    Lemine, O. M.

    2012-10-01

    Magnetite (Fe 3O 4) nanoparticles were successfully synthesized by a sol-gel method. The obtained nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDAX), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) and Mössbauer spectrometry. XRD and Mössbauer measurements indicate that the obtained nanoparticles are single phase. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of about 8 nm. Room temperature ferromagnetics behavior was confirmed by SQUID measurements. The mechanism of nanoparticles formation and the comparison with recent results are discussed. Finally, the synthesized nanoparticles present a potential candidate for hyperthermia application given their saturation magnetization. © 2012 Elsevier Ltd. All rights reserved.

  4. The preparation of Fe3O4 cube-like nanoparticles via the ethanol reduction of ?-Fe2O3 and the study of its electromagnetic wave absorption

    Science.gov (United States)

    Zhang, Lili; Dai, Peng; Yu, Xinxin; Li, Yang; Bao, Zhiwei; Zhu, Jin; Zhu, Kerong; Wu, Mingzai; Liu, Xiansong; Li, Guang; Bi, Hong

    2015-12-01

    Cube-like Fe3O4 nanoparticles with size between 60 nm and 80 nm were reduced via ethanol using ?-Fe2O3 nanocubes as precursors at 350 °C. The possible mechanism for the CH3CH2OH reduction of ?-Fe2O3 into Fe3O4 was discussed. Electromagnetic wave absorption test showed that these Fe3O4 nanoparticles possessed excellent microwave absorption performance due to its complementary effect of dielectric loss and magnetic loss. The minimum absorption reflection loss value is -47.8 dB for Fe3O4 nanoparticles/paraffin wax composite sample with thickness of 4 mm, much higher than that of the commercial microwave absorber [Fe, Ni].

  5. Ternary hybrid nanoparticle isomers: directing the nucleation of Ag on Pt-Fe(3)O(4) using a solid-state protecting group.

    Science.gov (United States)

    Hodges, James M; Biacchi, Adam J; Schaak, Raymond E

    2014-01-28

    Colloidal hybrid nanoparticles are an important class of materials that incorporate multiple nanoparticles into a single system through solid-state interfaces, which can result in multifunctionality and the emergence of synergistic properties not found in the individual components. These hybrid structures are typically produced using seeded-growth methods, where preformed nanoparticles serve as seeds onto which additional domains are added through subsequent reactions. For hybrid nanoparticles that contain more than two domains, multiple configurations with distinct connectivities and functionalities are possible, and these can be considered as nanoparticle analogues of molecular isomers. However, accessing one isomer relative to others in the same hybrid nanoparticle system is challenging, particularly when the formation of a target isomer is disfavored relative to more stable or synthetically accessible configurations. Here, we show that an iron oxide shell installed onto the Pt domain of Pt-Fe3O4 hybrid nanoparticles serves as a solid-state protecting group that can direct the nucleation of a third domain to an otherwise disfavored site. Under traditional conditions, Ag nucleates exclusively onto the Pt domain of Pt-Fe3O4 heterodimers, resulting in the formation of the Ag-Pt-Fe3O4 heterotrimer isomer. When the Pt surface is covered with an iron oxide protecting group, the nucleation of Ag is redirected onto the Fe3O4 domain, producing the distinct and otherwise inaccessible Pt-Fe3O4-Ag isomer. Similar results are obtained for the Au-Pt-Fe3O4 system, where formation of the favored Au-Pt-Fe3O4 configuration is blocked by the iron oxide protecting group. The thickness of the iron oxide shell that protects the Pt domain can be systematically tuned by adjusting the ratio of oleic acid to iron pentacarbonyl during the synthesis of the Pt-Fe3O4 heterodimers, and this insight is important for controllably implementing the protecting group chemistry. PMID:24328300

  6. A novel green synthesis of Fe3O4-Ag core shell recyclable nanoparticles using Vitis vinifera stem extract and its enhanced antibacterial performance

    International Nuclear Information System (INIS)

    We described a novel and eco-friendly method for preparing Fe3O4-Ag core shell nanoparticles (CSNPs) with high magnetism and potent antibacterial activity. The Fe3O4-Ag CSNPs were obtained using waste material of Vitis vinifera (grape) stem extract as the green solvent, reducing and capping agent. The result recorded from X-ray powder diffraction (XRD), UV–vis spectrum, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) supports the biosynthesis and characterization of Fe3O4-Ag CSNPs. From transmission electron microscopy (TEM) the size of the Fe3O4-Ag nanoparticles was measured below 50 nm; high-resolution TEM (HRTEM) indicates the core shell structure; and selected area electron diffraction (SAED) has revealed polycrystalline nature. Vibrating sample magnetometer (VSM) shows the ferromagnetic nature of Fe3O4-Ag CSNPs at room temperature with saturation magnetization of 15.74 emu/g. Further, these biogenic nanoparticles were highly hazardous to microorganisms. The antibacterial activity of biogenic Fe3O4-Ag CSNPs showed potent inhibitory activity against both Gram-positive and Gram-negative pathogens. These nanoparticles may also be reusable because of its excellent ferromagnetic property

  7. A novel green synthesis of Fe3O4-Ag core shell recyclable nanoparticles using Vitis vinifera stem extract and its enhanced antibacterial performance

    Science.gov (United States)

    Venkateswarlu, Sada; Natesh Kumar, B.; Prathima, B.; Anitha, K.; Jyothi, N. V. V.

    2015-01-01

    We described a novel and eco-friendly method for preparing Fe3O4-Ag core shell nanoparticles (CSNPs) with high magnetism and potent antibacterial activity. The Fe3O4-Ag CSNPs were obtained using waste material of Vitis vinifera (grape) stem extract as the green solvent, reducing and capping agent. The result recorded from X-ray powder diffraction (XRD), UV-vis spectrum, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) supports the biosynthesis and characterization of Fe3O4-Ag CSNPs. From transmission electron microscopy (TEM) the size of the Fe3O4-Ag nanoparticles was measured below 50 nm; high-resolution TEM (HRTEM) indicates the core shell structure; and selected area electron diffraction (SAED) has revealed polycrystalline nature. Vibrating sample magnetometer (VSM) shows the ferromagnetic nature of Fe3O4-Ag CSNPs at room temperature with saturation magnetization of 15.74 emu/g. Further, these biogenic nanoparticles were highly hazardous to microorganisms. The antibacterial activity of biogenic Fe3O4-Ag CSNPs showed potent inhibitory activity against both Gram-positive and Gram-negative pathogens. These nanoparticles may also be reusable because of its excellent ferromagnetic property.

  8. Multifunctional superparamagnetic fe3O4@SiO2 core/shell nanoparticles: design and application for cell imaging.

    Science.gov (United States)

    Zhao, Xueling; Zhao, Hongli; Yuan, Huihui; Lan, Minbo

    2014-02-01

    Highly biocompatible sub-50-nm monodisperse superparamagnetic Fe3O4@SiO2 core/shell nanoparticles with luminescent silica shells were synthesized by a w/o-microemulsion technique. And then these nanoparticles were coated with the covalently bonded biocompatible polymer poly(ethylene glycol) (PEG) and modified with the biological cancer targeting ligand folic acid (FA). After characterized by means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transformed infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), UV-vis, fluorescence spectroscopy and confocal laser scanning microscopy (CLSM), we confirmed that Fe3O4@SiO2 (FITC)-PEG-FA nanocomposites (SMNPs-FA) could be efficiently taken up by HeLa cancer cells and KB cells which are of over-expression of folate receptors. The multifunctional nanomaterials exhibited superparamagnetic, monodisperse, highly biocompatible, intensively fluorescent and capable of recognizing and binding cells that overexpress folate receptors, which would be useful for targeting cell imaging and provide an excellent platform for further development of an efficient cancer therapy. PMID:24738334

  9. Rapamycin loaded magnetic Fe3O4/carboxymethylchitosan nanoparticles as tumor-targeted drug delivery system: Synthesis and in vitro characterization.

    Science.gov (United States)

    Li, Guiyin; Cao, Liangli; Zhou, Zhide; Chen, Zhencheng; Huang, Yong; Zhao, Yongxiang

    2015-04-01

    A novel tumor-targeted drug delivery system (Fe3O4/CMCS-Rapa NPs) was prepared using magnetic Fe3O4/carboxymethylchitosan nanoparticles (Fe3O4/CMCS NPs) as carrier and rapamycin (Rapa) as the model anti-tumor drug. The morphology, composition, and properties of the Fe3O4/CMCS-Rapa NPs were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal analysis (TG/DSC), vibration sample magnetometer (VSM), and drug release kinetics, cytotoxicity, cellular uptake, apoptosis studies in vitro. The results showed that the synthesized Fe3O4/CMCS-Rapa NPs were spherical in shape with an average size of 30±2 nm, the saturated magnetization reached 67.1 emu/g, and the loading efficiency of Rapa was approximately 6.32±0.34%. In addition, the in vitro drug release behavior displayed that the Fe3O4/CMCS NPs exhibited a biphasic drug release pattern with initial burst release and consequently sustained release. Furthermore, the Fe3O4/CMCS-Rapa NPs showed lower cytotoxicity to liver cell line (LO2) and comparatively higher cytotoxicity to human hepatocarcinoma cell line (HepG2) than native Rapa. Fe3O4/CMCS-Rapa NPs could enhance cellular uptake and reduce Rapa drug damage to the normal cells so as to improve the curative effect of drug to tumor cells. All these results demonstrated that the Fe3O4/CMCS-Rapa NPs may be useful as a promising candidate for targeted cancer diagnostic and therapy. PMID:25779605

  10. Preparation of Fe3O4-Embedded Poly(styrene/Poly(thiophene Core/Shell Nanoparticles and Their Hydrogel Patterns for Sensor Applications

    Directory of Open Access Journals (Sweden)

    Yong Seok Kim

    2014-01-01

    Full Text Available This research describes the preparation and sensor applications of multifunctional monodisperse, Fe3O4 nanoparticles-embedded poly(styrene/poly(thiophene (Fe3O4-PSt/PTh, core/shell nanoparticles. Monodisperse Fe3O4-PSt/PTh nanoparticles were prepared by free-radical combination (mini-emulsion/emulsion polymerization for Fe3O4-PSt core and oxidative seeded emulsion polymerization for PTh shell in the presence of FeCl3/H2O2 as a redox catalyst, respectively. For applicability of Fe3O4-PSt/PTh as sensors, Fe3O4-PSt/PTh-immobilized poly(ethylene glycol (PEG-based hydrogels were fabricated by photolithography. The hydrogel patterns showed a good sensing performance under different H2O2 concentrations. They also showed a quenching sensitivity of 1 µg/mL for the Pd2+ metal ion within 1 min. The hydrogel micropatterns not only provide a fast water uptake property but also suggest the feasibility of both H2O2 and Pd2+ detection.

  11. Influence of different synthesis conditions on properties of oleic acid-coated-Fe3O4 nanoparticles

    Directory of Open Access Journals (Sweden)

    Aliakbari Atieh

    2015-03-01

    Full Text Available In the present paper, iron oxide nanoparticles coated by oleic acid have been synthesized in different conditions by coprecipitation method. For investigating the effect of time spent on adding the oleic acid to the precursor solution, two different processes have been considered. The as synthesized samples were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM and Fourier transform infrared spectroscopy (FT-IR. Magnetic measurement was carried out at room temperature using a vibrating sample magnetometer (VSM. The results show that the magnetic nanoparticles decorated with oleic acid decreased the saturation of magnetization. From the data, it can also be concluded that the magnetization of Fe3O4/oleic acid nanoparticles depends on synthesis conditions.

  12. One-step synthesis Fe3N surface-modified Fe3O4 nanoparticles with excellent lithium storage ability

    International Nuclear Information System (INIS)

    The Fe3N modified Fe3O4 nanoparticles with an excellent performance in lithium-ion batteries were prepared via a one-step and an efficient method. The layer of Fe3N could significantly decrease the variation of volume and enhance the conductivity of Fe3O4 simultaneously during the reaction of lithium ions in the charge-discharge process. There are two main advantages of this material: (1) their size distribution, ranging from 100 to 500 nm and (2) the fact that these particles are connected with each other by the Fe3N layer. These two features allow such material to exhibit a high reversible capacity of 739 and 620 mA h g?1 after each 60 cycles at the current density of 50 and 200 mA g?1, respectively. More importantly, since its introduction, this new concept of coating metal oxides with a layer of metal nitride to form core-shell structured metal oxide@metal nitride can be widely applied in the fields of catalysis, electrochemistry, energy, environmental and materials science with improved performance.

  13. Synthesis and characterization of magnetically recyclable Ag nanoparticles immobilized on Fe3O4@C nanospheres with catalytic activity

    Science.gov (United States)

    Li, Wei-hong; Yue, Xiu-ping; Guo, Chang-sheng; Lv, Jia-pei; Liu, Si-si; Zhang, Yuan; Xu, Jian

    2015-04-01

    A novel approach for the synthesis of Ag-loaded Fe3O4@C nanospheres (Ag-Fe3O4@C) was successfully developed. The catalysts possessed a carbon-coated magnetic core and grew active silver nanoparticles on the outer shell using hydrazine monohydrate as the AgNO3 reductant in ethanol. The morphology, inner structure, and magnetic properties of the as-prepared composites were studied with transmission electron microscopy (TEM), X-ray powder diffraction (XRD), fourier translation infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. Catalytic activity was investigated by degrading rhodamine B (RhB) in the designed experiment. The obtained products were monodispersed and bifunctional with high magnetization, as well as exhibited excellent catalytic activity toward organic dye with 98% of RhB conversion within 20 min in the presence of NaBH4. The product also exhibited convenient magnetic separability and maintained high catalytic activity after six cycle runs.

  14. Fe3O4 nanoparticles and nanocomposites with potential application in biomedicine and in communication technologies: Nanoparticle aggregation, interaction, and effective magnetic anisotropy

    OpenAIRE

    Allia, Paolo Maria Eugenio Icilio; Sangermano, Marco

    2014-01-01

    Magnetite nanoparticles with a size of 5-6 nm with potential impact on biomedicine and information/communication technologies were synthesized by thermal decomposition of Fe(acac)3 and subsequently coated with a silica shell exploiting a water-in-oil synthetic procedure. The as-produced powders (comprised of either Fe3O4 or Fe3O4@silica nanoparticles) were mixed with a photocurable resin obtaining two magnetic nanocomposites with the same nominal amount of magnetic material. The static magnet...

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

    International Nuclear Information System (INIS)

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

  16. Remoción de pesticidas órgano-fosforados en aguas con nanopartículas magnéticas de Fe3O4 soportadas en sílice / Removal of organophosphorus pesticides in water with supported silica Fe3O4 magnetic nanoparticles

    Scientific Electronic Library Online (English)

    Yosmery, Vitta Brito; Alberto, Fernández Cuervo; Yolanda, Moliner-Martínez; Pilar, Campíns Falco.

    2014-09-01

    Full Text Available En este trabajo se evaluó la eficiencia de Nanopartículas, (Nps), magnéticas de Fe3O4 incorporadas en una matriz de sílice mediante el método sol-gel, como adsorbente de los pesticidas organofosforados: Chlorfenvifos (Chlorf) y Chlorpyrifos (Chlorp) en aguas de efluentes residuales. Las Nps de Fe3O4 [...] -SiO2 presentaron un tamaño promedio de 5 nm. Los límites de detección fueron de 1 ?g L-1 y 2 ?g L-1 para el Chlorf y el Chlorp respectivamente, obteniendo una precisión intradiaria del 2 % e inter-diaria del 3%. La isoterma de adsorción según Langmuir, reportó que el Chlorp fue la especie más adsorbida por el nano-adsorbente con una capacidad máxima de adsorción, Smáx de 0,70 ± 0,35 ?g g-1, mientras que el Chlorf reportó un Smáx de 0,40 ± 0,12 ?g g-1. El procedimiento fue ensayado en aguas residuales, alcanzando una remoción entre el 60 - 85% en los analitos. El mecanismo de adsorción de los pesticidas, se atribuye a la interacción entre estos compuestos apolares y las cadenas alifáticas de las micelas del Bromuro de hexadeciltrimetilamonio, CTAB, del adsorbente, dado que los porcentajes de los analitos en el líquido fueron inferiores al 10%. Abstract in english This paper evaluates the efficiency of Fe3O4 magnetic nanoparticles embedded in silica matrix, by a sol-gel method, as adsorbent of two organophosphate pesticides, Chlorfenvifos (Chlorf) and Chlorpyrifos (Chlorp), in sewage. The Fe3O4- SiO2 Nps have an average size of 5 nm. The detection limits were [...] 1 ? g L-1 for the Chlorf and 2 ? g L-1 for the Chlorp, obtaining an intra-day precision of 2% and inter-day 3%. According to the Langmuir adsorption isotherm, the Chlorp was identified as the more adsorbed species with Smax = de 0.70 ± 0.15 ?g g-1, while Smax = 0.40 ± 0.12 ?g g-1 for Chlorf. The procedure was tested on sewage, reaching analyte’s removal between 60 - 85%. The adsorption mechanism of pesticides is attributed to the hydrophobic interaction between these compounds and aliphatic chains of CTAB micelles, since the percentage of compounds in the liquid was less than 10%.

  17. The effect of suspended Fe3O4 nanoparticle size on magneto-optical properties of ferrofluids

    Science.gov (United States)

    Brojabasi, Surajit; Muthukumaran, T.; Laskar, J. M.; Philip, John

    2015-02-01

    We investigate the effect of hydrodynamic particle size on the magnetic field induced light transmission and transmitted speckle pattern in water based ferrofluids containing functionalized Fe3O4 nanoparticles of size ranging from 15 to 46 nm. Three water-based magnetic nanofluids, containing Fe3O4 nanoparticles functionalized with poly-acrylic acid (PAA), tetra-methyl ammonium hydroxide (TMAOH) and phosphate, are used in the present study. In all three cases, the transmitted light intensity starts decreasing above a certain magnetic field (called first critical field) and becomes a minimum at another field (second critical field). These two critical fields signify the onset of linear aggregation process and zippering transitions between fully grown chains, respectively. Both these critical fields shift towards a lower magnetic field with increasing hydrodynamic diameter, due to stronger magnetic dipolar interactions. The first and the second critical fields showed a power law dependence on the hydrodynamic diameters. The dipolar resonances occurring at certain values of the scatterer size, leads to the field induced extinction of light. Both the onset of chaining and zippering transitions were clearly evident in the time dependent transmitted light intensity. Above the first critical field, the lobe part of the transmitted intensity and the lobe speckle contrast values increase with increasing external magnetic field due to reduced Brownian motion of the field induced aggregates. The speckle contrast was highest for nanoparticle with the largest hydrodynamic diameter, due to reduced Brownian motion. These results provide better insight into field dependent light control in magnetic colloids, which may find interesting applications in magneto-optical devices.

  18. Electrooxidation behavior of warfarin in Fe3O4 nanoparticles modified carbon paste electrode and its determination in real samples.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Torkashvand, Maryam; Yavari, Eilnaz

    2015-03-01

    In the present work, a simple and sensitive electrochemical sensor based on magnetic Fe3O4 nanoparticles modified carbon paste electrode (CPE) was introduced for detection of low level with 0.21?M of warfarin. Under the optimum experimental conditions the oxidation peak current of warfarin was used for its monitoring for the first time. The analytical curve was linear for warfarin concentrations from 0.5 to 1000?M with a limit of detection of 0.21?M by square wave anodic stripping voltammetry (SWASV). The proposed sensor showed excellent stability and was used for the determination of warfarin in tablet, human serum and urine with satisfactory results. PMID:25579919

  19. Sensitive electrochemical sensor for hydrogen peroxide using Fe3O4 magnetic nanoparticles as a mimic for peroxidase

    International Nuclear Information System (INIS)

    A sensor for hydrogen peroxide is described that is based on an indium tin oxide electrode modified with Fe3O4 magnetic nanoparticles which act as a mimic for the enzyme peroxidase and greatly improve the analytical performance of the sensor. The amperometric current is linearly related to the concentration of H2O2 in the range from 0.2 mM to 2 mM, the regression equation is y = -0.5-1.82x, the correlation coefficient is 0.998 (n = 3), and the detection limit is 0.01 mM (S/N = 3). The sensor exhibits favorable selectivity and excellent stability. (author)

  20. Preparation and in vitro evaluation of doxorubicin-loaded Fe3O4 magnetic nanoparticles modified with biocompatible copolymers

    Directory of Open Access Journals (Sweden)

    Akbarzadeh A

    2012-02-01

    Full Text Available Abolfazl Akbarzadeh1, Haleh Mikaeili2, Nosratollah Zarghami3, Rahmati Mohammad3, Amin Barkhordari3, Soodabeh Davaran21Drug Applied Research Center, 2Tuberculosis and Lung Disease Research Center of Tabriz, 3Department of Clinical Biochemistry and Laboratory Medicine, Division of Medical Biotechnology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IranBackground: Superparamagnetic iron oxide nanoparticles are attractive materials that have been widely used in medicine for drug delivery, diagnostic imaging, and therapeutic applications. In our study, superparamagnetic iron oxide nanoparticles and the anticancer drug, doxorubicin hydrochloride, were encapsulated into poly (D, L-lactic-co-glycolic acid poly (ethylene glycol (PLGA-PEG nanoparticles for local treatment. The magnetic properties conferred by superparamagnetic iron oxide nanoparticles could help to maintain the nanoparticles in the joint with an external magnet.Methods: A series of PLGA:PEG triblock copolymers were synthesized by ring-opening polymerization of D, L-lactide and glycolide with different molecular weights of polyethylene glycol (PEG2000, PEG3000, and PEG4000 as an initiator. The bulk properties of these copolymers were characterized using 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared spectroscopy, and differential scanning calorimetry. In addition, the resulting particles were characterized by x-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometry.Results: The doxorubicin encapsulation amount was reduced for PLGA:PEG2000 and PLGA:PEG3000 triblock copolymers, but increased to a great extent for PLGA:PEG4000 triblock copolymer. This is due to the increased water uptake capacity of the blended triblock copolymer, which encapsulated more doxorubicin molecules into a swollen copolymer matrix. The drug encapsulation efficiency achieved for Fe3O4 magnetic nanoparticles modified with PLGA:PEG2000, PLGA:PEG3000, and PLGA:PEG4000 copolymers was 69.5%, 73%, and 78%, respectively, and the release kinetics were controlled. The in vitro cytotoxicity test showed that the Fe3O4-PLGA:PEG4000 magnetic nanoparticles had no cytotoxicity and were biocompatible.Conclusion: There is potential for use of these nanoparticles for biomedical application. Future work includes in vivo investigation of the targeting capability and effectiveness of these nanoparticles in the treatment of lung cancer.Keywords: superparamagnetic iron oxide nanoparticles, triblock copolymer, doxorubicin encapsulation, water uptake, drug encapsulation efficiency

  1. Polyol synthesis of Mn3+ substituted Fe3O4 nanoparticles: Cation distribution, structural and electrical properties

    Science.gov (United States)

    Amir, Md.; Ünal, B.; Shirsath, Sagar E.; Geleri, M.; Sertkol, M.; Baykal, A.

    2015-09-01

    In this study, MnxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanoparticles were synthesized by polyol route and the effect of Mn3+ substitution on structural and dielectric properties of Fe3O4 was studied. X-ray powder diffraction (XRD) patterns confirmed the single spinel ferrite phase formation (Rietveld analysis). Crystallite size of the synthesized materials lie in the range of 12-25 nm as calculated X-ray diffraction patterns using Scherrer's formula. The microstructural features were examined by SEM images. Cation distribution calculations confirmed Fe3+ ions have both tetrahedral and ochedral site preferences whereas Mn3+ ions mostly occupies tetrahedral A-site. The ac electrical and dielectric properties of Mn3+ ion substituted Fe3O4 nanoparticle show that there were significant changes in both conductivity and complex permittivity as well as dielectric loss tangent as Mn3+ ion concentration is varied from zero to unity. It is clearly seen that conductivity increases with increase in temperature which may be due to increase in hopping capability of charge carriers at higher temperatures. Detailed evaluation of analysis reveals that at higher frequencies there is less effect of temperature on conductivity which can be interpreted on the basis of interfacial, dipolar, ionic and electronic polarization as detailed above section in explanation of variation of dielectric loss. The dielectric permittivity shows dielectric behavior can be clarified on the basis of Koop's interpretations in accordance with two layer Maxwell-Wagner model by accounting for surface charges. The electrical and dielectric properties, i.e. ac/dc conductivity, real/complex dielectric permittivity, and dielectric loss (tan ?) decrease with Mn3+ ion doping in some aspects.

  2. Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe3O4-silica-Au magnetic nanoparticles

    International Nuclear Information System (INIS)

    Monodisperse Fe3O4 magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe3O4-silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 × 10?9 mol·cm?2, and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 ± 0.6 s?1. The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 ?A·mM?1 cm?2 and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe3O4-silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: ? Synthesis of monodispersed Fe3O4 nanoparticles. ? Fabrication of core/shell Fe3O4-silica-Au nanoparticles. ? Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

  3. Immobilization of cyclodextrin glucanotransferase on aminopropyl-functionalized silica-coated superparamagnetic nanoparticles

    Scientific Electronic Library Online (English)

    Abdelnasser S.S., Ibrahim; Ali A, Al-Salamah; Ahmed Mohamed, El-Toni; Mohamed A, El-Tayeb; Yahya B, Elbadawi.

    2013-11-15

    Full Text Available Background: Cyclodextrin glycosyltransferase (CGTase) from Amphibacillus sp. NPST-10 was successfully covalently immobilized on aminopropyl-functionalized silica coated superparamagnetic nanoparticles; and the properties of immobilized enzyme were investigated. The synthesis process included prepari [...] ng of core magnetic magnetite (Fe3O4) nanoparticles using solvothermal synthesis; followed by coating of Fe3O4 nanoparticles with dense amino-functionalized silica (NH2-SiO2) layer using in situ functionalization method. The structure of synthesized Fe3O4@NH2-SiO2 nanoparticles was characterized using TEM, XRD, and FT-IR analysis. Fe3O4@NH2-SiO2 nanoparticles were further activated by gluteraaldehyde as bifunctional cross linker, and the activated nanoparticles were used for CGTase immobilization by covalent attachment. Results: Magnetite nanoparticles was successfully synthesized and coated with and amino functionalized silica layer (Fe3O4/NH2-SiO2), with particle size of 50-70 nm. The silica coated magnetite nanoparticles showed with saturation magnetization of 65 emug-1, and can be quickly recovered from the bulk solution using an external magnet within 10 sec. The activated support was effective for CGTase immobilization, which was confirmed by comparison of FT-IR spectra of free and immobilized enzyme. The applied approach for support preparation, activation, and optimization of immobilization conditions, led to high yields of CGTase immobilization (92.3%), activity recovery (73%), and loading efficiency (95.2%); which is one of the highest so far reported for CGTase. Immobilized enzyme showed shift in the optimal temperature from 50 to 55ºC, and significant enhancement in the thermal stability compared with free enzyme. The optimum pH for enzyme activity was pH 8 and pH 7.5 for free and immobilized CGTase, respectively, with slight improvement of pH stability of immobilized enzyme. Furthermore, kinetic studies revealed that immobilized CGTase had higher affinity toward substrate; with k m values of 1.18 ± 0.05 mg/ml and 1.75 ± 0.07 mg/ml for immobilized and free CGTase, respectively. Immobilized CGTase retained 87% and 67 of its initial activity after 5 and 10 repeated batches reaction, indicating that immobilized CGTase on Fe3O4/NH2-SiO2 had good durability and magnetic recovery. Conclusion: The improvement in kinetic and stability parameters of immobilized CGTase makes the proposed method a suitable candidate for industrial applications of CGTase. To best of our knowledge, this is the first report about CGTase immobilization on silica coated magnetite nanoparticles.

  4. One-step synthesis of water-dispersible cysteine functionalized magnetic Fe3O4 nanoparticles for mercury(II) removal from aqueous solutions

    International Nuclear Information System (INIS)

    Graphical abstract: Using Fe2+ as precursors, air as oxidant and cysteine as protectant, this novel cysteine functionalized Fe3O4 magnetic nanoparticles (Cys-Fe3O4 MNPs) was facilely one-pot synthesized at room temperature by oxidation–precipitation method with the assistance of sonication. Then the Cys-Fe3O4 MNPs were demonstrated as an inexpensive and quite efficient magnetic nano-adsorbent for as high as 95% Hg(II) removal efficiency. These results indicated that Cys-Fe3O4 MNPs is a potentially attractive material for the removal of Hg(II) from water. - Highlights: • A simplified one-step synthesis method of superparamagnetic Cys-Fe3O4 MNPs was developed. • It was synthesized at room temperature by oxidation-precipitation method with the assistance of sonication. • It was demonstrated as an inexpensive and quite efficient magnetic nano-adsorbent for Hg(II) removal. - Abstract: Cysteine functionalized Fe3O4 magnetic nanoparticles (Cys-Fe3O4 MNPs) were prepared facilely for Hg(II) removal from aqueous solutions. Using Fe2+ as precursors, air as oxidant and Cys as protectant, this novel material was one-pot synthesis at room temperature by oxidation–precipitation method with the assistance of sonication. The MNPs were characterized by TEM, VSM, FTIR, X-ray powder diffraction analysis (XRD) and TGA methods. Under the optimum experimental conditions, the removal efficiency was as high as 95% and the maximum sorption capacity is found to be 380 mg/mol for Hg(II). Study on adsorption kinetics shows that adsorption of Hg(II) onto Cys-Fe3O4 MNPs follows pseudo-first-order kinetic model and the adsorption rate constant was 0.22 min?1. Additionally, the Hg(II)-loaded Cys-Fe3O4 MNPs could be easily regenerated up to 95% using 1.0 M acetic acid. These results indicated that Cys-Fe3O4 MNPs is a potentially attractive material for the removal of Hg(II) from water

  5. Removal of reactive red-120 and 4-(2-pyridylazo) resorcinol from aqueous samples by Fe3O4 magnetic nanoparticles using ionic liquid as modifier

    International Nuclear Information System (INIS)

    Highlights: ? Ionic liquids modify the dye-adsorption characteristics of magnetic nanoparticles. ? Modified nanoparticles improved the sensitivity of dye measurements. ? Water-solubility is an important factor for choosing an ionic liquid as a modifier for nanoparticles. - Abstract: The nanoparticles of Fe3O4 as well as the binary nanoparticles of ionic liquid and Fe3O4 (IL-Fe3O4) were synthesized for removal of reactive red 120 (RR-120) and 4-(2-pyridylazo) resorcinol (PAR) as model azo dyes from aqueous solutions. The mean size and the surface morphology of the nanoparticles were characterized by TEM, DLS, XRD, FTIR and TGA techniques. Adsorption of RR-120 and PAR was studied in a batch reactor at different experimental conditions such as nanoparticle dosage, dye concentration, pH of the solution, ionic strength, and contact time. Experimental results indicated that the IL-Fe3O4 nanoparticles had removed more than 98% of both dyes under the optimum operational conditions of a dosage of 60 mg, a pH of 2.5, and a contact time of 2 min when initial dyes concentrations of 10-200 mg L-1 were used. The maximum adsorption capacity of IL-Fe3O4 was 166.67 and 49.26 mg g-1 for RR-120 and PAR, respectively. The isotherm experiments revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The Langmuir adsorption constants were 5.99 and 3.62 L mg-1 for adsorptions of RR-120 and PAR, respectively. Both adsorption processes were endothermic and dyes could be desorbed from IL-Fe3O4 by using a mixed NaCl-acetone solution and adsorbent was reusable.

  6. One-pot polyol synthesis of monosize PVP-coated sub-5 nm Fe3O4 nanoparticles for biomedical applications

    International Nuclear Information System (INIS)

    Polyvinylpyrrolidone (PVP)-coated sub-5 nm monosize Fe3O4 nanoparticles were synthesized by reduction of Fe(III) acetylacetonate in the presence of PVP polymer as surfactant in one-pot polyol process. Their microstructure and magnetic properties were characterized by XRD, TEM/HRTEM and VSM. It is found that the nanoparticles have high crystallinity with distinct lattices and the magnetic measurements reveal their well-defined superparamagnetic behavior at room temperature. Such Fe3O4 nanoparticles with tailorable size and tunable magnetic properties are promising for biomedical applications

  7. Characterisation of Co@Fe3O4 core@shell nanoparticles using advanced electron microscopy.

    OpenAIRE

    Knappett, BR; Abdulkin, P; Ringe, E; Jefferson, DA; Lozano-Perez, S.; Rojas, TC; Fernández, A.; Wheatley, AE

    2013-01-01

    Cobalt nanoparticles were synthesised via the thermal decomposition of Co2(CO)8 and were coated in iron oxide using Fe(CO)5. While previous work focused on the subsequent thermal alloying of these nanoparticles, this study fully elucidates their composition and core@shell structure. State-of-the-art electron microscopy and statistical data processing enabled chemical mapping of individual particles through the acquisition of energy-filtered transmission electron microscopy (EFTEM) images and ...

  8. Synthesis and characterization of PVP-functionalized superparamagnetic Fe3O4 nanoparticles as an MRI contrast agent

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available The magnetite (Fe3O4 nanoparticles (MNPs coated with poly(N-vinyl pyrrolidone (PVP via covalent bonds were prepared as T2 contrast agent for magnetic resonance imaging (MRI. The surface of MNPs was first coated with 3-(trimethoxysilyl propyl methacrylate (silan A by a silanization reaction to introduce reactive vinyl groups onto the surface, then poly(N-vinyl pyrrolidone was grafted onto the surface of modified-MNPs via surface-initiated radical polymerization. The obtained nanoparticles were characterized by FT-IR (Fourier transform infrared spectroscopy, XRD (X-ray diffraction, TEM (transmission electron microscopy, VSM (vibrating sample magnetometer, and TGA (thermogravimetric analysis. The MNPs had an average size of 14 nm and exhibited superparamagnetism and high saturation magnetization at room temperature. T2-weighted MRI images of PVP-grafted MNPs showed that the magnetic resonance signal is enhanced significantly with increasing nanoparticle concentration in water. The r1 and r2 values per millimole Fe, and r2/r1 value of the PVP-grafted MNPs were calculated to be 2.6 , 72.1, and 28.1(mmol/l–1•s–1, respectively. These results indicate that the PVP-grafted MNPs have great potential for application in MRI as a T2 contrast agent.

  9. Enzyme-free fluorescent biosensor for the detection of DNA based on core-shell Fe3O4 polydopamine nanoparticles and hybridization chain reaction amplification.

    Science.gov (United States)

    Li, Na; Hao, Xia; Kang, Bei Hua; Xu, Zhen; Shi, Yan; Li, Nian Bing; Luo, Hong Qun

    2016-03-15

    A novel, highly sensitive assay for quantitative determination of DNA is developed based on hybridization chain reaction (HCR) amplification and the separation via core-shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs). In this assay, two hairpin probes are designed, one of which is labeled with a 6-carboxyfluorescein (FAM). Without target DNA, auxiliary hairpin probes are stable in solution. However, when target DNA is present, the HCR between the two hairpins is triggered. The HCR products have sticky ends of 24nt, which are much longer than the length of sticky ends of auxiliary hairpins (6nt) and make the adsorption much easier by Fe3O4@PDA NPs. With the addition of Fe3O4@PDA NPs, HCR products could be adsorbed because of the strong interaction between their sticky ends and Fe3O4@PDA NPs. As a result, supernatant of the solution with target DNA emits weak fluorescence after separation by magnet, which is much lower than that of the blank solution. The detection limit of the proposed method is as low as 0.05nM. And the sensing method exhibits high selectivity for the determination between perfectly complementary sequence and target with single base-pair mismatch. Importantly, the application of the sensor for DNA detection in human serum shows that the proposed method works well for biological samples. PMID:26469729

  10. Multifunctional Fe3O4/TaO(x) core/shell nanoparticles for simultaneous magnetic resonance imaging and X-ray computed tomography.

    Science.gov (United States)

    Lee, Nohyun; Cho, Hye Rim; Oh, Myoung Hwan; Lee, Soo Hong; Kim, Kangmin; Kim, Byung Hyo; Shin, Kwangsoo; Ahn, Tae-Young; Choi, Jin Woo; Kim, Young-Woon; Choi, Seung Hong; Hyeon, Taeghwan

    2012-06-27

    Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, a sol-gel reaction of tantalum(V) ethoxide in a microemulsion containing Fe(3)O(4) nanoparticles (NPs) was used to synthesize multifunctional Fe(3)O(4)/TaO(x) core/shell NPs, which were biocompatible and exhibited a prolonged circulation time. When the NPs were intravenously injected, the tumor-associated vessel was observed using computed tomography (CT), and magnetic resonance imaging (MRI) revealed the high and low vascular regions of the tumor. PMID:22676237

  11. Controlling dynamic SERS hot spots on a monolayer film of Fe3O4@Au nanoparticles by a magnetic field.

    Science.gov (United States)

    Guo, Qing-Hua; Zhang, Chen-Jie; Wei, Chao; Xu, Min-Min; Yuan, Ya-Xian; Gu, Ren-Ao; Yao, Jian-Lin

    2016-01-01

    A large surface-enhanced Raman scattering (SERS) effect is critically dependent on the gap distance of adjacent nanostructures, i.e., "hot spots". However, the fabrication of dynamically controllable hot spots still remains a remarkable challenge. In the present study, we employed an external magnetic field to dynamically control the interparticle spacing of a two-dimensional monolayer film of Fe3O4@Au nanoparticles at a hexane/water interface. SERS measurements were performed to monitor the expansion and shrinkage of the nanoparticles gaps, which produced an obvious effect on SERS activities. The balance between the electrostatic repulsive force, surface tension, and magnetic attractive force allowed observation of the magnetic-field-responsive SERS effect. Upon introduction of an external magnetic field, a very weak SERS signal appeared initially, indicating weak enhancement due to a monolayer film with large interparticle spacing. The SERS intensity reached maximum after 5s and thereafter remained almost unchanged. The results indicated that the observed variations in SERS intensities were fully reversible after removal of the external magnetic field. The reduction of interparticle spacing in response to a magnetic field resulted in about one order of magnitude of SERS enhancement. The combined use of the monolayer film and external magnetic field could be developed as a strategy to construct hot spots both for practical application of SERS and theoretical simulation of enhancement mechanisms. PMID:26232577

  12. Non-aqueous synthesis of water-dispersible Fe3O4-Ca3(PO4)2 core-shell nanoparticles

    International Nuclear Information System (INIS)

    The Fe3O4-Ca3(PO4)2 core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe3O4 and the bioactive functions of Ca3(PO4)2 into single entities. The Fe3O4 nanoparticles were pre-formed first by thermal reduction of Fe(acac)3 and then the Ca3(PO4)2 layer was coated by simultaneous deposition of Ca2+ and PO43-. The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca3(PO4)2 shell forms an hcp phase (a = 7.490 A, c = 9.534 A) on the Fe3O4 surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca3(PO4)2 and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe3O4 and Ca3(PO4)2 in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.

  13. Direct Electrochemistry and Electrocatalysis of Horseradish Peroxidase Immobilized in a DNA/Chitosan-Fe3O4 Magnetic Nanoparticle Bio-Complex Film

    Directory of Open Access Journals (Sweden)

    Tingting Gu

    2014-02-01

    Full Text Available A DNA/chitosan-Fe3O4 magnetic nanoparticle bio-complex film was constructed for the immobilization of horseradish peroxidase (HRP on a glassy carbon electrode. HRP was simply mixed with DNA, chitosan and Fe3O4 nanoparticles, and then applied to the electrode surface to form an enzyme-incorporated polyion complex film. Scanning electron microscopy (SEM was used to study the surface features of DNA/chitosan/Fe3O4/HRP layer. The results of electrochemical impedance spectroscopy (EIS show that Fe3O4 and enzyme were successfully immobilized on the electrode surface by the DNA/chitosan bio-polyion complex membrane. Direct electron transfer (DET and bioelectrocatalysis of HRP in the DNA/chitosan/Fe3O4 film were investigated by cyclic voltammetry (CV and constant potential amperometry. The HRP-immobilized electrode was found to undergo DET and exhibited a fast electron transfer rate constant of 3.7 s?1. The CV results showed that the modified electrode gave rise to well-defined peaks in phosphate buffer, corresponding to the electrochemical redox reaction between HRP(Fe(III and HRP(Fe(II. The obtained electrode also displayed an electrocatalytic reduction behavior towards H2O2. The resulting DNA/chitosan/Fe3O4/HRP/glassy carbon electrode (GCE shows a high sensitivity (20.8 A·cm?2·M?1 toward H2O2. A linear response to H2O2 measurement was obtained over the range from 2 µM to 100 µM (R2 = 0.99 and an amperometric detection limit of 1 µM (S/N = 3. The apparent Michaelis-Menten constant of HRP immobilized on the electrode was 0.28 mM. Furthermore, the electrode exhibits both good operational stability and storage stability.

  14. Aggregates of perylene bisimide stabilized superparamagnetic Fe3O4 nanoparticles: an efficient catalyst for the preparation of propargylamines and quinolines via C-H activation.

    Science.gov (United States)

    Kaur, Sandeep; Kumar, Manoj; Bhalla, Vandana

    2015-11-01

    Aggregates of the perylene bisimide derivative act as reactors and stabilizers for the preparation of superparamagnetic Fe3O4 nanoparticles (NPs) which exhibit excellent catalytic efficiency in (i) A(3)-coupling and aldehyde free coupling reactions for the preparation of propargylamines and (ii) tandem intramolecular cyclization reaction for the synthesis of quinolines via C-H activation. PMID:26399895

  15. Green synthesis of Fe3O4 nanoparticles embedded in a porous carbon matrix and its use as anode material for Li-ion batteries

    OpenAIRE

    Latorre Sánchez, Marcos; Primo Arnau, Ana Maria; García Gómez, Hermenegildo

    2012-01-01

    A scalable and simple process was developed for the preparation of Fe3O4 nanoparticles embedded in carbon using nontoxic and affordable materials. The resulting composite showed a high reversible capacity of 702 mA h g(-1) as anode material in a Li-ion battery after 50 cycles.

  16. A comparative study for adsorption of lysozyme from aqueous samples onto Fe3O4 magnetic nanoparticles using different ionic liquids as modifier.

    Science.gov (United States)

    Kamran, Sedigheh; Absalan, Ghodratollah; Asadi, Mozaffar

    2015-12-01

    In this paper, nanoparticles of Fe3O4 as well as their modified forms with different ionic liquids (IL-Fe3O4) were prepared and used for adsorption of lysozyme. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption studies of lysozyme were performed under different experimental conditions in batch system on different modified magnetic nanoparticles such as, lysozyme concentration, pH of the solution, and contact time. Experimental results were obtained under the optimum operational conditions of pH 9.0 and a contact time of 10 min when initial protein concentrations of 0.05-2.0 mg mL(-1) were used. The isotherm evaluations revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The maximum obtained adsorption capacities were 370.4, 400.0 500.0 and 526.3 mg of lysozyme for adsorption onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br] per gram of adsorbent, respectively. The Langmuir adsorption constants were 0.004, 0.019, 0.024 and 0.012 L mg(-1) for adsorptions of lysozyme onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br], respectively. The adsorption capacity of lysozyme was found to be dependent on its chemical structure, pH of the solution, temperature and type of ionic liquid as modifier. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated. Furthermore, the thermodynamic parameters were calculated. Protein could desorb from IL-Fe3O4 nanoparticles by using NaCl solution at pH 9.5 and was reused. PMID:26149480

  17. Synthesis and photocatalytic property of Fe3O4@TiO2 core/shell nanoparticles supported by reduced graphene oxide sheets

    International Nuclear Information System (INIS)

    Highlights: •Fe3O4@TiO2 nanoparticles loaded on graphene sheets are synthesized for the first time. •This ternary structure can induce photo-degradation of methyl orange. •The interfacial structure between TiO2 and Fe3O4 is stable at 450 °C. •Fe3O4@TiO2/graphene as ternary photocatalyst can be retrieved by magnetic field. -- Abstract: A ternary nanocomposite of Fe3O4@TiO2/reduced graphene oxide (FTR) was prepared successfully by a facile route in this work. Fe3O4@TiO2 core/shell nanospheres were loaded on the surface of reduced graphene oxide (RGO), making the ternary nanocomposite possessed enhanced charge separation efficiency in combined with the supporting media of RGO. The morphology of the ternary nanocomposite was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic degradation efficiency on methyl orange of the FTR nanocomposite was investigated. The photocatalytic degradation efficiency of ternary composite was about three times than that of pure TiO2. The result show that the photocatalytic efficiency of 25 mg FTR can reach 83.8% in 50 min, In addition to the high efficiency of the degradation property, the ternary composite can be easily recycled by normal magnet due to the magnetite core. It is suggested that the FTR ternary composite of Fe3O4@TiO2/reduced graphene oxide can be an efficient multifunctional photocatalyst for the degradation of hazardous compounds in waste water

  18. Fluorescence-based immunoassay for human chorionic gonadotropin based on polyfluorene-coated silica nanoparticles and polyaniline-coated Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    We report on an ultrasensitive fluorescence immunoassay for human chorionic gonadotrophin antigen (hCG). It is based on the use of silica nanoparticles coated with a copolymer (prepared from a fluorene, a phenylenediamine, and divinylbenzene; PF.SiO2) that acts as a fluorescent label for the secondary monoclonal antibody to ?-hCG antigen. In parallel, Fe3O4 nanoparticles were coated with polyaniline, and these magnetic particles (Fe3O4.PANI) served as a solid support for the primary monoclonal antibody to ?-hCG antigen. The PF.SiO2 exhibited strong fluorescence and good dispersibility in water. A fluorescence sandwich immunoassay was developed that enables hCG concentrations to be determined in the 0.01–100 ng·mL?1 concentration range, with a detection limit of 3 pg·mL?1. (author)

  19. Functionalized magnetic iron oxide (Fe3O4) nanoparticles for capturing gram-positive and gram-negative bacteria.

    Science.gov (United States)

    Reddy, P Muralidhar; Chang, Kai-Chih; Liu, Zhen-Jun; Chen, Cheng-Tung; Ho, Yen-Peng

    2014-08-01

    The development of nanotechnology in biology and medicine has raised the need for conjugation of nanoparticles (NPs) to biomolecules. In this study, magnetic and functionalized magnetic iron oxide nanoparticles were synthesized and used as affinity probes to capture Gram-positive/negative bacteria. The morphology and properties of the magnetic NPs were examined by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. Furthermore, this study investigated the interaction between functionalized magnetic nanoparticles and Gram positive/negative bacteria. The positively and negatively charged magnetic nanoparticles include functionalities of Fe3O4, SiO2, TiO2, ZrO2, poly ethyleneimine (PEI) and poly acrylic acid. Their capture efficiencies for bacteria were investigated based on factors such as zeta potential, concentration and pH value. PEI particles carry a positive charge over a range of pH values from 3 to 10, and the particles were found to be an excellent candidate for capturing bacteria over such pH range. Since the binding force is mainly electrostatic, the architecture and orientation of the functional groups on the NP surface are not critical. Finally the captured bacteria were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The minimum detection limit was 10(4) CFU/mL and the analysis time was reduced to be less than 1 hour. In addition, the detection limit could be reduced to an extremely low concentration of 50 CFU/mL when captured bacteria were cultivated. PMID:25016643

  20. Reversal in multidrug resistance by magnetic nanoparticle of Fe3O4 loaded with adriamycin and tetrandrine in K562/A02 leukemic cells

    Directory of Open Access Journals (Sweden)

    Baoan Chen

    2008-06-01

    Full Text Available Baoan Chen1,5, Qian Sun1,5, Xuemei Wang2, Feng Gao1, Yongyuan Dai1, Yan Yin1, Jiahua Ding1, Chong Gao1, Jian Cheng1, Jingyuan Li2, Xinchen Sun1, Ningna Chen1, Wenlin Xu3, Huiling Shen3, Delong Liu41Department of Hematology, Zhongda Hospital, Southeast University, Nanjing, China; 2State Key Lab of Bioelectronics(Chien-Shiung Wu Laboratory, Southeast University, Nanjing 210096, China; 3Department of Hematology, The First People’s Hospital of Zhenjiang, Zhenjiang, China; 4Westchester Medical Center, New York Medical College, NY, USA; 5These authors have contributed equally to this work.Abstract: Drug resistance is a primary hindrance for efficiency of chemotherapy. To investigate whether Fe3O4-magnetic nanoparticles (Fe3O4-MNPs loaded with adriamycin (ADM and tetrandrine (Tet would play a synergetic reverse role in multidrug resistant cell, we prepared the drug-loaded nanoparticles by mechanical absorption polymerization to act with K562 and one of its resistant cell line K562/A02. The survival of cells which were cultured with these conjugates for 48 h was observed by MTT assay. Using cells under the same condition described before, we took use of fluorescence microscope to measure fluorescence intensity of intracellular ADM at an excitation wavelength of 488 nm. P-glycoprotein (P-gp was analyzed with flow cytometer. The expression of mdr1 mRNA was measured by RT-PCR. The results showed that the growth inhibition efficacy of both the two cells increased with augmenting concentrations of Fe3O4-MNPs which were loaded with drugs. No linear correlation was found between fluorescence intensity of intracellular adriamycin and augmenting concentration of Fe3O4-MNPs. Tet could downregulate the level of mdr-1 gene and decrease the expression of P-gp. Furthermore, Tet polymerized with Fe3O4-MNPs reinforced this downregulation, causing a 100-fold more decrease in mdr1 mRNA level, but did not reduce total P-gp content. Our results suggest that Fe3O4-MNPs loaded with ADM or Tet can enhance the effective accumulation of the drugs in K562/A02. We propose that Fe3O4-MNPs loaded with ADM and Tet probably have synergetic effect on reversal in multidrug resistance.Keywords: magnetic nanoparticles, tetrandrine, adriamycin, multidrug resistance reversal, leukemia K562/A02

  1. Biodesel Production from Pseudomonas Fluorescens Lp1 Lipase Immobilized on Amino-silane Modified Super Paramagnetic Fe3O4 Nanoparticles

    International Nuclear Information System (INIS)

    An extracellular lipase from Pseudomonas fluorescens Lp1 isolated from oil contaminated soil was immobilized onto amino silane modified superparamagnetic Fe3O4 nanoparticles. The magnetic nanoparticles, magnetite was synthesized chemically by co-precipitation and characterized by Scanning Electron Microscopy (SEM), Fourier Transformed Infrared Spectroscopy (FT-IR) and Powder X-ray diffraction studies (XRD). The structure of the synthesized magnetic nanoparticles was uniform, spherical and the size was determined around 31 nm by powder XRD. The biodiesel production mixture was prepared by addition of waste cooking oil, lipase immobilized magnetite and methanol. The transesterified products were analyzed by Gas Liquid chromatography-Mass spectroscopy (GC-MS). The methyl esters such as Oxiraneundecanoic acid, 3-pentyl-methyl ester, Hexadecanoic acid, methyl ester and 10-Octadecenoic acid, methyl ester were obtained. The study experimentally proved the use of amino silane modified superparamagnetic Fe3O4 nanoparticles in biodiesel production from waste cooking oil.

  2. Biodesel Production from Pseudomonas Fluorescens Lp1 Lipase Immobilized on Amino-silane Modified Super Paramagnetic Fe3O4 Nanoparticles

    Science.gov (United States)

    Kanimozhi, S.; Perinbam, K.

    2013-04-01

    An extracellular lipase from Pseudomonas fluorescens Lp1 isolated from oil contaminated soil was immobilized onto amino silane modified superparamagnetic Fe3O4 nanoparticles. The magnetic nanoparticles, magnetite was synthesized chemically by co-precipitation and characterized by Scanning Electron Microscopy (SEM), Fourier Transformed Infrared Spectroscopy (FT-IR) and Powder X-ray diffraction studies (XRD). The structure of the synthesized magnetic nanoparticles was uniform, spherical and the size was determined around 31 nm by powder XRD. The biodiesel production mixture was prepared by addition of waste cooking oil, lipase immobilized magnetite and methanol. The transesterified products were analyzed by Gas Liquid chromatography-Mass spectroscopy (GC-MS). The methyl esters such as Oxiraneundecanoic acid, 3-pentyl-methyl ester, Hexadecanoic acid, methyl ester and 10-Octadecenoic acid, methyl ester were obtained. The study experimentally proved the use of amino silane modified superparamagnetic Fe3O4 nanoparticles in biodiesel production from waste cooking oil.

  3. Metallic Nanoparticle (TiO2 and Fe3O4) Application Modifies Rhizosphere Phosphorus Availability and Uptake by Lactuca sativa.

    Science.gov (United States)

    Zahra, Zahra; Arshad, Muhammad; Rafique, Rafia; Mahmood, Arshad; Habib, Amir; Qazi, Ishtiaq A; Khan, Saud A

    2015-08-12

    Application of engineered nanoparticles (NPs) with respect to nutrient uptake in plants is not yet well understood. The impacts of TiO2 and Fe3O4 NPs on the availability of naturally soil-bound inorganic phosphorus (Pi) to plants were studied along with relevant parameters. For this purpose, Lactuca sativa (lettuce) was cultivated on the soil amended with TiO2 and Fe3O4 (0, 50, 100, 150, 200, and 250 mg kg(-1)) over a period of 90 days. Different techniques, such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman, and Fourier transform infrared spectroscopy (FTIR) were used to monitor translocation and understand the possible mechanisms for phosphorus (P) uptake. The trends for P accumulation were different for roots (TiO2 > Fe3O4 > control) and shoots (Fe3O4 > TiO2 > control). Cystine and methionine were detected in the rhizosphere in Raman spectra. Affinities of NPs to adsorb phosphate ions, modifications in P speciation, and NP stress in the rhizosphere had possibly contributed to enhanced root exudation and acidification. All of these changes led to improved P availability and uptake by the plants. These promising results can help to develop an innovative strategy for using NPs for improved nutrient management to ensure food security. PMID:26194089

  4. A facile and flexible process of ?-cyclodextrin grafted on Fe3O4 magnetic nanoparticles and host-guest inclusion studies

    International Nuclear Information System (INIS)

    In this study, a kind of novel surface-functionalized magnetic nanoparticles was fabricated by the Fe3O4 nanoparticles surface modification with mono-6-deoxy-6-(p-tolylsulfonyl)-cyclodextrin (6-TsO-?-CD), which were employed to interact with uric acid and their behavior was investigated by electrochemical methods. The architecture has been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), which confirmed that cyclodextrins have been effectively functionalized on the surface of Fe3O4 nanoparticles. The analyses of vibration sample magnetometer (VSM) verified that the nanoparticles owned good magnetic property. The grafted ?-cyclodextrin on the Fe3O4 nanoparticles contributed to as a modified electrode for detecting uric acid with cyclic voltammograms. Electrochemical results revealed that the new materials could exhibit excellent molecules recognition ability and show high electrochemical response. The new nanoparticles simultaneously had unique properties of magnetic nanoparticles and cyclodextrins through combining their individual distinct advantages.

  5. A facile and flexible process of ?-cyclodextrin grafted on Fe 3O 4 magnetic nanoparticles and host-guest inclusion studies

    Science.gov (United States)

    Zhu, Jie; He, Jiang; Du, Xiaoyan; Lu, Ruihua; Huang, Lizhen; Ge, Xia

    2011-08-01

    In this study, a kind of novel surface-functionalized magnetic nanoparticles was fabricated by the Fe 3O 4 nanoparticles surface modification with mono-6-deoxy-6-(p-tolylsulfonyl)-cyclodextrin (6-TsO-?-CD), which were employed to interact with uric acid and their behavior was investigated by electrochemical methods. The architecture has been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), which confirmed that cyclodextrins have been effectively functionalized on the surface of Fe 3O 4 nanoparticles. The analyses of vibration sample magnetometer (VSM) verified that the nanoparticles owned good magnetic property. The grafted ?-cyclodextrin on the Fe3O4 nanoparticles contributed to as a modified electrode for detecting uric acid with cyclic voltammograms. Electrochemical results revealed that the new materials could exhibit excellent molecules recognition ability and show high electrochemical response. The new nanoparticles simultaneously had unique properties of magnetic nanoparticles and cyclodextrins through combining their individual distinct advantages.

  6. Co-encapsulation of magnetic Fe3O4 nanoparticles and doxorubicin into biodegradable PLGA nanocarriers for intratumoral drug delivery

    Directory of Open Access Journals (Sweden)

    Jia Y

    2012-03-01

    Full Text Available Yanhui Jia1, Mei Yuan1, Huidong Yuan1, Xinglu Huang2, Xiang Sui1, Xuemei Cui1, Fangqiong Tang2, Jiang Peng1, Jiying Chen1, Shibi Lu1, Wenjing Xu1, Li Zhang1, Quanyi Guo11Institute of Orthopedics, General Hospital of the Chinese People's Liberation Army, Beijing, People's Republic of China; 2Laboratory of Controllable Preparation and Application of Nanomaterials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of ChinaAbstract: In this study, the authors constructed a novel PLGA [poly(D,L-lactic-co-glycolic acid]-based polymeric nanocarrier co-encapsulated with doxorubicin (DOX and magnetic Fe3O4 nanoparticles (MNPs using a single emulsion evaporation method. The DOX-MNPs showed high entrapment efficiency, and they supported a sustained and steady release of DOX. Moreover, the drug release was pH sensitive, with a faster release rate in an acidic environment than in a neutral environment. In vitro, the DOX-MNPs were easily internalized into murine Lewis lung carcinoma cells and they induced apoptosis. In vivo, the DOX-MNPs showed higher antitumor activity than free DOX solution. Furthermore, the antitumor activity of the DOX-MNPs was higher with than without an external magnetic field; they were also associated with smaller tumor volume and a lower metastases incidence rate. This work may provide a new modality for developing an effective drug delivery system.Keywords: antitumor activity, external magnetic field, intratumoral injection, apoptosis, Lewis lung carcinoma

  7. Novel magnetic-fluorescent CS-Fe3O4@ZnS:Mn/ZnS (core/shell) nanoparticles: Preparation, characterization and damage to bovine serum albumin under UV irradiation

    International Nuclear Information System (INIS)

    Novel magnetic-fluorescent nanoparticles (CS-Fe3O4@ZnS:Mn/ZnS) combined ZnS:Mn/ZnS semiconductor nanoparticles and Fe3O4 magnetic nanoparticles with chitosan (CS) matrix were prepared and characterized. Characterization results indicate that CS-Fe3O4@ZnS:Mn/ZnS (core/shell) nanoparticles show superparamagnetic and strong fluorescent properties. Introduction of ZnS shell significantly enhances the photoluminescence intensity by 3.5 times. The saturation magnetization of CS-Fe3O4@ZnS:Mn/ZnS nanoparticles was 14.85 emu g?1 at room temperature. The interaction and damage of CS-Fe3O4@ZnS:Mn/ZnS to bovine serum albumin (BSA) under UV irradiation was investigated by ultraviolet–visible and fluorescence spectra. The results show that electrostatic interaction is the major force for the binding processes of BSA to the surface of CS-Fe3O4@ZnS:Mn/ZnS. The damage of BSA is prone to happen in the presence of CS-Fe3O4@ZnS:Mn/ZnS under UV irradiation. CS-Fe3O4@ZnS:Mn/ZnS may be potential candidate for application as photosensitizers in photodynamic therapy, and fluorescence imaging and magnetic resonance imaging contrast agents for theranostics of cancer. - Highlights: • Novel magnetic-fluorescent CS-Fe3O4@ZnS:Mn/ZnS nanoparticles were synthesized. • CS-Fe3O4@ZnS:Mn/ZnS possesses superparamagnetic and bright fluorescent properties. • Introduction of ZnS shell significantly enhances the PL intensity by 3.5 times. • BSA molecule was effectively damaged by CS-Fe3O4@ZnS:Mn/ZnS under UV irradiation. • Magnetic-fluorescent nanoparticles would be potential agents for cancer treatment

  8. Synergistic effect of the combination of triethylene-glycol modified Fe3O4 nanoparticles and ultrasound wave on MCF-7 cells

    Science.gov (United States)

    Ebrahimi Fard, Ali; Zarepour, Atefeh; Zarrabi, Ali; Shanei, Ahmad; Salehi, Hossein

    2015-11-01

    Cancer is a group of disease characterized by uncontrolled growth and spread of abnormal cells in the body. The clinical treatments for cancer include surgery, chemotherapy and radiotherapy. Currently, employing new approaches for treatment has attracted more attentions. One of these approaches is sonodynamic therapy, which is an analogous approach based on the synergistic effect of ultrasound and a chemical component referred to as sonosensitizer. Recent years applications of nanotechnology have witnessed a tremendous expansion of research in medicine especially in treatment of cancers. The combination of sonodynamic therapy and nanotechnology can introduce a new way for cancer therapy. In this study, we used therapeutic ultrasonic waves with intensity of 1 MHz and different concentrations of Fe3O4 nanoparticles, as sonosensitizer, to investigate their combination effect on MCF-7 cell line. Briefly, we divided cells into four different groups; control, cells which got in touch with nanoparticles, cells that with exposure to ultrasound waves and cells which were influenced with combination of nanoparticles and ultrasonic waves. Finally, cell viability assay was used for detection of cytotoxicity effects. Experimental results revealed a significant decrease in viability of cells, which were affected by the combined action of ultrasound field and Fe3O4 nanoparticles, compared to the separate exposure of Fe3O4 nanoparticles or ultrasonic field. The synergic effect of ultrasound waves and Fe ions might be due to the production of toxic free radicals.

  9. The effect of surface charge of functionalized Fe3O4 nanoparticles on protein adsorption and cell uptake.

    Science.gov (United States)

    Calatayud, M Pilar; Sanz, Beatriz; Raffa, Vittoria; Riggio, Cristina; Ibarra, M Ricardo; Goya, Gerardo F

    2014-08-01

    Nanoparticles engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the nanoparticle's surface, forming a swaddling layer that has been described as a 'protein corona', the nature of which is expected to influence not only the physicochemical properties of the particles but also the internalization into a given cell type. We have investigated the process of protein adsorption onto different magnetic nanoparticles (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. The role of the MNPs surface charge has been assessed by synthesizing two colloids with the same hydrodynamic size and opposite surface charge: magnetite (Fe3O4) cores of 25-30 nm were in situ functionalized with (a) positive polyethyleneimine (PEI-MNPs) and (b) negative poly(acrylic acid) (PAA-MNPs). After few minutes of incubation in cell culture medium the wrapping of the MNPs by protein adsorption resulted in a 5-fold increase of the hydrodynamic size. After 24 h of incubation large MNP-protein aggregates with hydrodynamic sizes of ?1500 nm (PAA-MNPs) and ?3000 nm (PEI-MNPs) were observed, each one containing an estimated number of magnetic cores between 450 and 1000. These results are consistent with the formation of large protein-MNPs aggregate units having a 'plum pudding' structure of MNPs embedded into a protein network that results in a negative surface charge, irrespective of the MNP-core charge. In spite of the similar negative ?-potential for both MNPs within cell culture, we demonstrated that PEI-MNPs are incorporated in much larger amounts than the PAA-MNPs units. Quantitative analysis showed that SH-SY5Y cells can incorporate 100% of the added PEI-MNPs up to ?100 pg/cell, whereas for PAA-MNPs the uptake was less than 50%. The final cellular distribution showed also notable differences regarding partial attachment to the cell membrane. These results highlight the need to characterize the final properties of MNPs after protein adsorption in biological media, and demonstrate the impact of these properties on the internalization mechanisms in neural cells. PMID:24816288

  10. Preparation and Characterization of Methylene Blue-Incorporated Folate-Functionalized Fe3O4/Mesoporous Silica Core/Shell Magnetic Nanoparticles.

    Science.gov (United States)

    Zhao, Xueiing; Zhao, Hongli; Chen, Zongyan; Zhang, Denghao; Lan, Minbo

    2015-07-01

    In the present work, a multifunctional nanomaterial, methylene blue-incorporated folate-functionalized Fe3O4/mesoporous silica core/shell magnetic nanoparticles, has been developed. Firstly, highly biocompatible monodisperse superparamagnetic Fe3O4@mSiO2 core/shell nanoparticles with mesoporous silica shells were synthesized. Then these particles were coated with the covalently bonded biocompatible polymer poly(ethylene glycol) (PEG) and modified with the cancer targeting ligand folic acid (FA). Finally, the water-soluble photosensitizer methylene blue (MB) was loaded into the mesoporous silica shell. Systematic experiments were performed to carefully evaluate the physical and chemical properties, cytotoxicity and cellular uptake of the multifunctional nanomaterial. PMID:26373064

  11. Investigation of magnetic field enriched surface enhanced resonance Raman scattering performance using Fe3O4@Ag nanoparticles for malaria diagnosis

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2014-03-01

    Recently, we have demonstrated the magnetic field-enriched surface-enhanced resonance Raman spectroscopy (SERRS) of ?-hematin by using nanoparticles with iron oxide core and silver shell (Fe3O4@Ag) for the potential application in the early malaria diagnosis. In this study, we investigate the dependence of the magnetic field-enriched SERRS performance of ?-hematin on the different core and shell sizes of the Fe3O4@Ag nanoparticles. We note that the core and shell parameters are critical in the realization of the optimal magnetic field-enrich SERRS ?-hematin signal. These results are consistent with our simulations that will guide the optimization of the magnetic SERRS performance for the potential early diagnosis in the malaria disease.

  12. Magnetic Fe3O4@TiO2 Nanoparticles-based Test Strip Immunosensing Device for Rapid Detection of Phosphorylated Butyrylcholinesterase

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xiaoxiao; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-12-15

    An integrated magnetic nanoparticles-based test-strip immunosensing device was developed for rapid and sensitive quantification of phosphorylated butyrylcholinesterase (BChE), the biomarker of exposure to organophosphous pesticides (OP), in human plasma. In order to overcome the difficulty in scarce availability of OP-specific antibody, here magnetic Fe3O4@TiO2 nanoparticles were used and adsorbed on the test strip through a small magnet inserted in the device to capture target OP-BChE through selective binding between TiO2 and OP moiety. Further recognition was completed by horseradish peroxidase (HRP) and anti-BChE antibody (Ab) co-immobilized gold nanoparticles (GNPs). Their strong affinities among Fe3O4@TiO2, OP-BChE and HRP/Ab-GNPs were characterized by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and square wave voltammetry (SWV) measurements. After cutting off from test strip, the resulted immunocomplex (HRP/Ab-GNPs/OP-BChE/Fe3O4@TiO2) was measured by SWV using a screen printed electrode under the test zone. Greatly enhanced sensitivity was achieved by introduction of GNPs to link enzyme and antibody at high ratio, which amplifies electrocatalytic signal significantly. Moreover, the use of test strip for fast immunoreactions reduces analytical time remarkably. Coupling with a portable electrochemical detector, the integrated device with advanced nanotechnology displays great promise for sensitive, rapid and in-filed on-site evaluation of OP poisoning.

  13. Anisotropy effects in magnetic hyperthermia: A comparison between spherical and cubic exchange-coupled FeO/Fe3O4 nanoparticles

    Science.gov (United States)

    Khurshid, H.; Alonso, J.; Nemati, Z.; Phan, M. H.; Mukherjee, P.; Fdez-Gubieda, M. L.; Barandiarán, J. M.; Srikanth, H.

    2015-05-01

    Spherical and cubic exchange-coupled FeO/Fe3O4 nanoparticles, with different FeO:Fe3O4 ratios, have been prepared by a thermal decomposition method to probe anisotropy effects on their heating efficiency. X-ray diffraction and transmission electron microscopy reveal that the nanoparticles are composed of FeO and Fe3O4 phases, with an average size of ˜20 nm. Magnetometry and transverse susceptibility measurements show that the effective anisotropy field is 1.5 times larger for the cubes than for the spheres, while the saturation magnetization is 1.5 times larger for the spheres than for the cubes. Hyperthermia experiments evidence higher values of the specific absorption rate (SAR) for the cubes as compared to the spheres (200 vs. 135 W/g at 600 Oe and 310 kHz). These observations point to an important fact that the saturation magnetization is not a sole factor in determining the SAR and the heating efficiency of the magnetic nanoparticles can be improved by tuning their effective anisotropy.

  14. Enhancement of algicidal properties of immobilized Bacillus methylotrophicus ZJU by coating with magnetic Fe3O4 nanoparticles and wheat bran.

    Science.gov (United States)

    Sun, Pengfei; Hui, Cai; Wang, Sheng; Khan, Rashid Azim; Zhang, Qichun; Zhao, Yu-Hua

    2016-01-15

    Algicidal bacteria offer a promising option for killing cyanobacteria. In this study, a newly isolated strain of Bacillus methylotrophicus, ZJU, was used to control Microcystis aeruginosa. Analyses of relative reactive oxygen level, malondialdehyde content, superoxide dismutase activity, and fluorescence staining indicated that oxidative damage caused by the algicidal supernatant of strain ZJU mainly affected the cell membrane and consequently the membrane permeability and membrane potential of M. aeruginosa cells. Furthermore, an embedded immobilization technique was employed to improve the practical application of strain ZJU as an algicidal agent. On this basis, we proposed a novel concept of enhancing the algicidal properties of immobilized ZJU by adding Fe3O4 nanoparticles and wheat bran in the process of immobilization. Our studies showed that Fe3O4 nanoparticles conferred the immobilized bacteria with a magnetization of 30.87emu/g, and this magnetization enabled efficient re-collection of the immobilized bacteria by magnetic means. Moreover, wheat bran endowed the immobilized bacteria with 10.34% higher algicidal activity than immobilized bacteria without wheat bran. The results indicate a novel concept of enhancing the algicidal property of bacteria against M. aeruginosa by adding Fe3O4 nanoparticles and wheat bran. PMID:26342577

  15. Effect of magnetic nanoparticles of Fe3O4 and 5-bromotetrandrine on reversal of multidrug resistance in K562/A02 leukemic cells

    Directory of Open Access Journals (Sweden)

    Jian Cheng

    2009-09-01

    Full Text Available Jian Cheng1*, Weiwei Wu1*, Bao-an Chen1, Feng Gao1, Wenlin Xu2, Chong Gao1, Jiahua Ding1, Yunyu Sun1, Huihui Song1, Wen Bao1, Xinchen Sun3, Cuirong Xu1, Wenji Chen1, Ningna Chen1, Lijie Liu4, Guohua Xia1, Xiaomao Li5, Xuemei Wang61Department of Hematology, 3Department of Oncology, The Afiliated Zhongda Hospital, Southeast University, Nanjing, People’s Republic of China; 2Department of Hematology, The First People’s Hospital of Zhengjiang, Zhenjiang, People’s Republic of China; 4Institution of Physiology, 6State Key Lab of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, People’s Republic of China; 5Department of Physics, University of Saarland, Saarbruechen, Germany; *These authors have contributed equally to this workAbstract: This study aims to evaluate the multidrug resistance (MDR reversal activity by magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4 and 5-bromotetrandrine (BrTet MDR cell line K562/A02 solitarily or symphysially. The proliferation of K562 and K562/A02 cells and the cytotoxicity on peripheral blood mononuclear cells (PMBCs were evaluated by MTT assay. Cellular accumulation of daunorubicin (DNR was analyzed by flow cytometry. Real-time polymerase chain reaction and Western blotting analyses were performed to examine the mRNA and protein levels of mdr1, respectively. The results showed that the combination of MNPs-Fe3O4 and BrTet with effective concentrations significantly increased cytotoxicity against MDR cell line K562/A02. Both BrTet and MNPs-Fe3O4 increased the intracellular DNR accumulation in the K562/A02 cell line, and downregulated the level of mdr1 gene and expression of P-glycoprotein. Furthermore, the combination did not have significant cytotoxicity in PMBCs. We propose that MNPs-Fe3O4 conjugated with DNR and BrTet probably have synergetic effects on MDR reversal.Keywords: magnetic nanoparticles of Fe3O4, 5-bromotetrandrine, multidrug resistance K562/A02

  16. Daunorubicin-loaded magnetic nanoparticles of Fe3O4 overcome multidrug resistance and induce apoptosis of K562-n/VCR cells in vivo

    Directory of Open Access Journals (Sweden)

    Bao-an Chen

    2009-09-01

    Full Text Available Bao-an Chen1, Bin-bin Lai1, Jian Cheng1, Guo-hua Xia1, Feng Gao1, Wen-lin Xu2, Jia-hua Ding1, Chong Gao1, Xin-chen Sun3, Cui-rong Xu1, Wen-ji Chen1, Ning-na Chen1, Li-jie Liu4, Xiao-mao Li5, Xue-mei Wang61Department of Hematology, 3Department of Oncology, the Affiliated Zhongda Hospital, Clinical Medical School, Southeast University, Nanjing, People’s Republic of China; 2Department of Hematology, the Affiliated People’s Hospital, Jiangsu University, Zhenjiang, People’s Republic of China; 4Institution of Physiology, 6State Key Lab of Bioelectronics (Chien-shiung Wu Laboratory, Southeast University, Nanjing, People’s Republic of China; 5Department of Physics, University of Saarland, Saarbruechen, GermanyAbstract: Multidrug resistance (MDR is a major obstacle to cancer chemotherapy. We evaluated the effect of daunorubicin (DNR-loaded magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4 on K562-n/VCR cells in vivo. K562-n and its MDR counterpart K562-n/VCR cell were inoculated into nude mice subcutaneously. The mice were randomly divided into four groups: group A received normal saline, group B received DNR, group C received MNPs-Fe3O4, and group D received DNR-loaded MNPs-Fe3O4. For K562-n/VCR tumor, the weight was markedly lower in group D than that in groups A, B, and C. The transcriptions of Mdr-1 and Bcl-2 gene were significantly lower in group D than those in groups A, B, and C. The expression of Bcl-2 was lower in group D than those in groups A, B, and C, but there was no difference in the expression of P-glycoprotein. The transcriptions and expressions of Bax and caspase-3 in group D were increased significantly when compared with groups A, B, and C. In conclusion, DNR-loaded MNPs-Fe3O4 can overcome MDR in vivo.Keywords: multidrug-resistance reversal, leukemia, magnetic nanoparticles of Fe3O4, in vivo

  17. Preparation and properties of Fe and Fe3O4 nanoparticles embedded in ZrO2 matrix

    International Nuclear Information System (INIS)

    The (Zr, ZrO2)-(Fe, Fe3O4) nanocomposites are investigated due to their magnetic properties and resistance against negative influence of the surrounding atmosphere namely at elevated temperatures. The particles of pure Zr and its intermetallic phases can effect as a getter protecting the iron particles against oxidation. We have investigated behaviour of the nanocrystalline powders prepared as a mixture from pure components. TEM and XRD were explored for standard phase composition and determination of the main particle size. Moessbauer spectra were collected by a standard transmission method at room temperature using 57Co/Rh source. Magnetic measurements were carried out using vibrating sample magnetometer at high temperature at (293 - 1093) K, in the vacuum (10-1 Pa) and in the pure hydrogen (5N) atmosphere. The structure study showed that as-prepared samples consist of Fe3O4 particles with the mean coherent length ?30 nm as determined by XRD which increased during the heat treatment up to ?50 - 100 nm. The samples annealed in vacuum were formed by particles of ZrO2-monoclinic, ZrO2-tetragonal and ZrO2-cubic and iron oxide (?-Fe2O3, Fe3O4 and FeO) phases. The annealing in hydrogen caused reduction of iron oxides to pure iron particles and clusters in ZrO2. The magnetic parameters confirm full transformation of iron oxides to bcc iron. (authors)

  18. Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

    Science.gov (United States)

    Kaur, Navjot; Chudasama, Bhupendra

    2015-05-01

    Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe3O4) nanoparticles and their coating with SiO2 is reported. Fe3O4 nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4 nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

  19. Fabrication of Pd Nanoparticles Embedded C@Fe3O4 Core-Shell Hybrid Nanospheres: An Efficient Catalyst for Cyanation in Aryl Halides.

    Science.gov (United States)

    Suresh Kumar, Basuvaraj; Amali, Arlin Jose; Pitchumani, Kasi

    2015-10-21

    Isolated chemical reactors were fabricated by integrating catalytically active sites (Pd) with magnetic functionality (Fe3O4) along with carbon while preserving the constituents functional properties to realize the structure-property relationship of Pd by comparing the catalytic activity of spherical Pd NPs with cubical Pd NPs for cyanation in aryl halides using K4[Fe(CN)6] as a green cyanating agent to yield corresponding nitriles. The superior catalytic reactivity of the cubical Pd NPs is attributed to the larger number of {100} surface facets. The TEM images of reused catalyst shows the change in structure from cubical to spherical nanoparticles, attributed to the efficient leaching susceptibility of Pd {100} surface facets. The cubical Pd NPs on carbon@Fe3O4 is attractive in view of its high catalytic efficiency, easy synthesis, magnetic separability, environmental friendliness, high stability, gram scale applicability, and reusability. PMID:26419954

  20. Fabrication of Fe3O4/SiO2 core–shell nanoparticle monolayer as catalyst for carbon nanotube growth using Langmuir–Blodgett technique

    International Nuclear Information System (INIS)

    In this work, an approach of controllable distance of catalytic nanoparticles (NPs) shrouded in shell layer for carbon nanotube (CNT) growth has been developed with the aid of the Langmuir–Blodgett (LB) technique. Coagulation of core–shell NPs was controlled by the surface pressure of the LB technique. Scanning electron microscope images show that core–shell NP LB film without coagulation and vacancies was observed. The approach of core–shell NP LB film revealed in this work could potentially be applied in catalytic NP monolayer formation and high activity of catalytic NPs for CNT growth. - Highlights: • Fe3O4 nanoparticles (NPs) and Fe3O4/SiO2 core–shell NPs were synthesized. • Fe3O4 NP as catalyst was almost retained at the center of SiO2 shell structure. • Core–shell NP monolayer without coagulation and vacancies was deposited on substrate. • Core–shell NP monolayer was closely packed by using Langmuir–Blodgett technique

  1. Synthesis and Properties of Fe3O4-Activated Carbon Magnetic Nanoparticles for Removal of Aniline from Aqueous Solution: Equilibrium, Kinetic and Thermodynamic Studies

    Directory of Open Access Journals (Sweden)

    Babak Kakavandi

    2013-02-01

    Full Text Available In this study, powder activated carbon (PAC and magnetic nanoparticles of iron (III oxide were used for synthesis of Fe3O4-activated carbon magnetic nanoparticles (AC-Fe3O4 MNPs as an adsorbent for the removal of aniline. The characteristics of adsorbent were evaluated by SEM, TEM, XRD and BET. Also, the impact of different parameters such as pH, contact time, adsorbent dosage, aniline initials concentration and solution temperature were studied. The experimental data investigated by Langmuir and Freundlich adsorption isotherms and two models kinetically of pseudo first-order and pseudo second-order. The results indicated that the adsorption followed Langmuir and pseudo second-order models with correlation r2?>?0.98 and r2?>?0.99, respectively. The equilibrium time was obtained after 5 h. According to Langmuir model, the maximum adsorption capacity was 90.91 mg/g at pH?=?6, and 20°C. The thermodynamic parameters indicated that adsorption of aniline on magnetic activated carbon was exothermic and spontaneous. This synthesized AC-Fe3O4 MNPs due to have advantages such as easy and rapid separation from solution could be applied as an adsorbent effective for removal of pollutants such as aniline from water and wastewater

  2. In-tube magnetic solid phase microextraction of some fluoroquinolones based on the use of sodium dodecyl sulfate coated Fe3O4 nanoparticles packed tube.

    Science.gov (United States)

    Manbohi, Ahmad; Ahmadi, Seyyed Hamid

    2015-07-23

    In-tube magnetic solid phase microextraction (in-tube MSPME) of fluoroquinolones from water and urine samples based on the use of sodium dodecyl sulfate (SDS) coated Fe3O4 nanoparticles packed tube has been reported. After the preparation of Fe3O4 nanoparticles (NPs) by a batch synthesis, these NPs were introduced into a stainless steel tube by a syringe and then a strong magnet was placed around the tube, so that the Fe3O4 NPs were remained in the tube and the tube was used in the in-tube SPME-HPLC/UV for the analysis of fluoroquinolones in water and urine samples. Plackett-Burman design was employed for screening the variables significantly affecting the extraction efficiency. Then, the significant factors were more investigated by Box-Behnken design. Calibration curves were linear (R(2)>0.990) in the range of 0.1-1000?gL(-1) for ciprofloxacin (CIP) and 0.5-500?gL(-1) for enrofloxacin (ENR) and ofloxacin (OFL), respectively. LODs for all studied fluoroquinolones ranged from 0.01 to 0.05?gL(-1). The main advantages of this method were rapid and easy automation and analysis, short extraction time, high sensitivity, possibility of fully sorbent collection after analysis, wide linear range and no need to organic solvents in extraction. PMID:26231896

  3. Fast assembling microarrays of superparamagnetic Fe3O4@Au nanoparticle clusters as reproducible substrates for surface-enhanced Raman scattering

    Science.gov (United States)

    Ye, Min; Wei, Zewen; Hu, Fei; Wang, Jianxin; Ge, Guanglu; Hu, Zhiyuan; Shao, Mingwang; Lee, Shuit-Tong; Liu, Jian

    2015-08-01

    It is currently a very active research area to develop new types of substrates which integrate various nanomaterials for surface-enhanced Raman scattering (SERS) techniques. Here we report a unique approach to prepare SERS substrates with reproducible performance. It features silicon mold-assisted magnetic assembling of superparamagnetic Fe3O4@Au nanoparticle clusters (NCs) into arrayed microstructures on a wafer scale. This approach enables the fabrication of both silicon-based and hydrogel-based substrates in a sequential manner. We have demonstrated that strong SERS signals can be harvested from these substrates due to an efficient coupling effect between Fe3O4@Au NCs, with enhancement factors >106. These substrates have been confirmed to provide reproducible SERS signals, with low variations in different locations or batches of samples. We investigate the spatial distributions of electromagnetic field enhancement around Fe3O4@Au NCs assemblies using finite-difference-time-domain (FDTD) simulations. The procedure to prepare the substrates is straightforward and fast. The silicon mold can be easily cleaned out and refilled with Fe3O4@Au NCs assisted by a magnet, therefore being re-useable for many cycles. Our approach has integrated microarray technologies and provided a platform for thousands of independently addressable SERS detection, in order to meet the requirements of a rapid, robust, and high throughput performance.It is currently a very active research area to develop new types of substrates which integrate various nanomaterials for surface-enhanced Raman scattering (SERS) techniques. Here we report a unique approach to prepare SERS substrates with reproducible performance. It features silicon mold-assisted magnetic assembling of superparamagnetic Fe3O4@Au nanoparticle clusters (NCs) into arrayed microstructures on a wafer scale. This approach enables the fabrication of both silicon-based and hydrogel-based substrates in a sequential manner. We have demonstrated that strong SERS signals can be harvested from these substrates due to an efficient coupling effect between Fe3O4@Au NCs, with enhancement factors >106. These substrates have been confirmed to provide reproducible SERS signals, with low variations in different locations or batches of samples. We investigate the spatial distributions of electromagnetic field enhancement around Fe3O4@Au NCs assemblies using finite-difference-time-domain (FDTD) simulations. The procedure to prepare the substrates is straightforward and fast. The silicon mold can be easily cleaned out and refilled with Fe3O4@Au NCs assisted by a magnet, therefore being re-useable for many cycles. Our approach has integrated microarray technologies and provided a platform for thousands of independently addressable SERS detection, in order to meet the requirements of a rapid, robust, and high throughput performance. Electronic supplementary information (ESI) available: XRD, reflection spectra, zeta potential, TEM images, evaluations of reproducibility, EDS, tables of EF and RSD values of different substrates. See DOI: 10.1039/c5nr02491a

  4. 56Co-labelled radioactive Fe3O4 nanoparticles for in vitro uptake studies on Balb/3T3 and Caco-2 cell lines

    International Nuclear Information System (INIS)

    Magnetite nanoparticles (Fe3O4 NPs) are manufactured nanomaterials increasingly used in healthcare for different medical applications ranging from diagnosis to therapy. This study deals with the irradiation of Fe3O4 NPs with a proton beam in order to produce 56Co as radiolabel and also with the possible use of nuclear techniques for the quantification of Fe3O4 NPs in biological systems. Particular attention has been focused on the size distribution (in the range of 100 nm) and the surface charge of the NPs characterizing them before and after the irradiation process in order to verify if these essential properties would be preserved during irradiation. Moreover, X-ray diffraction studies have been performed on radioactive and non-radioactive NPs, to assess if major changes in NPs structure might occur due to thermal and/or radiation effects. The radiation emitted from the radiolabels has been used to quantify the cellular uptake of the NPs in in vitro studies. As for the biological applications two cell lines have been selected: immortalized mouse fibroblast cell line (Balb/3T3) and human epithelial colorectal adenocarcinoma cell line (Caco-2). The cell uptake has been quantified by radioactivity measurements of the 56Co radioisotope performed with high resolution ?-ray spectrometry equipment. This study has showed that, under well-established irradiation conditions, Fe3O4 NPs do not undergo significant structural modifications and thus the obtained results are in line with the uptake studies carried out with the same non-radioactive nanomaterials (NMs). Therefore, the radiolabelling method can be fruitfully applied to uptake studies because of the low-level exposure where higher sensitivity is required.

  5. Gambogic acid-loaded magnetic Fe3O4 nanoparticles inhibit Panc-1 pancreatic cancer cell proliferation and migration by inactivating transcription factor ETS1

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    Wang C

    2012-02-01

    Full Text Available Cailian Wang1, Haijun Zhang1, Yan Chen1, Fangfang Shi1, Baoan Chen2,31Department of Oncology, 2Department of Hematology, Zhongda Hospital, 3Faculty of Oncology, Medical School, Southeast University, Nanjing, People’s Republic of ChinaBackground: E26 transformation-specific sequence-1 (ETS1 transcription factor plays important roles in both carcinogenesis and the progression of a wide range of malignancies. Aberrant ETS1 expression correlates with aggressive tumor behavior and a poorer prognosis in patients with various malignancies. The aim of the current study was to evaluate the efficacy of a drug delivery system utilizing gambogic acid-loaded magnetic Fe3O4 nanoparticles (GA-MNP- Fe3O4 on the suppression of ETS1-mediated cell proliferation and migration in Panc-1 pancreatic cancer cells.Methods: The effects caused by GA-MNP- Fe3O4 on the proliferation of Panc-1 pancreatic cancer cells were evaluated using a MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay while inhibition of tumor cell migration was investigated in a scratch assay. The expressions of ETS1, cyclin D1, urokinase-type plasminogen activator (u-PA, and VEGF (vascular endothelial growth factor were examined by Western blot to elucidate the possible mechanisms involved.Results: In Panc-1 pancreatic cancer cells, we observed that application of GA-MNP- Fe3O4 was able to suppress cancer cell proliferation and prevent cells from migrating effectively. After treatment, Panc-1 pancreatic cancer cells showed significantly decreased expression of ETS1, as well as its downstream target genes for cyclin D1, u-PA, and VEGF.Conclusion: Our novel finding reaffirmed the significance of ETS1 in the treatment of pancreatic cancer, and application of GA-MNP- Fe3O4 nanoparticles targeting ETS1 should be considered as a promising contribution for better pancreatic cancer care.Keywords: ETS1 transcription factor, gambogic acid, pancreatic cancer, magnetic nanoparticles

  6. Synthesis and diameter control of vertically-aligned carbon nanotube growth from Langmuir-Blodgett films deposited Fe3O4@SiO2 core-shell nanoparticles

    Science.gov (United States)

    Ohashi, Masaaki; Sugawara, Takehiro; Kawasaki, Kohei; Kushida, Masahito

    2014-02-01

    We synthesized Fe3O4 nanoparticles (NPs) and Fe3O4@SiO2 core-shell NPs. Vertically-aligned carbon nanotubes (VA-CNTs) were grown from Fe3O4 NP monolayer and Fe3O4@SiO2 core-shell NP monolayer, respectively, by thermal chemical vapor deposition (CVD). The monolayer was prepared on SiO2/Si substrate by Langmuir-Blodgett (LB) technique. Fe3O4 NP monolayer was used as catalyst for CNT growth, and core-shell NP monolayer was used as catalyst for CNT growth, too. We found that Fe3O4 NP covered with SiO2 shell was moved from the center to the surface of core-shell NP during pre-thermal process at thermal CVD. The CNT carpet height tended to increase with the increasing thermal annealing time and decreasing shell thickness. And the average diameter of CNTs grown from core-shell LB film was smaller than that of CNTs grown from Fe3O4 LB film, and average diameter of CNTs almost conformed to Fe3O4 core size with SiO2 shell.

  7. Polyetherimide-grafted Fe3O4@SiO2 nanoparticles as theranostic agents for simultaneous VEGF siRNA delivery and magnetic resonance cell imaging

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    Li T

    2015-07-01

    Full Text Available Tingting Li,1 Xue Shen,1 Yin Chen,1 Chengchen Zhang,1 Jie Yan,1 Hong Yang,1 Chunhui Wu,1,2 Hongjun Zeng,1,2 Yiyao Liu1,21Department of Biophysics, School of Life Science and Technology, 2Center for Information in Biomedicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, People’s Republic of ChinaAbstract: Engineering a safe and high-efficiency delivery system for efficient RNA interference is critical for successful gene therapy. In this study, we designed a novel nanocarrier system of polyethyleneimine (PEI-modified Fe3O4@SiO2, which allows high efficient loading of VEGF small hairpin (shRNA to form Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites for VEGF gene silencing as well as magnetic resonance (MR imaging. The size, morphology, particle stability, magnetic properties, and gene-binding capacity and protection were determined. Low cytotoxicity and hemolyticity against human red blood cells showed the excellent biocompatibility of the multifunctional nanocomposites, and also no significant coagulation was observed. The nanocomposites maintain their superparamagnetic property at room temperature and no appreciable change in magnetism, even after PEI modification. The qualitative and quantitative analysis of cellular internalization into MCF-7 human breast cancer cells by Prussian blue staining and inductively coupled plasma atomic emission spectroscopy analysis, respectively, demonstrated that the Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could be easily internalized by MCF-7 cells, and they exhibited significant inhibition of VEGF gene expression. Furthermore, the MR cellular images showed that the superparamagnetic iron oxide core of our Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could also act as a T2-weighted contrast agent for cancer MR imaging. Our data highlight multifunctional Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites as a potential platform for simultaneous gene delivery and MR cell imaging, which are promising as theranostic agents for cancer treatment and diagnosis in the future.Keywords: core/shell nanoparticle, PEI, VEGF silence, MR imaging, theranostics

  8. Reversal of multidrug resistance by magnetic Fe3O4 nanoparticle copolymerizating daunorubicin and MDR1 shRNA expression vector in leukemia cells

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    Bao-an Chen

    2010-06-01

    Full Text Available Bao-an Chen1, Pei-pei Mao1, Jian Cheng1, Feng Gao1, Guo-hua Xia1, Wen-lin Xu2, Hui-lin Shen2, Jia-hua Ding1, Chong Gao1, Qian Sun1, Wen-ji Chen1, Ning-na Chen1, Li-jie Liu3, Xiao-mao Li4, Xue-mei Wang51Department of Hematology, The Affiliated Zhongda Hospital, Clinical Medical School, Southeast University, Nanjing, People’s Republic of China; 2Department of Hematology, The Affiliated People’s Hospital, Jiangsu University, Zhenjiang, People’s Republic of China; 3Institution of Physiology, Southeast University, Nanjing, People’s Republic of China; 4Department of Physics, University of Saarland, Saarbruecken, Germany; 5State Key Lab of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, People’s Republic of ChinaAbstract: In many instances, multidrug resistance (MDR is mediated by increasing the expression at the cell surface of the MDR1 gene product, P-glycoprotein (P-gp, a 170-kD energy-dependent efflux pump. The aim of this study was to investigate the potential benefit of combination therapy with magnetic Fe3O4 nanoparticle [MNP (Fe3O4] and MDR1 shRNA expression vector in K562/A02 cells. For stable reversal of “classical” MDR by short hairpin RNA (shRNA aiming directly at the target sequence (3491–3509, 1539–1557, and 3103–3121 nucleotide of MDR1 mRNA. PGC silencer-U6-neo-GFP-shRNA/MDR1 called PGY1–1, PGY1–2, and PGY1–3 were constructed and transfected into K562/A02 cells by lipofectamine 2000. After transfected and incubated with or without MNP (Fe3O4 for 48 hours, the transcription of MDR1 mRNA and the expression of P-gp were detected by quantitative real-time PCR and Western-blot assay respectively. Meanwhile intracellular concentration of DNR in K562/A02 cells was detected by flow cytometry (FCM. PGC silencer-U6-neo-GFP-shRNA/MDR1 was successfully constructed, which was confirmed by sequencing and PGY1–2 had the greatest MDR1 gene inhibitory ratio. Analysis of the reversal ratio of MDR, the concentration of daunorubicin (DNR and the transcription of MDR1 gene and expression of P-gp in K562/A02 showed that combination of DNR with either MNP (Fe3O4 or PGY1–2 exerted a potent cytotoxic effect on K562/A02 cells, while combination of MNP (Fe3O4 and PGY1–2 could synergistically reverse multidrug resistance. Thus our in vitro data strongly suggested that a combination of MNP (Fe3O4 and shRNA expression vector might be a more sufficient and less toxic anti-MDR method on leukemia. Keywords: K562/A02 cell line, multidrug resistance, magnetic nanoparticle of Fe3O4, recombinant plasmid vector PGY1–2

  9. Study of magnetic and structural and optical properties of Zn doped Fe3O4 nanoparticles synthesized by co-precipitation method for biomedical application

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    Zahra Rezay Marand

    2014-09-01

    Full Text Available Abstract Objective(s: This paper describes synthesizing of magnetic nanocomposite with co-precipitation method. Materials and Methods: Magnetic ZnxFe3-xO4 nanoparticles with 0-14% zinc doping (x=0, 0.025, 0.05, 0.075, 0.1 and 0.125 were successfully synthesized by co-precipitation method. The prepared zinc-doped Fe 3O4 nanoparticles were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FTIR, vibrating sample magnetometer (VSM and UV-Vis spectroscopy. Results: results obtained from X-ray diffraction pattern have revealed the formation of single phase nanoparticles with cubic inverse spinal structures which size varies from 11.13 to 12.81 nm. The prepared nanoparticles have also possessed superparamagnetic properties at room temperature and high level of saturation magnetization with the maximum level of 74.60 emu/g for x=0.075. Ms changing in pure magnetite nanoparticles after impurities addition were explained based on two factors of “particles size” and “exchange interactions”. Optical studies results revealed that band gaps in all Zn-doped NPs are higher than pure Fe 3O4. As doping percent increases, band gap value decreases from 1.26 eV to 0.43 eV. Conclusion: these magnetic nanocomposite structures since having superparamagnetic property offer a high potential for biosensing and biomedical application.

  10. Synthesis and properties of magnetic and luminescent Fe3O4/SiO2/Dye/SiO2 nanoparticles

    International Nuclear Information System (INIS)

    A simple and reproducible method was developed to synthesize a novel class of Fe3O4/SiO2/dye/SiO2 composite nanoparticles. As promising candidates for use in bioassays, the obtained nanoparticles have an average diameter of 30 nm, and the thickness of the outer shell of silica could be tuned by changing the concentration of the silicon precursor tetraethyl orthosilicate during the synthesis. These multifunctional nanoparticles were found to be highly luminescent, photostable and superparamagnetic. The luminescence intensity of the nanoparticles was increased as the dye concentration was increased in the preparation process. The color of the luminescence was successfully tuned by incorporating different dyes into the nanoparticles. The measurements of the emission spectra indicated that relative to the dye molecules dissolved in ethanol, the emission of the dye-doped nanoparticles exhibited either a red shift or a blue shift, to which a tentative explanation was given

  11. Adsorption of acidic, basic, and neutral proteins from aqueous samples using Fe3O4 magnetic nanoparticles modified with an ionic liquid

    International Nuclear Information System (INIS)

    We have prepared and characterized Fe3O4 nanoparticles and their binary mixtures (IL-Fe3O4) with 1-hexyl-3-methylimidazolium bromide as ionic liquid for use in the adsorption of lysozyme (LYS), bovine serum albumin (BSA), and myoglobin (MYO). The optimum operational conditions for the adsorption of proteins (at 0.05-2.0 mg mL-1) were 4.0 mg mL-1 of nanoparticles and a contact time of 10 min. The maximum adsorption capacities are 455, 182 and 143 mg for LYS, BSA, and MYO per gram of adsorbent, respectively. The Langmuir model better fits the adsorption isotherms, with adsorption constants of 0.003, 0.015 and 0.008 L mg-1, in order, for LYS, BSA, MYO. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. The adsorption processes are endothermic. The proteins can be desorbed from the nanoparticles by using NaCl solution at pH 9.5, and the nanoparticles thus can be recycled. (author)

  12. Synthesis of water-dispersed magnetic nanoparticles (H2O-DMNPs) of ?-cyclodextrin modified Fe3O4 and its catalytic application in Kabachnik-Fields multicomponent reaction

    Science.gov (United States)

    Rostamnia, Sadegh; Doustkhah, Esmail

    2015-07-01

    Water-dispersed magnetic nanoparticles (H2O-DMNPs) of ?-cyclodextrin modified Fe3O4 were successfully synthesized. ?-Cyclodextrin acts as stabilizer and structure directing agent of Fe3O4. Subsequently, the dispersion of Fe3O4@?-CD was applied for the Kabachnik-Fields multicomponent reaction through three-component synthesis of an amine, aldehyde, and dimethylphosphonate. ?-CD had also a drastic effect in accelerating the catalysis of phosphonate synthesis. By this protocol, phosphonate derivatives were synthesized in high yields and the catalyst was recycled for 10 successful runs.

  13. Design and construction of polymerized-chitosan coated Fe3O4 magnetic nanoparticles and its application for hydrophobic drug delivery.

    Science.gov (United States)

    Ding, Yongling; Shen, Shirley Z; Sun, Huadong; Sun, Kangning; Liu, Futian; Qi, Yushi; Yan, Jun

    2015-03-01

    In this study, a novel hydrogel, chitosan (CS) crosslinked carboxymethyl-?-cyclodextrin (CM-?-CD) polymer modified Fe3O4 magnetic nanoparticles was synthesized for delivering hydrophobic anticancer drug 5-fluorouracil (CS-CDpoly-MNPs). Carboxymethyl-?-cyclodextrin being grafted on the Fe3O4 nanoparticles (CDpoly-MNPs) contributed to an enhancement of adsorption capacities because of the inclusion abilities of its hydrophobic cavity with insoluble anticancer drugs through host-guest interactions. Experimental results indicated that the amounts of crosslinking agent and bonding times played a crucial role in determining morphology features of the hybrid nanocarriers. The nanocarriers exhibited a high loading efficiency (44.7±1.8%) with a high saturation magnetization of 43.8emu/g. UV-Vis spectroscopy results showed that anticancer drug 5-fluorouracil (5-Fu) could be successfully included into the cavities of the covalently linked CDpoly-MNPs. Moreover, the free carboxymethyl groups could enhance the bonding interactions between the covalently linked CDpoly-MNPs and anticancer drugs. In vitro release studies revealed that the release behaviors of CS-CDpoly-MNPs carriers were pH dependent and demonstrated a swelling and diffusion controlled release. A lower pH value led to swelling effect and electrostatic repulsion contributing to the protonation amine impact of NH3(+), and thus resulted in a higher release rate of 5-Fu. The mechanism of 5-Fu encapsulated into the magnetic chitosan nanoparticles was tentatively proposed. PMID:25579950

  14. Gold Nanoparticles on Mesoporous SiO2-Coated Magnetic Fe3O4 Spheres: A Magnetically Separatable Catalyst with Good Thermal Stability

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    Huan Liu

    2013-11-01

    Full Text Available Fe3O4 spheres with an average size of 273 nm were prepared in the presence of CTAB by a solvothermal method. The spheres were modified by a thin layer of SiO2, and then coated by mesoporous SiO2 (m-SiO2 films, by using TEOS as a precursor and CTAB as a soft template. The resulting m-SiO2/Fe3O4 spheres, with an average particle size of 320 nm, a high surface area (656 m2/g, and ordered nanopores (average pore size 2.5 nm, were loaded with gold nanoparticles (average size 3.3 nm. The presence of m-SiO2 coating could stabilize gold nanoparticles against sintering at 500 °C. The material showed better performance than a conventional Au/SiO2 catalyst in catalytic reduction of p-nitrophenol with NaBH4. It can be separated from the reaction mixture by a magnet and be recycled without obvious loss of catalytic activity. Relevant characterization by XRD, TEM, N2 adsorption-desorption, and magnetic measurements were conducted.

  15. Preconcentration of emerging contaminants in environmental water samples by using silica supported Fe3O4 magnetic nanoparticles for improving mass detection in capillary liquid chromatography.

    Science.gov (United States)

    Moliner-Martínez, Yolanda; Ribera, Antonio; Coronado, Eugenio; Campíns-Falcó, P

    2011-04-22

    A magnetic material based on Fe(3)O(4) magnetic nanoparticles incorporated in a silica matrix by using a sol-gel procedure has been used to extract and preconcentrate emerging contaminants such as acetylsalicylic acid, acetaminophen, diclofenac and ibuprofen from environmental water samples prior to the analysis with Capillary LC-MS. The use of the proposed silica supported Fe(3)O(4) magnetic nanoparticles enables surfactant free extracts for the analysis with MS detection without interferences in the ionisation step. Under the optimum conditions, we demonstrated the reusability of the magnetic sorbent material during 20 uses without loss in the extraction efficiency. In addition, no cleanup was necessary. The preconcentration factor was 100 and the detection limits were between 50 and 150 ng/L. The proposed procedure has been applied to the analysis of water samples obtaining recoveries between 80 and 110% and RSD values lower than 12%. Concentrations of the target analytes over the range 1.7 and 0.1 ?g/L have been found in different water samples. PMID:21388625

  16. Magnetic BaFe12O19 nanofiber filter for effective separation of Fe3O4 nanoparticles and removal of arsenic

    International Nuclear Information System (INIS)

    Magnetic nanoparticles are promising in applications where magnetic separation is intended, although material losses via leaching mechanisms are often inevitable. Magnetic separations with widely available permanent magnets can effectively trap particles, leading to a complete removal of used or waste particles. In this report, we first demonstrate the synthesis of the thinnest (112.7 ± 16.4 nm) and most magnetic (71.96 emu g?1) barium hexaferrite (BaFe12O19, BHF—fridge magnet) via an organic solvent-free electrospinning procedure. When the fibers are then packed into a column, they clearly remove 12 nm magnetite (Fe3O4) nanoparticles quantitatively. The same BHF cartridge also removes more than 99.9 % As-treated magnetite nanoparticles at capacities up to 70 times of its weight. As a result, one liter of 150 ?g L?1 As-contaminated water can be purified rapidly at a material cost of less than 2 US cents

  17. Studies on Properties of Rice Straw/Polymer Nanocomposites Based on Polycaprolactone and Fe3O4 Nanoparticles and Evaluation of Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Roshanak Khandanlou

    2014-10-01

    Full Text Available Modified rice straw/Fe3O4/polycaprolactone nanocomposites (ORS/Fe3O4/ PCL-NCs have been prepared for the first time using a solution casting method. The RS/Fe3O4-NCs were modified with octadecylamine (ODA as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD, Scanning electron microscopy (SEM, Transmission electron microscopy (TEM, Thermogravimetric analysis (TGA and Fourier transform infrared spectroscopy (FT-IR. The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe3O4-NCs content in comparison with PCL peaks, the Fe3O4-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe3O4-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe3O4-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe3O4/PCL-NCs decreased with the increase of ORS/Fe3O4-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe3O4-NCs. The antibacterial activities of the ORS/Fe3O4/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli and Gram-positive bacteria (Staphylococcus aureus by diffusion method using nutrient agar. The results indicated that ORS/Fe3O4/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe3O4-NCs in the PCL.

  18. Bare and protein-conjugated Fe3O4 ferromagnetic nanoparticles for utilization in magnetically assisted hemodialysis: biocompatibility with human blood cells

    International Nuclear Information System (INIS)

    Magnetically assisted hemodialysis is a development of conventional hemodialysis and is based on the circulation of ferromagnetic nanoparticle-targeted binding substance conjugates (FN-TBS Cs) in the bloodstream of the patient and their eventual removal by means of a 'magnetic dialyzer'. Presented here is an in vitro investigation on the biocompatibility of bare Fe3O4 FNs and Fe3O4-bovine serum albumin Cs with blood cells, namely red blood cells (RBCs), white blood cells (WBCs) and platelets (Plts). Atomic force microscopy (AFM) and optical microscopy (OM) enabled the examination of blood cells at the nanometer and micrometer level, respectively. The observations made on FN- and C-maturated blood samples are contrasted to those obtained on FN- and C-free reference blood samples subjected to exactly the same maturation procedure. Qualitatively, both AFM and OM revealed no changes in the overall shape of RBCs, WBCs and Plts. Incidents where bare FNs or Cs were bound onto the surface of RBCs or internalized by WBCs were very rare. Detailed examination by means of OM proved that impaired coagulation of Plts is not initiated/promoted either by FNs or Cs. Quantitatively, the statistical analysis of the obtained AFM images from RBC surfaces clearly revealed that the mean surface roughness of RBCs maturated with bare FNs or Cs was identical to the one of reference RBCs.

  19. Bare and protein-conjugated Fe3O4 ferromagnetic nanoparticles for utilization in magnetically assisted hemodialysis: biocompatibility with human blood cells

    Science.gov (United States)

    Stamopoulos, D.; Manios, E.; Gogola, V.; Benaki, D.; Bouziotis, P.; Niarchos, D.; Pissas, M.

    2008-12-01

    Magnetically assisted hemodialysis is a development of conventional hemodialysis and is based on the circulation of ferromagnetic nanoparticle-targeted binding substance conjugates (FN-TBS Cs) in the bloodstream of the patient and their eventual removal by means of a 'magnetic dialyzer'. Presented here is an in vitro investigation on the biocompatibility of bare Fe3O4 FNs and Fe3O4-bovine serum albumin Cs with blood cells, namely red blood cells (RBCs), white blood cells (WBCs) and platelets (Plts). Atomic force microscopy (AFM) and optical microscopy (OM) enabled the examination of blood cells at the nanometer and micrometer level, respectively. The observations made on FN- and C-maturated blood samples are contrasted to those obtained on FN- and C-free reference blood samples subjected to exactly the same maturation procedure. Qualitatively, both AFM and OM revealed no changes in the overall shape of RBCs, WBCs and Plts. Incidents where bare FNs or Cs were bound onto the surface of RBCs or internalized by WBCs were very rare. Detailed examination by means of OM proved that impaired coagulation of Plts is not initiated/promoted either by FNs or Cs. Quantitatively, the statistical analysis of the obtained AFM images from RBC surfaces clearly revealed that the mean surface roughness of RBCs maturated with bare FNs or Cs was identical to the one of reference RBCs.

  20. Enhanced performance of polymer solar cells using PEDOT:PSS doped with Fe3O4 magnetic nanoparticles aligned by an external magnetostatic field as an anode buffer layer.

    Science.gov (United States)

    Wang, Kai; Yi, Chao; Hu, Xiaowen; Liu, Chang; Sun, Yan; Hou, Jianhui; Li, Yongfang; Zheng, Jie; Chuang, Steven; Karim, Alamgir; Gong, Xiong

    2014-08-13

    Low efficiency and poor stability are two major obstacles limiting the manufacturing of renewable and cost-effective polymer solar cell (PSCs). To address these problems, solution-processed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) doped with Fe3O4 magnetic nanoparticles ((PEDOT:PSS):Fe3O4), and above (PEDOT:PSS):Fe3O4 thin film aligned by an external magnetostatic field ([(PEDOT:PSS):Fe3O4] W/H) were used as the anode buffer layer for PSCs, respectively. As compared with PSCs with PEDOT:PSS as an anode buffer layer, 38.5% enhanced efficiency and twice improved stability are observed from PSCs incorporated with [(PEDOT:PSS):Fe3O4] W/H anode buffer layer. It was found that enhanced efficiency and improved stability resulted from a combination of reduced acidity of PEDOT:PSS and enhanced electrical conductivity that originated from generated counterions and the paramagnetism of Fe3O4 magnetic nanoparticles by an external magnetostatic field. PMID:24980462

  1. Fabrication of flexible and self-standing inorganic-organic three phase magneto-dielectric PVDF based multiferroic nanocomposite films through a small loading of graphene oxide (GO) and Fe3O4 nanoparticles.

    Science.gov (United States)

    Jayakumar, O D; Abdelhamid, Ehab H; Kotari, Vasundhara; Mandal, Balaji P; Rao, Rekha; Jagannath; Naik, Vaman M; Naik, Ratna; Tyagi, A K

    2015-09-28

    Flexible inorganic-organic magneto-electric (ME) nanocomposite films (PVDF, PVDF-GO, PVDF-Fe3O4 and PVDF-GO-Fe3O4), composed of well-dispersed graphene oxide (GO 5 wt%) and magnetic Fe3O4 nanoparticles (5 wt%) embedded into a poly(vinylidene-fluoride) (PVDF) matrix, have been prepared by a solvent casting route. The magnetic, ferroelectric, dielectric, magneto-dielectric (MD) coupling and structural properties of these films have been systematically investigated. Magnetic (Ms = 2.21 emu g(-1)) and ferroelectric (P = 0.065 ?C cm(-2)) composite films of PVDF-GO-Fe3O4 (PVDF loaded with 5% GO and 5% Fe3O4) with an MD coupling of 0.02% at room temperature (RT) showed a three times higher dielectric constant than that of the pure PVDF film, with a dielectric loss as low as 0.6. However, the PVDF-Fe3O4 film, which exhibited improved magnetic (Ms = 2.5 emu g(-1)) and MD coupling (0.04%) properties at RT with a lower dielectric loss (0.3), exhibited decreased ferroelectric properties (P = 0.06 ?C cm(-2)) and dielectric constant compared to the PVDF-GO-Fe3O4 film. MD coupling measurements carried out as a function of temperature on the multi-functional PVDF-GO-Fe3O4 film showed a systematic increase in MD values up to 100 K and a decrease thereafter. The observed magnetic, ferroelectric, dielectric, MD coupling and structural properties of the nanocomposite films are attributed to the homogeneous dispersion and good alignment of Fe3O4 nanoparticles and GO in the PVDF matrix along with a partial conversion of nonpolar ?-phase PVDF to polar ?-phase. The above multi-functionality of the composite films of PVDF-Fe3O4 and PVDF-GO-Fe3O4 paves the way for their application in smart multiferroic devices. PMID:26274764

  2. Three Birds with One Fe3O4 Nanoparticle: Integration of Microwave Digestion, Solid Phase Extraction, and Magnetic Separation for Sensitive Determination of Arsenic and Antimony in Fish.

    Science.gov (United States)

    Jia, Yun; Yu, Huimin; Wu, Li; Hou, Xiandeng; Yang, Lu; Zheng, Chengbin

    2015-06-16

    An environmentally friendly and fast sample treatment approach that integrates accelerated microwave digestion (MWD), solid phase extraction, and magnetic separation into a single step was developed for the determination of arsenic and antimony in fish samples by using Fe3O4 magnetic nanoparticles (MNPs). Compared to conventional microwave digestion, the consumption of HNO3 was reduced significantly to 12.5%, and the digestion time and temperature were substantially decreased to 6 min and 80 °C, respectively. This is largely attributed to Fe3O4 magnetic nanoparticles being a highly effective catalyst for rapid generation of oxidative radicals from H2O2, as well as an excellent absorber of microwave irradiation. Moreover, potential interferences from sample matrices were eliminated because the As and Sb species adsorbed on the nanoparticles were efficiently separated from the digests with a hand-held magnet prior to analysis. Limits of detection for arsenic and antimony were in the range of 0.01-0.06 ?g g(-1) and 0.03-0.08 ?g g(-1) by using hydride generation atomic fluorescence spectrometry, respectively, and further improved to 0.002-0.005 ?g g(-1) and 0.005-0.01 ?g g(-1) when inductively coupled plasma mass spectrometry was used as a detector. The precision of replicate measurements (n = 9) was better than 6% by analyzing 0.1 g test sample spiked with 1 ?g g(-1) arsenic and antimony. The proposed method was validated by analysis of two certified reference materials (DORM-3 and DORM-4) with good recoveries (90%-106%). PMID:25962876

  3. Separation and preconcentration of trace amounts of silver (I) in water samples based on dithizone modified sodium dodecyl sulfate-coated Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Complete text of publication follows. Using magnetic nanoparticles for separation and preconcentration in analytical chemistry is opening a new methodology that is faster, simpler and more precise than old ones. In this work, a simple and reliable solid-phase extraction method has been developed to selectively separate and preconcentrate trace amounts of silver (I) from aqueous samples for subsequent measurement by atomic absorption spectrometry. Silver ion was adsorbed quantitatively from aqueous solution onto magnetic nano-adsorbent with dithizone (DTZ) immobilized on sodium dodecyl sulfate (SDS)-coated Fe3O4 nanoparticles (DTZ-S-IONPs). SDS as a surfactant makes admicelle on the surface of Fe3O4 nanoparticles, which allows the metal complexing agent of DTZ, to be immobilized in its hydrocarbon cores. This assemble, as a chelating adsorbent, has made the separation and preconcentration of silver ion possible. It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of silver (I) at 25 deg C. Different parameters such as pH, temperature, ionic strength, equilibrium time, type and least amount of stripping solution were optimized. The effect of some co-existing ions on the determination was investigated. An aqueous solution containing thiourea has been used in order to selectively desorb the adsorbed silver ion from the surface of the adsorbent. No serious interferences have been observed due to the presence of another species in the sample. The separation selectivity of the adsorbent for other cations was studied. To improve this, EDTA was added to the source solution before applying to the DTZ-S-IONPs as chelating adsorbent. The procedure was applied for analysis of two real samples. The method is simple and inexpensive. This research was supported by the Department of Chemistry and Nanoscience and Nanotechnology Research Laboratory (NNRL) Payame Noor University of Sirjan.

  4. Fe3O4 magnetic core coated by silver and functionalized with N-acetyl cysteine as novel nanoparticles in ferritin adsorption

    International Nuclear Information System (INIS)

    A novel metal-chelate affinity matrix utilizing N-acetyl cysteine as a metal chelating agent was synthesized. For this, magnetic Fe3O4 core was coated with silver by chemical reduction. Then, these magnetic silver nanoparticles were covered with N-acetyl cysteine, and Fe3+ was chelated to this modified magnetic silver nanoparticle. These magnetic nanoparticles were characterized by SEM, AFM, EDX, and ESR analysis. Synthesized nanoparticles were spherical and average size is found to be 69 nm. Fe3+ chelated magnetic silver nanoparticles were used for the adsorption of ferritin from its aqueous solution. Optimum conditions for the ferritin adsorption experiments were performed at pH 6.0 phosphate buffer and 25 °C of medium temperature and the maximum ferritin adsorption capacity is found to be 89.57 mg/g nanoparticle. Ferritin adsorption onto magnetic silver nanoparticles was increased with increasing ferritin concentration while adsorption capacity was decreased with increasing ionic strength. Affinity of the magnetic silver nanoparticles to the ferritin molecule was shown with SPR analysis. It was also observed that the adsorption capacity of the magnetic silver nanoparticles was not significantly changed after the five adsorption/desorption cycles.

  5. Superparamagnetism and metamagnetic transition in Fe3O4 nanoparticles synthesized via co-precipitation method at different pH

    Science.gov (United States)

    Rani, Stuti; Varma, G. D.

    2015-09-01

    In the present work, Fe3O4 nanoparticles have been synthesized via low temperature co-precipitation method at different pH (7.0, 11.0 and 12.4) with the aim to study the variation of pH on the structural, optical and magnetic properties of samples. Further, the sample synthesized at pH ~12.4 has been annealed at 230 °C for 10 h to study the effect of annealing on structural, optical and magnetic properties. X-ray diffraction (XRD) results reveal the formation of pure spinel phase with the space group Fd-3m. Further, XRD, FESEM and TEM results confirm the nanocrystalline nature of the as synthesized samples, and the particle size of the samples decreases as the pH increases and increases after annealing at 230 °C. FTIR analysis indicates that the sample synthesized at pH ~12.4 and the same sample annealed at 230 °C are pure spinel Fe3O4, whereas the samples synthesized at pH ~7.0 and 11.0 have small content of ?-Fe2O3. The optical measurements of the as synthesized samples show two band gaps in all synthesized samples. Field dependent magnetization measurements (M-H) reveal superparamagnetic nature of all the synthesized samples at room temperature and ferromagnetic behavior at low temperature (~5 K). Furthermore, M-H plots measured at 5 K show presence of metamagnetic transition in all samples. The metamagnetic transition along with ferromagnetic behavior at low temperature in Fe3O4 nanoparticles are observed first time in the present work to the best of our knowledge. Further the value of magnetization decreases with decreasing particle size at both temperatures. The fitting of the field cooled (FC) temperature dependent magnetization (M-T) measurements data with modified Bloch-spin wave model with additional surface disorder term and mixed magnetic phases indicates surface spin disorder and mixed magnetic phases in the as synthesized samples, which may be the possible reason for the existence of metamagnetic transition in the samples. The correlation between the observed magnetic properties and structural characteristics of the samples with the synthesizing parameters (pH value and annealing effect) has been described and discussed in this paper.

  6. Comparison of the magnetic, radiolabeling, hyperthermic and biodistribution properties of hybrid nanoparticles bearing CoFe2O4 and Fe3O4 metal cores

    International Nuclear Information System (INIS)

    Metal oxide nanoparticles, hybridized with various polymeric chemicals, represent a novel and breakthrough application in drug delivery, hyperthermia treatment and imaging techniques. Radiolabeling of these nanoformulations can result in new and attractive dual-imaging agents as well as provide accurate in vivo information on their biodistribution profile. In this paper a comparison study has been made between two of the most promising hybrid core–shell nanosystems, bearing either magnetite (Fe3O4) or cobalt ferrite (CoFe2O4) cores, regarding their magnetic, radiolabeling, hyperthermic and biodistribution properties. While hyperthermic properties were found to be affected by the metal-core type, the radiolabeling ability and the in vivo fate of the nanoformulations seem to depend critically on the size and the shell composition. (paper)

  7. Magnetic Fe3O4-C nanoparticles modified with 1-(2-thiazolylazo)-2-naphthol as a novel solid-phase extraction sorbent for preconcentration of copper (II)

    International Nuclear Information System (INIS)

    We report on a new magnetic nanosorbent for solid phase extraction of Cu(II) before its determination by flame atomic absorption spectrometry. The magnetic sorbent is composed of carbon-coated magnetite nanoparticles (Fe3O4-C) synthesized by a single-step solvothermal reaction and then loaded with the chelator 1-(2-thiazolylazo)-2-naphthol. It was used for the preconcentration of Cu(II) ions from water and food samples. The effects of pH value and volume of sample, of type and volume of eluent, and of interfering ions were investigated. Under the optimum conditions, the calibration graph is linear in the 4.0–400 ?g L?1 concentration range, with a detection limit of 1.5 ?g L?1. The method was validated by using a certified reference material (NIST 1566b; oyster tissue) and applied to the determination of trace copper in spiked water and food samples. (author)

  8. An amperometric acetylcholinesterase sensor based on Fe3O4 nanoparticle/multi-walled carbon nanotube-modified ITO-coated glass plate for the detection of pesticides

    International Nuclear Information System (INIS)

    Highlights: ? Constructed AChE biosensor based on AChE/Fe3O4NPs/c-MWCNT/ITO electrode. ? Enzyme electrode was characterized by AFM, FTIR, CV and EIS. ? Detection limit and working range of biosensor were 0.1 nM and 0.1–100 nM. ? Half life of enzyme electrode was 3 months. ? Biosensor measured pesticides in environmental and food samples. - Abstract: A method is described for the construction of a highly sensitive electrochemical biosensor for the detection of malathion, chlorpyrifos, monocrotophos and endosulfan based on covalent immobilization of acetylcholinesterase (AChE) on iron oxide nanoparticles (Fe3O4NPs)-decorated carboxylated multi-walled carbon nanotubes (c-MWCNTs) electrodeposited onto indium tin oxide (ITO)-coated glass plate. Transmission electron microscopic (TEM) and UV analysis of nanocomposite materials demonstrated that Fe3O4NPs were well deposited on the outer walls of c-MWCNTs. The modified electrode was characterized by atomic force microscopy (AFM), cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The resulting biosensor exhibited a linear response for acetylthiocholine in a concentration range of 0.1–700 ?mol L?1 with a remarkable sensitivity of 0.402 mA/?mol L?1. Under optimum conditions, the inhibition rates of pesticides were proportional to their concentrations in the range of 0.1–70 nmol L?1, 0.1–50 nmol L?1, 0.1–70 nmol L?1 and 0.1–100 nmol L?1 for malathion, chlorpyrifos, monocrotophos and endosulfan, respectively. The detection limit of the biosensor for all pesticides was 0.1 nmol L?1 at a signal-to-noise ratio of 3. The biosensor showed good reproducibility, no interference by metal ions and long-term stability. The measurement results obtained by the present biosensor were in good agreement with those obtained by the standard gas chromatography–mass spectrometry method. The biosensor was employed for the determination of pesticides in environmental and food samples.

  9. A facile method for the room-temperature synthesis of water-soluble magnetic Fe3O4 nanoparticles: Combination of in situ synthesis and decomposition of polymer hydrogel

    International Nuclear Information System (INIS)

    Highlights: ? A facile room-temperature method for achieving water-soluble magnetic Fe3O4 nanoparticles (NPs) by combining in situ synthesis and decomposition of magnetic polymer hydrogel has been demonstrated. ? The Fe3O4 NPs with average diameters of 6.3-8.3 nm were synthesized in a crosslinked polyacrylamide hydrogel. ? The saturation magnetization was 44.6 and 54.7 emu g-1 at 300 K and 5 K, respectively. ? The dried magnetic Fe3O4 NPs were easily dispersed in alkaline aqueous media. ? This study would be prospect for preparing functional water-soluble NPs used in metals and semiconductors. - Abstract: We propose and demonstrate a facile room-temperature synthetic method for obtaining water-soluble magnetic Fe3O4 nanoparticles (NPs) by combining the in situ synthesis and decomposition of a magnetic polymer hydrogel. The Fe3O4 NPs with average diameters of 6.3-8.3 nm were synthesized in a cross-linked polyacrylamide (PAAm) hydrogel by coprecipitating iron ions. The decomposition of the magnetic polymer hydrogel by an aqueous solution of sodium hydroxide led to the transfer of Fe3O4 NPs into the aqueous medium. The NPs can be dispersed stably in water for more than three months. The Fe3O4 NPs were characterized by X-ray photoelectron spectra (XPS), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The saturation magnetization of the Fe3O4 NPs was 44.6 and 54.7 emu g-1 at 300 K and 5 K, respectively. The dried magnetic Fe3O4 NPs were easily dispersed in alkaline aqueous media (pH > ?8) and kept stable for a long time. This room-temperature synthetic method for water-soluble magnetic Fe3O4 NPs can be expected for wide applications in the preparation of functional water-soluble NPs, such as those used in metals and semiconductors.

  10. Room temperature synthesis of magnetite (Fe3??O4) nanoparticles by a simple reverse co-precipitation method.

    Czech Academy of Sciences Publication Activity Database

    Mahmed, N.; Heczko, Oleg; Söderberg, O.; Hannula, S.-P.

    2011-01-01

    Ro?. 18, ?. 3 (2011), 032020/1-032020/4. ISSN 1757-8981 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferromagnetic nanoparticles * magnetite nanoparticles synthesis * maghemi Subject RIV: BM - Solid Matter Physics ; Magnetism

  11. Synthesis of amino-silane modified superparamagnetic Fe3O4 nanoparticles and its application in immobilization of lipase from Pseudomonas fluorescens Lp1

    International Nuclear Information System (INIS)

    Highlights: ? Magnetic nanoparticles were synthesized by chemical co-precipitation method. ? Surface was functionalized with amino-silane and used for lipase immobilization. ? Characterized through TEM, SEM, XRD, FT-IR and VSM analysis. ? The functionalization and immobilization did not affect the magnetite properties. ? The immobilized lipase showed greater functional property than free lipase. - Abstract: Superparamagnetic nanoparticles (Fe3O4–magnetite) were prepared by chemical co-precipitation method and their surface was functionalized with 3-aminopropyltriethoxysilane via silanization reaction to obtain amino functionalized magnetic nanoparticles. The purified lipase from Pseudomonas fluorescens Lp1 was immobilized onto functionalized magnetite using glutaraldehyde as the coupling agent. The characterization of the nanoparticles was done by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, vibrating sample magnetometry and Fourier transformed infrared spectroscopy. The size of the magnetite was measured about 10–30 nm. The results of characterization study revealed the successful immobilization of lipase on to functionalized magnetite. The saturation magnetization of magnetic nanoparticles was found to be 28.34 emu/g whereas the immobilized magnetic nanoparticle was 17.074 emu/g. The immobilized lipase had greater activity at 50 °C and thermal stability upto 70 °C. It exhibited excellent reusability for 4 cycles and storage stability upto 15 days by retaining 75% of its initial activity

  12. Sonochemical synthesis of magnetic core-shell Fe3O4-ZrO2 nanoparticles and their application to the highly effective immobilization of myoglobin for direct electrochemistry

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ? Magnetic core-shell Fe3O4-ZrO2 nanoparticle was synthesized by sonochemical approach. ? Fe3O4-ZrO2 NPs provided high capacity for trapping Mb on magnetic glassy carbon electrode surface. ? The constructed Mb/Fe3O4-ZrO2 film exhibited excellent electrocatalytic ability for the reduction of H2O2. ? The proposed method simplifies the immobilization methodology of proteins. - Abstract: In this study, bifunctional Fe3O4-ZrO2 magnetic core-shell nanoparticles (NPs), synthesized by a simple and effective sonochemical approach, were attached to the surface of a magnetic glassy carbon electrode (MGCE) and successfully applied to the immobilization/adsorption of myoglobin (Mb) for constructing a novel biosensor platform. With the advantages of the magnetism and the excellent biocompatibility of the Fe3O4-ZrO2 NPs, Mb could be easily immobilized on the surface of the electrode in the present of external magnetic field and well retained its bioactivity, hence dramatically facilitated direct electron transfer of Mb was demonstrated. The proposed Mb/Fe3O4-ZrO2 biofilm electrode exhibited excellent electrocatalytic behaviors towards the reduction of H2O2 with a linear range from 0.64 ?M to 148 ?M. This presented system avoids the complex synthesis for protecting Fe3O4 NPs, supplies a simple, effective and inexpensive way to immobilize protein, and is promising for construction of third-generation biosensors and other bio-magnetic induction devices.

  13. Adsorption of phosphate from water by easily separable Fe3O4@SiO2 core/shell magnetic nanoparticles functionalized with hydrous lanthanum oxide.

    Science.gov (United States)

    Lai, Li; Xie, Qiang; Chi, Lina; Gu, Wei; Wu, Deyi

    2016-03-01

    Hydrous lanthanum oxide was loaded onto the surface of Fe3O4@SiO2 core/shell magnetic nanoparticles to obtain an easily separable adsorbent (abbreviated as Fe-Si-La) for efficient separation of phosphate from water. Fe-Si-La was characterized with XRF, XRD, TEM, specific surface area and magnetization and their performance for phosphate removal was investigated. The Fe3O4@SiO2 core/shell structure was confirmed and the hydrous lanthanum oxide was successfully loaded onto its surface. The newly developed adsorbent had magnetization of 51.27emu/g. The Langmuir adsorption capacity of phosphate by Fe-Si-La reached 27.8mg/g by loading only 1mmol lanthanum per gram of magnetite. The adsorption was fast; nearly 99% of phosphate could be removed within 10min. The removal of phosphate was favored within the pH range 5.0-9.0. The adsorption on Fe-Si-La was not significantly influenced by ionic strength and by the coexistence of the anions of chloride and nitrate but sulfate, bicarbonate and humic acid showed slightly greater negative effects. Phosphate removal efficiency of higher than 95% was attained for real effluent of a wastewater treatment plant when the dose of adsorbent was >0.2kg/ton. The results showed that adsorbed phosphate could be nearly completely desorbed with NaOH solution for further use. In conclusion, Fe-Si-La is a promising adsorbent for the removal and recovery of phosphate from water. PMID:26641568

  14. A Novel DNA Nanosensor Based on CdSe/ZnS Quantum Dots and Synthesized Fe3O4 Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Roozbeh Hushiarian

    2014-04-01

    Full Text Available Although nanoparticle-enhanced biosensors have been extensively researched, few studies have systematically characterized the roles of nanoparticles in enhancing biosensor functionality. This paper describes a successful new method in which DNA binds directly to iron oxide nanoparticles for use in an optical biosensor. A wide variety of nanoparticles with different properties have found broad application in biosensors because their small physical size presents unique chemical, physical, and electronic properties that are different from those of bulk materials. Of all nanoparticles, magnetic nanoparticles are proving to be a versatile tool, an excellent case in point being in DNA bioassays, where magnetic nanoparticles are often used for optimization of the hybridization and separation of target DNA. A critical step in the successful construction of a DNA biosensor is the efficient attachment of biomolecules to the surface of magnetic nanoparticles. To date, most methods of synthesizing these nanoparticles have led to the formation of hydrophobic particles that require additional surface modifications. As a result, the surface to volume ratio decreases and nonspecific bindings may occur so that the sensitivity and efficiency of the device deteriorates. A new method of large-scale synthesis of iron oxide (Fe3O4 nanoparticles which results in the magnetite particles being in aqueous phase, was employed in this study. Small modifications were applied to design an optical DNA nanosensor based on sandwich hybridization. Characterization of the synthesized particles was carried out using a variety of techniques and CdSe/ZnS core-shell quantum dots were used as the reporter markers in a spectrofluorophotometer. We showed conclusively that DNA binds to the surface of ironoxide nanoparticles without further surface modifications and that these magnetic nanoparticles can be efficiently utilized as biomolecule carriers in biosensing devices.

  15. Sub-10 nm Fe3O4@Cu2-xS core-shell nanoparticles for dual-modal imaging and photothermal therapy

    KAUST Repository

    Tian, Qiwei

    2013-06-12

    Photothermal nanomaterials have recently attracted significant research interest due to their potential applications in biological imaging and therapeutics. However, the development of small-sized photothermal nanomaterials with high thermal stability remains a formidable challenge. Here, we report the rational design and synthesis of ultrasmall (<10 nm) Fe3O 4@Cu2-xS core-shell nanoparticles, which offer both high photothermal stability and superparamagnetic properties. Specifically, these core-shell nanoparticles have proven effective as probes for T 2-weighted magnetic resonance imaging and infrared thermal imaging because of their strong absorption at the near-infrared region centered around 960 nm. Importantly, the photothermal effect of the nanoparticles can be precisely controlled by varying the Cu content in the core-shell structure. Furthermore, we demonstrate in vitro and in vivo photothermal ablation of cancer cells using these multifunctional nanoparticles. The results should provide improved understanding of synergistic effect resulting from the integration of magnetism with photothermal phenomenon, important for developing multimode nanoparticle probes for biomedical applications. © 2013 American Chemical Society.

  16. Magnetic loading of TiO2/SiO2/Fe3O4 nanoparticles on electrode surface for photoelectrocatalytic degradation of diclofenac

    International Nuclear Information System (INIS)

    Highlights: ? Magnetic TSF nanoparticles are immobilized on electrode surface with aid of magnet. ? Magnetically attached TSF electrode shows high photoelectrochemical activity. ? Diclofenac is effectively degraded on TSF-loaded electrode by photoelectrocatalysis. ? Photoelectrocatalytic degradation of diclofenac is monitored with voltammetry. - Abstract: A novel magnetic nanomaterials-loaded electrode developed for photoelectrocatalytic (PEC) treatment of pollutants was described. Prior to electrode fabrication, magnetic TiO2/SiO2/Fe3O4 (TSF) nanoparticles were synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and FT-IR measurements. The nanoparticles were dispersed in ethanol and then immobilized on a graphite electrode surface with aid of magnet to obtain a TSF-loaded electrode with high photoelectrochemical activity. The performance of the TSF-loaded electrode was tested by comparing the PEC degradation of methylene blue in the presence and absence of magnet. The magnetically attached TSF electrode showed higher PEC degradation efficiency with desirable stability. Such a TSF-loaded electrode was applied to PEC degradation of diclofenac. After 45 min PEC treatment, 95.3% of diclofenac was degraded on the magnetically attached TSF electrode.

  17. Protein adsorption onto Fe3O4 nanoparticles with opposite surface charge and its impact on cell uptake

    OpenAIRE

    Catalayud, M. P.; Sanz, B.; Raffa, V; Riggio, C.; Ibarra, M. R.; Goya, G.F.

    2014-01-01

    Nanoparticles (NPs) engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the NP surface, forming a swaddling layer called protein corona that influences cell internalization. We present a study on protein adsorption onto different magnetic NPs (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. Two colloids with magnetite cores of 25 nm, sa...

  18. Correlation of structural and magnetic properties of Fe3O4 nanoparticles with their calorimetric and magnetorheological performance.

    Czech Academy of Sciences Publication Activity Database

    Sedla?ík, M.; Mou?ka, R.; Kozáková, Z.; Kazantseva, N. E.; Pavlínek, V.; Ku?itka, I.; Kaman, Ond?ej; Peer, Petra

    2013-01-01

    Ro?. 326, january (2013), s. 7-13. ISSN 0304-8853 Grant ostatní: UTB Zlín(CZ) IGA/25/FT/10/D; GA MŠk(CZ) ED2.1.00/03.0111 Institutional support: RVO:67985874 ; RVO:68378271 Keywords : iron oxide * nanoparticle * ferrofluid * hyperthermia * embolization * microwave synthesis * magnetorheology Subject RIV: BK - Fluid Dynamics; BM - Solid Matter Physics ; Magnetism (FZU-D) Impact factor: 2.002, year: 2013

  19. Anti-fish bacterial pathogen effect of visible light responsive Fe3O4@TiO2 nanoparticles immobilized on glass using TiO2 sol–gel

    International Nuclear Information System (INIS)

    This paper demonstrates a fish pathogen reduction procedure that uses TiO2 sol–gel coating Fe3O4@TiO2 powder on glass substrate. Such procedure can effectively relieve two constraints that haunt TiO2 sterilization applications: 1) the need for UV for overcoming the wide band gap of pure TiO2 and 2) the difficulty of its recovering from water for reuse. In the process, visible light responsive Fe3O4/TiO2 nanoparticles are synthesized and immobilized on glass using TiO2 sol–gel as the binder for fish bacterial pathogen disinfection test. After 3 h of visible light irradiation, the immobilized Fe3O4@TiO2's inhibition efficiencies for fish bacterial pathogen are, respectively, 50% for Edwardsiella tarda (BCRC 10670) and 23% for Aeromonas hydrophila (BCRC 13018)

  20. Surfactant-free green synthesis of Fe3O4 nanoparticles capped with 3,4-dihydroxyphenethylcarbamodithioate: stable recyclable magnetic nanoparticles for the rapid and efficient removal of Hg(ii) ions from water.

    Science.gov (United States)

    Venkateswarlu, Sada; Yoon, Minyoung

    2015-11-14

    Mercury is considered one of the most notorious global pollutants due to its high toxicity and widespread use in industry. Although many materials have been developed for the removal of mercury for water purification, most of these materials are difficult to reuse, which may lead to an increase in the mercury handling expense. Therefore, new sustainable materials that can be easily recycled and are highly efficient for the removal of mercury are required. Herein, we report the surfactant-free green synthesis of Fe3O4 magnetic nanoparticles (MNPs) using a watermelon (Citrullus lanatus) rind extract. The Fe3O4 MNPs were further functionalized with 3,4-dihydroxyphenethylcarbamodithioate (DHPCT) and applied to the removal of Hg(ii). Evaluation of the mercury removal efficiency and the amount adsorbed by DHPCT@Fe3O4 MNPs demonstrated a high Hg(ii) removal efficiency (98%) with a maximum Hg(ii) adsorption capacity of 52.1 mg g(-1). Systematic studies of the adsorption mechanism and selectivity suggest that the soft ligand (DHPCT) can preferentially coordinate with the soft metal ion (Hg(ii)) resulting in selective mercury removal. The developed DHPCT@Fe3O4 MNPs were readily recycled several times using an external magnet by exploiting their ferromagnetic character, without a significant decline in the Hg(ii) removal efficiency. This study provides a new insight into the preparation of a highly efficient adsorbent for Hg(ii) removal by an eco-friendly method. PMID:26436867

  1. Protein adsorption onto Fe3O4 nanoparticles with opposite surface charge and its impact on cell uptake

    CERN Document Server

    Catalayud, M P; Raffa, V; Riggio, C; Ibarra, M R; Goya, G F

    2014-01-01

    Nanoparticles (NPs) engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the NP surface, forming a swaddling layer called protein corona that influences cell internalization. We present a study on protein adsorption onto different magnetic NPs (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. Two colloids with magnetite cores of 25 nm, same hydrodynamic size and opposite surface charge were in situ coated with (a) positive polyethyleneimine (PEI-MNPs) and (b) negative poly(acrylic acid) (PAA-MNPs). After few minutes of incubation in cell culture medium the wrapping of the MNPs by protein adsorption resulted in a 5-fold size increase. After 24 h of incubation large MNP-protein aggregates with hydrodynamic sizes 1500 to 3000 nm (PAA-MNPs and PEI-MNPs respectively) were observed. Each cluster contained an estimated number of magnetic cores between 450 and 1000, indicating the...

  2. [Solid-phase extraction based on mesoporous Fe3O4 @ mSiO2 @ Cu2+ magnetic nanoparticles coupled with high performance liquid chromatography for the determination of microcystins in water samples].

    Science.gov (United States)

    Sun, Hong; Lou, Dawei; Lian, Lili; Han, Xue; Guo, Tingxiu; Chen, Tujun

    2015-05-01

    Mesoporous magnetic nanoparticles of Fe3O4 @ mSiO2 @ Cu2+ were synthesized by two methods of hydrothermal synthesis and room temperature synthesis. The synthesized mesoporous Fe3O4 @ mSiO2 @ Cu2+ nanoparticles presented uniform sizes, good magnetic properties and specific selectivity. In this work, a novel magnetic solid-phase extraction (MSPE) method based on mesoporous Fe3O4 @ mSiO2 @ Cu2+ nanoparticles (NPs) coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction of trace amount of microcystin-LR (MC-LR) in water samples. The MSPE extraction conditions and HPLC conditions were optimized. The results showed that good linear relationship (r = 0.999 4) was obtained between peak area and mass concentration of MC-LR in the range of 0.1-15 µg/L. The limit of detection was 0.025 µg/L, and the limit of quantification was 0.082 µg/L. Furthermore, this method was used for the analysis of algal toxins in water samples with the recovery of 78%. The results indicated that Fe3O4 @ mSiO2 @ Cu2+ magnetic nanoparticles were good pretreatment alternatives for the concentration of microcystin-LR in water samples. PMID:26387200

  3. Controlled flame synthesis of ?Fe2O3 and Fe3O4 nanoparticles: effect of flame configuration, flame temperature, and additive loading

    International Nuclear Information System (INIS)

    Superparamagnetic iron oxide nanoparticles are used in diverse applications, including optical magnetic recording, catalysts, gas sensors, targeted drug delivery, magnetic resonance imaging, and hyperthermic malignant cell therapy. Combustion synthesis of nanoparticles has significant advantages, including improved nanoparticle property control and commercial production rate capability with minimal post-processing. In the current study, superparamagnetic iron oxide nanoparticles were produced by flame synthesis using a coflow flame. The effect of flame configuration (diffusion and inverse diffusion), flame temperature, and additive loading on the final iron oxide nanoparticle morphology, elemental composition, and particle size were analyzed by transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy. The synthesized nanoparticles were primarily composed of two well known forms of iron oxide, namely hematite ?Fe2O3 and magnetite Fe3O4. We found that the synthesized nanoparticles were smaller (6-12 nm) for an inverse diffusion flame as compared to a diffusion flame configuration (50-60 nm) when CH4, O2, Ar, and N2 gas flow rates were kept constant. In order to investigate the effect of flame temperature, CH4, O2, Ar gas flow rates were kept constant, and N2 gas was added as a coolant to the system. TEM analysis of iron oxide nanoparticles synthesized using an inverse diffusion flame configuration with N2 cooling demonstrated that particles no larger than 50-60 nm in diameter can be grown, indicating that nanoparticles did not coalesce in the cooler flame. Raman spectroscopy showed that these nanoparticles were primarily magnetite, as opposed to the primarily hematite nanoparticles produced in the hot flame configuration. In order to understand the effect of additive loading on iron oxide nanoparticle morphology, an Ar stream carrying titanium-tetra-isopropoxide (TTIP) was flowed through the outer annulus along with the CH4 in the inverse diffusion flame configuration. When particles were synthesized in the presence of the TTIP additive, larger monodispersed individual particles (50-90 nm) were synthesized as observed by TEM. In this article, we show that iron oxide nanoparticles of varied morphology, composition, and size can be synthesized and controlled by varying flame configuration, flame temperature, and additive loading.

  4. Synthesis, characterization, and comparative gas-sensing properties of Fe2O3 prepared from Fe3O4 and Fe3O4-chitosan

    International Nuclear Information System (INIS)

    Highlights: ? We have demonstrated a facile method to prepare Fe3O4 nanoparticles and chitosan-coated Fe3O4 nanoparticles. ? ?-Fe2O3 sensors prepared from those Fe3O4 materials have been investigated and compared. ? The results show potential application of ?-Fe2O3 for CO sensors in environmental monitoring. - Abstract: In this paper, Fe3O4 and chitosan (CS)-coated Fe3O4 nanoparticles were synthesized via co-precipitation method and subsequent covalent binding of CS onto the surface for functionalization, respectively. Characterization of the crystal structures and morphologies of as-synthesized nanoparticles by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy demonstrated that Fe3O4 had a cubic spinal structure with irregular shapes and average diameters of 10–20 nm. The surface states and magnetic properties of Fe3O4-CS nanoparticles were characterized by Fourier transform infrared spectra and vibrating sample magnetometry. Results showed that Fe3O4-CS nanoparticles possessed super-paramagnetic properties, with saturated magnetization up to 60 emu/g. In addition, Fe3O4 and CS-coated Fe3O4 nanoparticles were used in the fabrication of ?-Fe2O3 based gas sensors. Gas sensing measurements revealed that the ?-Fe2O3 gas sensor prepared from Fe3O4-CS had a better response to H2, CO, C2H5OH, and NH3 compared with the device prepared from pristine Fe3O4. Furthermore, the ?-Fe2O3 sensor prepared from Fe3O4-CS nanoparticles exhibited the highest response to CO among the test gases, suggesting that it has great potential for practical applications in environmental monitoring.

  5. Dispersive Micro-Solid-Phase Extraction Based on Decanoic Acid Coated-Fe3 O4 Nanoparticles for HPLC Analysis of Phthalate Esters in Liquor Samples.

    Science.gov (United States)

    Wang, Juan; Zhang, Lei; Xin, Dingqiang; Yang, Yaling

    2015-11-01

    A novel, simple and low cost through coating Fe3 O4 magnetic nanoparticles (MNPs) with decanoic acid were synthesized. The functionalized MNPs showed excellent dispersibility in aqueous solution and were applied to dispersive micro-solid-phase extraction (D-?-SPE) followed by high performance liquid chromatographic analysis for 4 phthalate esters (PAEs) including benzyl butyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-n-butyl phthalate (DBP), and di-n-octyl phthalate (DNOP) from liquor samples. The extraction equilibrium is achieved in 1 min. The MNPs allow easy and rapid isolation of PAEs by using an external magnet, which can be reused 5 times. The 4 PAEs linear dynamic ranges were in the range of 5 to 1000 ng/mL and the correlation coefficients values were 0.9999. The limits of detection were in the range of 0.91 to 2.43 ng/mL. The influences of the adsorbent dosage and the use frequency of adsorbent, the adsorption time, the solution pH and ionic strength were investigated and optimized. The proposed method was used to determine of PAEs in liquor samples and recoveries between 88.9% and 105.4%, with the relative standard deviations were below 4.0%. PMID:26447907

  6. Fe3O4/TiO2 core/shell nanoparticles as affinity probes for the analysis of phosphopeptides using TiO2 surface-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Chen, Cheng-Tai; Chen, Yu-Chie

    2005-09-15

    Columns packed with microsized titanium dioxide particles have been used effectively as precolumns for enriching phosphopeptides from complex mixtures. Nanosized titanium dioxide particles have a higher specific surface area and, hence, potentially higher trapping capacities toward phosphopeptides than do microsized particles. Thus, in this study, we employed TiO2-coated magnetic (Fe3O4/TiO2 core/shell) nanoparticles to selectively concentrate phosphopeptides from protein digest products. Because of their magnetic properties, the Fe3O4/TiO2 core/shell nanoparticles that are conjugated to the target peptides can be isolated readily from the sample solutions by employing a magnetic field. In this paper, we also demonstrate that the Fe3O4/TiO2 core/shell nanoparticles behave as an effective SALDI matrix: our upper detectable mass limit was approximately 24 000 Da, whereas the detection limit for peptides was in the low-femtomole range. That is to say, the target analytes trapped by the Fe3O4/TiO2 nanoparticles can be identified by introducing the particles directly into the mass spectrometer for TiO2-SALDI-MS analysis without the need for any further treatment. For example, elution steps are not necessary when using this approach. In addition, the trapping selectivity of these Fe3O4/TiO2 nanoparticles toward phosphopeptides was quite good. These properties combine to result in the low detection limits. The lowest detectable concentration of phosphopeptides that we analyzed using this approach was 500 pM for a 100-microL tryptic digest solution of beta-casein; this level is much lower than that which can be obtained using any other currently available method. PMID:16159121

  7. Synthesis of Fe3O4/SiO2/Ag nanoparticles and its application in surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    To obtain a recyclable surface-enhanced Raman scattering (SERS) material, we developed a composite of Fe3O4/SiO2/Ag with core/shell/particles structure. The designed particles were synthesized via an ultrasonic route. The Raman scattering signal of Fe3O4 could be shielded by increasing the thickness of the SiO2 layer to 60 nm. Dye rhodamine B (RB) was chosen as probe molecule to test the SERS effect of the synthesized Fe3O4/SiO2/Ag particles. On the synthesized Fe3O4/SiO2/Ag particles, the characteristic Raman bands of RB could be observed when the RB solution was diluted to 5 ppm (1x10-5 M). Furthermore, the synthesized particles could keep their efficiency till four cycles. -- Graphical Abstract: Fe3O4/SiO2/Ag particles, a recyclable surface-enhanced Raman scattering (SERS) material, were designed and synthesized via a simple ultrasonic route. Display Omitted

  8. Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures : Topotaxial Oxidation of Fe1-xO|Fe3-?O4 Core|Shell Nanocubes to Single-Phase Particles

    OpenAIRE

    Wetterskog, Erik; Tai, Cheuk-Wai; Grins, Jekabs; Bergström, Lennart; Salazar-Alvarez, German

    2013-01-01

    Here we demonstrate that the anomalous magnetic properties of iron oxide nanoparticles are correlated with defects in their interior. We studied the evolution of microstructure and magnetic properties of biphasic core|shell Fe1–xO|Fe3??O4 nanoparticles synthesized by thermal decomposition during their topotaxial oxidation to single-phase nanoparticles. Geometric phase analysis of high-resolution electron microscopy images reveals a large interfacial strain at the core|shell interface and the ...

  9. Study of the intra-arterial distribution of Fe3O4 nanoparticles in a model of colorectal neoplasm induced in rat liver by MRI and spectrometry

    Directory of Open Access Journals (Sweden)

    Echevarria-Uraga JJ

    2012-05-01

    Full Text Available José J Echevarria-Uraga,1 Ignacio García-Alonso,2 Fernando Plazaola,3 Maite Insausti,3 Néstor Etxebarria,3 Alberto Saiz-López,4 Begoña Fernández-Ruanova51Radiology Department, Hospital de Galdakao-Usánsolo, Bizkaia, Spain; 2Experimental Surgery Laboratory, Medicine Faculty, University of the Basque Country, Bizkaia, Spain; 3Faculty of Science and Technology, University of the Basque Country, Bizkaia, Spain; 4Pathology Department, Hospital de Galdakao-Usánsolo, Bizkaia, Spain; 5Osatek SA Unidad del Hospital de Galdakao-Usánsolo, Bizkaia, SpainPurpose: To evaluate, in an experimental model, the reliability of MRI for determining whether a higher iron concentration was obtained in tumor tissue than in normal liver parenchyma after intra-arterial administration of Fe3O4 lipophilic nanoparticles.Materials and methods: WAG/RijCrl rats were inoculated in the left hepatic lobe with 25,000 syngeneic CC-531 colon adenocarcinoma cells, after which they were randomized into two groups: control (CG and infused (IG. After confirming tumor induction, the IG rats received intra-arterial suspensions of Fe3O4 nanoparticles (2.6 mg in Lipiodol® (0.15 mL. To calculate the iron concentration, [Fe], in the tumor and liver tissues of both groups of rats, measurements of signal intensity from the tumors, healthy liver tissue, and paravertebral muscles were made on a 1.5T MRI system in gradient-echo DP* and T2*-weighted sequences. In addition, samples were collected to quantify the [Fe] by inductively coupled plasma-mass spectrometry (ICP-MS, as well as for histological analysis. Statistical analysis was performed with non-parametric tests, and Bland–Altman plots were produced; P values <0.05 were considered significant.Results: In the CG rats (n = 23, the mean [Fe] values estimated by MRI and ICP-MS were 13.2 µmol • g-1 and 5.9 µmol • g-1, respectively, in the tumors, and 19.0 µmol • g-1 and 11.7 µmol • g-1, respectively, in the hepatic tissue. In the IG rats (n = 19, the values obtained by MRI and ICP-MS were 148.9 µmol • g-1 and 9.4 µmol • g-1, respectively, in the tumors, and 115.3 µmol • g-1 and 11.6 µmol • g-1, respectively, in the healthy liver tissue. The IG results revealed a clear disagreement between MRI and ICP-MS. In the comparative analysis between the groups regarding the [Fe] values obtained by ICP-MS, significant differences were found for the tumor samples (P < 0.001, but not for the hepatic tissue (P = 0.92. Under microscopy, scattered intravascular deposits of nanoparticles were observed, especially in the tumors.Conclusion: ICP-MS demonstrated significant uptake of exogenous iron in tumor tissue. MRI was useful for quantifying the [Fe] in the different tissues in the CG animals, but not in the IG animals. Although the irregular distribution of nanoparticles caused an important bias in the measurements obtained by MRI, the relative increase in iron content inside the tumor was suggested.Keywords: liver neoplasm, hepatic arterial infusion, ferromagnetic particle, iron concentration, MRI, spectrometry 

  10. Determination of triacetone triperoxide with a N,N-dimethyl-p-phenylenediamine sensor on nafion using Fe3O4 magnetic nanoparticles.

    Science.gov (United States)

    Can, Ziya; Üzer, Ay?em; Türkekul, Kader; Erça?, Erol; Apak, Re?at

    2015-10-01

    The explosive triacetone triperoxide (TATP) can be easily manufactured from readily accessible reagents and is extremely difficult to detect, owing to the lack of UV absorbance, fluorescence, or facile ionization. The developed method is based on the acidic hydrolysis of TATP into H2O2, pH adjustment to 3.6, and the addition of magnetite nanoparticles (Fe3O4 MNPs) to the medium to produce hydroxyl radicals from H2O2, owing to the peroxidase-like activity of MNPs. The formed radicals converted the N,N-dimethyl-p-phenylenediamine (DMPD) probe to the colored DMPD(+) radical cation, the optical absorbance of which was measured at a wavelength of 554 nm. The molar absorptivity (?) of the method for TATP was 21.06 × 10(3) L mol(-1) cm(-1). The colored DMPD(+) product in solution could be completely retained on a cation-exchanger Nafion membrane, constituting a colorimetric sensor for TATP and increasing the analytical sensitivity. The proposed method did not respond to a number of hand luggage items like detergent, sweetener, sugar, acetylsalicylic acid (aspirin), and paracetamol-caffeine-based analgesic drugs. On the other hand, TATP could be almost quantitatively recovered from a household detergent and sweetener that can be used as camouflage for the analyte. Neither common soil and groundwater ions (e.g., Ca(2+), Mg(2+), K(+), Cl(-), SO4(2-), and NO3(-)) at 100-fold ratios nor nitro-explosives of trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) at 10-fold amounts interfered with the proposed assay. The method was statistically validated against the standard GC/MS reference method. PMID:26356315

  11. Fe3O4 nanoparticle loaded paclitaxel induce multiple myeloma apoptosis by cell cycle arrest and increase cleavage of caspases in vitro

    International Nuclear Information System (INIS)

    Multiple myeloma (MM) still remains an incurable disease in spite of extending the patient survival by new therapies. The hypothesis of cancer stem cells (CSCs) states that although chemotherapy kills most tumor cells, it is believed to leave a reservoir of CSCs that allows the tumor cell propagation. The objective of this research was to evaluate the therapeutic effect of new paclitaxel-Fe3O4 nanoparticles (PTX-NPs) with an average size range of 7.17 ± 1.31 nm on MM CSCs in vitro. The characteristics of CD138?CD34? cells, isolated from human MM RPMI 8226 and NCI-H929 cell lines by the magnetic associated cell sorting method, were identified by the assays of colony formation, cell proliferation, drug resistance, cell migration, and tumorigenicity in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice, respectively. Inhibitory effects of PTX-NPs on CD138?CD34? cells were evaluated by a variety of assays in vitro. The results showed that the CD138?CD34? cells were capable of forming colonies, exhibited high proliferative and migratory ability, possessed a strong drug resistance, and had powerful tumorigenicity in NOD/SCID mice compared to non-CD138?CD34? cells. PTX-NPs significantly inhibited CD138? CD34? cell viability and invasive ability, and resulted in G0/G1 cell cycle arrest and apoptosis compared with PTX alone. We concluded that the CD138?CD34? phenotype cells might be CSCs in RPMI 8226 and NCI-H929 cell lines. PTX-NPs had an obvious inhibitory effect on MM CD138?CD34? CSCs. The findings may provide a guideline for PTX-NPs’ treatment of MM CSCs in preclinical investigation

  12. A highly efficient nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a solid acid catalyst for synthesis of 1,8-dioxo-octahydroxanthene derivatives

    International Nuclear Information System (INIS)

    The functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acid were afforded sulfonic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2–SO3H) that can be applied as an organic–inorganic hybrid heterogeneous catalyst. The used Fe3O4 magnetic nanoparticles are 18–30 nm sized that was rapidly functionalized and can be used as catalyst in organic synthesis. The prepared nanoparticles were characterized by X-ray diffraction analysis, magnetization curve, scanning electron microscope, dynamic laser scattering, and FT-IR measurements. The resulting immobilized catalysts have been successfully used in the synthesis of 1,8?dioxo-octahydroxanthene derivatives under solvent free condition. This procedure has many advantages such as; a much milder method, a shorter reaction time, a wide range of functional group tolerance, and absence of any tedious workup or purification. Other remarkable features include the catalyst can be reused at least five times without any obvious change in its catalytic activity. This procedure also avoids hazardous reagents/solvents, and thus can be an eco-friendly alternative to the existing methods.Graphical AbstractA highly efficient nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a solid acid catalyst for synthesis of 1,8-dioxo-octahydroxanthene derivatives

  13. Size-controlled synthesis of Fe2O3 and Fe3O4 nanoparticles onto zeolite by means of a modified activated-coprecipitation method: effect of the HCl concentration during the activation

    International Nuclear Information System (INIS)

    Synthetic sodium type A zeolite bearing Fe2O3 and Fe3O4 nanoparticles composites have been prepared by means of a coprecipitation method with two different activation methodologies, one using Sn and the other using Sn/Pd nanoparticles as activators. Sn activation generates hematite nanoparticles while Sn/Pd produces magnetite nanoparticles. Amount of HCl used during the activation of the zeolite with SnCl2 showed a correlation between the stannous activating species and the particle size. Both Sn and Sn–Pd activated nanocomposites show nearly narrow size distributions but only those iron oxides obtained with Sn–Pd showed supermagnetism.

  14. One-step synthesis of silica-coated magnetite nanoparticles by electrooxidation of iron in sodium silicate solution

    International Nuclear Information System (INIS)

    Silica-coated magnetite nanoparticles have been synthesized successfully using a one-step electrochemical method. In this method, pure iron in a dilute aqueous sodium silicate solution that served as a silica precursor was electrooxidized. We show that the presence of silicate can significantly enhance the purity of the magnetite formed. Impurities in the form of FeOOH (found in the magnetite prepared in water) are not found. The magnetite nanoparticles produced by this method are nearly spherical with a mean size ranging from 6 to 10 nm, which is lower than the size of particles prepared in water, and this size range depends on the applied voltage and the sodium silicate concentration. The magnetite nanoparticles exhibit superparamagnetic properties with saturation magnetization ranging from 15 to 22 emu g?1, which is lower than the saturation magnetization of the Fe3O4 bulk materials (Ms = 92 emu g?1). This facile method appears to be promising as a synthetic route for producing silica-coated magnetite nanoparticles.

  15. Fabrication and characterization of superparamagnetic and thermoresponsive hydrogels based on oleic-acid-coated Fe3O4 nanoparticles, hexa(ethylene glycol) methyl ether methacrylate and 2-(acetoacetoxy)ethyl methacrylate

    International Nuclear Information System (INIS)

    Stimuli-responsive hydrogel nanocomposites comprised of swollen polymer networks, in which magnetic nanoparticles are embedded, are a relatively new class of 'smart' soft materials presenting a significant impact on various technological and biomedical applications. A novel approach for the fabrication of hydrogel nanocomposites exhibiting temperature- and magneto-responsive behavior involves the random copolymerization of hexa(ethylene glycol) methyl ether methacrylate (HEGMA, hydrophilic, thermoresponsive) and 2-(acetoacetoxy)ethyl methacrylate (AEMA, hydrophobic, metal-chelating) in the presence of preformed oleic-acid-coated magnetite nanoparticles (OA.Fe3O4). In total, two series of hydrogel nanocomposites have been prepared in two different solvent systems: ethyl acetate (series A) and tetrahydrofuran (series B). The degrees of swelling (DSs) of all conetworks were determined in organic and in aqueous media. The nanocrystalline phase adopted by the embedded magnetic nanoparticles was investigated by X-ray diffraction (XRD) spectroscopy. The obtained diffraction patterns indicated the presence of magnetite (Fe3O4). Deswelling kinetic studies that were carried out at ?60 oC in water demonstrated the thermoresponsive properties of the hydrogel nanocomposites, attributed to the presence of the hexaethylene glycol side chains within the conetworks. Moreover, thermal gravimetric analysis (TGA) measurements showed that these materials exhibited superior thermal stability compared to the pristine hydrogels. Further to the characterization of compositional and thermal properties, the assessment of magnetic characteristics by vibrational sample magnetometry (VSM) disclosed superparamagnetic behavior. The tunable superparamagnetic behavior exhibited by these materials depending on the amount of magnetic nanoparticles incorporated within the networks combined with their thermoresponsive properties may allow for their future exploitation in the biomedical field. - Research Highlights: ? Fabrication of novel, dual stimuli-responsive conetworks based on hexa(ethylene glycol) methyl ether methacrylate (HEGMA, hydrophilic, thermoresponsive), 2-(acetoacetoxy)ethyl methacrylate (AEMA, hydrophobic, metal-chelating) and oleic-acid-coated magnetite nanoparticles (OA.Fe3O4). ? Tuneable superparamagnetic behavior. ? Thermoresponsive properties.

  16. Core-Shell Nanostructure of ?-Fe2O3/Fe3O4: Synthesis and Photocatalysis for Methyl Orange

    OpenAIRE

    Yang Tian; Di Wu; Xiao Jia; Binbin Yu; Sihui Zhan

    2011-01-01

    Fe3O4 nanoparticle was synthesized in the solution involving water and ethanol. Then, ?-Fe2O3 shell was produced in situ on the surface of the Fe3O4 nanoparticle by surface oxidation in molten salts, forming ?-Fe2O3/Fe3O4 core-shell nanostructure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe3O4 nanoparticles were oxidized. Furthermore, the obtained ?-Fe2O3/Fe3O4 core-shell nanoparticles were used to ...

  17. Preparation of Fe3O4Spherical Nanoporous Particles Facilitated by Polyethylene Glycol 4000

    OpenAIRE

    Wang Li-Li; Jiang Ji-Sen

    2009-01-01

    Abstract Much interest has been attracted to the magnetic materials with porous structure because of their unique properties and potential applications. In this report, Fe3O4nanoporous particles assembled from small Fe3O4nanoparticles have been prepared by thermal decomposition of iron acetylacetonate in the presence of polyethylene glycol 4000. The size of the spherical nanoporous particles is 100–200 nm. Surface area measurement shows that these Fe3O4nanoporous particles have a high s...

  18. Cellular biosensor based on red blood cells immobilized on Fe3O4 Core/Au Shell nanoparticles for hydrogen peroxide electroanalysis

    International Nuclear Information System (INIS)

    A core/shell Fe3O4/gold nanocomposite was prepared for immobilizing of red blood cells on a gold electrode via conjugation to a cysteamine monolayer. The hemoglobin in the film undergoes direct electron transfer at a formal potential of -330 mV and displays excellent electrocatalytic response to hydrogen peroxide, with a linear range from 9. 6 ?M to 2. 6 mM. The limit of detection is 4. 4 ?M (S/N = 3). The Michaelis-Menten constant is 120 ?M. Owing to its good biocompatibility, the biosensor exhibits good stability and acceptable reproducibility. The nanocomposite film provided a good matrix for the immobilization of cells and for the preparation of cellular biosensors. (author)

  19. Confined nanospace pyrolysis for the fabrication of coaxial Fe3O4@C hollow particles with a penetrated mesochannel as a superior anode for Li-ion batteries.

    Science.gov (United States)

    Lei, Cheng; Han, Fei; Sun, Qiang; Li, Wen-Cui; Lu, An-Hui

    2014-01-01

    In this study, a method is developed to fabricate Fe3O4@C particles with a coaxial and penetrated hollow mesochannel based on the concept of "confined nanospace pyrolysis". The synthesis involves the production of a polydopamine coating followed by a silica coating on a rod-shaped ?-FeOOH nanoparticle, and subsequent treatment by using confined nanospace pyrolysis and silica removal procedures. Typical coaxial hollow Fe3O4@C possesses a rice-grain morphology and mesoporous structure with a large specific surface area, as well as a continuous and flexible carbon shell. Electrochemical tests reveal that the hollow Fe3O4@C with an open-ended nanostructure delivers a high specific capacity (ca. 864 mA h g(-1) at 1 A g(-1)), excellent rate capability with a capacity of about 582 mA h g(-1) at 2 A g(-1), and a high Coulombic efficiency (>97%). The excellent electrochemical performance benefits from the hollow cavity with an inner diameter of 18 nm and a flexible carbon shell that can accommodate the volume change of the Fe3O4 during the lithium insertion/extraction processes as well as the large specific surface area and open inner cavity to facilitate the rapid diffusion of lithium ions from electrolyte to active material. This fabrication strategy can be used to generate a hollow or porous metal oxide structure for high-performance Li-ion batteries. PMID:24273057

  20. A novel H2O2 biosensor based on Fe3O4–Au magnetic nanoparticles coated horseradish peroxidase and graphene sheets–Nafion film modified screen-printed carbon electrode

    International Nuclear Information System (INIS)

    A disposable biosensor for determination of hydrogen peroxide (H2O2) based on Fe3O4–Au magnetic nanoparticles coated horseradish peroxidase (HRP) and graphene sheets (GS)–Nafion film modified screen-printed carbon electrode (SPCE) was fabricated. To construct the H2O2 biosensor, GS–Nafion solution was first dropped onto the surface of SPCE. Subsequently, the biocomposites of Fe3O4–Au magnetic nanoparticles coated HRP were adsorbed on the surface with the aid of an external magnetic field to fabricate the SPCE|GS–Nafion/Fe3O4–Au-HRP electrode. X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry(i–t curve) were employed to study the synthesis of GS, the construction processes and electrochemical properties of the biosensor. Under optimized experimental conditions, CV demonstrated that the direct electron transfer (DET) of HRP was realized. The biosensor had an excellent performance in terms of electrocatalytic reduction toward H2O2. The linear response of the biosensor to H2O2 was in the concentration range of 2.0 × 10?5 mol/L to 2.5 × 10?3 mol/L (R = 0.9994) with a detection limit of 1.2 × 10?5 mol/L (S/N = 3). The proposed electrochemical biosensor was sensitive, rapid, disposable with low cost, fewer sample volume, easy preparation and strong anti-interference, which showed great promise for screen-determination of trace H2O2 in real samples

  1. Surfactant-assisted synthesis of Fe2O3 nanoparticles and F-doped carbon modification toward an improved Fe3O4@CFx/LiNi0.5Mn1.5O4 battery.

    Science.gov (United States)

    Ming, Hai; Ming, Jun; Oh, Seung-Min; Tian, Shu; Zhou, Qun; Huang, Hui; Sun, Yang-Kook; Zheng, Junwei

    2014-09-10

    A simple surfactant-assisted reflux method was used in this study for the synthesis of cocklebur-shaped Fe2O3 nanoparticles (NPs). With this strategy, a series of nanostructured Fe2O3 NPs with a size distribution ranging from 20 to 120 nm and a tunable surface area were readily controlled by varying reflux temperature and the type of surfactant. Surfactants such as cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (F127) and sodium dodecyl benzenesulfonate (SDBS) were used to achieve large-scale synthesis of uniform Fe2O3 NPs with a relatively low cost. A new composite of Fe3O4@CFx was prepared by coating the primary Fe2O3 NPs with a layer of F-doped carbon (CFx) with a one-step carbonization process. The Fe3O4@CFx composite was utilized as the anode in a lithium ion battery and exhibited a high reversible capacity of 900 mAh g(-1) at a current density of 100 mA g(-1) over 100 cycles with 95% capacity retention. In addition, a new Fe3O4@CFx/LiNi(0.5)Mn(1.5)O4 battery with a high energy density of 371 Wh kg(-1) (vs cathode) was successfully assembled, and more than 300 cycles were easily completed with 66.8% capacity retention at 100 mA g(-1). Even cycled at the high temperature of 45 °C, this full cell also exhibited a relatively high capacity of 91.6 mAh g(-1) (vs cathode) at 100 mA g(-1) and retained 54.6% of its reversible capacity over 50 cycles. Introducing CFx chemicals to modify metal oxide anodes and/or any other cathode is of great interest for advanced energy storage and conversion devices. PMID:25141154

  2. Preparation and characterization of a magneto-polymeric nanocomposite: Fe 3O 4 nanoparticles in a grafted, cross-linked and plasticized poly(vinyl chloride) matrix

    Science.gov (United States)

    Rodríguez-Fernández, Oliverio S.; Rodríguez-Calzadíaz, C. A.; Yáñez-Flores, Isaura G.; Montemayor, Sagrario M.

    In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) "plastic films" and (2) magnetic plastic films "magneto-polymeric nanocomposites" were prepared. Precursor solutions or "plastisols" used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect of the cross-linking agent and their content on the degree of cross-linking. The magneto-polymeric nanocomposites were obtained by mixing the optimum composition of the plastisols (analyzed previously) with magnetite (Fe 3O 4)-based ferrofluid and DOP. Later, flexible films were obtained by static casting of the plastisol/ferrofluid systems. The magnetic films were characterized by the above-mentioned techniques and X-ray diffraction, vibrating sample magnetometry and thermogravimetrical analysis.

  3. Preparation and characterization of a magneto-polymeric nanocomposite: Fe3O4 nanoparticles in a grafted, cross-linked and plasticized poly(vinyl chloride) matrix

    International Nuclear Information System (INIS)

    In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) 'plastic films' and (2) magnetic plastic films 'magneto-polymeric nanocomposites' were prepared. Precursor solutions or 'plastisols' used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect of the cross-linking agent and their content on the degree of cross-linking. The magneto-polymeric nanocomposites were obtained by mixing the optimum composition of the plastisols (analyzed previously) with magnetite (Fe3O4)-based ferrofluid and DOP. Later, flexible films were obtained by static casting of the plastisol/ferrofluid systems. The magnetic films were characterized by the above-mentioned techniques and X-ray diffraction, vibrating sample magnetometry and thermogravimetrical analysis

  4. Maximizing surface-enhanced Raman scattering sensitivity of surfactant-free Ag-Fe3O4 nanocomposites through optimization of silver nanoparticle density and magnetic self-assembly

    Science.gov (United States)

    Bao, Zhi Yong; Dai, Jiyan; Yuan Lei, Dang; Wu, Yucheng

    2013-09-01

    Magnetic composite nanomaterials consisting of more than two functional constituents have been attracting much research interests due to the realization of multiple functionalities in a single entity. In particular, integration of ferromagnetic oxides and noble metal nanoparticles (NPs) in composites results in simultaneous magnetic activity and optical response where the optical property of the whole system could be modulated by application of an external magnetic field. In this work, we prepared Ag NPs-coated Fe3O4 microspheres as a novel surfactant-free surface-enhanced Raman scattering (SERS) substrate through a solid-phase thermal decomposition reaction. The SERS sensitivity of the fabricated nanocomposites is maximized by adjusting the size and density of Ag NPs supported on the Fe3O4 microspheres and further increased by magnetic-field-directed self-assembly of the composite substrates, with both effects attributed to the efficient generation of plasmonic near-field "hot" spots. At the optimal conditions, the prepared substrate is capable of detecting rhodamine 6G molecules at a concentration down to 10-12 M, thus demonstrating the great potential of using bifunctional nanocomposites as an excellent candidate for ultra-high sensitive Raman spectroscopy and biosensors. We also reveal the underlying mechanisms responsible for the observed SERS enhancements through full-wave numerical simulations.

  5. Core-Shell Nanostructure of ?-Fe2O3/Fe3O4: Synthesis and Photocatalysis for Methyl Orange

    Directory of Open Access Journals (Sweden)

    Yang Tian

    2011-01-01

    Full Text Available Fe3O4 nanoparticle was synthesized in the solution involving water and ethanol. Then, ?-Fe2O3 shell was produced in situ on the surface of the Fe3O4 nanoparticle by surface oxidation in molten salts, forming ?-Fe2O3/Fe3O4 core-shell nanostructure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe3O4 nanoparticles were oxidized. Furthermore, the obtained ?-Fe2O3/Fe3O4 core-shell nanoparticles were used to photocatalyse solution of methyl orange, and the results revealed that ?-Fe2O3/Fe3O4 nanoparticles were more efficient than the self-prepared ?-Fe2O3 nanoparticles. At the same time, the photocatalyzer was recyclable by applying an appropriate magnetic field.

  6. Double-Layer Magnetic Nanoparticle-Embedded Silica Particles for Efficient Bio-Separation

    Science.gov (United States)

    Kang, Homan; Cho, Hong-Jun; Park, Sung-Jun; Yang, Jin-Kyoung; Kim, Sehoon; Kim, Hyung-Mo; Jun, Bong-Hyun; Lee, Yoon-Sik

    2015-01-01

    Superparamagnetic Fe3O4 nanoparticles (NPs) based nanomaterials have been exploited in various biotechnology fields including biomolecule separation. However, slow accumulation of Fe3O4 NPs by magnets may limit broad applications of Fe3O4 NP-based nanomaterials. In this study, we report fabrication of Fe3O4 NPs double-layered silica nanoparticles (DL MNPs) with a silica core and highly packed Fe3O4 NPs layers. The DL MNPs had a superparamagnetic property and efficient accumulation kinetics under an external magnetic field. Moreover, the magnetic field-exposed DL MNPs show quantitative accumulation, whereas Fe3O4 NPs single-layered silica nanoparticles (SL MNPs) and silica-coated Fe3O4 NPs produced a saturated plateau under full recovery of the NPs. DL MNPs are promising nanomaterials with great potential to separate and analyze biomolecules. PMID:26599084

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

    Science.gov (United States)

    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 (?'', ?', ?'' and ?') 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 (R4 GHz).

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

    International Nuclear Information System (INIS)

    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 (?-prime, ?', ?-prime and ?') 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 (R4 GHz)

  9. Sandwich-Structured Graphene-Fe3O4@Carbon Nanocomposites for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Zhao, Li; Gao, Miaomiao; Yue, Wenbo; Jiang, Yang; Wang, Yuan; Ren, Yu; Hu, Fengqin

    2015-05-13

    Advanced anode materials for high power and high energy lithium-ion batteries have attracted great interest due to the increasing demand for energy conversion and storage devices. Metal oxides (e.g., Fe3O4) usually possess high theoretical capacities, but poor electrochemical performances owing to their severe volume change and poor electronic conductivity during cycles. In this work, we develop a self-assembly approach for the synthesis of sandwich-structured graphene-Fe3O4@carbon composite, in which Fe3O4 nanoparticles with carbon layers are immobilized between the layers of graphene nanosheets. Compared to Fe3O4@carbon and bulk Fe3O4, graphene-Fe3O4@carbon composite shows superior electrochemical performance, including higher reversible capacity, better cycle and rate performances, which may be attributed to the sandwich structure of the composite, the nanosized Fe3O4, and the carbon layers on the surface of Fe3O4. Moreover, compared to the reported graphene-Fe3O4 composite, the particle size of Fe3O4 is controllable and the content of Fe3O4 in this composite can be arbitrarily adjusted for optimal performance. This novel synthesis strategy may be employed in other sandwich-structured nanocomposites design for high-performance lithium-ion batteries and other electrochemical devices. PMID:25886399

  10. Hollow Fe3O4 microspheres as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    In this study, we proposed a unique method for hollow Fe3O4 microspheres and confirmed their electrochemical properties as anode materials for lithium-ion batteries. Poly(MAA/EGDMA)/Fe3O4 core–shell microspheres were prepared by simple ionic attraction between hydrogel microspheres with negative charge and magnetic Fe3O4 nanoparticles under alkaline conditions. The poly(MAA/EGDMA) core spheres were removed by heat treatment in order to form the hollow structure of Fe3O4 microspheres. Their hollow structure prevents cracking of the electrode during the volume change of repetitive Li-ion insertion and extraction reactions and improves the Li-ion transfer during cycling. The morphologies and structure of the hollow Fe3O4 microspheres were confirmed by scanning electron microscopy, focused ion beam-scanning electron microscopy, transmission electron microscopy, optical microscopy and X-ray diffraction. The electrochemical performance of the composite electrode was evaluated by constant current charging and discharging, cyclic voltammetry and cycling performance at various cycling rates. The results showed excellent cycle stability compared with a composite electrode containing bare Fe3O4 nanoparticles. These results indicate that the unique structures of Fe3O4 microspheres contribute to the excellent life and high reversible capacity of the battery when they are used as an anode of a lithium-ion battery.

  11. A survey of approaches for morphological, optical, and transport characterization of Fe3O4 and ?-Fe2O3 nanoparticles

    International Nuclear Information System (INIS)

    Nanoparticles’ structure, size, morphology, and surface conditions have significant influence on their performance and considerable impact on their application in biosystems. In this study some methods of nanoparticle analysis including structural x-ray diffraction, scanning electron and transmission electron microscopy size distribution and morphology characterization, superconducting quantum interference device and Faraday method magnetic and temperature dependence of specific resistance measurements, infrared spectroscopy, and laser light scattering based estimation of particle size distribution are surveyed. These methods illustrate the importance of a versatile approach to nanoparticle characterization, as the basis for their selection for particular applications. Since the methods of synthesis crucially affect the nanoparticle characteristics, the presented characterization techniques could also help to choose the most appropriate one. (paper)

  12. A survey of approaches for morphological, optical, and transport characterization of Fe3O4 and ?-Fe2O3 nanoparticles

    Science.gov (United States)

    Mamula Tartalja, Danica; Sre?kovi?, Milesa

    2014-09-01

    Nanoparticles’ structure, size, morphology, and surface conditions have significant influence on their performance and considerable impact on their application in biosystems. In this study some methods of nanoparticle analysis including structural x-ray diffraction, scanning electron and transmission electron microscopy size distribution and morphology characterization, superconducting quantum interference device and Faraday method magnetic and temperature dependence of specific resistance measurements, infrared spectroscopy, and laser light scattering based estimation of particle size distribution are surveyed. These methods illustrate the importance of a versatile approach to nanoparticle characterization, as the basis for their selection for particular applications. Since the methods of synthesis crucially affect the nanoparticle characteristics, the presented characterization techniques could also help to choose the most appropriate one.

  13. NOVEL SYNTHESIS OF PEG COATED IRON NANOPARTICLES (Fe3O4 AND IT’S EVALUATION OF CONTROLLED RELEASE KINETICS IN DRUG DELIVERY SYSTEM

    Directory of Open Access Journals (Sweden)

    Doppalapudi Swathi

    2014-06-01

    Full Text Available Magnetic Nanoparticles (MNPs because of their high magnetic responsiveness, biodegradability, high delivery efficiency and potential targeting function is a possible material as drug delivery system, since drug –loaded MNPs can be directly injected in to solid tumors and are expected to be held in place by an external magnetic field and to release the drug in a controlled manner. In the present research study Synthesis, Characterization and in vitro rate studies of super paramagnetic Iron Nanoparticles coated with PEG has been carried out. The nanoparticle synthesized in the present study had an average particle size of ~ 30 nm. starch-based polysaccharide nanocarrier encapsulated with the drug i.e. THC and MNPs as anticancer drug delivery was constructed. This efficiently reduces tumor growth thus providing a proof of concept for the utilization of this formulation in cannabinoid-based anti-cancer therapies. Evaluation of THC loaded magnetic nanoparticles was successfully carried out and correlation coefficient (R2 value 0.999 and drug released was found to be 97% for 48hrs at pH7.0. The entrapment efficiency and drug loading of THC-MNPs in the starch based nanoparticles was found to be high.

  14. Acute Phase Pulmonary Responses to a Single Intratracheal Spray Instillation of Magnetite (Fe3O4) Nanoparticles in Fischer 344 Rats

    OpenAIRE

    Tada, Yukie; Yano, Norio; Takahashi, Hiroshi; Yuzawa, Katsuhiro; Ando, Hiroshi; Kubo, Yoshikazu; Nagasawa, Akemichi; Ogata, Akio; Nakae, Dai

    2012-01-01

    Iron nanomaterials are of considerable interest for application to nanotechnology-related fields including environmental catalysis, biomedical imaging, drug delivery and hyperthermia, because of their superparamagnetic characteristics and high catalytic abilities. However, information about potential risks of iron nanomaterials is limited. The present study assessed pulmonary responses to a single intratracheal spray instillation of triiron tetraoxide nanoparticles (magnetite) ...

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

    Science.gov (United States)

    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

  16. Calcein-functionalized Fe3O4-SiO2 nanoparticles as a reusable fluorescent nanoprobe for copper(II) ion

    International Nuclear Information System (INIS)

    Calcein was first covalently grafted onto the surface of magnetic silica nanoparticles to obtain a novel fluorescent nanoprobe for sensitive and selective determination of Cu(II) ion. The nanoparticles were synthesized in a two-step reaction under mild conditions and characterized using small-angle X-ray scattering, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The nanoprobe also displays good selectivity over other metal ions and is highly stable under conditions of high ionic strength. The response to Cu(II) ranges from 80 nM to 1.25 ?M. The detection limit (LOD) is 43 nM which is lower than previously reported LODs. The probe can be regenerated by adding the complexing agent EDTA and also can be separated from a sample mixture by applying a magnetic field. We conclude that this method represents a new and convenient approach to the development of magnetic and reusable optical probes. (author)

  17. The investigation of electrochemical properties for Fe3O4@Pt nanocomposites and an enhancement sensing for nitrite

    International Nuclear Information System (INIS)

    Highlights: •Electrochemical characteristics on nanoparticles and nanocomposites were compared. •The reasons for superior electrochemical activity of Fe3O4@Pt were discussed. •We report an excellent nitrite biosensor based on Fe3O4@Pt. •Electro-analytical parameters of nitrite at Fe3O4@Pt were evaluated in detail. -- Abstract: The electrochemical differences (such as charge transfer resistivity, electroactive surface, standard electron transfer rate constant, adsorption amount and analytical performance of nitrite sensor) between Fe3O4@Pt nanocomposites with two elements and core–shell structure and NPs (Fe3O4 nanoparticles and Pt nanoparticles) with single component and simple structure were investigated in detail. Above those investigations, it is believed that for the Fe3O4@Pt core–shell nanocomposites, Pt shell could provide more electro-catalytic activity while magnetic Fe3O4 core could provide larger surface area and facilitate the purification of nanocomposites. After that, Fe3O4@Pt nanocomposites modified GCE served as a nitrite sensor. Electrochemical parameters of nitrite at Fe3O4@Pt nanocomposites such as electron transfer number, electron transfer coefficient, standard heterogeneous rate constant and electron diffusion coefficient were evaluated. With the proposed electrochemical sensors, nitrite in tap water and orange juice could be detected. This investigation suggested that core–shell nanocomposites were superior for the fabrication of electrochemical sensors

  18. Development of a silica monolith modified with Fe3O4 nano-particles in centrifugal spin column format for the extraction of phosphorylated compounds.

    Science.gov (United States)

    Alwy, Ali; Clarke, Sarah P; Brougham, Dermot F; Twamley, Brendan; Paull, Brett; White, Blánaid; Connolly, Damian

    2015-01-01

    In this study, citrate-stabilised iron oxide nano-particles (?16 nm) have been immobilised on commercial silica monolithic centrifugal spin columns (MonoSpin) for the extraction of phosphorylated compounds. Two alternative strategies were adopted involving either direct electrostatic attachment to an aminated MonoSpin (single-layer method) in the first instance, or the use of a layer-by-layer method with poly(diallyldimethylammonium) chloride. Field-emission scanning electron spectroscopy and energy-dispersive X-ray spectroscopy was used for confirming notably higher coverage of nano-particles using the layer-by-layer method (2.49 ± 0.53 wt%) compared with the single-layer method (0.43 ± 0.30 wt%). The modified monolith was used for the selective separation/extraction of adenosine monophosphate, adenosine diphosphate and adenosine triphosphate with elution using a phosphate buffer. A reversed-phase liquid chromatographic assay was used for confirming that adenosine, as a non-phosphorylated control was not retained on the modified MonoSpin devices, whereas recovery of 80% for adenosine monophosphate, 86% for adenosine diphosphate and 82% for adenosine triphosphate was achieved. PMID:25376605

  19. Construction of a sensitive and selective sensor for morphine using chitosan coated Fe3O4 magnetic nanoparticle as a modifier.

    Science.gov (United States)

    Dehdashtian, Sara; Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Kariminia, Samira

    2016-01-01

    A simple and sensitive sensor based on carbon paste electrode (CPE) modified by chitosan-coated magnetic nanoparticle (CMNP) was developed for the electrochemical determination of morphine (MO). The proposed sensor was characterized with scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrooxidation of MO was studied on modified carbon paste electrode using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. The oxidation peak potential of morphine on the CMNP/CPE appeared at 380mV which was accompanied with smaller overpotential and increase in oxidation peak current compared to that obtained on the bare carbon paste electrode (CPE). Under optimum conditions the sensor provides two linear DPV responses in the range of 10-2000nM and 2-720?M for MO with a detection limit of 3nM. The proposed sensor was successfully applied for monitoring of MO in serum and urine samples and satisfactory results were obtained. PMID:26478286

  20. Removal of Cr(VIin water by Fe3O4/IP6

    Directory of Open Access Journals (Sweden)

    CHEN Lu

    2014-12-01

    Full Text Available The preparation of functional ferroferric oxide (Fe3O4 magnetic nanoparticles is widely concerned.However,during their preparation,it is difficult to control the morphology of Fe3O4 nanoparticles and also a serious agglomeration exists,greatly restricting their applications.In present paper,an economical and ?green? reagent-phytic acid (IP6 can form micelle in the water and then the nanoparticles can grow in a soft template.The as-prepared Fe3O4/IP6 exhibited a good stability and high dispersion.Fe3O4/IP6 can chelate with Cr (VI due to its phosphate structure.The Fe3O4/IP6 chelated with Cr (VI can be removed conveniently from water using an external magnet.Fe3O4/IP6 nanocomposites have a good adsorption capacity to Cr (VI within a short time (10 min.Additionally,the effect of pH on adsorption efficiency was studied.

  1. Fast identification of lipase inhibitors in oolong tea by using lipase functionalised Fe3O4 magnetic nanoparticles coupled with UPLC-MS/MS.

    Science.gov (United States)

    Zhu, Yuan-Ting; Ren, Xiao-Yun; Yuan, Li; Liu, Yi-Ming; Liang, Jian; Liao, Xun

    2015-04-15

    Oolong tea is an important member in tea family, which claims for various health benefits such as preventing obesity and improving lipid metabolism. In this work, using pancreatic lipase (PL) functionalised magnetic nanoparticles (PL-MNPs) as solid phase extraction absorbent in combination with ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS), we developed a method for rapid screening and identification of lipase inhibitors from oolong tea. Three PL ligands were selectively extracted and identified as (-)-epigallocatechin-3-O-gallate (EGCG), (-)-gallocatechin-3-O-gallate (GCG) and (-)-epicatechin-3-O-gallate (ECG). Their lipase inhibitory activities were significantly higher than those non-ligands. Structure-activity analysis revealed that the presence of a galloyl moiety in the structure was required for binding to PL-MNPs, and therefore, exhibiting a strong inhibition on the enzyme. Taking advantages of the specificity in enzyme binding and the convenience of magnetic separation, this method has great potential for fast screening of lipase inhibitors from natural resources. PMID:25466054

  2. Catalysis of Rice Straw Hydrolysis by the Combination of Immobilized Cellulase from Aspergillus niger on ?-Cyclodextrin-Fe3O4 Nanoparticles and Ionic Liquid

    Science.gov (United States)

    Huang, Po-Jung; Chang, Ken-Lin; Chen, Shui-Tein

    2015-01-01

    Cellulase from Aspergillus niger was immobilized onto ?-cyclodextrin-conjugated magnetic particles by silanization and reductive amidation. The immobilized cellulase gained supermagnetism due to the magnetic nanoparticles. Ninety percent of cellulase was immobilized, but the activity of immobilized cellulase decreased by 10%. In this study, ionic liquid (1-butyl-3-methylimidazolium chloride) was introduced into the hydrolytic process because the original reaction was a solid-solid reaction. The activity of immobilized cellulase was improved from 54.87 to 59.11?U?g immobilized cellulase?1 at an ionic liquid concentration of 200?mM. Using immobilized cellulase and ionic liquid in the hydrolysis of rice straw, the initial reaction rate was increased from 1.629 to 2.739?g?h?1?L?1. One of the advantages of immobilized cellulase is high reusability—it was usable for a total of 16 times in this study. Compared with free cellulase, magnetized cellulase can be recycled by magnetic field and the activity of immobilized cellulase was shown to remain at 85% of free cellulase without denaturation under a high concentration of glucose (15?g?L?1). Therefore, immobilized cellulase can hydrolyze rice straw continuously compared with free cellulase. The amount of harvested glucose can be up to twentyfold higher than that from the hydrolysis by free cellulase. PMID:25874210

  3. Supercritical fluid mediated synthesis of poly(2-hydroxyethyl methacrylate)/Fe3O4 hybrid nanocomposite

    International Nuclear Information System (INIS)

    Graphical abstract: We successfully developed an easier and more effective method to prepare a magnetic polymer nanocomposite by in situ radical polymerization of 2-hydroxyethyl methacrylate in the presence of the surface-modified Fe3O4 nanoparticles with a coupling agent in supercritical CO2. FE-TEM pictures showed that the nanoparticles were well dispersed in the polymer matrix. The incorporation of Fe3O4 in the nanocomposite was confirmed by FT-IR, XRD and XPS. Thermal stability and magnetic property increase with the increasing amount of Fe3O4 nanoparticles in the composite. This new environmentally benign green synthetic route may offer advantages of easy separation and solvent removal. Highlights: ? A magnetic polymer nanocomposite (Fe3O4-g-PHEMA) was successfully synthesized via in-situ dispersion polymerization in supercritical carbon dioxide. ? The Fe3O4 nanoparticles were well dispersed in the polymer matrix. ? The resulting nanocomposites have an excellent superparamagnetic property, which is favorable for their bio-applications. ? This new environmentally benign green synthetic route offers advantages of avoiding the use of organic solvents as well as easy separation of solvent. - Abstract: Poly(2-hydroxyethyl methacrylate) (PHEMA) and magnetic nanoparticle (Fe3O4) hybrid nanocomposite was synthesized by dispersion polymerization in supercritical carbon dioxide (scCO2) using a copolymeric stabilizer, poly[(2-dimethylamino)ethyl methacrylate-co-1H,1H-perfluorooctyl methacrylate] (PDMAEMA-co-PFOMA). Fe3O4 nanoparticles were first surface-modified with a silane coupling agent methacryloxypropyltrimethoxysilane (MPTMS), which provides a reactive C=C bond and can copolymerize with 2-hydroxyethyl methacrylate (HEMA). After immobilization of the silane coupling agent, polymer chains were successfully grafted onto the surface of Fe3O4, resulting in the formation of core-shell nanostructure. FE-TEM pictures showed that the nanoparticles were well dispersed in the polymer matrix. The incorporation of Fe3O4 in the nanocomposite was confirmed by FT-IR, XRD and XPS. Thermal stability and magnetic property increase with the increasing amount of Fe3O4 nanoparticles in the composite. This new environmentally benign green synthetic route may offer advantages of easy separation and solvent removal.

  4. Large scale growth and magnetic properties of Fe and Fe3O4 nanowires

    International Nuclear Information System (INIS)

    Fe and Fe3O4 nanowires have been synthesized by thermal decomposition of Fe(CO)5, followed by heat treatments. The Fe wires are formed through the aggregation of nanoparticles generated by decomposition of Fe(CO)5. A core-shell structure with an iron oxide shell and Fe core is observed for the as-prepared Fe wires. Annealing in air leads to the formation of Fe2O3/Fe3O4 wires, which after heat treatment in a N2/alcohol atmosphere form Fe3O4 wires with a sharp Verwey [Nature (London) 144, 327 (1939)] transition at 125 K. The Fe3O4 wires have coercivities of 261 and 735 Oe along the wire axis at RT and 5 K, respectively. The large increase of coercivity at 5 K as compared to RT is due to the increase of anisotropy resulting from the Verwey transition

  5. Polythiophene-coated Fe3O4 nanoparticles as a selective adsorbent for magnetic solid-phase extraction of silver(I), gold(III), copper(II) and palladium(II)

    International Nuclear Information System (INIS)

    We have developed a fast method for sensitive extraction and determination of the metal ions silver(I), gold(III), copper(II) and palladium(II). Fe3O4 magnetic nanoparticles were modified with polythiophene and used for extraction the metal ions without a chelating agent. Following extraction, the ions were determined by flow injection inductively coupled plasma optical emission spectrometry. The influence of sample pH, type and volume of eluent, amount of adsorbent, sample volume and time of adsorption and desorption were optimized. Under the optimum conditions, the calibration plots are linear in the 0.75 to 100 ?g L?1 concentration range (R2?>?0.998), limits of detection in the range from 0.2 to 2.0 ?g L?1, and enhancement factors in the range from 70 to 129. Precisions, expressed as relative standard deviations, are lower than 4.2 %. The applicability of the method was demonstrated by the successful analysis of tap water, mineral water, and river water. (author)

  6. One-pot synthesis of silica-coated copper nanoparticles with high chemical and thermal stability.

    Science.gov (United States)

    Shiomi, Shohei; Kawamori, Makoto; Yagi, Shunsuke; Matsubara, Eiichiro

    2015-12-15

    With the recent development of nanotechnology, enhancement of the stability of nanomaterials is becoming ever more important for their practical applications. We studied the silica-coating of Cu nanoparticles and the enhanced stability of silica-coated Cu nanoparticles to oxidation. The metallic nanoparticles are easily oxidized and agglomerated compared with the bulk metals because the nanoparticles possess large specific surfaces. The Cu nanoparticle is one of the most difficult nanoparticles to be handled due to its absence of the oxidation stability. In the synthesis of silica-coated Cu nanoparticles via a sol-gel process using tetraethyl orthosilicate, the addition of NH3 as a catalyst of sol-gel reaction yielded homogeneous silica-coating. However, a large amount of Cu nanoparticles is instantly dissolved by forming complex ions in a NH3 solution during and before the silica-coating process. This is the difficulty in the silica-coating of Cu nanoparticles. In the present work, the dissolution behavior of Cu nanoparticles was electrochemically examined. This electrochemistry-based optimization of reducing power of a reaction bath enabled us to synthesize the silica-coated Cu nanoparticle via a consecutive liquid-phase reaction which requires only basic equipment and involves no separate centrifuging or extraction step. Cu nanoparticles coated by silica shells had the remarkable stability even in the presence of a strong oxidizing agent. Furthermore, we demonstrated that the highly stable Cu nanoparticles can be applied to a red pigment using a unique red color of Cu nanoparticles because of its surface plasmon resonance. PMID:26313712

  7. Magnetic Control of Fe3O4 Nanomaterial for Fat Ablation in Microchannel

    Directory of Open Access Journals (Sweden)

    Ming Chang

    2015-11-01

    Full Text Available In this study, surface modification of iron (II, III oxide Fe3O4 nanoparticles by oleic acid (OA coating is investigated for the microablation of fat in a microchannel. The nanoparticles are synthesized by the co-precipitation method and then dispersed in organic solvent prior to mixing with the OA. The magnetization, agglomeration, and particle size distribution properties of the OA-coated Fe3O4 nanoparticles are characterized. The surface modification of the Fe3O4 nanoparticles reveals that upon injection into a microchannel, the lipophilicity of the OA coating influences the movement of the nanoparticles across an oil-phase barrier. The motion of the nanoparticles is controlled using an AC magnetic field to induce magnetic torque and a static gradient field to control linear translation. The fat microablation process in a microchannel is demonstrated using an oscillating driving field of less than 1200 Am?1.

  8. Architecture of Fe3O4–graphene oxide nanocomposite and its application as a platform for amino acid biosensing

    International Nuclear Information System (INIS)

    Highlights: ? Fe3O4–GO nanocomposites are prepared. ? Fe3O4–GO exhibits high catalysis towards the oxidation of cysteine and N-acetyl cysteine. ? Mediating Fe3O4–GO on a glassy carbon electrode developed an electrochemical sensor. ? The sensor showed high selectivity and stability. - Abstract: The Fe3O4–graphene oxide (Fe3O4–GO) nanocomposites were prepared by a chemical co-precipitation of FeSO4, FeCl3,·NH3·H2O and GO. The Fe3O4–GO was characterized by scanning electron microscopy, X-ray powder diffraction, thermogravimetric analysis and electrochemical method. The results showed that ultrafine Fe3O4 nanoparticles was prepared and densely assembled on GO nanosheets. The Fe3O4–GO exhibits large surface area and high catalysis towards the oxidation of cysteine and N-acetyl cysteine, which could be used for cysteine and N-acetyl cysteine sensing with a wide linear range (0.5–13.5 mM for cysteine and 0.12–13.3 mM for N-acetyl cysteine) and low detection limit (56 ?M for cysteine and 25 ?M for N-acetyl cysteine). The excellent catalytic activity, high sensitivity and good stability made such Fe3O4–GO nanocomposites to be promising nanomaterials for constructing nonenzymatic sensor.

  9. Novel method of room temperature ionic liquid assisted Fe3O4 nanocubes and nanoflakes synthesis

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • First time [Bmim][TfO] IL is used for the Fe3O4 nanoparticle synthesis. • Novel method tunes Fe3O4 nanocubes and nanoflakes forms influenced by the base and IL. • Fe3O4 oxidized topotactically into ?-Fe2O3 nanoparticles by annealing and base. • Uniform morphology with average size of 33 nm negligible superstructure are formed. • Ms values are characterized by thin layer of ?-Fe2O3 on the nanoparticle surface. - Abstract: For the first time, the nanomagnetite superparamagnetic particles are successfully synthesized by precipitation method using 1-n-butyl-3-methylimidazolium trifluoromethane sulfonate [Bmim][TfO] ionic liquid medium/surfactant. The obtained Fe3O4 particles are nanocubes and nanoflakes and this formation is influenced by the base concentration and anisotropic circumstances produced by the ionic liquid and their size varies from 20 nm to 150 × 300 nm (width × length). The synthesized magnetite nanoparticles are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) studies. The results show that the core of the Fe3O4 nanoparticles is surrounded by a thin layer of ?-Fe2O3 by topotactical partial oxidation, which is remarkably proceed with the subsequent calcination. The magnetite nanocubes have high saturation magnetization value and exhibit superparamagnetic hysteresis loop

  10. Synthesis and characterization of Fe3O4 magnetic nanofluid

    Scientific Electronic Library Online (English)

    Javier A, Lopez; Ferney, González; Flavio A, Bonilla; Gustavo, Zambrano; Maria E, Gómez.

    2010-06-01

    Full Text Available Los ferrofluidos son sistemas coloidales compuestos de nanopartículas magnéticas con mono-dominios magnéticos, dispersas en un líquido portador. En el presente trabajo, nanopartículas magnéticas de ferrita (Fe3O4) se sintetizaron por el método de co-precipitación química, y se recubrieron con ácido [...] oleico como agente surfactante. Las propiedades magnéticas de las nanopartículas en el ferrofluido fueron investigadas por medio de un magnetómetro de muestra vibrante (VSM) a temperatura ambiente, mostrando un comportamiento superparamagnético, característico de estas nanopartículas magnéticas. Esto se determinó a partir de la curva de histéresis de M vs H. La muestra en polvo se caracterizó por medio de Difracción de Rayos X. El patrón DRX resultante muestra la presencia del pico más intenso correspondiente a la orientación cristalográfica (311) de la fase espinel para las nanopartículas magnéticas de Fe3O4. El tamaño medio de las nanopartículas se determinó a partir del patrón de difracción de rayos X utilizando la aproximación de Scherrer, siendo este tamaño medio de 9,64 nm. La microscopía de fuerza atómica, se utilizó para visualizar la morfología de las nanopartículas y para determinar su diámetro. Las medidas de AFM muestran un diámetro promedio para las nanopartículas de D N = 15,3 nm La espectroscopia de absorción FTIR se utilizó para confirmar la formación de los enlaces Fe-O, permitiendo identificar la estructura tipo espinela de la ferrita, así como la presencia de otras sustancias químicas adsorbidas en la superficie de las partículas. Abstract in english Ferrofluids are colloidal systems composed of single domain of magnetic nanoparticles dispersed in a liquid carrier. In the present work, Fe3O4 magnetic ferrite nanoparticles were synthesized by chemical coprecipitation method, and were coated with oleic acid as surfactant agent. Magnetic properties [...] of nanoparticles in ferrofluids were investigated with the aid of a vibrating sample magnetometer (VSM) at room temperature. Superparamagnetic behavior, characteristic of magnetic nanoparticles, was determined from the hysteresis loop of M vs. H measurements. The sample as powder was characterized by means of X-ray diffraction. XRD pattern result shows the presence of the most intense peak corresponds to the (311) crystallographic orientation of the spinel phase of Fe3O4 magnetic nanoparticles. The mean size of the nanoparticles was determined from the X-ray diffraction pattern by using the Scherrer approximation. The particle size was calculated to be 9.64 nm. Atomic Force Microscopy was used to visualize the morphology of nanoparticles and to measure their diameter. The AFM method showed an average nanoparticles diameter of D N = 15.3 nm. FTIR absorption spectroscopy was used to confirm the formation of Fe-O bonds, allowing to identify the inverse ferrites spinel structure, as well as, the presence of other chemical substances adsorbed on the surface of particles.

  11. Magnetic composite nanofibers fabricated by electrospinning of Fe3O4/gelatin aqueous solutions

    International Nuclear Information System (INIS)

    Graphical abstract: Superparamagnetic Fe3O4/GE composite nanofibers with saturation magnetization of 12.87 em? g?1 were prepared from gelatin aqueous solution at an elevated temperature by electrospinning. - Highlights: • Electrospinning GE aqueous solution at higher temperature. • Presenting a simple and effective technique, combining wet blending with high temperature electrospinning to prepare magnetic composite nanofibers. • Developing composite nanofibers with higher superparamagnetic properties is expected to be useful in application for the biomedical field. - Abstract: We have fabricated magnetic composite nanofibers containing superparamagnetic Fe3O4 nanoparticles by the electrospinning method. Highly dispersed Fe3O4 magnetic nanoparticles were synthesized by one-step co-precipitation of Fe2+/Fe3+ under an alkaline condition with 4 wt% poly(vinyl alcohol) (PVA) aqueous solution as the stabilizer. Gelatin (GE) was used as a polymeric matrix for fabricating the nanocomposites. The prepared Fe3O4/GE composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. These composite nanofibers show uniform and continuous morphology with the Fe3O4 nanoparticles embedded in the nanofibers. By studying the magnetic properties of the Fe3O4/GE composite nanofibers, we confirm that the composite nanofibers possess superparamagnetic properties with a high saturated magnetization (Ms = 12.87 em? g?1) at room temperature. The features of this approach for getting one-dimensional magnetic nanostructure are its simplicity, effectiveness and safety. The Fe3O4/GE nanofibers with superparamagnetic properties would be potentially applied in biomedical field

  12. Core-Shell Nano structure of a-Fe2O3/Fe3O4: Synthesis and Photo catalysis for Methyl Orange

    International Nuclear Information System (INIS)

    Fe3O4 nanoparticle was synthesized in the solution involving water and ethanol. Then, a-Fe2O3 shell was produced in situ on the surface of the Fe3O4 nanoparticle by surface oxidation in molten salts, forming ?-Fe2O3/Fe3O4 core-shell nano structure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe3O4 nanoparticles were oxidized. Furthermore, the obtained a-Fe2O3/Fe3O4 core-shell nanoparticles were used to photo catalyse solution of methyl orange, and the results revealed that a-Fe2O3/Fe3O4 nanoparticles were more efficient than the self-prepared ?-Fe2O3 nanoparticles. At the same time, the photo catalyzer was recyclable by applying an appropriate magnetic field.

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

    Science.gov (United States)

    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

  14. Incorporation of Fe3O4/CNTs nanocomposite in an epoxy coating for corrosion protection of carbon steel

    Science.gov (United States)

    Pham, Gia Vu; Truc Trinh, Anh; To, Thi Xuan Hang; Duong Nguyen, Thuy; Trang Nguyen, Thu; Hoan Nguyen, Xuan

    2014-09-01

    In this study Fe3O4/CNTs composite with magnetic property was prepared by attaching magnetic nanoparticles (Fe3O4) to carbon nanotubes (CNTs) by hydrothermal method. The obtained Fe3O4/CNTs composite was characterized by Fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction and transmission electron microscopy. The Fe3O4/CNTs composite was then incorporated into an epoxy coating at concentration of 3 wt%. Corrosion protection of epoxy coating containing Fe3O4/CNTs composite was evaluated by electrochemical impedance spectroscopy and adhesion measurement. The impedance measurements show that Fe3O4/CNTs composite enhanced the corrosion protection of epoxy coating. The corrosion resistance of the carbon steel coated by epoxy coating containing Fe3O4/CNTs composite was significantly higher than that of carbon steel coated by clear epoxy coating and epoxy coating containing CNTs. FE-SEM photographs of fracture surface of coatings showed good dispersion of Fe3O4/CNTs composite in the epoxy matrix.

  15. Incorporation of Fe3O4/CNTs nanocomposite in an epoxy coating for corrosion protection of carbon steel

    International Nuclear Information System (INIS)

    In this study Fe3O4/CNTs composite with magnetic property was prepared by attaching magnetic nanoparticles (Fe3O4) to carbon nanotubes (CNTs) by hydrothermal method. The obtained Fe3O4/CNTs composite was characterized by Fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction and transmission electron microscopy. The Fe3O4/CNTs composite was then incorporated into an epoxy coating at concentration of 3 wt%. Corrosion protection of epoxy coating containing Fe3O4/CNTs composite was evaluated by electrochemical impedance spectroscopy and adhesion measurement. The impedance measurements show that Fe3O4/CNTs composite enhanced the corrosion protection of epoxy coating. The corrosion resistance of the carbon steel coated by epoxy coating containing Fe3O4/CNTs composite was significantly higher than that of carbon steel coated by clear epoxy coating and epoxy coating containing CNTs. FE-SEM photographs of fracture surface of coatings showed good dispersion of Fe3O4/CNTs composite in the epoxy matrix. (paper)

  16. Polymide/Fe3O4-carbonized Membranes for Gas Separation

    Directory of Open Access Journals (Sweden)

    ZHAO Xuan-Ying,WANG Tong-Hua,LI Lin,LIU Ying,CAO Yi-Ming

    2010-07-01

    Full Text Available Novel functional carbon membranes for gas separation were designed and prepared by incorporating Fe3O4 nanoparticles into carbon membranes precursor polyimide. The assynthesized membranes were characterized by TEM, XRD and VSM. The effects of Fe3O4 addition and the final pyrolysis temperature on the gas permeability were investigated. The results show that Fe3O4 nanoparticles transformed into other phase morphologies are helpful to form the graphite-like layers during the pyrolysis process, which make the membrane with two types of carbon structure : amorphous carbon and graphite-like layers. All the functional carbon membranes exhibit magnetism. Single gas permeation test results show that the assynthesized membranes exhibit an outstanding molecular sieving capability together with high gas permeability. The gas permeability of H2 is 61 times higher than the pure carbon membrane and the H2/CO2 selectivity is also improved. Fe3O4 addition and the final pyrolysis temperature siginificantly impair the gas permeability. When the Fe3O4 content is 20wt%, the permeabilities of pure gas H2, CO2, O2, N2, CH4 in the functional carbon membrane are 15476, 4385, 1565, 193 and 114 Barrers (1Barrer=1×10-10 cm3 (STP ·cm/(cm2·s·cmHg, respecticvely. The final pyrolysis temperature also has a remarkable effect on the gas separation performance.

  17. Mössbauer study of a Fe3O4/PMMA nanocomposite synthesized by sonochemistry

    Science.gov (United States)

    Martínez, H.; D'Onofrio, L.; González, G.

    2014-01-01

    Magnetite nanoparticles of 10 nm average size were synthesized by ultrasonic waves from the chemical reaction and precipitation of ferrous and ferric iron chloride (FeCl3 · 6H2O y FeCl2 · 4H2O) in a basic medium. The formation and the incorporation of the magnetite in PMMA were followed by XRD and Mössbauer Spectroscopy. These magnetite nanoparticles were subsequently incorporated into the polymer by ultrasonic waves in order to obtain the final sample of 5 % weight Fe3O4 into the polymethylmethacrylate (PMMA). Both samples Fe3O4 nanoparticles and 5 % Fe3O4/PMMA nanocomposite, were studied by Mössbauer spectroscopy in the temperature range of 300 K-77 K. In the case of room temperature, the Mössbauer spectrum of the Fe3O4 nanoparticles sample was fitted with two magnetic histograms, one corresponding to the tetrahedral sites (Fe3 + ) and the other to the octahedral sites (Fe3 + and Fe2 + ), while the 5 % Fe3O4/PMMA sample was fitted with two histograms as before and a singlet subspectrum related to a superparamagnetic behavior, caused by the dispersion of the nanoparticles into the polymer. The 77 K Mössabuer spectra for both samples were fitted with five magnetic subspectra similar to the bulk magnetite and for the 5 % Fe3O4/PMMA sample it was needed to add also a superparamagnetic singlet. Additionally, a study of the Verwey transition has been done and it was observed a different behavior compared with that of bulk magnetite.

  18. Synthesis of Fe3O4 nanocrystals using hydrothermal approach

    International Nuclear Information System (INIS)

    Magnetite (Fe3O4) nanocrystals were synthesized using a facile hydrothermal method. FeCl2, FeCl3 and NaOH with a molar ratio of 1:2:8 were added into an autoclave and this was followed by heat treatment at elevated temperature (100, 150 and 200 °C). The produced results show that the average crystallite and the physical size of the resulting Fe3O4 nanocrystals increased with the hydrothermal temperature. The Fe3O4 nanocrystals exhibited superparamagnetic behavior. The saturation magnetization and coercivity of the produced nanocrystals also increased with the hydrothermal temperature. - Highlights: ? The crystallinity of Fe3O4 nanocrystals has been improved. ? The particle and crystallite size of nanocrystals are well-fitted with single crystal structure. ? The crystallite and physical sizes of the nanocrystals increased with hydrothermal temperature. ? The Ms and Hc of Fe3O4 nanocrystals enhanced with increase of hydrothermal temperature.

  19. Preparation and Characterization of Silica-Coated Magnetic–Fluorescent Bifunctional Microspheres

    Directory of Open Access Journals (Sweden)

    Xiao Qi

    2009-01-01

    Full Text Available Abstract Bifunctional magnetic–fluorescent composite nanoparticles (MPQDs with Fe3O4MPs and Mn:ZnS/ZnS core–shell quantum dots (QDs encapsulated in silica spheres were synthesized through reverse microemulsion method and characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer, and photoluminescence (PL spectra. Our strategy could offer the following features: (1 the formation of Mn:ZnS/ZnS core/shell QDs resulted in enhancement of the PL intensity with respect to that of bare Mn:ZnS nanocrystals due to the effective elimination of the surface defects; (2 the magnetic nanoparticles were coated with silica, in order to reduce any detrimental effects on the QD PL by the magnetic cores; and (3 both Fe3O4MPs and Mn:ZnS/ZnS core–shell QDs were encapsulated in silica spheres, and the obtained MPQDs became water soluble. The experimental conditions for the silica coating on the surface of Fe3O4nanoparticles, such as the ratio of water to surfactant (R, the amount of ammonia, and the amount of tetraethoxysilane, on the photoluminescence properties of MPQDs were studied. It was found that the silica coating on the surface of Fe3O4could effectively suppress the interaction between the Fe3O4and the QDs under the most optimal parameters, and the emission intensity of MPQDs showed a maximum. The bifunctional MPQDs prepared under the most optimal parameters have a typical diameter of 35 nm and a saturation magnetization of 4.35 emu/g at room temperature and exhibit strong photoluminescence intensity.

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

    Science.gov (United States)

    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.

  1. CeO2-based Pd(Pt) nanoparticles grafted onto Fe3O4/graphene: a general self-assembly approach to fabricate highly efficient catalysts with magnetic recyclable capability.

    Science.gov (United States)

    Wang, Xiao; Liu, Dapeng; Song, Shuyan; Zhang, Hongjie

    2013-04-15

    New Pd(Pt) catalysts have been fabricated by assembling multicomponents of Fe3O4 and CeO2/Pd(Pt) on the surface of reduced graphene oxide (RGO) nanosheets in layers. The as-obtained Pd(Pt) catalysts exhibit extremely high catalytic activity in the selective hydrogenation reaction of nitrobenzene. Owing to the presence of Fe3O4, the catalysts can be easily recycled from the catalytic system through magnetic separation. Their high activity, stability, and magnetic recyclability make the as-obtained hybrids very promising as catalysts in catalytic applications. Compared to other traditional multishell magnetic catalysts that were prepared by means of layer-by-layer technology, our process is much more facile and more easily controlled. PMID:23463604

  2. In vitro and ex vivo evaluation of silica-coated super paramagnetic iron oxide nanoparticles (SPION) as biomedical photoacoustic contrast agent

    Science.gov (United States)

    Alwi, Rudolf; Telenkov, Sergey A.; Mandelis, Andreas; Leshuk, Timothy; Gu, Frank; Oladepo, Sulayman; Michaelian, Kirk; Dickie, Kristopher

    2013-03-01

    The employment of contrast agents in photoacoustic imaging has gained significant attention within the past few years for their biomedical applications. In this study, the use of silica-coated superparamagnetic iron oxide (Fe3O4) nanoparticles (SPION) was investigated as a contrast agent in biomedical photoacoustic imaging. SPIONs have been widely used as Food-and-Drug-Administration (FDA)-approved contrast agents for magnetic resonance imaging (MRI) and are known to have an excellent safety profile. Using our frequency-domain photoacoustic correlation technique ("the photoacoustic radar") with modulated laser excitation, we examined the effects of nanoparticle size, concentration and biological medium (e.g. serum, sheep blood) on its photoacoustic response in turbid media (intralipid solution). Maximum detection depth and minimum measurable SPION concentration were determined experimentally. The detection was performed using a single element transducer. The nanoparticle-induced optical contrast ex vivo in dense muscular tissues (avian pectus) was evaluated using a phased array photoacoustic probe and the strong potential of silicacoated SPION as a possible photoacoustic contrast agent was demonstrated. This study opens the way for future clinical applications of nanoparticle-enhanced photoacoustic imaging in cancer therapy.

  3. Silica coating of CeO2 nanoparticles by a fast microwave irradiation method

    International Nuclear Information System (INIS)

    A rapid and simple route for silica coating with base catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS) precursor in water-ethanol solvent using microwave irradiation to encapsulate CeO2 nanoparticles with a silica shell is studied. From X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectra analysis, it was confirmed that silica in the coating is attached on the CeO2 nanoparticles surface through Ce-O-Si chemical bonds. The coating extent was increased with increasing in TEOS loading and surface characteristics of coated CeO2 nanoparticles with high silica extents showed similar electrokinetic behavior to SiO2 particles. The high resolution transmission electron microscope (HR-TEM) images also showed that SiO2 coated the cubic shaped CeO2 nanoparticles as thin uniform layers (5 nm). The catalytic activities of non-coated and silica coated CeO2 nanoparticles for oxidation of organic compound were evaluated by degradation of methylene blue in air atmosphere at 403 K. Furthermore, the optical properties of non-coated and silica coated CeO2 nanoparticles were evaluated by UV-vis spectroscopic analyses. These analytical results indicated that silica coated CeO2 nanoparticles with thin silica layer could be prepared using sol-gel method assisted by microwave irradiation within 2 min and this material showed better performances than original CeO2 nanoparticles.

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

    International Nuclear Information System (INIS)

    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 f-dot 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 0.011x-(Fe3O4)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

  5. Fabrication of magnetically recyclable Fe3O4@Cu nanocomposites with high catalytic performance for the reduction of organic dyes and 4-nitrophenol

    International Nuclear Information System (INIS)

    A facile and efficient approach to synthesize Fe3O4@Cu nanocomposites using L-Lysine as a linker was developed. The morphology, composition and crystallinity of the Fe3O4@Cu nanocomposites were characterized by Fourier Transform infrared spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. In addition, the magnetic properties were determined with vibrating sample magnetometer. The surface of the Fe3O4 contained many small Cu nanoparticles with sizes of about 3 nm. It was found that the Fe3O4@Cu nanocomposites could catalyze the degradation of organic dyes. The catalytic activities of the Fe3O4@Cu nanocomposites for the reduction of nitrophenol were also studied. The Fe3O4@Cu nanocomposites are more efficient catalysts compared with Cu nanoparticles and can easily be recovered from the reaction mixture with magnet. The cost effective and recyclable Fe3O4@Cu nanocomposites provide an exciting new material for environmental protection applications. - Highlights: • Cu nanoparticles as small as 3 nm are synthesized. • Low cost Fe3O4@Cu magnetical nanoparticles show catalytic activity for organic dyes and 4-nitrophenol. • The Fe3O4@Cu display high catalytic activity after 13 cycles

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Chitosan polymers doped with Fe3O4 are prepared by the solution casting technique. • The structural, magnetic, and microwave absorption properties of the samples are analyzed. • The polymer behaves like a superparamagnetic material with high blocking temperature. • The effective magnetization shows gradual increments with the concentration of Fe3O4. • The microwave absorption characteristic shows low reflection loss

  7. Synthesis of Fe3O4-LaF3:Ce,Tb nanocomposites with bright fluorescence and strong magnetism

    International Nuclear Information System (INIS)

    In this paper, fluorescent-magnetic Fe3O4-LaF3:Ce,Tb nanocomposites were synthesized by combining fluorescent LaF3:Ce,Tb and magnetic Fe3O4 nanoparticles into new 'two-in-one' entities. The obtained Fe3O4-LaF3:Ce,Tb nanocomposites were small (about 30 nm in diameter) and well dispersed in water. Under ultraviolet light irradiation, the Fe3O4-LaF3:Ce,Tb nanocomposites emitted bright green fluorescence, and they could be easily manipulated by an external magnetic field. Such bifunctional nanocomposites may find many biomedical applications, such as cancer detection and drug delivery. And the method we used can be extended to the synthesis of other nanocomposites based on lanthanide-doped materials and metal oxides.

  8. Spectroscopic and photoluminescence studies on optically transparent magnetic nanocomposites based on sol-gel glass: Fe3O4

    International Nuclear Information System (INIS)

    Sol-gel glasses with Fe3O4 nanoparticles having particle sizes laying in the range 10-20 nm were encapsulated in the porous network of silica resulting in nanocomposites having both optical and magnetic properties. Spectroscopic and photoluminescence studies indicated that Fe3O4 nanocrystals are embedded in the silica matrix with no strong Si-O-Fe bonding. The composites exhibited a blue luminescence. The optical absorption edge of the composites red shifted with increasing concentration of Fe3O4 in the silica matrix. There is no obvious shift in the position of the luminescence peak with the concentration of Fe3O4 except that the intensity of the peak is decreased. The unique combinations of magnetic and optical properties are appealing for magneto-optical applications

  9. A novel technique to extract Bi from mechanochemically prepared Bi-Fe3O4 nanocomposite

    International Nuclear Information System (INIS)

    The solid-state reduction of Bi2O3 to bismuth (Bi) nanoparticles by high-energy ball milling of raw materials (Bi2O3 and Fe) in air and argon atmospheres has been described. XRD results show that in addition to bismuth, a second phase of nanocrystalline magnetite is also formed. This is due to the formation of Fe2O3 and the subsequent change to Fe3O4 in the course of ball milling. Mean particle sizes of the obtained Bi and Fe3O4 particles were 22 and 18 nm, respectively, using Scherrer's formula. A saturation magnetization of 80 emu/g is achieved for magnetic phase (Fe3O4). As both Bi and magnetite were nanosized particles, it was not possible to separate these two phases by the magnetic separation technique. A novel technique based on different thermal expansions of the Bi and Fe3O4 was then used to extract metallic Bi from the as-milled powders

  10. Chemically synthesized Au-Fe3O4 nanostructures with controlled optical and magnetic properties

    Science.gov (United States)

    Velasco, Victor; Muñoz, Laura; Mazarío, Eva; Menéndez, Nieves; Herrasti, Pilar; Hernando, Antonio; Crespo, Patricia

    2015-01-01

    Au-Fe3O4 dumbbell-like, flower-like and core-shell nanostructures with different sizes ranging between 4-15?nm have been synthesized via the thermal decomposition of iron pentacarbonyl and reduction of gold salts. By means of the variation of the precursors’ molar ratio, the injection temperature and the reaction time, the optical and magnetic properties have been tailored. A strong dependence on the dielectric function of the present Fe3O4 nanoparticles (NPs) was detected. The gold characteristic plasmon peak shifts from 525?nm (pure gold NPs) to close to 600?nm showing an electron damping in the Au NPs surrounded by Fe3O4. These NPs are ferromagnetic at low temperature, exhibiting a coercive field ranging between 85-500?Oe, whereas they behave as a superparamagnetic system above the blocking temperature, which is found to be between 18-110?K. A high magnetic anisotropy is generated in the interface of Au-Fe3O4 NPs.

  11. Tribological Properties of Graphene-based Fe3O4 Nanocomposite Materials

    Directory of Open Access Journals (Sweden)

    QIAO Yu-Lin, ZHAO Hai-Chao, ZANG Yan, ZHANG Qing

    2015-01-01

    Full Text Available Graphene-based Fe3O4 nanocomposite materials were prepared by the melthod of Liquid-phase Ultrasonic Exfoliation. Morphologies of nanocomposite materials were characterized by means of SEM and TEM. Its tribological properties as a pure water additive were investigated using multi-functional reciprocating friction and wear tester. The lubrication mechanism was discussed based on results of analyses of SEM, XPS. The results showed that the Fe3O4 nanoparticles with size of 20­90 nm were densely and randomly deposited on interlamination and surface of graphene sheets. The nanocomposite materials as a pure water additive displayed good friction-reducing and antiwear performance. Compared with pure water, the graphene-based Fe3O4 nanocomposite could reduce the friction coefficient of 26.7% and the wear mass of 35.4% under condition of 10 N of load and 0.01wt% of concentration. The prosperity was attributed to the effect of adsorption membrane and boundary lubrication film containing graphene and Fe3O4 which inhibited oxidation of Fe and reduced wear on the frictional surface.

  12. Silica-coated super paramagnetic iron oxide nanoparticles (SPION) as biocompatible contrast agent in biomedical photoacoustics

    OpenAIRE

    Alwi, Rudolf; Telenkov, Sergey; Mandelis, Andreas; Leshuk, Timothy; Gu, Frank; Oladepo, Sulayman; Michaelian, Kirk

    2012-01-01

    In this study, we report for the first time the use of silica-coated superparamagnetic iron oxide nanoparticles (SPION) as contrast agents in biomedical photoacoustic imaging. Using frequency-domain photoacoustic correlation (the photoacoustic radar), we investigated the effects of nanoparticle size, concentration and biological media (e.g. serum, sheep blood) on the photoacoustic response in turbid media. Maximum detection depth and the minimum measurable SPION concentration were determined ...

  13. Enhanced Cellular Uptake of Silica-Coated Magnetite Nanoparticles Compared with PEG-Coated Ones in Stem Cells.

    Science.gov (United States)

    Lee, Dong Heon; Kang, Myunggoo; Lee, Hong Jai; Kim, Jeong Ah; Choi, Yun-Kyong; Cho, Hyunjin; Park, Jung-Keug; Park, Tai Hyun; Jung, Hyun

    2015-08-01

    Monodispersed magnetite (Fe3O4) nanoparticles (NPs) were prepared through the thermal decomposition method. The obtained NPs were surface modified with silica (SiO2) and polyethylene glycol (PEG), to enhance their stability in aqueous environment and their cellular uptake efficiency for biomedical applications. The NPs were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR) spectroscopy, and dynamic light scattering (DLS). The cytotoxicity of these NPs on bone marrow mesenchymal stem cells (BM-MSCs) was measured by MTT assay (cell viability test) at various concentrations (2, 5, 12.5, 25, and 50 µg/mL). The cells remained more than 90% viable at concentrations as high as 50 µg/mL. To compare the cellular uptake efficiency, these NPs were treated in BM-MSCs and the Fe concentration within the cells was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. The uptake process displayed a time- and dose-dependency. The uptake amount of SiO2-coated Fe3O4 (Fe3O4@SiO2) NPs was about 10 times higher than that of the PEG-coated ones (Fe3O4@PEG). PMID:26369110

  14. Nonquenching of charge carriers by Fe3O4 core in Fe3O4/ZnO nanosheet photocatalyst.

    Science.gov (United States)

    Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai; Jayabharathi, Jayaraman

    2014-12-16

    Fe3O4-implanted ZnO and pristine ZnO nanosheets have been synthesized hydrothermally. High-resolution scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, elemental mapping, selected area electron diffractometry, powder X-ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, solid state impedance spectroscopy, UV-visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy show implantation of Fe3O4 in ZnO nanosheets. Fe3O4 core with ZnO shell is of type I core/shell heterostructure which is to quench charge carriers and suppress photocatalysis. But the photocatalytic activity is not suppressed on implantation of Fe3O4 in ZnO nanosheets, and time controlled single photon counting lifetime spectroscopy shows that the photogenerated charge carriers are not quenched by the Fe3O4 core in the ZnO nanosheets. The composite nanosheets are photostable, reusable, and magnetically recoverable, revealing potential application in mineralization of organic pollutants. PMID:25425261

  15. Synthesis of BSA/Fe3O4 magnetic composite microspheres for adsorption of antibiotics

    International Nuclear Information System (INIS)

    BSA/Fe3O4 magnetic composite microspheres with high saturation magnetization and paramagnetic property were prepared via inverse emulsion technology at room temperature, bovine serum albumin (BSA, 60 KD), magnetic nanoparticles (Fe3O4) and glutaraldehyde as macromonomer, inorganic particles and cross-linking agent, respectively. Fourier transform infrared (FTIR), scanning electron microscope (SEM), metalloscope, and particle size analyzer were used to characterize morphology and structure of composite microspheres. Vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA) were used to test magnetic properties of the synthesized samples, adsorption capacity of microspheres was determined by ultraviolet spectrophotometer (UV). The results showed that BSA/Fe3O4 microspheres were 43 ?m with relatively narrow particle size distribution, perfect sphere-shaped morphologies, superparamagnetism with a saturation magnetization of 11 emu/g, and high magnetic content with a value of 57.29%. The main factors influencing properties of microspheres including raw material ratio, the amount of emulsifier and cross-linking agent, agitation speed were investigated and optimized. Furthermore, these microspheres accompanying with high separable and reusable efficient may have great potential application in the field of separation, in particular, removal of antibiotics. Adsorption capacities of the microspheres of four different kinds of antibiotics (erythromycin, streptomycin, tetracycline and chloramphenicol) ranging from 69.35 mg/g to 147.83 mg/g were obtained, and Langmuir isotherm model coincided with equilibrium data than that of the Freundlich model. - Highlights: • BSA/Fe3O4 microspheres with high saturation magnetization were prepared. • BSA/Fe3O4 microspheres for the removal of antibiotics are proposed. • The obtained results have significant importance in environmental processes

  16. Multifunctional nanotube-like Fe3O4/PANI/CDs/Ag hybrids: An efficient SERS substrate and nanocatalyst.

    Science.gov (United States)

    Yan, Manqing; Shen, Yang; Zhang, Guiyang; Bi, Hong

    2016-01-01

    In this paper, the stable and environment-friendly Fe3O4 nanotubes with polyaniline (Fe3O4 NTs/PANI hybrids) have been prepared via mesoporous anodic alumina oxide (AAO) template, sol-gel method and in-situ polymerization. Then multifunctional Fe3O4 NTs/PANI/Ag hybrids have been obtained by decorating Ag nanoparticles by glucose reduction on surface of Fe3O4 NTs/PANI hybrids. The morphologies and structures of these hybrids were subsequently investigated by SEM, XRD, TEM and XPS measurements. The Fe3O4 NTs/PANI/Ag hybrids presented high catalytic activity due to the template-assisted presence, preventing Ag particulate agglomeration. Importantly, the Fe3O4 NTs/PANI/Ag hybrids achieve sensitive surface-enhanced Raman scattering (SERS) signals. Furthermore, the introduction of carbon dots (CDs) endows these hybrids good dispersion and stable photoluminescence (PL). Therefore, the obtained hybrids may have potential applications in waste water treatment, biomedicine, photocatalyst, and environmental analysis. PMID:26478345

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

    Directory of Open Access Journals (Sweden)

    Salehizadeh Hossein

    2012-01-01

    Full Text Available Abstract 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.

  18. Optical properties of silica-coated Y2O3:Er,Yb nanoparticles in the presence of polyvinylpyrrolidone

    International Nuclear Information System (INIS)

    The optical properties of polyvinylpyrrolidone (PVP)-adsorbed and silica-coated Y2O3:Er,Yb nanoparticles produced by using PVP were studied for potential bio-applications of upconversion nanoparticles. We utilized PVP to better disperse Y2O3:Er,Yb nanoparticles in solution and to prepare silica-coated Y2O3:Er,Yb nanoparticles. The fluorescent intensity of PVP-adsorbed Y2O3:Er,Yb nanoparticles was 1.25 times higher than non-adsorbed Y2O3:Er,Yb nanoparticles, which was probably due to surface defects in Y2O3:Er,Yb nanoparticles being covered by the PVP. However, the fluorescent intensity of silica-coated Y2O3:Er,Yb nanoparticles decreased as silica layer thickness increased. This could be ascribed to the higher vibrational energy of PVP than that of the silica structure. Therefore, the optimum silica layer thickness is important in bio-applications to avoid deterioration of the optical properties of Y2O3:Er,Yb nanoparticles. - Highlights: • We prepared the silica-coated upconversion nanoparticles by using PVP. • We showed that PVP played an important role in coating nanoparticles. • PL intensity of silica-coated nanoparticles decreased as silica layer thickness increased

  19. Antifungal activity of multifunctional Fe3O4-Ag nanocolloids

    International Nuclear Information System (INIS)

    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 Fe3O4-Ag nanocolloids against A. glaucus isolates. Controlled experiments are also carried out with Ag nanocolloids in order to understand the role of core (Fe3O4) in the antifungal action. The minimum inhibitory concentration (MIC) of nanocolloids is determined by the micro-dilution method. MIC of A. glaucus is 2000 ?g/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. - Research Highlights: ?Synthesis of Fe3O4-Ag core-shell nanocolloids. ?Antifungal activity of Fe3O4-Ag nanocolloids against Aspergillus glaucus isolates. ?The MIC value for A. glaucus is 2000 ?g/mL. ?Antifungal activity is better or comparable with most prominent antibiotics.

  20. Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters

    CERN Document Server

    Dash, Monika

    2013-01-01

    Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

  1. Synthesis of Cu-Fe3O4@graphene composite: A magnetically separable and efficient catalyst for the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Highlights: • The Cu-Fe3O4@GE composite was prepared by one-step solvent–thermal method. • The Cu-Fe3O4@GE composite exhibited the highest catalytic activity with excellent stability. • The Cu-Fe3O4@GE composite was magnetically separable. - Abstract: In this work, the Cu-Fe3O4@GE composite was prepared easily by a one-step solvent–thermal method, which achieved the formation of Cu nanoparticles (Cu NPs), Fe3O4 nanoparticles (Fe3O4 NPs) and reduction of GO simultaneously. The morphology and structure of the composite was fully characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM). The time-dependent adsorption spectra of the reaction mixture was measured by UV–vis absorption spectroscopy. The results demonstrated that the Cu NPs and Fe3O4 NPs were densely and evenly deposited on the graphene (GE) sheets. It was found that the Cu-Fe3O4@GE composite exhibited high catalytic activities on the reduction of p-nitrophenol to p-aminophenol. Furthermore, the composite catalyst can be easily recovered due to its magnetic separability and high stability

  2. Lipid peroxidation and its control in Anguilla anguilla hepatocytes under silica-coated iron oxide nanoparticles (with or without mercury) exposure.

    Science.gov (United States)

    Srikanth, Koigoora; Anjum, Naser A; Trindade, Tito; Duarte, Armando C; Pereira, Edurda; Ahmad, Iqbal

    2015-07-01

    Having multidisciplinary applications, iron oxide nanoparticles can inevitably enter aquatic system and impact inhabitants such as fish. However, the studies in this context have ignored the significance of obvious interaction of iron oxide nanoparticles with other persistent co-contaminants such as mercury (Hg) in the modulation of the toxicity and underlying mechanisms of iron oxide nanoparticles and Hg alone, and concomitant exposures. This study aimed to evaluate lipid peroxidation (LPO) and its control with glutathione (GSH) and associated enzymes (such as glutathione reductase, GR; glutathione peroxidase, GPX; glutathione sulfo-transferase, GST) in European eel (Anguilla anguilla L.) hepatocytes exposed to stressors with following schemes: (i) no silica-coated iron oxide nanoparticles functionalized with dithiocarbamate (Fe3O4@SiO2/Si DTC, hereafter called 'FeNPs'; size range 82?±?21 to 100?±?30 nm) or Hg, (ii) FeNPs (2.5 ?g L(-1)) alone, (iii) Hg (50 ?g L(-1)) alone and (iv) FeNPs + Hg concomitant condition during 0 to 72 h. The exhibition of a differential coordination between GSH regeneration (determined as GR activity) and GSH metabolism (determined as the activity of GPX and GST) was perceptible in A. anguilla hepatocytes in order to control FeNPs, Hg and FeNPs + Hg exposure condition-mediated LPO. This study revealed the significance of a fine tuning among GR, GPX and GST in keeping LPO level under control during FeNPs or Hg alone exposure, and a direct role of total GSH (TGSH) in the control of LPO level and impaired GSH metabolism under the concomitant (FeNPs + Hg) exposure. An interpretation of the fish risk to FeNPs in a multi-pollution state should equally consider the potential outcome of the interaction of FeNPs with other contaminants. PMID:25613805

  3. Synthesis and magnetic properties of core/shell FeO/Fe3O4 nano-octopods

    Science.gov (United States)

    Khurshid, Hafsa; Chandra, Sayan; Li, Wanfeng; Phan, M. H.; Hadjipanayis, G. C.; Mukherjee, P.; Srikanth, H.

    2013-05-01

    We report the synthesis and magnetic properties of core/shell FeO/Fe3O4 nanoparticles with an average size of 30 nm in a complex quasi-octopod shape. FeO nanoparticles were synthesized by a wet chemical synthesis route followed by partial oxidation to form core/shell structured FeO/Fe3O4 octopods. X-ray diffraction and transmission electron microscopy confirmed the presence of iron oxide phases and the formed core/shell FeO/Fe3O4 morphology. Magnetic measurements revealed two distinct temperatures corresponding to the thermally activated Verwey transition (TV ˜ 120 K) of the ferrimagnetic Fe3O4 shell and the Neel temperature (TN ˜ 230 K) of the antiferromagnetic FeO core. The nanoparticles exhibited a strong horizontal shift in the field-cooled hysteresis loop (the so-called exchange bias (EB) effect) accompanied by enhanced coercivity. The Meiklejohn-Bean model has been implemented to quantify the amount of frozen spins that locate at the interface between FeO and Fe3O4 and are responsible for the observed EB effect.

  4. A facile synthesis of superparamagnetic Fe3O4 supraparticles@MIL-100(Fe) core-shell nanostructures: Preparation, characterization and biocompatibility.

    Science.gov (United States)

    Yu, Shoushan; Wan, Jiaqi; Chen, Kezheng

    2016-01-01

    Superparamagnetic Fe3O4 supraparticles@MIL-100(Fe) core-shell nanostructure microspheres were successfully constructed by a facile step-by-step method. The polyacrylate formed in situ during the process of the preparation of Fe3O4 supraparticles not only acted as a stabilizer on the Fe3O4 nanoparticles surface, but also played a crucial role as a "bridge" in the initial stage of the framework components selectively assembly on the Fe3O4 supraparticle surfaces. The structure and composition of the obtained microspheres were characterized by SEM, TEM, DLS, XRD, FTIR, and TG analysis. The MPMS results revealed that the introduction of the MOF shells can inhibit the interplay among the neighboring Fe3O4 supraparticles while an external magnetic field applied. The well-dispersed microspheres are biocompatible, which endow the microspheres great potential in drug targeting applications with enhanced efficiency. PMID:26397925

  5. Chemical vapor deposition prepared bi-morphological carbon-coated Fe3O4 composites as anode materials for lithium-ion batteries

    Science.gov (United States)

    Wang, Junhua; Gao, Mingxia; Wang, Dingsheng; Li, Xiang; Dou, Yibo; Liu, Yongfeng; Pan, Hongge

    2015-05-01

    Carbon coated Fe3O4 composite (Fe3O4@C) with bi-morphological architecture has been prepared via a chemical vapor deposition at 450 °C from Fe2O3 nanoparticles by using acetylene as the deposition vapor and carbon source. The Fe2O3 are fully reduced to Fe3O4 in a 10 min of deposition, showing submicron-sized octahedral Fe3O4 particles coated partially with a thin carbon layer mainly, and a few nano-sized Fe3O4 particles coated with carbon also. The deposition period of 20 min results in a further growth of the octahedral Fe3O4 particles and a reduction of the number of the nano-sized ones, correlating to a thick and fully coated carbon layer. Impurities of iron carbides generate in the composite with further prolonging the deposition to 30 min. The Fe3O4@C composite from 20 min of deposition shows superior electrochemical property to others. An initial reversible capacity of 570 mAh g-1 is obtained and the capacity fading is less than 5% after 60 cycles. The fabrication method is facile and time-saving. Such submicron size-predominated Fe3O4@C composite is hopefully not only favorable in alleviating the agglomeration of the iron oxide during cycling, but also helpful in getting high packing density of the anode material.

  6. Synthesis and characterization of Fe3O4 and ZnO nanocomposites by the sol-gelmethod

    Science.gov (United States)

    Hasanpour, A.; Niyaifar, M.; Asan, M.; Amighian, J.

    2013-05-01

    In this work, magnetite (Fe3O4) nanoparticles were first prepared from ferric nitrate (Fe(NO3)3 9H2O) and ethylene glycol (C2H6O2) in inert atmosphere using the sol-gel method. In the next stage, composite nanopowders of Fe3O4-ZnO were obtained from zinc acetate and diethanolamine via the sol-gel method. The precursor was first dried and then annealed in vacuum furnace at different temperatures. The X-ray diffraction results confirm the formation of Fe3O4-ZnO nanocomposites. Transmission Electron Microscopy showed that the prepared powders are made of the spherical shape particles with an average size of about 40 nm. Fourier transform infrared spectra for the characteristic absorption of Zn-O bond is at 453.1 cm-1and of Fe-O bond is 540.2 cm-1. Results of vibrating sample magnetometer reveal that the Fe3O4 nanoparticles are superparamagnetic, whereas in the form of Fe3O4-ZnO nanocomposites arenot.

  7. Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells

    International Nuclear Information System (INIS)

    Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to 'smart' drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were non-toxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications.

  8. Hyperthermia HeLa cell treatment with silica coated manganese oxide nanoparticles

    CERN Document Server

    Villanueva, A; Alonso, JM; Rueda, T; Martínez, A; Crespo, P; Morales, MP; Fernandez, MA Gonzalez; Valdes, J; Rivero, G

    2009-01-01

    HeLa tumour cells incubated with ferromagnetic nanoparticles of manganese oxide perovskite La0.56(SrCa)0.22MnO3 were treated with a high frequency alternating magnetic field. The particles were previously coated with silica to improve their biocompatibility. The control assays made with HeLa tumour cells showed that cell survival and growth rate were not affected by the particle internalization in cells, or by the electromagnetic field on cells without nanoparticles. The application of an alternating electromagnetic field to cells incubated with this silica coated manganese oxide induced a significant cellular damage that finally lead to cell death by an apoptotic mechanism.

  9. Genetic Variation of BCL2 (rs2279115), NEIL2 (rs804270), LTA (rs909253), PSCA (rs2294008) and PLCE1 (rs3765524, rs10509670) Genes and Their Correlation to Gastric Cancer Risk Based on Universal Tagged Arrays and Fe3O4 Magnetic Nanoparticles.

    Science.gov (United States)

    Mou, Xianbo; Li, Taotao; Wang, Jiuhai; Ali, Zeeshan; Zhang, Yuanying; Chen, Zhu; Deng, Yan; Li, Song; Su, Enben; Jia, Qiongying; He, Nongyue; Ni, Jian; Cui, Daxiang

    2015-11-01

    With the help of Fe3O4 nagnetic nanoparticles as a solid carrier and an excellent tool for separation, six SNP loci (rs2279115 of BCL2 gene, rs804270 of NEIL2 gene, rs909253 of LTA gene, rs2294008 of PSCA gene, rs3765524 and rs10509670 of PLCE1 gene) were selected to evaluate their relation to gastric cancer risk. Using two kinds of functionalized magnetic nanoparticles and universal tagged arrays, the whole operation procedure including genome DNA extraction and SNP genotyping was performed. All genotypes and allele frequencies were calculated in the cases and controls respectively to analyze their association with gastric cancer risk. Totally 200 pathological samples and 134 normal control subjects were collected. The results demonstrated that four SNP loci (rs2279115, rs804270, rs909253 and rs3765524) showed a potential association with gastric cancer risk, and the other two (rs2294008, rs10509670) possessed no difference/association among cases and controls. PMID:26554163

  10. Synthesis, characterization and application studies of self-made Fe3O4/PES nanocomposite membranes in microbial fuel cell

    International Nuclear Information System (INIS)

    Highlights: ? In this study, a novel, potentially low-priced PEM using nano-size particles of Fe3O4 was used as alternative for proton exchange membrane in microbial fuel cell (MFC). ? Fe3O4 nanoparticles were prepared by co precipitation of iron chloride salts with sodium hydroxide. ? The new synthesized PEM and Nafion 117 were tested in MFC. ? The power density with the new synthesized membrane of Fe3O4 was 29% more than what has been achieved with Nafion as PEM in MFC. - Abstract: Nanocomposite membranes are a promising alternative for proton exchange membrane (PEM) because it has the capability of transferring protons, is inexpensive, and also have higher resistance against fouling compared to other membranes in microbial fuel cells (MFCs). In this study, Saccharomyces cerevisiae was used as an active biocatalyst and neutral red with low concentration (200 ?mol l?1) was selected as electron shuttle in anode chamber. Moreover, four different concentrations of Fe3O4/PES have been tested as new generation of nanocomposite membrane and its efficiencies were compared with Nafion 117 in dual chamber MFC. To improve the performance of PEM, several nanoparticle (5%, 10%, 15% and 20% of Fe3O4 nanoparticle) concentrations were used. Maximum generated power and current with new synthesized membrane and 15% Fe3O4 nanoparticle were 20 mW m?2 and 148 mA m?2, while it was 15.4 mW m?2 and 112 mA m?2, respectively by using Nafion 117 at the same experimental condition. The highest obtained voltage was 656 mV and it was stable for 72 h of operation time.

  11. Surface reconstruction of Fe3O4(100)

    International Nuclear Information System (INIS)

    Preliminary results of low-energy ion scattering (LEIS) and low-energy electron diffraction (LEED) studies of Fe3O4(100) are presented. Thin epitaxial Fe3O4(100) films were grown by O2-assisted molecular beam epitaxy (MBE) of Fe on a MgO(100) substrate. LEED measurements revealed a (?2x?2)R45 reconstruction pattern as has already been reported in the literature. The surface structure on an atomic scale was studied by LEIS. The sample surface was bombarded with 3 or 6 keV Ar+ ions in a grazing-angle geometry, and azimuthal scans of the yields of the recoiled Fe and O atoms emitted at scattering angles of 37 deg. and 53 deg. were measured. The scans were analyzed by performing computer simulations of the scattering and recoiling of atoms for a number of trial models. We confirm the presence of two mutually perpendicular structural domains at the surface of the films grown. Bulk Fe3O4 contains Fe atoms in tetrahedral and octahedral positions. The surface was found to be terminated by tetrahedral Fe atoms. Further details of the atomic arrangement and surface relaxation were studied

  12. Sustained magnetization oscillations in polyaniline-Fe3O4 nanocomposites.

    Science.gov (United States)

    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, ?-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

  13. Gold and silica-coated gold nanoparticles as thermographic labels for DNA detection.

    Science.gov (United States)

    Cerruti, Marta G; Sauthier, Marc; Leonard, Donovan; Liu, Dage; Duscher, Gerard; Feldheim, Daniel L; Franzen, Stefan

    2006-05-15

    The infrared emissivity of Au and silica-coated Au nanoparticles (Au NPs) deposited on indium tin oxide substrates was investigated. NPs were irradiated with laser light at a frequency close to the Au plasmon resonance band, and the blackbody radiation emitted as a result was monitored with an IR camera equipped with an InAs array detector. The differences in temperature before and after laser irradiation were recorded (T-jumps) and were found to be directly proportional to the number of particles present on the slide and to the laser power used in the experiment. Coating Au NPs with silica increased the measured T-jumps 2-5 times, depending on the thickness of the silica shell. This was in agreement with the observation that silica has a much higher IR emissivity than Au. Both Au and silica-coated Au NPs were then tested as labels for thermographic DNA detection. Target DNA concentrations as low as 100 pM were recorded when Au NPs were used as labels and as low as 10 pM when silica-coated Au NPs were used. PMID:16689528

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Due to the decoration of silver nano-particles, the inorganic magnetic composite particle shows excellent dielectric loss in the almost whole test frequency range and good magnetic loss at 2 GHz to 5 GHz, especially the particle also has infrared reflection characteristic. • The well-performed obstacle Ag/Fe3O4 particles will be expected to be used as electromagnetic shielding particles in multiband smoke agent to improve the IR and electromagnetic interference performance of the smoke screen

  15. New insight on optical and magnetic Fe3O4 nanoclusters promising for near infrared theranostic applications.

    Science.gov (United States)

    Huang, Chih-Chia; Chang, Po-Yang; Liu, Chien-Liang; Xu, Jia-Pu; Wu, Shu-Pao; Kuo, Wen-Chuan

    2015-08-01

    Extensive efforts have been devoted to the development of a new biophotonic system using near infrared (NIR) nano-agents for non-invasive cancer diagnosis and therapy. Here, we developed a simple synthesis reaction of ligands, hydrazine, and iron(ii) chloride to fabricate Fe3O4 cluster-structured nanoparticles (CNPs) with interesting NIR photonics and high magnetization (Ms: 98.3 emu g(-1) and proton relaxivity r2: 234.6 mM(-1) s(-1)). These Fe3O4 CNPs exhibited optical absorption and reflection over all wavelengths, showing a U-shape absorption band with a low absorbance at a range of 750-950 nm and a progressive evolution in the second near infrared region. Strengthening of the scattering effect by incubating Fe3O4 CNPs with HeLa cells was observed when optical contrast enhancement was performed in an optical coherence tomography (OCT) microscope system with a laser light source at 860 nm. Using a 1064 nm laser at a low power density (380 mW cm(-2)) to excite the Fe3O4 CNPs (375 ppm[Fe]) led to a rise in the water temperature from 25 °C to 58 °C within 10 min. Finally, we present the first example of magnetomotive OCT cellular imaging combined with enhanced photothermal therapy using Fe3O4 CNPs and applying a magnetic field, which is promising for preclinical and clinical trials in the future. PMID:26151814

  16. Synthesis and Characterization of Rice Straw/Fe3O4 Nanocomposites by a Quick Precipitation Method

    Directory of Open Access Journals (Sweden)

    Katayoon Kalantari

    2013-06-01

    Full Text Available Small sized magnetite iron oxide nanoparticles (Fe3O4-NPs with were successfully synthesized on the surface of rice straw using the quick precipitation method in the absence of any heat treatment. Ferric chloride (FeCl3·6H2O, ferrous chloride (FeCl2·4H2O, sodium hydroxide (NaOH and urea (CH4N2O were used as Fe3O4-NPs precursors, reducing agent and stabilizer, respectively. The rice straw fibers were dispersed in deionized water, and then urea was added to the suspension, after that ferric and ferrous chloride were added to this mixture and stirred. After the absorption of iron ions on the surface layer of the fibers, the ions were reduced with NaOH by a quick precipitation method. The reaction was carried out under N2 gas. The mean diameter and standard deviation of metal oxide NPs synthesized in rice straw/Fe3O4 nanocomposites (NCs were 9.93 ± 2.42 nm. The prepared rice straw/Fe3O4-NCS were characterized using powder X-ray diffraction (PXRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy dispersive X-ray fluorescence (EDXF and Fourier transforms infrared spectroscopy (FT?IR. The rice straw/Fe3O4-NCs prepared by this method have magnetic properties.

  17. Preparation of graphene-Fe3O4 nanocomposites using Fe3+ ion-containing magnetic ionic liquid

    International Nuclear Information System (INIS)

    Graphene-Fe3O4 (GN-Fe3O4) magnetic nanocomposites were prepared, GN-coated magnetic ionic liquid (MIL) as its precursors, which were used as both a magnetic resource and solvent. The method has proved to be valuable for the Fe3O4 nanoparticles (NPs) well dispersed in the solution through strong interactions with GN, which are of interest because of their stability and chemical properties. In the process, strong interactions creates a condition for uniform dispersion in GN and [BMIm]FeCl4 (MIL) solution, and accelerate the formation of Fe3O4 NPs. A transmission electron microscopy image has shown that the as-formed Fe3O4 NPs with a diameter as small as 5–7 nm were deposited on GN sheets. Furthermore, the final material showed a superior properties than conventional method, which can be ascribed to the fact that [BMIm]FeCl4 plays a vital role in the process of producing small NPs size

  18. Improved electrochemical performance of porous Fe3O4/carbon core/shell nanorods as an anode for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: ? We prepared porous Fe3O4/C core/shell nanorods by a facile hydrothermal method using porous Fe2O3 nanorods as the precursor. ? The Fe3O4/C nanorods are homogenously coated by an amorphous carbon layer. ? The Fe3O4/C nanorod electrode shows high capacity and good cycle stability, as well as enhanced rate performance. - Abstract: Porous Fe3O4/C core/shell nanorods have been prepared by a facile hydrothermal method using porous Fe2O3 nanorods as the precursor and glucose as the carbon source. The Fe3O4/C nanorods possess a uniform size with 50–80 nm in diameter and 300–500 nm in length, and are homogenously coated by amorphous carbon layer. The porous nanorods greatly increase the electrical contact, thus facilitating the Li-ion and electron transportation, and enhancing the reactivity of the electrode. Also, the carbon layer can effectively limit the volume expansion and detachment of Fe3O4, and thus increase its structure stability during cycling. In the context of lithium storage behavior, the Fe3O4/C nanorod electrode shows high capacity and good cycle stability, as well as enhanced rate performance. After 50 cycles, the reversible capacity of the porous Fe3O4/C nanorods is 762.1 mAh g?1 at 0.1 C and 597.2 mAh g?1 at 0.5 C, much higher than that of ?-Fe2O3 nanorods (276.4 mAh g?1) and Fe3O4 nanoparticles (307.9 mAh g?1). At a high rate of 1 C, the specific capacity of Fe3O4/C nanorods is still as high as 630.1 mAh g?1.

  19. Synthesis and characterization of heteropolytungstate-ionic liquid supported on the surface of silica coated magnetite nanoparticles

    Science.gov (United States)

    Bagheri, M.; Masteri-Farahani, M.; Ghorbani, M.

    2013-02-01

    Silica coated magnetic nanoparticles supported ionic liquid, IL-SCMNPs, was prepared by covalent attachment of chloropropyl silyl groups and reacted with 1-methyl imidazole on the surface of the silica coated magnetic nanoparticles. Then, reaction of IL-SCMNPs with H3PW12O40 resulted in the preparation of heteropolytungstate-ionic liquid supported on the surface of silica coated magnetite nanoparticles, PW-IL-SCMNPs. The PW-IL-SCMNPs were characterized with different physicochemical methods such as Fourier transform Infrared and atomic absorption spectroscopies, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and thermogravimetric analyses. VSM analysis showed superparamagnetic properties of the materials and TEM and SEM analyses indicated the relatively uniform spherical nanoparticles with 20 nm average size. Finally, catalytic activity of the prepared PW-IL-SCMNPs was examined in the epoxidation of olefins with H2O2.

  20. Generation of BiFeO3-Fe3O4 Janus particles based on droplet microfluidic method

    Science.gov (United States)

    Li, Shasha; Yu, Xiaolei; You, Sujian; Cai, Bo; Liu, Chang; Liu, Huiqin; Liu, Wei; Guo, Shi-Shang; Zhao, Xing-Zhong

    2014-07-01

    We report on the feasible generation of BiFeO3-Fe3O4 Janus particles (JPs) based on droplet microfluidic method. Utilizing laminar flow and flow-focusing in microchannels, BiFeO3 and Fe3O4 nanoparticles were separately embedded in each hemisphere of one hydrogel particle. The size of the Janus particles showed favorable uniformity at micron scale and could be precisely controlled by flow rate regulation. The magnetism and ferroelectricity of the JPs were confirmed by magnetization and polarization measurements, indicating potential in multiferroic applications.

  1. SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF A Fe3O4/C12 CORE/SHELL NANOSYSTEM

    Directory of Open Access Journals (Sweden)

    Alexandru Mihai Grumezescu

    2012-06-01

    Full Text Available Lauric acid (C12 functionalized Fe3O4 nanoparticles were fabricated and characterized by XRD, FT-IR, DTA-TG and TEM. Lauric acid was used as a coating agent, controlling particle size and aggregation during the synthesis. XRD confirms the formation of magnetite. FT-IR evidenced the successful surface fictionalization with C12, peaks assigned to lauric acid being identified in the nanopowder. The obtained core/shell nanostructure consists of spherical particles of several nanometers long, according to TEM characterization. The interaction with HEp2 cell line proved that Fe3O4/C12 nanostructures are biocompatible.

  2. Synthesis and characterization of silica-coated nanoparticles of magnetite

    International Nuclear Information System (INIS)

    Magnetic nanoparticles coated with silica have been subjected of extensive, and, in many aspects, also intensive investigations because of their potential application in different technological fields, particularly in biomedicine. This work was conceived and is being carried out in two main parts: (1) synthesis of the ferrimagnetic nanoparticles, specifically magnetite, and (2) coating these particles with tetraethyl orthosilicate (TEOS). The nanosized magnetite sample was prepared by the reduction-precipitation and the nanomagnetite particles were coated by the sol-gel method, based on the hydrolysis of tetraethyl orthosilicate (TEOS). The so obtained materials were characterized with powder X-ray diffraction (XRD), FTIR spectroscopy, saturation magnetization measurements, and 57Fe Moessbauer spectroscopy at room temperature.

  3. Hybrid silica coated magnetic nanoparticles decorated with gold.

    Czech Academy of Sciences Publication Activity Database

    Koktan, Jakub; Kaman, Ond?ej; Veverka, Miroslav; Veverka, Pavel; Herynek, V.; ?ezanka, P.

    Dresden : Technische Universität, 2014. s. 98-98. [International Conference on the Scientific and Clinical Applications of Magnetic Carriers /10./. 10.06.2014-14.06.2014, Dresden] R&D Projects: GA MPO FR-TI3/521; GA ?R(CZ) GAP108/11/0807 Institutional support: RVO:68378271 Keywords : magnetic nanoparticles * cobalt-zinc ferrite * silica encapsulation * manganite perovskites * gold decoration Subject RIV: BM - Solid Matter Physics ; Magnetism

  4. Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Navjot, E-mail: navjot.dhindsa2989@gmail.com; Chudasama, Bhupendra, E-mail: bnchudasama@gmail.com [School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

    2015-05-15

    Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe{sub 3}O{sub 4}) nanoparticles and their coating with SiO{sub 2} is reported. Fe{sub 3}O{sub 4} nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4?nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

  5. Silica-coated nanocomposites of magnetic nanoparticles and quantum dots.

    Science.gov (United States)

    Yi, Dong Kee; Selvan, S Tamil; Lee, Su Seong; Papaefthymiou, Georgia C; Kundaliya, Darshan; Ying, Jackie Y

    2005-04-13

    Quantum dots (QDs) and magnetic nanoparticles (MPs) are of interest for biological imaging, drug targeting, and bioconjugation because of their unique optoelectronic and magnetic properties, respectively. To provide for water solubility and biocompatibility, QDs and MPs were encapsulated within a silica shell using a reverse microemulsion synthesis. The resulting SiO2/MP-QD nanocomposite particles present a unique combination of magnetic and optical properties. Their nonporous silica shell allows them to be surface modified for bioconjugation in various biomedical applications. PMID:15810812

  6. Theory of the Verwey transition in Fe3O4

    International Nuclear Information System (INIS)

    The metal-insulator transition in magnetite Fe3O4, the so-called Verwey transition, is re-investigated theoretically, motivated by recent experiments. We propose a scenario other than charge order, which has been considered to be its origin so far. We find that the orbital order in the t2g orbitals can make the system effectively one dimensional, so that the bond dimerization is induced due to the Peierls instability. Based on considerations of the elastic energy in the presence of such bond dimer, we argue that an anti-phase configuration of these bond dimer is realized in the actual compound

  7. Multifunctional Au-Fe3O4@MOF core-shell nanocomposite catalysts with controllable reactivity and magnetic recyclability

    Science.gov (United States)

    Ke, Fei; Wang, Luhuan; Zhu, Junfa

    2014-12-01

    The recovery and reuse of expensive catalysts are important in both heterogeneous and homogeneous catalysis due to economic and environmental reasons. This work reports a novel multifunctional magnetic core-shell gold catalyst which can be easily prepared and shows remarkable catalytic properties in the reduction of 4-nitrophenol. The novel Au-Fe3O4@metal-organic framework (MOF) catalyst consists of a superparamagnetic Au-Fe3O4 core and a porous MOF shell with controllable thickness. Small Au nanoparticles (NPs) of 3-5 nm are mainly sandwiched between the Fe3O4 core and the porous MOF shell. Catalytic studies show that the core-shell structured Au-Fe3O4@MOF catalyst has a much higher catalytic activity than other reported Au-based catalysts toward the reduction of 4-nitrophenol. Moreover, this catalyst can be easily recycled due to the presence of the superparamagnetic core. Therefore, compared to conventional catalysts used in the reduction of 4-nitrophenol, this porous MOF-based magnetic catalyst is green, cheap and promising for industrial applications.The recovery and reuse of expensive catalysts are important in both heterogeneous and homogeneous catalysis due to economic and environmental reasons. This work reports a novel multifunctional magnetic core-shell gold catalyst which can be easily prepared and shows remarkable catalytic properties in the reduction of 4-nitrophenol. The novel Au-Fe3O4@metal-organic framework (MOF) catalyst consists of a superparamagnetic Au-Fe3O4 core and a porous MOF shell with controllable thickness. Small Au nanoparticles (NPs) of 3-5 nm are mainly sandwiched between the Fe3O4 core and the porous MOF shell. Catalytic studies show that the core-shell structured Au-Fe3O4@MOF catalyst has a much higher catalytic activity than other reported Au-based catalysts toward the reduction of 4-nitrophenol. Moreover, this catalyst can be easily recycled due to the presence of the superparamagnetic core. Therefore, compared to conventional catalysts used in the reduction of 4-nitrophenol, this porous MOF-based magnetic catalyst is green, cheap and promising for industrial applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05421k

  8. Cleavable ester linked magnetic nanoparticles for labeling of solvent exposed primary amine groups of peptides/proteins

    Science.gov (United States)

    In order to study the solvent exposed lysine residues of peptides/proteins, we previously reported disulfide linked N-hydrosuccinimide ester modified silica coated iron oxide magnetic nanoparticles (NHS-SS-SiO2@Fe3O4 MNPs). The presence of a disulfide bond in the linker limits the use of disulfide r...

  9. Core/shell fluorescent magnetic silica-coated composite nanoparticles for bioconjugation

    International Nuclear Information System (INIS)

    A new class of highly fluorescent, photostable, and magnetic core/shell nanoparticles has been synthesized from a reverse microemulsion method. The obtained bifunctional nanocomposites were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectrometry, photoluminescence (PL) spectrometry, and fluorescence microscopy in a magnetic field. To further improve their biocompatibility, the silica-coated nanoparticles were functionalized with amino groups. The fluorescent magnetic composite nanoparticles (FMCNPs) had a typical diameter of 50 ± 5 nm and a saturation magnetization of 3.21 emu g-1 at room temperature, and exhibited strong excitonic photoluminescence. Through activation with glutaraldehyde, the FMCNPs were successfully conjugated with goat anti-mouse immunoglobin G (GM IgG), and the bioactivity and binding specificity of the as-prepared FMCNPs-GM IgG were confirmed via immunofluorescence assays, commonly used in bioanalysis. So they are potentially useful for many applications in biolabelling, imaging, drug targeting, bioseparation and bioassays

  10. Sol-gel derived silica/chitosan/Fe3O4 nanocomposite for direct electrochemistry and hydrogen peroxide biosensing

    Science.gov (United States)

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

    2015-01-01

    A novel strategy to fabricate hydrogen peroxide third generation biosensor has been developed from sol-gel of silica/chitosan (SC) organic-inorganic hybrid material assimilated with iron oxide magnetic nanoparticles (Fe3O4). The large surface area of Fe3O4 and porous morphology of the SC composite facilitates a high loading of horseradish peroxidase (HRP). Moreover, the entrapped enzyme preserves its conformation and biofunctionality. The fabrication of hydrogen peroxide biosensor has been carried out by drop casting of the SC/F/HRP nanocomposite on glassy carbon electrode (GCE) for study of direct electrochemistry. The x-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) confirms the phase purity and particle size of as-synthesized Fe3O4 nanoparticles, respectively. The nanocomposite was characterized by UV-vis spectroscopy, fluorescence spectroscopy and Fourier transform infrared (FTIR) for the characteristic structure and conformation of enzyme. The surface topographies of the nanocomposite thin films were investigated by scanning electron microscopy (SEM). Dynamic light scattering (DLS) was used to determine the particle size distribution. The electrostatic interactions of the SC composite with Fe3O4 nanoparticles were studied by the zeta potential measurement. Electrochemical impedance spectroscopy (EIS) of the SC/F/HRP/GCE electrode displays Fe3O4 nanoparticles as an excellent candidate for electron transfer. The SC/F/HRP/GCE exhibited a pair of well-defined quasi reversible cyclic voltammetry peaks due to the redox couple of HRP-heme Fe (III)/Fe (II) in pH 7.0 potassium phosphate buffer. The biosensor was employed to detect H2O2 with linear range of 5 ?M to 40 ?M and detection limit of 5 ?M. The sensor displays excellent selectivity, sensitivity, good reproducibility and long term stability.

  11. Constructing magnetic polyaniline/metal hybrid nanostructures using polyaniline/Fe3O4 composite hollow spheres as supports

    International Nuclear Information System (INIS)

    Polyaniline (PANI)/Fe3O4 composite hollow spheres have been successfully synthesized in one step using sulfonated polystyrene (PS) spheres as templates. The magnetic PANI hollow spheres were used as supports for noble metal nanoparticles (NPs) such as Au and Pd. The morphology, composition and magnetic properties of the resulting products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma (ICP) atomic spectra and vibrating sample magnetometer. The catalytic activity of magnetic PANI/Au composite shells on the oxidation of dopamine was investigated by cyclic voltammetry. The obtained results provide our product with a practical application for the detection of dopamine. On the other hand, the catalytic activity of magnetic PANI/Pd composite shells on the reduction of 4-nitroaniline was investigated by spectroscopic methods and compared with Pd/C catalyst which was already widely used in industrial production. - Graphical abstract: TEM image of PANI/Fe3O4 hollow spheres which can be used as supports for a variety of catalysts such as noble metal nanoparticles. Based on the unique properties of polyaniline hollow spheres and Fe3O4 NPs, we designed the synthesis of polyaniline/Fe3O4 NPs composite hollow spheres as supports for catalysts such as noble metal NPs. As a result, the obtained composites exhibit enhanced catalytic activities and can be easily separated from reaction mixture by using an NdFeB permanent magnet.

  12. MAPLE Fabricated Fe3O4@Cinnamomum verum Antimicrobial Surfaces for Improved Gastrostomy Tubes

    Directory of Open Access Journals (Sweden)

    Alina Georgiana Anghel

    2014-06-01

    Full Text Available 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.

  13. A convenient two-step bottom-up approach for developing Au/Fe3O4 nanocomposites with useful optical and magnetic properties

    International Nuclear Information System (INIS)

    Graphical abstract: Au/Fe3O4 nanocomposites were successfully synthesized using a two-step bottom up approach under co-precipitation followed by solvothermal synthesis without using capping agents or additives. TEM results indicate that nanocomposites with less agglomeration and high monodispersion can be obtained even in the absence of additives or capping ligands. - Highlights: • Au/Fe3O4 nanocomposites without using additives, mediator or capping ligands. • Surface morphology study reveals the uniform AuNPs coating in the nanocomposites. • Soft ferromagnetic behavior with larger Ms values is observed at room temperature. - Abstract: A convenient two-step bottom-up approach is reported for the preparation of Au/Fe3O4 nanocomposites. The synthesis of Fe3O4 was achieved by co-precipitation method and rapid synthesis procedure was adopted for forming Au nanoparticles. The solutions containing the Fe3O4 and Au nanoparticles were mixed in two different ratios and then solvothermally treated to obtain the Au/Fe3O4 nanocomposites. The structural and optical properties of the nanocomposites were investigated by powder X-ray diffraction and optical absorption spectroscopic techniques. The field emission scanning electron microscopy pictures illustrate the surface morphology of the as-prepared nanocomposites. The energy dispersive X-ray analysis spectrum was taken to estimate the exact percentage of elemental composition of the nanopowder. The transmission electron microscopy analysis of the nanocomposites confirmed the presence and morphology of the Au and Fe3O4 nanoparticles. The Au/Fe3O4 nanocomposites were found to exhibit soft ferromagnetic behavior

  14. Synthesis and self-assembly of silica-coated anisotropic gold nanoparticle films

    Science.gov (United States)

    Wang, Chungang; Ma, Zhanfang; Su, Zhongmin

    2006-04-01

    Silica-coated anisotropic gold nanoparticles (Au@SiO2), including rod- and 'dogbone'-like outlines with different aspect ratios, have been prepared using an improved Stöber method. The obtained Au@SiO2 have a pure silica surface for straightforward and rapid self-assembly onto poly(4-vinylpyridine) (PVP) functionalized quartz substrates. The large-scale assemblies exhibit highly reversible optical changes that can be observed spectroscopically or with the naked eye when repeatedly cycled between a dry and wet process. The relationship among the optical properties of two-dimensional assemblies, the aspect ratio and shape of the gold nanoparticles and the environmental refractive index is also investigated.

  15. A simple way to prepare Au@polypyrrole/Fe3O4 hollow capsules with high stability and their application in catalytic reduction of methylene blue dye

    Science.gov (United States)

    Yao, Tongjie; Cui, Tieyu; Wang, Hao; Xu, Linxu; Cui, Fang; Wu, Jie

    2014-06-01

    Metal nanoparticles are promising catalysts for dye degradation in treating wastewater despite the challenges of recycling and stability. In this study, we have introduced a simple way to prepare Au@polypyrrole (PPy)/Fe3O4 catalysts with Au nanoparticles embedded in a PPy/Fe3O4 capsule shell. The PPy/Fe3O4 capsule shell used as a support was constructed in one-step, which not only dramatically simplified the preparation process, but also easily controlled the magnetic properties of the catalysts through adjusting the dosage of FeCl2.4H2O. The component Au nanoparticles could catalyze the reduction of methylene blue dye with NaBH4 as a reducing agent and the reaction rate constant was calculated through the pseudo-first-order reaction equation. The Fe3O4 nanoparticles permitted quick recycling of the catalysts with a magnet due to their room-temperature superparamagnetic properties; therefore, the catalysts exhibited good reusability. In addition to catalytic activity and reusability, stability is also an important property for catalysts. Because both Au and Fe3O4 nanoparticles were wrapped in the PPy shell, compared with precursor polystyrene/Au composites and bare Fe3O4 nanoparticles, the stability of Au@PPy/Fe3O4 hollow capsules was greatly enhanced. Since the current method is simple and flexible to create recyclable catalysts with high stability, it would promote the practicability of metal nanoparticle catalysts in industrial polluted water treatment.Metal nanoparticles are promising catalysts for dye degradation in treating wastewater despite the challenges of recycling and stability. In this study, we have introduced a simple way to prepare Au@polypyrrole (PPy)/Fe3O4 catalysts with Au nanoparticles embedded in a PPy/Fe3O4 capsule shell. The PPy/Fe3O4 capsule shell used as a support was constructed in one-step, which not only dramatically simplified the preparation process, but also easily controlled the magnetic properties of the catalysts through adjusting the dosage of FeCl2.4H2O. The component Au nanoparticles could catalyze the reduction of methylene blue dye with NaBH4 as a reducing agent and the reaction rate constant was calculated through the pseudo-first-order reaction equation. The Fe3O4 nanoparticles permitted quick recycling of the catalysts with a magnet due to their room-temperature superparamagnetic properties; therefore, the catalysts exhibited good reusability. In addition to catalytic activity and reusability, stability is also an important property for catalysts. Because both Au and Fe3O4 nanoparticles were wrapped in the PPy shell, compared with precursor polystyrene/Au composites and bare Fe3O4 nanoparticles, the stability of Au@PPy/Fe3O4 hollow capsules was greatly enhanced. Since the current method is simple and flexible to create recyclable catalysts with high stability, it would promote the practicability of metal nanoparticle catalysts in industrial polluted water treatment. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00023d

  16. Verwey transition in epitaxial Fe3O4 films

    International Nuclear Information System (INIS)

    Thin magnetite films grown on cleaved MgO (100) substrates were studied by in-situ conversion electron Moessbauer spectroscopy (CEMS) in the temperature range of 80 K - 300 K. The film growth was monitored by low energy electron diffraction revealing a perfect epitaxy in the whole thickness range from 430 nm down to 3 nm. CEMS measurements proved an ideal magnetite stoichiometry of the 430 nm thick film reflected both in the hyperfine pattern and in the Verwey transition. The thinner films shoved strong deviation from the bulk properties, which was attributed to the modification of composition at the MgO/Fe3O4 interface, at which a magnesium rich phase is supposed based on CEM spectra. This phase, which was not observed previously, could be detected thanks to highly sensitive low-temperature measurements. (author)

  17. Metallization of magnetite (Fe3O4) under high pressure

    International Nuclear Information System (INIS)

    Electrical resistivity measurements have been made on a good qualified single crystalline magnetite (Fe3O4) at temperatures from 300 down to 3.0 K under pressure up to 10 GPa. A steep change in resistivity at the Verwey transition temperature has been observed at pressure below 6.5 GPa, which shows a quite distinct result reported in prior work. Moreover, the Verwey transition temperature has been found to decrease nonlinearly with increasing pressure and it disappears at around 8 GPa. Above 8 GPa magnetite exhibits metallic behavior. The residual-resistivity ratio of the metallic state is observed to be more than 350. This finding of a metallic ground state in magnetite provides insight into the understanding of the Verwey transition in magnetite. [copyright] 2001 American Institute of Physics

  18. A new method to prepare water based Fe3O4 ferrofluid with high stabilization

    Science.gov (United States)

    Guo, Tongxiao; Bian, Xiufang; Yang, Chuncheng

    2015-11-01

    A new method to prepare water based Fe3O4 ferrofluid with high stabilization has been reported in this paper. Oleic acid/ polyethylene glycol 4000 (PEG 4000)/agar/oleic acid have been used as surfactants and added to the fluid one after another. X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS) method, Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) have been used to characterize the structure, component and morphology of magnetic nanoparticles, respectively. We have observed the microstructure of chain-like (or stick-like) structure under applied magnetic field, which composes of several nanoparticles in the width direction and hundreds of nanoparticles in the length direction. Vibrating sample magnetometer (VSM) and Gouy magnetic balance (GMB) have been used to measure the magnetic properties and stability of the ferrofluid. The result shows that the magnetic nanoparticles have high saturation magnetization and the ferrofluid has high stability under magnetic and gravitational field.

  19. Label-free detection of aflatoxin M1 with electrochemical Fe3O4/polyaniline-based aptasensor

    International Nuclear Information System (INIS)

    The selective detection of ultratrace amounts of aflatoxin M1 (AFM1) is extremely important for food safety since it is the most toxic mycotoxin class that is allowed to be present on cow milk with strictly low regulatory levels. In this work, Fe3O4 incorporated polyaniline (Fe3O4/PANi) film has been polymerized on interdigitated electrode (IDE) as sensitive film for AFM1 electrochemical biosensor. The immobilized aptamers as an affinity capture reagent and magnetic nanoparticles for signal amplification element have been employed in the sensing platform. Label-free and direct detection of the aptamer-AFM1 on Fe3O4/PANi interface were performed via electrochemical signal change, acquired by cyclic and square wave voltammetries. With a simplified strategy, this electrochemical aptasensor shows a good sensitivity to AFM1 in the range of 6–60 ng·L?1, with the detection limit of 1.98 ng·L?1. The results open up the path for designing cost effective aptasensors for other biomedical applications. Highlights: ? Label-free detection of the aptamer-AFM1 on Fe3O4/PANi interface ? Electrochemical aptasensor with a good sensitivity to AFM1 in the range of 6–60 ng·L?1, with detection limit of 1.98 ng·L?1 ? Advantages over other analytical techniques in terms of label free format, sensitivity, stability and analysis time

  20. Bio-based hyperbranched polyurethane/Fe3O4 nanocomposites: smart antibacterial biomaterials for biomedical devices and implants

    International Nuclear Information System (INIS)

    The fabrication of a smart magnetically controllable bio-based polymeric nanocomposite (NC) has immense potential in the biomedical domain. In this context, magneto-thermoresponsive sunflower oil modified hyperbranched polyurethane (HBPU)/Fe3O4 NCs with different wt.% of magnetic nanoparticles (Fe3O4) were prepared by an in situ polymerization technique. Fourier-transform infrared, x-ray diffraction, vibrating sample magnetometer, scanning electron microscope, transmission electron microscope, thermal analysis and differential scanning calorimetric were used to analyze various physico-chemical structural attributes of the prepared NC. The results showed good interfacial interactions between HBPU and well-dispersed superparamagnetic Fe3O4, with an average diameter of 7.65 nm. The incorporation of Fe3O4 in HBPU significantly improved the thermo-mechanical properties along with the shape-memory behavior, antibacterial activity, biocompatibility as well as biodegradability in comparison to the pristine system. The cytocompatibility of the degraded products of the NC was also verified by in vitro hemolytic activity and MTT assay. In addition, the in vivo biocompatibility and non-immunological behavior, as tested in Wistar rats after subcutaneous implantation, show promising signs for the NC to be used as antibacterial biomaterial for biomedical device and implant applications. (paper)

  1. Ubbelohde viscometer measurement of water-based Fe3O4 magnetic fluid prepared by coprecipitation

    International Nuclear Information System (INIS)

    Fe3O4 nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid. - Highlights: • Fe3O4 nanoparticles were prepared using co-precipitation and coated by sodium dodecyl benzene sulfonate to obtain water-based magnetic fluid. • The viscosity of different magnetic fluids was measured using an Ubbelohde viscometer. • The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity of magnetic fluids were studied

  2. Nano-scale Au supported on Fe3O4: characterization and application in the catalytic treatment of 2,4-dichlorophenol

    Science.gov (United States)

    Gómez-Quero, Santiago; Cárdenas-Lizana, Fernando; Keane, Mark A.

    2012-07-01

    Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe3O4 have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on ?-Fe2O3 with subsequent temperature-programmed reduction at 673 K (Au/Fe3O4-step); (ii) direct deposition of Au on Fe3O4 (Au/Fe3O4-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe3O4-dir relative to Au/Fe3O4-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe2O3. Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe3O4-step delivered a two-fold higher rate (2 × 10-4 molCl h-1 mAu-2) when compared with Au/Fe3O4-dir. This unprecedented selectivity response is attributed to activation of the ortho-C-Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.

  3. Dendrimer-Assisted Formation of Fe3 O4 /Au Nanocomposite Particles for Targeted Dual Mode CT/MR Imaging of Tumors.

    Science.gov (United States)

    Cai, Hongdong; Li, Kangan; Li, Jingchao; Wen, Shihui; Chen, Qian; Shen, Mingwu; Zheng, Linfeng; Zhang, Guixiang; Shi, Xiangyang

    2015-09-01

    A unique dendrimer-assisted approach is reported to create Fe3 O4 /Au nanocomposite particles (NCPs) for targeted dual mode computed tomography/magnetic resonance (CT/MR) imaging of tumors. In this approach, preformed Fe3 O4 nanoparticles (NPs) are assembled with multilayers of poly(?-glutamic acid) (PGA)/poly(l-lysine)/PGA/folic acid (FA)-modified dendrimer-entrapped gold nanoparticles via a layer-by-layer self-assembly technique. The interlayers are crosslinked via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide chemistry, the assembled Au core NPs are then used as seed particles for subsequent seed-mediated growth of Au shells via iterative Au salt reduction process, and subsequent acetylation of the remaining amines of dendrimers leads to the formation of Fe3 O4 /Aun .Ac-FA NCPs with a tunable molar ratio of Au/Fe3 O4 . It is shown that the Fe3 O4 /Aun. Ac-FA NCPs at an optimized Au/Fe3 O4 molar ratio of 2.02 display a relatively high R2 relaxivity (92.67 × 10(-3) M(-1) s(-1) ) and good X-ray attenuation property, and are cytocompatible and hemocompatible in the given concentration range. Importantly, with the FA-mediated targeting, the Fe3 O4 /Aun. Ac-FA NCPs are able to be specifically uptaken by cancer cells overexpressing FA receptors, and be used as an efficient nanoprobe for targeted dual mode CT/MR imaging of a xenografted tumor model. With the versatile dendrimer chemistry, the developed Fe3 O4 /Au NCPs may be differently functionalized, thereby providing a unique platform for diagnosis and therapy of different biological systems. PMID:26061810

  4. Nano-scale Au supported on Fe3O4: characterization and application in the catalytic treatment of 2,4-dichlorophenol

    International Nuclear Information System (INIS)

    Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe3O4 have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on ?-Fe2O3 with subsequent temperature-programmed reduction at 673 K (Au/Fe3O4-step); (ii) direct deposition of Au on Fe3O4 (Au/Fe3O4-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe3O4-dir relative to Au/Fe3O4-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe2O3. Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe3O4-step delivered a two-fold higher rate (2 × 10?4 molCl h?1 mAu?2) when compared with Au/Fe3O4-dir. This unprecedented selectivity response is attributed to activation of the ortho-C–Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.

  5. Inorganic-organic elastomer nanocomposites from integrated ellipsoidal silica-coated hematite nanoparticles as crosslinking agents

    International Nuclear Information System (INIS)

    We report on the synthesis of nanocomposites with integrated ellipsoidal silica-coated hematite (SCH) spindle type nanoparticles which can act as crosslinking agents within an elastomeric matrix. Influence of the surface chemistry of the hematite, leading either to dispersed particles or crosslinked particles to the elastomer matrix, was studied via swelling, scattering and microscopy experiments. It appeared that without surface modification the SCH particles aggregate and act as defects whereas the surface modified SCH particles increase the crosslinking density and thus reduce the swelling properties of the nanocomposite in good solvent conditions. For the first time, inorganic SCH particles can be easily dispersed into a polymer network avoiding aggregation and enhancing the properties of the resulting inorganic-organic elastomer nanocomposite (IOEN).

  6. Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

    Directory of Open Access Journals (Sweden)

    2010-03-01

    Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

  7. Synthesis, structure and electromagnetic properties of mesoporous Fe3O4 aerogels by sol–gel method

    International Nuclear Information System (INIS)

    Highlights: • Fe3O4 aerogels possess quite low density and large specific surface area. • The porous Fe3O4 aerogels show superparamagnetism and high saturation magnetization. • We study the influences of concentration, molar ratios of reactants and calcinations on the textural and magnetic properties. • The porous material with electromagnetic properties can be a microwave absorbent. - Abstract: The Fe3O4 aerogels have been prepared by the sol–gel method and subsequent supercritical drying with CO2, FeCl3·6H2O, FeCl2·4H2O and propylene oxide was used as precursor and gelling accelerator, respectively. The result from XRD indicated that the aerogels were composed of nano-crystals. XPS was employed to further characterize the structure of products and confirmed the existence of Fe and O. SEM and TEM showed a fine microstructure of the as-prepared aerogels with three dimensional network, and the skeletons of aerogels were consist of interconnected nanoparticles. The Fe3O4 aerogels also possessed quite low density (0.249–0.393 m2 g?1), large specific surface area (60.26–330.20 m2 g?1) and superior saturation magnetization (14.64–52.28 emu g?1). Moreover, the textural and magnetic properties of the aerogels could be controlled by solution concentration, molar ratio of propylene oxide (PO) to Fe3+ and calcination temperature. The fabricated Fe3O4 aerogels exhibited certain electromagnetic properties in the frequency range of 2–18 GHz, and the maximum value of tan ?e and tan ?m is 0.07 and 0.27, respectively

  8. Silica-coated Gd(DOTA)-loaded protein nanoparticles enable magnetic resonance imaging of macrophages

    Science.gov (United States)

    Bruckman, Michael A.; Randolph, Lauren N.; Gulati, Neetu M.; Stewart, Phoebe L.; Steinmetz, Nicole F.

    2015-01-01

    The molecular imaging of in vivo targets allows non-invasive disease diagnosis. Nanoparticles offer a promising platform for molecular imaging because they can deliver large payloads of imaging reagents to the site of disease. Magnetic resonance imaging (MRI) is often preferred for clinical diagnosis because it uses non-ionizing radiation and offers both high spatial resolution and excellent penetration. We have explored the use of plant viruses as the basis of for MRI contrast reagents, specifically Tobacco mosaic virus (TMV), which can assemble to form either stiff rods or spheres. We loaded TMV particles with paramagnetic Gd ions, increasing the ionic relaxivity compared to free Gd ions. The loaded TMV particles were then coated with silica maintaining high relaxivities. Interestingly, we found that when Gd(DOTA) was loaded into the interior channel of TMV and the exterior was coated with silica, the T1 relaxivities increased by three-fold from 10.9 mM?1 s?1 to 29.7 mM?1s?1 at 60 MHz compared to uncoated Gd-loaded TMV. To test the performance of the contrast agents in a biological setting, we focused on interactions with macrophages because the active or passive targeting of immune cells is a popular strategy to investigate the cellular components involved in disease progression associated with inflammation. In vitro assays and phantom MRI experiments indicate efficient targeting and imaging of macrophages, enhanced contrast-to-noise ratio was observed by shape-engineering (SNP > TMV) and silica-coating (Si-TMV/SNP > TMV/SNP). Because plant viruses are in the food chain, antibodies may be prevalent in the population. Therefore we investigated whether the silica-coating could prevent antibody recognition; indeed our data indicate that mineralization can be used as a stealth coating option to reduce clearance. Therefore, we conclude that the silica-coated protein-based contrast agent may provide an interesting candidate material for further investigation for in vivo delineation of disease through macrophage imaging.

  9. Fabrication of silica coated Al2O3 nanoparticles via a fast and facile route utilizing microwave irradiation

    International Nuclear Information System (INIS)

    Highlights: ? MW irradiation resulted in a fast coating of the Al2O3 nanoparticles within 2 min. ? The uniform heating produced by the MW method resulted in a uniform coating of the nanoparticles. ? The coating of Al2O3 nanoparticles with silica improves their dispersibility. - Abstract: A facile, simple and rapid method based on microwave irradiation for preparing silica coated alumina (?-Al2O3) nanoparticles is presented. Microwave heating resulted in a thin but homogenous coverage of silica on the ?-Al2O3 nanoparticles surface within a very short time. The structure of the non-coated and silica coated ?-Al2O3 particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. Changes in the shape of the zeta potential pH dependence corresponding to formation of silica layers were accompanied by changes in the FT-IR and XPS spectra. HR-TEM images of the silica coated particles revealed that the ?-Al2O3 were coated with silica with typical diameters of about 3-4 nm. The coating of ?-Al2O3 nanoparticles with silica improves their dispersibility as indicated by the zeta potential measurements.

  10. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications.

    Science.gov (United States)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-03-01

    Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min(-1) and turnover frequency is 5457 h(-1). PMID:25665732

  11. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    Science.gov (United States)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-03-01

    Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min?1 and turnover frequency is 5457 h?1.

  12. Magnetic solid-phase extraction based on mesoporous silica-coated magnetic nanoparticles for analysis of oral antidiabetic drugs in human plasma

    International Nuclear Information System (INIS)

    In the present work, magnetic nanoparticles embedded into mesoporous silica were prepared in two steps: first, magnetite was synthesized by oxidation–precipitation method, and next, the magnetic nanoparticles were coated with mesoporous silica by using nonionic block copolymer surfactants as structure-directing agents. The mesoporous SiO2-coated Fe3O4 samples were functionalized using octadecyltrimethoxysilane as silanizing agent. The pure and functionalized silica nanoparticles were physicochemically and morphologically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resultant magnetic silica nanoparticles were applied as sorbents for magnetic solid-phase extraction (MSPE) of oral antidiabetic drugs in human plasma. Our results revealed that the magnetite nanoparticles were completely coated by well-ordered mesoporous silica with free pores and stable pore walls, and that the structural and magnetic properties of the Fe3O4 nanoparticles were preserved in the applied synthesis route. Indeed, the sorbent material was capable of extracting the antidiabetic drugs from human plasma, being useful for the sample preparation in biological matrices. - Highlights: • SBA-15/Fe3O4 was synthesized and functionalized with octadecyltrimethoxysilane. • Magnetite nanoparticles were completely coated by well-ordered mesoporous silica. • The samples were used as sorbent for magnetic solid-phase extraction (MSPE). • The sorbent material was capable of extracting drugs from human plasma. • The extraction ability makes the material a candidate to be employed as MSPE

  13. SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF A Fe3O4/C12 CORE/SHELL NANOSYSTEM

    OpenAIRE

    Alexandru Mihai Grumezescu; Ecaterina Andronescu; Anton Ficai; Dan Eduard Mihaiescu; Bogdan Stefan Vasile; Coralia Bleotu

    2012-01-01

    Lauric acid (C12) functionalized Fe3O4 nanoparticles were fabricated and characterized by XRD, FT-IR, DTA-TG and TEM. Lauric acid was used as a coating agent, controlling particle size and aggregation during the synthesis. XRD confirms the formation of magnetite. FT-IR evidenced the successful surface fictionalization with C12, peaks assigned to lauric acid being identified in the nanopowder. The obtained core/shell nanostructure consists of spherical particles of several nanometers long, acc...

  14. Magnetorheological Payne effect in bidisperse MR fluids containing Fe nanorods and Fe3O4 nanospheres: a dynamic rheological study

    OpenAIRE

    Arief, Injamamul; P. K. Mukhopadhyay

    2015-01-01

    The spherical Fe3O4 with 300 nm in diameter was synthesized by typical thermal decomposition of Fe (III) organo-metallic precursor in polyol and polyacrylic acid. Fe-nanorods were prepared by reducing Fe (III) nitrate in presence of polyol-hydrazine-CTAB. Morphology and magnetic characterization of the nanoparticles were performed by ESEM, XRD and VSM studies. We performed detailed non-linear magnetorheological properties of three MR fluids (10 vol%) containing isotropic Fe3...

  15. Silica coating magnetic nanoparticle-based silver enhancement immunoassay for rapid electrical detection of ricin toxin.

    Science.gov (United States)

    Zhuang, Jie; Cheng, Tao; Gao, Lizeng; Luo, Yongting; Ren, Quan; Lu, Di; Tang, Fangqiong; Ren, Xiangling; Yang, Dongling; Feng, Jing; Zhu, Jingdong; Yan, Xiyun

    2010-01-01

    We developed a novel silica coating magnetic nanoparticle-based silver enhancement immunoassay (SEIA) for ricin toxin (RT) rapid electrical detection using interdigitated array microelectrodes (IDAMs) as electrodes. This novel system was developed by taking advantage of the separation and enrichment properties of magnetic nanoparticles (MNPs) and the catalytic properties of gold nanoparticles (GNPs). In this system, MNPs labeled with anti-ricin A chain antibody 6A6 were used to capture ricin and GNPs labeled with anti-ricin B chain antibody 7G7 were used as detectors. To enhance the electrical signal, the catalytic properties of GNPs were used to promote silver reduction. In the presence of ricin, a sandwich structure was formed which could be separated by a magnetic field. The sandwich complex was then transferred to IDAMs. The silver particles bridged the IDAM gaps and gave rise to an enhancing electrical signal that was detected by conductivity measurements. The results showed that the sensitivity of the SEIA for ricin electrical detection was five times greater than that of conventional colorimetric sandwich ELISA. Once the antibody used for detection was coated on the plates or MNPs, our system was three times more rapid than colorimetric sandwich ELISA. This rapid and sensitive detection system provides promising new potential for ricin detection. PMID:19631678

  16. Optical properties of silica-coated Y{sub 2}O{sub 3}:Er,Yb nanoparticles in the presence of polyvinylpyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Kunio, E-mail: fujii.k.ab@m.titech.ac.jp; Kitamoto, Yoshitaka; Hara, Masahiko; Odawara, Osamu; Wada, Hiroyuki

    2014-12-15

    The optical properties of polyvinylpyrrolidone (PVP)-adsorbed and silica-coated Y{sub 2}O{sub 3}:Er,Yb nanoparticles produced by using PVP were studied for potential bio-applications of upconversion nanoparticles. We utilized PVP to better disperse Y{sub 2}O{sub 3}:Er,Yb nanoparticles in solution and to prepare silica-coated Y{sub 2}O{sub 3}:Er,Yb nanoparticles. The fluorescent intensity of PVP-adsorbed Y{sub 2}O{sub 3}:Er,Yb nanoparticles was 1.25 times higher than non-adsorbed Y{sub 2}O{sub 3}:Er,Yb nanoparticles, which was probably due to surface defects in Y{sub 2}O{sub 3}:Er,Yb nanoparticles being covered by the PVP. However, the fluorescent intensity of silica-coated Y{sub 2}O{sub 3}:Er,Yb nanoparticles decreased as silica layer thickness increased. This could be ascribed to the higher vibrational energy of PVP than that of the silica structure. Therefore, the optimum silica layer thickness is important in bio-applications to avoid deterioration of the optical properties of Y{sub 2}O{sub 3}:Er,Yb nanoparticles. - Highlights: • We prepared the silica-coated upconversion nanoparticles by using PVP. • We showed that PVP played an important role in coating nanoparticles. • PL intensity of silica-coated nanoparticles decreased as silica layer thickness increased.

  17. Controlled surface functionalization of silica-coated magnetic nanoparticles with terminal amino and carboxyl groups

    International Nuclear Information System (INIS)

    General and versatile methods for the functionalization of superparamagnetic, silica-coated, maghemite nanoparticles by surface amino and/or carboxyl groups have been established. The nanoparticles were synthesized using co-precipitation from aqueous solutions and coated with a thin layer of silica using the hydrolysis and condensation of tetraethoxysilane (TEOS). For the amino functionalization, 3-(2-aminoethylamino)propylmethyldimethoxysilane (APMS) was grafted onto the nanoparticle surfaces in their aqueous suspensions. The grafting process was followed by measurements of the ?-potential and a determination of the concentration of the surface amino groups with conductometric titrations. The surface concentration of the amino groups could be varied by increasing the amount of APMS in the grafting process up to approximately 2.3 –NH2 groups per nm2. The carboxyl functionalization was obtained in two ways: (i) by a ring-opening linker elongation reaction of the surface amines at the functionalized nanoparticles with succinic anhydride (SA) in non-aqueous medium, and (ii) by reacting the APMS and SA first, followed by grafting of the carboxyl-terminated reagent onto the nanoparticle surfaces. Using the first method, the SA only reacted with the terminal primary amino groups (–NH2) of the surface-grafted APMS molecules. Infra-red spectroscopy (ATR FTIR) and mass spectrometry (HRMS) showed that the second method enables the bonding of up to two SA molecules per one APMS molecule, since the SA reacted with both the primary (–NH2) and secondary amino (–NH–) groups of the APMS molecule. When using both methods, the ratio between the surface amino and carboxyl groups can be controlled.

  18. Nano-sized Fe3O4/carbon as anode material for lithium ion battery

    International Nuclear Information System (INIS)

    Nano-sized Fe3O4/carbon material is prepared via a simple citric-nitrate combustion method combining with a hydrothermal carbon coating technique. The synthesized Fe3O4/carbon composite shows a high reversible specific capacity (ca. 850 mAh g?1 at 100 mA g?1; ca. 600 mAh g?1 at 500 mA g?1), good rate-capability as well as superior cycling stability as anode for lithium-ion batteries. The ameliorated electrochemical performance of Fe3O4/carbon electrode is associated to the nano-sized particle feature and the continuous carbon coating layer. The former provides short lithium-ion/electron diffusion distance, while the latter enables the fast electron transport pathways. Besides, the carbon layer can act as a protective component to prevent the active particle Fe3O4 from aggregation and pulverization during the charge/discharge processes. - Highlights: • Nano-sized Fe3O4/C was prepared by a simple citric-nitrate combustion process. • Fe3O4/C particles show core–shell structure. • Fe3O4/C powder displays high specific capacity and good cycling stability. • Fe3O4/C composite exhibits a superior rate-capability

  19. Covalent bridging of surface functionalized Fe3O4 and YPO4:Eu nanostructures for simultaneous imaging and therapy.

    Science.gov (United States)

    Barick, K C; Sharma, Anusha; Shetake, Neena G; Ningthoujam, R S; Vatsa, R K; Babu, P D; Pandey, B N; Hassan, P A

    2015-08-11

    Magnetic luminescent hybrid nanostructures (MLHN) have received a great deal of attention due to their potential biomedical applications such as thermal therapy, magnetic resonance imaging, drug delivery and intracellular imaging. We report the development of bifunctional Fe3O4 decorated YPO4:Eu hybrid nanostructures by covalent bridging of carboxyl PEGylated Fe3O4 and amine functionalized YPO4:Eu particles. The surface functionalization of individual nanoparticulates as well as their successful conjugation was evident from Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), zeta-potential and transmission electron microscopy (TEM) studies. X-ray diffraction (XRD) analysis reveals the formation of highly crystalline hybrid nanostructures. TEM micrographs clearly show the binding/anchoring of 10 nm Fe3O4 nanoparticles onto the surface of 100-150 nm rice grain shaped YPO4:Eu nanostructures. These MLHN show good colloidal stability, magnetic field responsivity and self-heating capacity under an external AC magnetic field. The induction heating studies confirmed localized heating of MLHN under an AC magnetic field with a high specific absorption rate. Photoluminescence spectroscopy and fluorescence microscopy results show optical imaging capability of MLHN. Furthermore, successful internalization of these MLHN in the cells and their cellular imaging ability are confirmed from confocal microscopy imaging. Specifically, the hybrid nanostructure provides an excellent platform to integrate luminescent and magnetic materials into one single entity that can be used as a potential tool for hyperthermia treatment of cancer and cellular imaging. PMID:26215789

  20. Magnetically separable Fe3O4@SiO2@TiO2-Ag microspheres with well-designed nanostructure and enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Graphical abstract: An effective route has been developed to synthesize magnetic Fe3O4@SiO2@TiO2-Ag microspheres with well-defined core–shell nanostructure and enhanced photocatalytic activity. -- Highlights: • Controllable synthesis of core–shell structured Fe3O4@SiO2@TiO2-Ag magnetic nanocomposite. • The unique nanostructure of Fe3O4@SiO2@TiO2-Ag can improve the total photocatalytic performance. • An easy magnetically separable and recoverable process. -- Abstract: Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical–chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron–hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application

  1. CMCTS stabilized Fe3O4 particles with extremely low toxicity as highly efficient near-infrared photothermal agents for in vivo tumor ablation

    Science.gov (United States)

    Shen, Song; Kong, Fenfen; Guo, Xiaomeng; Wu, Lin; Shen, Haijun; Xie, Meng; Wang, Xinshi; Jin, Yi; Ge, Yanru

    2013-08-01

    With the potential uses of photothermal therapy (PTT) in cancer treatment with excellent efficacy, and the growing concerns about the nanotoxicity of hyperthermia agents such as carbon nanotubes and gold-based nanomaterials, the importance of searching for a biocompatible hyperthermia agent cannot be emphasized too much. In this work, a novel promising hyperthermia agent employing magnetic Fe3O4 particles with fairly low toxicity was proposed. This hyperthermia agent showed rapid heat generation under NIR irradiation. After modification with carboxymethyl chitosan (CMCTS), the obtained Fe3O4@CMCTS particles could disperse stably in PBS and serum without any aggregation. The modification of CMCTS could decrease the adsorption of bovine serum albumin (BSA) and improve the cellular uptake. In a comparative study with hollow gold nanospheres (HAuNS), Fe3O4@CMCTS particles exhibited a comparable photothermal effect and fairly low cytotoxicity. The in vivo magnetic resonance (MR) images of mice revealed that by attaching a magnet to the tumor, Fe3O4@CMCTS particles accumulated in the tumor after intravenous injection and showed a low distribution in the liver. After being exposed to a 808 nm laser for 5 min at a low power density of 1.5 W cm-2, the tumors on Fe3O4@CMCTS-injected mice reached a temperature of ~52 °C and were completely destroyed. Thus, a kind of multifunctional magnetic nanoparticle with extremely low toxicity and a simple structure for simultaneous MR imaging, targeted drug delivery and photothermal therapy can be easily fabricated.With the potential uses of photothermal therapy (PTT) in cancer treatment with excellent efficacy, and the growing concerns about the nanotoxicity of hyperthermia agents such as carbon nanotubes and gold-based nanomaterials, the importance of searching for a biocompatible hyperthermia agent cannot be emphasized too much. In this work, a novel promising hyperthermia agent employing magnetic Fe3O4 particles with fairly low toxicity was proposed. This hyperthermia agent showed rapid heat generation under NIR irradiation. After modification with carboxymethyl chitosan (CMCTS), the obtained Fe3O4@CMCTS particles could disperse stably in PBS and serum without any aggregation. The modification of CMCTS could decrease the adsorption of bovine serum albumin (BSA) and improve the cellular uptake. In a comparative study with hollow gold nanospheres (HAuNS), Fe3O4@CMCTS particles exhibited a comparable photothermal effect and fairly low cytotoxicity. The in vivo magnetic resonance (MR) images of mice revealed that by attaching a magnet to the tumor, Fe3O4@CMCTS particles accumulated in the tumor after intravenous injection and showed a low distribution in the liver. After being exposed to a 808 nm laser for 5 min at a low power density of 1.5 W cm-2, the tumors on Fe3O4@CMCTS-injected mice reached a temperature of ~52 °C and were completely destroyed. Thus, a kind of multifunctional magnetic nanoparticle with extremely low toxicity and a simple structure for simultaneous MR imaging, targeted drug delivery and photothermal therapy can be easily fabricated. Electronic supplementary information (ESI) available: The size distribution and the XPS spectra of PEGylated Fe3O4 and Fe3O4@CMCTS, the linear fitting curve of absorbance-concentration plots for Fe3O4@CMCTS particles, photothermal cytotoxicity of KB cells. See DOI: 10.1039/c3nr01447a

  2. Magnetic fluid: Comparative study of nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil using Moessbauer spectroscopy with a high velocity resolution

    International Nuclear Information System (INIS)

    Comparative study of nanosized magnetite and magnetite suspended in Copaiba oil (biocompatible magnetic fluid) was made using Moessbauer spectroscopy with a high velocity resolution (spectra were measured in 4096 channels). The better fit of room temperature spectra was done using 15 sextets and 1 doublet employing different parameters while spectra measured at 90 K were better fitted using 15 sextets with different parameters. These component numbers were related to multi-domain structure and non-stoichiometry of magnetite. Observed differences of magnetic hyperfine fields and relative areas of spectral components for nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil may be related to the effect of surface interactions of Fe3O4 and polar molecules of Copaiba oil.

  3. Magnetic fluid: Comparative study of nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil using Mössbauer spectroscopy with a high velocity resolution

    Science.gov (United States)

    Oshtrakh, M. I.; Rodriguez, A. F. R.; Semionkin, V. A.; Santos, J. G.; Milder, O. B.; Silveira, L. B.; Marmolejo, E. M.; Ushakov, M. V.; de Souza-Parise, M.; Morais, P. C.

    2010-03-01

    Comparative study of nanosized magnetite and magnetite suspended in Copaiba oil (biocompatible magnetic fluid) was made using Mössbauer spectroscopy with a high velocity resolution (spectra were measured in 4096 channels). The better fit of room temperature spectra was done using 15 sextets and 1 doublet employing different parameters while spectra measured at 90 K were better fitted using 15 sextets with different parameters. These component numbers were related to multi-domain structure and non-stoichiometry of magnetite. Observed differences of magnetic hyperfine fields and relative areas of spectral components for nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil may be related to the effect of surface interactions of Fe3O4 and polar molecules of Copaiba oil.

  4. Biocompatibility of hydrophilic silica-coated CdTe quantum dots and magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Ruan Jing

    2011-01-01

    Full Text Available Abstract Fluorescent magnetic nanoparticles exhibit great application prospects in biomedical engineering. Herein, we reported the effects of hydrophilic silica-coated CdTe quantum dots and magnetic nanoparticles (FMNPs on human embryonic kidney 293 (HEK293 cells and mice with the aim of investigating their biocompatibility. FMNPs with 150 nm in diameter were prepared, and characterized by high-resolution transmission electron microscopy and photoluminescence (PL spectra and magnetometer. HEK293 cells were cultured with different doses of FMNPs (20, 50, and 100? g/ml for 1-4 days. Cell viability and adhesion ability were analyzed by CCK8 method and Western blotting. 30 mice were randomly divided into three groups, and were, respectively, injected via tail vein with 20, 60, and 100 ?g FMNPs, and then were, respectively, raised for 1, 7, and 30 days, then their lifespan, important organs, and blood biochemical parameters were analyzed. Results show that the prepared water-soluble FMNPs had high fluorescent and magnetic properties, less than 50 ?g/ml of FMNPs exhibited good biocompatibility to HEK293 cells, the cell viability, and adhesion ability were similar to the control HEK293 cells. FMNPs primarily accumulated in those organs such as lung, liver, and spleen. Lung exposed to FMNPs displayed a dose-dependent inflammatory response, blood biochemical parameters such as white blood cell count (WBC, alanine aminotransferase (ALT, and aspartate aminotransferase (AST, displayed significant increase when the FMNPs were injected into mice at dose of 100?g. In conclusion, FMNPs exhibit good biocompatibility to cells under the dose of less than 50 ?g/ml, and to mice under the dose of less than 2mg/kg body weight. The FMNPs' biocompatibility must be considered when FMNPs are used for in vivo diagnosis and therapy.

  5. Fe3O4–Au and Fe2O3–Au Hybrid Nanorods: Layer-by-Layer Assembly Synthesis and Their Magnetic and Optical Properties

    OpenAIRE

    Zhu, Hongliang; Zhu, Enze; Ou, Guofu; Gao, Linhui; Chen, Jianjun

    2010-01-01

    A layer-by-layer technique has been developed to synthesize FeOOH–Au hybrid nanorods that can be transformed into Fe2O3–Au and Fe3O4–Au hybrid nanorods via controllable annealing process. The homogenous deposition of Au nanoparticles onto the surface of FeOOH nanorods can be attributed to the strong electrostatic attraction between metal ions and polyelectrolyte-modified FeOOH nanorods. The annealing atmosphere controls the phase transformation from FeOOH–Au to Fe3O4–Au and ?-Fe2O3–Au. Moreov...

  6. Space charge inhibition effect of nano-Fe3O4 on improvement of impulse breakdown voltage of transformer oil based on improved Kerr optic measurements

    Science.gov (United States)

    Yang, Qing; Yu, Fei; Sima, Wenxia; Zahn, Markus

    2015-09-01

    Transformer oil-based nanofluids (NFs) with 0.03 g/L Fe3O4 nanoparticle content exhibit 11.2% higher positive impulse breakdown voltage levels than pure transformer oils. To study the effects of the Fe3O4 nanoparticles on the space charge in transformer oil and to explain why the nano-modified transformer oil exhibits improved impulse breakdown voltage characteristics, the traditional Kerr electro-optic field mapping technique is improved by increasing the length of the parallel-plate electrodes and by using a photodetector array as a high light sensitivity device. The space charge distributions of pure transformer oil and of NFs containing Fe3O4 nanoparticles can be measured using the improved Kerr electro-optic field mapping technique. Test results indicate a significant reduction in space charge density in the transformer oil-based NFs with the Fe3O4 nanoparticles. The fast electrons are captured by the nanoparticles and are converted into slow-charged particles in the NFs, which then reduce the space charge density and result in a more uniform electric field distribution. Streamer propagation in the NFs is also obstructed, and the breakdown strengths of the NFs under impulse voltage conditions are also improved.

  7. LNA aptamer based multi-modal, Fe3O4-saturated lactoferrin (Fe3O4-bLf) nanocarriers for triple positive (EpCAM, CD133, CD44) colon tumor targeting and NIR, MRI and CT imaging.

    Science.gov (United States)

    Roy, Kislay; Kanwar, Rupinder K; Kanwar, Jagat R

    2015-12-01

    This is the first ever attempt to combine anti-cancer therapeutic effects of emerging anticancer biodrug bovine lactoferrin (bLf), and multimodal imaging efficacy of Fe3O4 nanoparticles (NPs) together, as a saturated Fe3O4-bLf. For cancer stem cell specific uptake of nanocapsules/nanocarriers (NCs), Fe3O4-bLf was encapsulated in alginate enclosed chitosan coated calcium phosphate (AEC-CP) NCs targeted (Tar) with locked nucleic acid (LNA) modified aptamers against epithelial cell adhesion molecule (EpCAM) and nucleolin markers. The nanoformulation was fed orally to mice injected with triple positive (EpCAM, CD133, CD44) sorted colon cancer stem cells in the xenograft cancer stem cell mice model. The complete regression of tumor was observed in 70% of mice fed on non-targeted (NT) NCs, with 30% mice showing tumor recurrence after 30 days, while only 10% mice fed with Tar NCs showed tumor recurrence indicating a significantly higher survival rate. From tumor tissue analyses of 35 apoptotic markers, 55 angiogenesis markers, 40 cytokines, 15 stem cell markers and gene expression studies of important signaling molecules, it was revealed that the anti-cancer mechanism of Fe3O4-bLf was intervened through TRAIL, Fas, Fas-associated protein with death domain (FADD) mediated phosphorylation of p53, to induce activation of second mitochondria-derived activator of caspases (SMAC)/DIABLO (inhibiting survivin) and mitochondrial depolarization leading to release of cytochrome C. Induction of apoptosis was observed by inhibition of the Akt pathway and activation of cytokines released from monocytes/macrophages and dendritic cells (interleukin (IL) 27, keratinocyte chemoattractant (KC)). On the other hand, the recurrence of tumor in AEC-CP-Fe3O4-bLf NCs fed mice mainly occurred due to activation of alternative pathways such as mitogen-activated protein kinases (MAPK)/extracellular signal-regulated kinases (ERK) and Wnt signaling leading to an increase in expression of survivin, survivin splice variant (survivin 2B) and other anti-apoptotic proteins Bad, Bcl-2 and XIAP. Apart from the promising anti-cancer efficacy and the exceptional tumor targeting ability observed by multimodal imaging using near-infrared (NIR) imaging, magnetic resonance imaging (MRI) and computerized tomographic (CT) techniques, these NCs also maintained the immunomodulatory benefits of bLf as they were able to increase the RBC, hemoglobin, iron calcium and zinc levels in mice. PMID:26318819

  8. Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application

    Science.gov (United States)

    Karamipour, Sh.; Sadjadi, M. S.; Farhadyar, N.

    2015-09-01

    Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au3+ with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used L-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of L-cysteine and folic acid to Fe3O4@Au nanoparticles.

  9. Size Dependence of Metal-Insulator Transition in Stoichiometric Fe3O4 Nanocrystals

    OpenAIRE

    Lee, Jisoo; Kwon, Soon Gu; Park, Je-Geun; Hyeon, Taeghwan

    2015-01-01

    Magnetite (Fe3O4) is one of the most actively studied materials with a famous metal-insulator transition (MIT), so-called the Verwey transition at around 123 K. Despite the recent progress in synthesis and characterization of Fe3O4 nanocrystals (NCs), it is still an open question how the Verwey transition changes on a nanometer scale. We herein report the systematic studies on size dependence of the Verwey transition of stoichiometric Fe3O4 NCs. We have successfully synthesi...

  10. Dark Field Observation of Fe3O4-?Fe2O3 Multiphase Films

    OpenAIRE

    Yamazaki, Y.; Namikawa, T.; Koizumi, Y.; Meguro, S.

    1997-01-01

    We investigated the phase separation of cubic and tetragonal systems in Fe3O4-?Fe2O3 intermediate thin films. An Fe thin film of 50 nm was deposited on a SiO2 substrate using an electron beam evaporator at room temperature. The film was oxidized to ?Fe2O3 at 400°C in air, then the film was reduced to Fe3O4 at 320°C in methanol vapor. The gradual oxidation of the Fe3O4 film to ?Fe2O3 film at 240°C was terminated when the coercive force of the film increased more than 1000 Oe at an intermediate...

  11. Spin motive force induced in Fe3O4 thin films with negative spin polarization

    Science.gov (United States)

    Nagata, Masaki; Moriyama, Takahiro; Tanabe, Kenji; Tanaka, Kensho; Chiba, Daichi; Ohe, Jun-ichiro; Hisamatsu, Yuki; Niizeki, Tomohiko; Yanagihara, Hideto; Kita, Eiji; Ono, Teruo

    2015-12-01

    Spin motive force (SMF) is induced by a time and spatial derivative of magnetizations and is dependent on spin polarization. We compare the SMF in FeNi with positive spin polarization with that in a magnetite (Fe3O4) with negative spin polarization. We observe the SMF induced by a nonuniform ferromagnetic resonance in Fe3O4 and find that the SMF in Fe3O4 is opposite to that in FeNi. This result originates from the negative spin polarization of Fe3O4. Our clear observation of the SMF depending on the sign of the spin polarization agrees well with the framework of the SMF theory.

  12. Polaronic effects on the Verwey transition in Fe3O4

    International Nuclear Information System (INIS)

    On the basis of a band model for the extra B-site electrons in Fe3O4 a detailed estimate of the relevant small-polaron (SP) parameters of Fe3O4 is given taking into account the interatomic Coulomb interaction, the formation of SP due to the interaction with phonons, and the SP correlation. The isotope and pressure effects on the Verwey transition temperature are explained as SP effects. (author)

  13. Superparamagnetic Fe3O4 nanocrystals@graphene composites for energy storage devices

    OpenAIRE

    B. Li(CPPM, Aix-Marseille Université and CNRS/IN2P3, Marseille, France); Cao, H; Shao, J; Qu, M (Mike); Warner, JH

    2011-01-01

    In this paper, a Fe3O4 nanocrystals@graphene composite (FGC) was synthesized via a chemical deposition method by using graphene oxide as a precursor. We also investigate the structures, physicochemical properties and applications of FGCs, involving superparamagnetic performance, and use as supercapacitors and lithium ion battery (LIBs). The results showed that the Fe3O4 NCs were formed and incorporated onto the surface of the graphene sheets. The composite material FGC with a micrometre scale...

  14. In vitro activity of the new water-dispersible Fe3O4@usnic acid nanostructure against planktonic and sessile bacterial cells

    International Nuclear Information System (INIS)

    A new water-dispersible nanostructure based on magnetite (Fe3O4) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe3O4@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcusaureus (S.aureus),Enterococcus faecalis (E.faecalis) and Gram-negative Escherichia coli (E.coli),Pseudomonasaeruginosa (P.aeruginosa) reference strains. Concerning the influence of Fe3O4@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E.faecalis and E.coli, as compared with the Fe3O4 control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S.aureus and E.faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E.coli biofilm development, only at high concentrations, while for P.aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe3O4@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains

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

    Science.gov (United States)

    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.

  16. Spectroscopic investigations of graphene derivatives coated with nanostructured Fe3O4

    Science.gov (United States)

    Hatel, Rhizlane; Khenfouch, Mohammed; Baitoul, Mimouna; Maaza, Malik

    2015-09-01

    Nanocomposites based on graphene oxide (GO)-iron oxide Fe3O4 and reduced GO (rGO)-Fe3O4 were synthesized by using a simple hydrothermal method, and their morphology and structure are investigated aiming to get an insight into on how the removal of oxygen group affects the dispersibility of Fe3O4 on GO layers. Transmission electron microscopy observations showed that nanostructured Fe3O4 with diameters of about 6-11 nm and lengths of 46-56 nm evenly spread over the GO/rGO sheets decorating their surface. The X-ray diffraction patterns prove the presence of the Fe3O4 on the surface of GO/rGO nanosheets leading to their disaggregation in addition to an in situ reduction of GO. Fourier transform infrared and Raman spectroscopic studies provide evidence of donor-acceptor interaction between the Fe3O4 and GO/rGO which can display additional functionalities of these heterostructures and thus will have great advantage for potential applications.

  17. Multifunctional Fe3O4/graphene oxide nanocomposites for magnetic resonance imaging and drug delivery

    International Nuclear Information System (INIS)

    It is significant interest in developing novel multifunctional nanocarrier with complementary roles in recent years. Magnetic Fe3O4/graphene oxide (GO) nanocomposites with integrated characteristics of magnetic resonance imaging (MRI) and controlled drug delivery were prepared by an inverse co-precipitation method. The microstructure and physical properties of Fe3O4/GO nanocomposites were investigated by transmission electron microscope, wide-angle X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analyzer and superconducting quantum interference device magnetometer. The obtained nanocomposites exhibited superparamagnetic property with the saturation magnetization of 63.3 Am2 kg?1 at room temperature. In vitro MRI experiments revealed that Fe3O4/GO nanocomposites possessed an excellent MRI enhancement effect. 5-Fluorouracil (5-FU) as an anti-tumor model drug was loaded onto the surface of Fe3O4/GO nanocomposites. The drug loading capacity of this nanocarrier was as high as 0.37 mg mg?1 and the drug release behavior showed pH-dependence. The results suggested that the as-prepared Fe3O4/GO nanocomposites showed great potential as an effective multifunctional nanoplatform for MRI and controlled drug delivery. - Highlights: • Fe3O4/GO nanocomposites were prepared by inverse co-precipitation method. • Dual-functional characteristics with complimentary roles of MRI characteristic and drug delivery. • In vitro MRI: excellent MRI enhancement effect. • Drug delivery: high drug loading capacity and pH-sensitive controlled release

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

    Science.gov (United States)

    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.

  19. Enhanced lifetime characteristics in flexible polymer light-emitting devices by encapsulation of epoxy/silica-coated gold nanoparticles resin (ESGR)

    International Nuclear Information System (INIS)

    This paper reports the effects of a new multilayer encapsulation for the lifetime of flexible PLEDs on plastic substrate. The multilayer encapsulation consisted of a novel epoxy/silica-coated gold nanoparticles resin (ESGR) as the pre-encapsulation layer and a SiO2 layer as the encapsulation cap. The ESGR was prepared by mixing UV-curable epoxy resin and powders of silica-coated gold nanoparticles. The silica-coated gold nanoparticles is a necessity because the epoxy resin is not a good moisture barrier. The flexible PLEDs with multilayer encapsulation exhibited no dark spots after being stored for over 300 h at 25 deg. C and 60% relative humidity. Also, the operational half-luminance decay time of device was 1360 h, seven times longer than that of a device without encapsulation. These results confirmed that the multilayer encapsulation, which restricted the moisture that penetrated into the devices, could be applied to the encapsulation of flexible PLEDs.

  20. Fe3O4-citrate-curcumin: Promising conjugates for superoxide scavenging, tumor suppression and cancer hyperthermia

    Science.gov (United States)

    Kitture, Rohini; Ghosh, Sougata; Kulkarni, Parag; Liu, X. L.; Maity, Dipak; Patil, S. I.; Jun, Ding; Dushing, Yogesh; Laware, S. L.; Chopade, B. A.; Kale, S. N.

    2012-03-01

    Fe3O4 nanoparticles have been conjugated to curcumin (CU) molecules via a citrate (CA) linker (Fe-CA-CU) and have been explored for superoxide scavenging, tumor suppression, and cancer hyperthermia. The conjugation chemistry reveals that Fe3+ ions on the nanoparticle surface readily conjugates to the available carboxyl sites on the CA molecule, which further conjugates to CU at its central enol -OH group. As seen from the UV-vis spectroscopy, the therapeutically active chromophore group of CU, which is seen at 423 nm, was intact, ensuring the activity the molecule. Magnetization measurements showed good hysteresis curves of Fe3O4 and Fe-CA-CU, indicating the presence of magnetism after conjugation. The loading percentage of citrate-curcumin was seen to be ˜10% from the thermo-gravimetric analysis. The systems when subjected to radio-frequency fields of 240 KHz, were seen to get heated up. The Fe3O4 heating exhibited better slope (1 °C/s) as compared to the Fe-CA-CU system (˜0.7 °C/s) for a sample of concentration 10 mg/ml in average time of ˜20 s to reach the required hyperthermia threshold temperature of ˜45 °C. Tumor suppression studies were done using potato assay, which showed that while only CU showed 100% suppression in 7 days, it was about 89% by the Fe-CA-CU. Upon subjecting these systems to the superoxide anion scavenging assay and superoxide radical scavenging assay (riboflavin), it was observed that the activity was enhanced in the Fe-CA-CU to 40% (from 38% in only CU) and 100% (from 5.75% in only CU). These studies promise Fe-CA-CU as a good cancer hyperthermia-cum-tumor suppressant and antioxidant agent.

  1. Investigation of temperature dependent magnetic hyperthermia in Fe3O4 ferrofluids

    Science.gov (United States)

    Nemala, Humeshkar Bhaskar

    Magnetic nanoparticles (MNPs) of Fe3O4 and gamma-Fe2O3 have been exploited in the biomedical fields for imaging, targeted drug delivery and magnetic hyperthermia. Magnetic hyperthermia (MHT), the production of heat using ferrofluids, colloidal suspensions of MNPs, in an external AC magnetic field (amplitude, 100-500 Oe and frequency 50 kHz -1MHz), has been explored by many researchers, both in vitro and in vivo, as an alternative viable option to treat cancer. The heat energy generated by Neel and Brownian relaxation processes of the internal magnetic spins could be used to elevate local tissue temperature to about 46 ?C to arrest cancerous growth. MHT, due to its local nature of heating, when combined with other forms of treatment such as chemotherapy and/or radiation therapy, it could become an effective therapy for cancer treatment. The efficiency of heat production in MHT is quantified by specific absorption rate (SAR), defined as the power output per gram of the MNPs used. In this thesis, ferrofluids consisting of Fe3O4 MNPs of three different sizes (˜ 10 - 13 nm) coated with two different biocompatible surfactants, dextran and polyethylene glycol (PEG), have been investigated. The structural and magnetic characterization of the MNPs were done using XRD, TEM, and DC magnetization measurements. While XRD revealed the crystallite size, TEM provided the information about morphology and physical size distribution of the MNPs. Magnetic measurements of M-vs-H curves for ferrofluids provided information about the saturation magnetization (Ms) and magnetic core size distribution of MNPs. Using MHT measurements, the SAR has been studied as a function of temperature, taking into account the heat loss due to non-adiabatic nature of the experimental set-up. The observed SAR values have been interpreted using the theoretical framework of linear response theory (LRT). We found the SAR values depend on particle size distribution of MNPs, Ms (65-80 emu/g) and the magnetic anisotropy energy density (K: 12-20 KJ/m3), as well as the amplitude and frequency of the applied AC field (amplitude, 150-250 Oe and frequency, 180-380 kHz). In general, Ms and magnetic core diameter of MNPs increased with the increase in particle size. However, our detailed analysis of MHT data show that although SAR increased with the particle size, the polydispersity of the particles as well as the magnetic anisotropy energy density significantly affected the SAR values. Dextran and PEG coatings essentially yielded similar SAR values ~ 100 W/g using ferrofluids of Fe3O4 MNPs with an average crystallite size of 11.6 +/- 2.1 nm, in AC field of 245 Oe and 375 KHz.

  2. Manganese porphyrin immobilized on magnetite nanoparticles as a recoverable nanocatalyst for epoxidation of olefins

    International Nuclear Information System (INIS)

    Efficient epoxidation of alkenes catalysed by tetraphenylporphyrinatomanganese(III) chloride, [Mn(TPP)Cl], supported on silica coated magnetite nanoparticles, SiO2–Fe3O4, is reported. First, the SiO2–Fe3O4 nanoparticles were modified with triethoxysilylpropyl chloride and then with imidazole. In the final step, [Mn(TPP)Cl] was attached to the support via axial ligation. The prepared catalyst was characterized by elemental analysis, FT-IR and diffuses reflectance UV–vis spectroscopic methods, and scanning electron microscopy. This new heterogenized catalyst was used for efficient epoxidation of alkenes with NaIO4 at room temperature. The catalyst is of high reusability in the epoxidation reactions, in which it was reused several times without significant loss of its catalytic activity. - Highlights: • The [Mn(TPP)Cl] was supported on silica coated magnetic nanoparticles. • The [Mn(TPP)Cl@Im–SiO2–Fe3O4] heterogeneous catalyst was characterized. • The [Mn(TPP)Cl@Im–SiO2–Fe3O4]/NaIO4 catalytic system was used for alkene epoxidation. • The catalyst was efficient and reusable

  3. Deposition of nano Fe3O4@mZrO2 onto exfoliated graphite oxide sheets and its application for removal of amaranth

    Science.gov (United States)

    Jiang, Hualin; Chen, Pinghua; Zhang, Weibo; Luo, Shenglian; Luo, Xubiao; Au, Chaktong (Peter); Li, Menglin

    2014-10-01

    Herein we report a novel method to exfoliate graphite to thin structure by depositing nanoparticles. Graphite was oxidated to graphite oxide (GO), and then nano Fe3O4@mZrO2 was loaded and inserted between GO sheets as GO being reduced to reduced graphite oxide (rGO) in one step by hydro-thermal co-precipitation. As-obtained nanocomposite Fe3O4@mZrO2/rGO was characterized by SEM, TEM, AFM, FT-IR, BET, XRD, VSM and EDX techniques. The microscopic studies show the thickness of Fe3O4@mZrO2/rGO sheet is significant thinner than that of rGO sheet. Evidences indicate the presence of nano Fe3O4@mZrO2 effectively preserves rGO sheets from stacking and forming thick structure. Amaranth was used as a model contamination to investigate the adsorption ability of the nanocomposite due to its hazardness. It shows effective adsorption ability. Based on all the evidence shown in studies, a possible mechanism for the adsorbent composing and its amaranth adsorption was postulated.

  4. Raman, UV-Vis, and Wide Angle X-Ray Scattering Investigations on Polyvinylidene Fluoride - Fe3O4 Nanocomposites

    Science.gov (United States)

    Contreras, Jerry; Elamin, Ibrahim; Parsons, Jason; Chipara, Dorina M.; Hinthorne, James; Lozano, Karen; Chipara, Mircea

    2015-03-01

    Fe3O4 nanoparticles of about 75 nm from Nanostructured & Amorphous Materials, Inc. have been dispersed within the polyvinylidene fluoride (PVDF) by melt mixing. Nanocomposites with various weight fraction of nanofiller (0%, 0.2 %, 0.6 %, 1.2%, 2.4 %, 5.8 %, 12 %, 23 %, and 30 %) have been obtained and measured by Wide Angle X-Ray Scattering (WAXS, Bruker Discovery 8 with the Cu K ? radiation), Raman spectroscopy (Bruker Senterra confocal Raman microscope operating at 785 nm), and UV-Vis. Raman spectra indicated that alpha PVDF is the main crystalline component of the polymeric matrix and revealed a fast decay of the polymeric lines as the loading with iron oxide is increased. The Raman lines have been successfully fitted by an extended Breit-Wigner Fano lineshape. The effect of the nanofiller on the position, amplitude, and width of Raman lines is analyzed in detail. WAXS investigations confirmed the presence of magnetite. The effect of the loading with nanoparticles on the position, amplitude, and width of WAXS lines of Fe3O4 and PVDF are reported.

  5. Mesoporous Fe3O4/hydroxyapatite composite for targeted drug delivery

    International Nuclear Information System (INIS)

    Highlights: • Mesoporous Fe3O4/hydroxyapatite composite was synthesized by a simple, efficient and environmental friendly method. • The prepared material had a large surface area, high pore volume, and good magnetic separability. • DOX-loaded Fe3O4/hydroxyapatite composite exhibited surprising slow drug release behavior and pH-dependent behavior. - Abstract: In this contribution, we introduced a simple, efficient, and green method of preparing a mesoporous Fe3O4/hydroxyapatite (HA) composite. The as-prepared material had a large surface area, high pore volume, and good magnetic separability, which made it suitable for targeted drug delivery systems. The chemotherapeutic agent doxorubicin (DOX) was used to investigate the drug release behavior of Fe3O4/HA composite. The drug release profiles displayed a little burst effect and pH-dependent behavior. The release rate of DOX at pH 5.8 was larger than that at pH 7.4, which could be attributed to DOX protonation in acid medium. In addition, the released DOX concentrations remained at 0.83 and 1.39 ?g/ml at pH 7.4 and 5.8, respectively, which indicated slow, steady, and safe release rates. Therefore, the as-prepared Fe3O4/hydroxyapatite composite could be an efficient platform for targeted anticancer drug delivery

  6. Magnetic and transport properties of epitaxial Fe3O4 films grown at different oxygen pressure

    Science.gov (United States)

    Alraddadi, S.; Hines, W.; Yilmaz, T.; Gu, G. D.; McDannald, A.; Jain, M.; Sinkovic, B.

    2015-06-01

    The performance of spintronic devices depends critically on the ability to control the properties of high spin-polarization materials such as magnetite (Fe3O4) in thin films. In this work, the effect of oxygen pressure on the transport and magnetic properties of Fe3O4 thin films was extensively investigated. The 20 nm Fe3O4 films were grown on MgO (001) substrates using molecular beam epitaxy under different oxygen pressure. The quality of epitaxial Fe3O4 thin films was judged by observation of the Verwey transition and corroborated by x-ray photoemission spectroscopy (XPS). In particular, the resistivity measurements showed the Verwey transition to be as sharp as bulk magnetite, which has not been seen in previous studies for film thicknesses less than 30 nm. Therefore, this work provides insight for the growth of ultrathin magnetite films with high crystal quality and sharp Verwey transition. Furthermore, the magnitude of the magnetization change at the Verwey transition was observed to be sensitive to the oxygen pressure during film growth. These results are consistent with the XPS measurements and indicate a relative narrow range of optimal oxygen pressure for the formation of high quality thin magnetite films with electronic and magnetic properties close to bulk Fe3O4.

  7. Low temperature hydrothermal synthesis of octahedral Fe3O4 microcrystals

    International Nuclear Information System (INIS)

    Octahedral Fe3O4 crystals in the size range of 200-300 nm have been prepared with a high yield at a low temperature of 90 deg. C using a simple polyethylene glycol (PEG)-mediated hydrothermal approach. It is found that both PEG molecules and NaOH content are crucial for the formation of Fe3O4 octahedrons because of the selective adsorption of PEG molecules on the (1 1 1) planes of Fe3O4 at higher NaOH concentrations, delaying the crystal growth along the [1 1 1] axis. The formation mechanisms related to Fe3O4 nuclei, octahedral crystals, and their linear self-assembly structures are discussed. Magnetization measurements show that the Fe3O4 octahedrons have a relatively high magnetic saturation value of 85.5 emu g-1 and a coercive field of 118 Oe, which is ascribed to the high crystalline perfection and chain-like structures of the sample.

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

    Science.gov (United States)

    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

  9. Preparation of composite with silica-coated nanoparticles of iron oxide spinels for applications based on magnetically induced hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Angela L. [Federal University of Ouro Preto (UFOP), Department of Chemistry (Brazil); Fabris, Jose D., E-mail: jdfabris@ufmg.br [Federal University of Jequitinhonha and Mucuri Valleys (UFVJM) (Brazil); Pereira, Marcio C. [Federal University of Jequitinhonha and Mucuri Valleys (UFVJM), Institute of Science, Engineering and Technology (Brazil); Domingues, Rosana Z. [Federal University of Minas Gerais (UFMG), Department of Chemistry (Brazil); Ardisson, Jose D. [Development Center of Nuclear Technology (CNEN/CDTN), Laboratory of Applied Physics (Brazil)

    2013-04-15

    It is reported a novel method to prepare magnetic core (iron oxide spinels)-shell (silica) composites containing well-dispersed magnetic nanoparticles in aqueous solution. The synthetic process consists of two steps. In a first step, iron oxide nanoparticles obtained through co-precipitation are dispersed in an aqueous solution containing tetramethylammonium hydroxide; in a second step, particles of this sample are coated with silica, through hydrolyzation of tetraethyl orthosilicate. The intrinsic atomic structure and essential properties of the core-shell system were assessed with powder X-ray diffraction, Fourier transform infrared spectrometry, Moessbauer spectroscopy and transmission electron microscopy. The heat released by this ferrofluid under an AC-generated magnetic field was evaluated by following the temperature evolution under increasing magnetic field strengths. Results strongly indicate that this ferrofluid based on silica-coated iron oxide spinels is technologically a very promising material to be used in medical practices, in oncology.

  10. Half-metallic Fe3O4 thin films and their applications for spintronic devices

    International Nuclear Information System (INIS)

    Among various half-metallic materials, simple formation of half-metallic Fe3O4 thin films in our letter is highly desired and unavoidable in spintronic application. Half-metallic Fe3O4 thin films were prepared at room temperature using an rf-sputtering system specially integrated with an external rf-source. Our study is centered around a metallic oxide material of Fe3O4 film, which possesses a relatively simple crystallographic structure in comparison to other candidate materials. The structural and electrical properties gave shift and broadening effects to Verwey temperature at various powers. The magnetization could only be saturated when an 300 Oe field was applied along an easy axis of magnetization during growth. However, there was no sign of saturation up to 5 T under zero-field growth. (author)

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

    International Nuclear Information System (INIS)

    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

  12. Preparation and characterization of Fe3O4/polystyrene composite particles via inverse emulsion polymerization

    International Nuclear Information System (INIS)

    Superparamagnetic magnetite/polystyrene (PS) composite particles were prepared by inverse emulsion polymerization with water-based ferrofluid as dispersing phase and organic solvent and styrene (St) as continuous phase. The resultant brownish Fe3O4/PS emulsion showed magnetic behavior in an applied magnetic field. The obtained magnetic Fe3O4/PS microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The magnetic Fe3O4/PS microspheres with a diameter of 200 nm were observed. The results showed that magnetite particles were well encapsulated in PS and the composite particles have high magnetite contents, which were more than 15%. In addition, the influences of magnetic field intensity on the rheological properties of ferrofluids were investigated using a rotating rheometer.

  13. L-edge inner shell spectroscopy of nanostructured Fe3O4

    International Nuclear Information System (INIS)

    We have measured magnetic circular dichroism at the Fe L edge in samples of colloidal Fe3O4 and in Fe3O4 powder. The results for the colloid can be interpreted in terms of the model presented by Sette et al. for the dichroism of bulk Fe3O4. We notice a shift in the position of the Fe L3 line in the colloid with regard to the powder, which is however in the opposite direction as expected for a cluster. We observe a new structure in the dichroism of the colloid spectrum that could be cluster-specific, in spite of the fact that, for the cluster size of our colloids, the fraction of atoms at the surface of the cluster is not large

  14. Fe3O4–CNTs nanocomposites: Inorganic dispersant assisted hydrothermal synthesis and application in lithium ion batteries

    International Nuclear Information System (INIS)

    Fe3O4–CNTs nanocomposites with a particle size of ?80 nm have been synthesized through an organic-free hydrothermal synthesis strategy by using Sn(OH)62? as an inorganic dispersant, and served as anode materials of lithium ion batteries. Nano-sized and micro-sized Fe3O4 without CNTs have also been prepared for comparison. The cycle performances of the as-obtained Fe3O4 are highly size-dependent. The Fe3O4–CNTs nanocomposites can deliver reversible discharge capacity of ?700 mA h/g at a current density of 50 mA/g after 50 cycles. The discharge capacity of the micro-sized Fe3O4 decreased to 171 mA h/g after 50 cycles. Our work not only provides new insights into the inorganic dispersant assisted hydrothermal synthesis of metal oxides nanocrystals but also gives guidance for finding new nanocomposites as anode materials of lithium ion batteries. - Graphical abstract: Fe3O4–CNTs nanocomposites have been prepared through an inorganic dispersant assisted hydrothermal synthesis strategy, and served as anode materials of lithium ion batteries with enhanced performance. - Highlights: • Sn(OH)62? is a good inorganic dispersant for the hydrothermal synthesis of nano Fe3O4. • The cycle performances of nano Fe3O4 anode are much better than that of micro Fe3O4 anode. • Compositing CNTs can enhance the cycle performances of nano Fe3O4 anode

  15. [Low-temperature preparation of TiO2/PS/Fe3O4, and its photocatalytic activity and magnetic recovery].

    Science.gov (United States)

    Wang, Xue-jiao; Ren, Xue-chang; Nian, Juan-ni; Xiao, Ju-qian; Wang, Gang; Chang, Qing

    2012-08-01

    This study reports the fabrication of magnetically responsive titania catalyst, which consisted of a magnetic core surrounded by a titania shell. The magnetic core (oleic acid-modified Fe3O4 nanoparticles) was modified with polystyrene as inert isolating layer. The magnetic photocatalyst was prepared at low temperature (90 degrees C) and a neutral pH (about 7). The phase composition, morphology, surface properties and magnetic properties of the composite particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier infrared photometer (FT-IR) and vibrating sample magnetometer (VSM). The photocatalytic activity of the samples were determined by degradation of phenol and their recovery characteristics were determined by a self-regulating magnetic recycling equipment. The results illustrated that the mean diameter of anatase titanium dioxide synthesized at low temperature was 2-5 nm, the catalyst TiO2/PS/Fe3O4 [the molar ratio of the magnetic photocatalyst was n(TiO2): n(St): n(Fe3O4) = 60:2.5:1] had the structural integrity of shell/shell/core, and titanium dioxide was loaded firmly on the PS/FeO4 surface. The photocatalytic degradation of phenol followed first-order reaction kinetics and the reaction rate constant K of the TiO2/PS/Fe3O4 [n(TiO2): n(St): n (Fe3O4) = 60:2.5:1] was 0.0258, which was close to that of pure TiO2 (K = 0.0262). After 5 times recycling, the K value reduced only by 0.0034. The catalyst had a strong magnetic induction, and the average recovery rate reached 92%. The magnetic TiO2 photocatalyst prepared by this low-temperature hydrolysis method has a good application prospect. PMID:23213901

  16. CMCTS stabilized Fe3O4 particles with extremely low toxicity as highly efficient near-infrared photothermal agents for in vivo tumor ablation.

    Science.gov (United States)

    Shen, Song; Kong, Fenfen; Guo, Xiaomeng; Wu, Lin; Shen, Haijun; Xie, Meng; Wang, Xinshi; Jin, Yi; Ge, Yanru

    2013-09-01

    With the potential uses of photothermal therapy (PTT) in cancer treatment with excellent efficacy, and the growing concerns about the nanotoxicity of hyperthermia agents such as carbon nanotubes and gold-based nanomaterials, the importance of searching for a biocompatible hyperthermia agent cannot be emphasized too much. In this work, a novel promising hyperthermia agent employing magnetic Fe3O4 particles with fairly low toxicity was proposed. This hyperthermia agent showed rapid heat generation under NIR irradiation. After modification with carboxymethyl chitosan (CMCTS), the obtained Fe3O4@CMCTS particles could disperse stably in PBS and serum without any aggregation. The modification of CMCTS could decrease the adsorption of bovine serum albumin (BSA) and improve the cellular uptake. In a comparative study with hollow gold nanospheres (HAuNS), Fe3O4@CMCTS particles exhibited a comparable photothermal effect and fairly low cytotoxicity. The in vivo magnetic resonance (MR) images of mice revealed that by attaching a magnet to the tumor, Fe3O4@CMCTS particles accumulated in the tumor after intravenous injection and showed a low distribution in the liver. After being exposed to a 808 nm laser for 5 min at a low power density of 1.5 W cm(-2), the tumors on Fe3O4@CMCTS-injected mice reached a temperature of ~52 °C and were completely destroyed. Thus, a kind of multifunctional magnetic nanoparticle with extremely low toxicity and a simple structure for simultaneous MR imaging, targeted drug delivery and photothermal therapy can be easily fabricated. PMID:23873020

  17. Magnetotransport Properties across Verwey Transition in Fe3O4(111) Epitaxial Thin Films

    Science.gov (United States)

    Matsuzaki, Kosuke; Hosono, Hideo; Susaki, Tomofumi

    2013-07-01

    We have studied the magnetoresistance (MR) of high-quality Fe3O4 thin films across the Verwey transition temperature (TV). Different from unsaturated MR observed in many other Fe3O4 films, MR of the present film at a high magnetic field is almost independent of the field, consistent with the fully saturated magnetization. The MR at low field strongly depends on temperature and orientation around TV: While out-of-plane MR sharply decreases from ˜+7 to ˜-5%, in-plane MR abruptly increases from ˜-6 to ˜+3% on cooling across TV.

  18. Room-temperature growth of epitaxial Fe3O4 films by ion beam deposition

    International Nuclear Information System (INIS)

    Epitaxial and polycrystalline Fe3O4 films were grown on MgO (100) and Si (100) substrates, respectively, at room temperature by using reactive ion beam deposition. The MS value of epitaxial Fe3O4 films was around 310 emu/cm3, and was almost independent of thickness from 45 to 195 nm. The MS value of polycrystalline films showed significant thickness dependence, which might be attributed to the formation of the initial layer. The Verwey transition at 110 K was observed on 195 nm epitaxial films, and decreased significantly with decreasing thickness. The reduction of the Verwey temperature may be related to the residual strain in the film

  19. Structural and magnetic characterization of the lithiated iron oxide LixFe3O4

    OpenAIRE

    Fontcuberta i Griñó, Josep; Rodríguez, J; Pernet, Michel; Longworth, Gary; Goodenough, John B.

    1986-01-01

    The Rietveld profile?analysis method is used to investigate the x?ray diffraction pattern of lithiated Fe3O4. It is shown that, after exposure to air, pure magnetite coexists with a lithium?inserted LixFe3O4 phase. The Mössbauer spectra at 300 and 4.2 K have been used to estimate the lithium content of the sample, the pure magnetite concentration, and the iron distribution over the available 16c and 16d sites of the spinel structure. Magnetization measurements from 4.2 to 120 K with an extern...

  20. Synthesis and characterization of polypropiolate sodium (PPNa)-Fe3O4 nanocomposite

    International Nuclear Information System (INIS)

    Highlights: · Polypropiolate sodium (PPNa)-Fe3O4 nanocomposite was successfully synthesized by reflux route. · FT-IR, TGA and TEM analyses showed that the presence of PPNa onto the surface of Fe3O4 NP's. · Magnetization measurements revealed that (PPNa)-Fe3O4 nanocomposite has superparamagnetic properties at room temperature. · Magnetic core size, particle size and crystallite size are coinciding with each other. · It is pointed out that the a.c. conductivity of the nanocomposite studied here obeys the well-known power law of frequency in whi