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1

Ag-deposited silica-coated Fe3O4 magnetic nanoparticles catalyzed reduction of p-nitrophenol  

International Nuclear Information System (INIS)

In this paper, a novel approach was successfully developed for advanced catalyst Ag-deposited silica-coated Fe3O4 magnetic nanoparticles, which possess a silica coated magnetic core and growth active silver nanoparticles on the outer shell using n-butylamine as the reductant of AgNO3 in ethanol. The as-synthesized nanoparticles have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectra (FT-IR), vibration sample magnetometer (VSM), and have been exploited as a solid phase catalyst for the reduction of p-nitrophenol in the presence of NaBH4 by UV-vis spectrophotometry. The obtained products exhibited monodisperse and bifunctional with high magnetization and excellent catalytic activity towards p-nitrophenol reduction. As a result, the as-obtained nanoparticles showed high performance in catalytic reduction of p-nitrophenol to p-aminophenol with conversion of 95% within 14 min in the presence of an excess amount of NaBH4, convenient magnetic separability, as well as remained activity after recycled more than 6 times. The Fe3O4-SiO2-Ag functional nanostructure could hold great promise for various catalytic reactions.

2

Zincon-immobilized silica-coated magnetic Fe3O4 nanoparticles for solid-phase extraction and determination of trace lead in natural and drinking waters by graphite furnace atomic absorption spectrometry.  

Science.gov (United States)

A new protocol using zincon-immobilized silica-coated magnetic Fe(3)O(4) nanoparticles (Zincon-Si-MNPs) as solid-phase extraction (SPE) medium has been developed for the separation and preconcentration of trace lead in water. Various parameters such as pH, extraction time, concentration and volume of eluent, sample volume, and influence of co-existing ions have been investigated in order to establish the optimum conditions for the determination of lead in combination with graphite furnace atomic absorption spectrometry (GFAAS). The detection limit (LOD) of the proposed method for lead based on an enrichment factor of 200 was 10 ng L(-1). The relative standard deviations (RSDs, n=5) were 8.3%, 7.8% and 9.2%, respectively, at 5, 0.5 and 0.05 ng mL(-1) levels. This method has been successfully applied to the analysis of trace lead in natural and drinking water samples and the recoveries for the spiked samples were in the range of 84-104%. PMID:22608444

Jiang, Hong-mei; Yan, Zhong-peng; Zhao, Yue; Hu, Xin; Lian, Hong-zhen

2012-05-30

3

Surface controlled magnetic properties of Fe3O4 nanoparticles  

Science.gov (United States)

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

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

2013-02-01

4

Microwave Magnetic Permeability of Fe3O4 Nanoparticles  

International Nuclear Information System (INIS)

Well-dispersed Fe3O4 nanoparticles are synthesized via an oxidization method with NaNO2 as oxidant. The microwave magnetic properties of the composites are studied with different volume fractions of Fe3O4 nanoparticles. It is found that a lower volume fraction corresponds to a higher magnetic resonance frequency. This could be ascribed to the enhancement of exchange interaction with a weakened dipolar interaction when the volume fraction decreases

5

Synthesis and properties of Au–Fe3O4 and Ag–Fe3O4 heterodimeric nanoparticles  

International Nuclear Information System (INIS)

Monodisperse Au–Fe3O4 heterodimeric nanoparticles (NPs) were prepared by injecting precursors into a hot reaction solution. The size of Au and Fe3O4 particles can be controlled by changing the injection temperature. UV–Vis spectra show that the surface plasma resonance band of Au–Fe3O4 heterodimeric NPs was evidently red-shifted compared with the resonance band of Au NPs of similar size. The as-prepared heterodimeric Au–Fe3O4 NPs exhibited superparamagnetic properties at room temperature. The Ag–Fe3O4 heterodimeric NPs were also prepared by this synthetic method simply using AgNO3 as precursor instead of HAuCl4. It is indicated that the reported method can be readily extended to the synthesis of other noble metal conjugated heterodimeric NPs. (condensed matter: structure, thermal and mechanical properties)

6

Enzymes immobilization on Fe 3O 4-gold nanoparticles  

Science.gov (United States)

In the present study Fe 3O 4 magnetic nanoparticles were synthesized by coprecipitation of Fe 2+ and Fe 3+ from chlorides. In the next step magnetite-gold core-shell nanoparticles were synthesized from HAuCl 4 using an ethanol as a reducing agent. Finally, magnetic nanoparticles were functionalized by hexadecanethiol. The immobilization of biological molecules (trypsin and glucose oxidase) to the thiol-modified and unmodified magnetite-gold nanoparticles surface was tested. The resulting nanoparticles were characterized by infrared spectroscopy, differential scanning calorimetry, Mössbauer spectroscopy and transmission electron microscopy.

Kalska-Szostko, B.; Rogowska, M.; Dubis, A.; Szyma?ski, K.

2012-01-01

7

Enzymes immobilization on Fe3O4-gold nanoparticles  

International Nuclear Information System (INIS)

In the present study Fe3O4 magnetic nanoparticles were synthesized by coprecipitation of Fe2+ and Fe3+ from chlorides. In the next step magnetite-gold core-shell nanoparticles were synthesized from HAuCl4 using an ethanol as a reducing agent. Finally, magnetic nanoparticles were functionalized by hexadecanethiol. The immobilization of biological molecules (trypsin and glucose oxidase) to the thiol-modified and unmodified magnetite-gold nanoparticles surface was tested. The resulting nanoparticles were characterized by infrared spectroscopy, differential scanning calorimetry, Mössbauer spectroscopy and transmission electron microscopy.

8

Origin of Surface Canting within Fe_{3}O_{4} Nanoparticles.  

Science.gov (United States)

The nature of near-surface spin canting within Fe_{3}O_{4} nanoparticles is highly debated. Here we develop a neutron scattering asymmetry analysis which quantifies the canting angle to between 23° and 42° at 1.2 T. Simultaneously, an energy-balance model is presented which reproduces the experimentally observed evolution of shell thickness and canting angle between 10 and 300 K. The model is based on the concept of T_{d} site reorientation and indicates that surface canting involves competition between magnetocrystalline, dipolar, exchange, and Zeeman energies. PMID:25325655

Krycka, K L; Borchers, J A; Booth, R A; Ijiri, Y; Hasz, K; Rhyne, J J; Majetich, S A

2014-10-01

9

Origin of Surface Canting within Fe3O4 Nanoparticles  

Science.gov (United States)

The nature of near-surface spin canting within Fe3O4 nanoparticles is highly debated. Here we develop a neutron scattering asymmetry analysis which quantifies the canting angle to between 23° and 42° at 1.2 T. Simultaneously, an energy-balance model is presented which reproduces the experimentally observed evolution of shell thickness and canting angle between 10 and 300 K. The model is based on the concept of Td site reorientation and indicates that surface canting involves competition between magnetocrystalline, dipolar, exchange, and Zeeman energies.

Krycka, K. L.; Borchers, J. A.; Booth, R. A.; Ijiri, Y.; Hasz, K.; Rhyne, J. J.; Majetich, S. A.

2014-10-01

10

Ni doped Fe3O4 magnetic nanoparticles.  

Science.gov (United States)

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

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

2012-03-01

11

Preparation and Characterization of Magnetite (Fe3O4) Nanoparticles  

Science.gov (United States)

Magnetite (Fe3O4) nanoparticles exhibit a superparamagnetic behavior when small. Our goal is to fabricate such particles and characterize their structural and magnetic properties as function of particle size and synthesis route. I will show the different fabrication methods we have utilized: one inorganic salt mixing method, an inorganic solution method, and lastly an organic solution method. The last approach should allow us to achieve monolayers of nanoparticles. I will present X-ray diffraction (XRD) results as well as Vibrating Sample Magnetometry (VSM) results, including Field Cooling (FC) versus Zero Field Cooling (ZFC) measurements to find the blocking temperature, or when the magnetic moments are frozen; to complement the magnetometry measurements. We will also include images of nanoparticles deposited on a wafer, recorded by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).

Trevino, Matea; Chesnel, Karine; Olsen, Betsy; Hancock, Jared; Harrison, Roger; Farrer, Jeffrey

2011-10-01

12

Electrostatic Force Microscopy of Fe3O4 nanoparticles  

Science.gov (United States)

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

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

2012-02-01

13

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

14

Preparation of SiO2/(PMMA/Fe3O4) from monolayer linolenic acid modified Fe3O4 nanoparticles via miniemulsion polymerization.  

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SiO2/(PMMA/Fe3O4) composite particles were prepared from linolenic acid (LA) instead of oleic acid (OA) modified Fe3O4 nanoparticles by miniemulsion polymerization. LA has three unsaturated double bonds with which it can polymerizate more easily than OA. And coating Fe3O4 with polymethyl methacrylate (PMMA) polymer beforehand can prevent magnetic nanoparticles from the aggregation that usually comes from the increasing of ionic strength during the hydrolyzation of tetraethoxysilane (TEOS) by the steric hindrance. Finally, the resulting PMMA/Fe3O4 nanoparticles were coated with silica, forming SiO2/(PMMA/Fe3O4) core-shell structure particles. The sizes of nanoparticles with core-shell structure were in the range from 300 to 600 nm. The nanoparticles were spherical particles and had consistent size. The result of magnetic measurement showed that the composite particles had superparamagnetic property. PMID:20201438

He, Lei; Li, Zhiyang; Fu, Jing; Deng, Yan; He, Nongyue; Wang, Zhifei; Wang, Hua; Shi, Zhiyang; Wang, Zunliang

2009-10-01

15

Size-controlled Synthesis and Characterization of Fe3O4 Nanoparticles by Chemical Coprecipitation Method  

International Nuclear Information System (INIS)

Magnetite (Fe3O4) nanoparticles have been synthesized using the chemical coprecipitation method. The Fe3O4 nanoparticles were likely formed via dissolution-recrystallization process. During the precipitation process, ferrihydrite and Fe(OH)2 particles formed aggregates and followed by the formation of spherical Fe3O4 particles. The synthesized Fe3O4 nanoparticles exhibited superparamagnetic behavior and in single crystal form. The synthesis temperature and the degree of agitation during the precipitation were found to be decisive in controlling the crystallite and particle size of the produced Fe3O4 nanoparticles. Lower temperature and higher degree of agitation were the favorable conditions for producing smaller particle. The magnetic properties (saturation magnetization and coercivity) of the Fe3O4 nanoparticles increased with the particle size. (author)

16

Enhanced specific absorption rate in silanol functionalized Fe3O4 core-shell nanoparticles: Study of Fe leaching in Fe3O4 and hyperthermia in L929 and HeLa cells.  

Science.gov (United States)

Core-shell Fe3O4-SiO2 magnetic nanoparticles (MNPs) have been synthesized using a simple synthesis procedure at different temperatures. These MNPs are used to investigate the effect of surface coating on specific absorption rate (SAR) under alternating magnetic field. The temperature achieved by silica coated Fe3O4 is higher than that by uncoated MNPs (Fe3O4). This can be attributed to extent of increase in Brownian motion for silica coated MNPs. The sample prepared at optimized temperature of 80°C shows the highest SAR value of 111W/g. It is found that SAR value decreases with increase in shell thickness. The chemical stability of these samples is analyzed by leaching experiments at pH 2-7. The silica coated samples are stable up to 7 days even at pH 2. Biocompatibility of the MNPs is evaluated in vitro by assessing their cytotoxicity on L929 and human cervical cancer cells (HeLa cells) using sulforhodamine-B assay. Their hyperthermic killing ability is also evaluated in HeLa cells using the same method. Cells treated with MNPs along with induction heating show decrease in viability as compared to that without induction heating. Further, cell death is found to be ?55% more in cells treated with silica coated MNPs under induction heating as compared to untreated control. These results establish the efficacy of Fe3O4-SiO2 prepared at 80°C in killing of tumor cells by cellular hyperthermia. PMID:25089699

Majeed, Jerina; Pradhan, Lina; Ningthoujam, Raghumani Singh; Vatsa, Rajesh Kumar; Bahadur, Dhirendra; Tyagi, Avesh Kumar

2014-10-01

17

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

Science.gov (United States)

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.

Sadat, M. E.; Kaveh Baghbador, Masoud; Dunn, Andrew W.; Wagner, H. P.; Ewing, Rodney C.; Zhang, Jiaming; Xu, Hong; Pauletti, Giovanni M.; Mast, David B.; Shi, Donglu

2014-09-01

18

Preparation and properties of magnetic Fe3O4-chitosan nanoparticles  

International Nuclear Information System (INIS)

Magnetic Fe3O4-chitosan nanoparticles were prepared by the covalent binding of chitosan (CTS) onto the surface of magnetic Fe3O4 nanoparticles which were prepared by hydrothermal method using H2O2 as an oxidizer. Transmission electron microscopy (TEM) showed that Fe3O4 particles and Fe3O4-chitosan nanocomposites were regular sphere with a mean diameter of 23 nm and 25 nm, respectively. X-ray diffraction patterns (XRD) indicated that the magnetic Fe3O4 nanoparticles were pure Fe3O4 with a spinel structure and the coating of chitosan did not result in a phase change. The coating of CTS onto the Fe3O4 nanoparticles was also demonstrated by the measurement of thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectra. Magnetic measurement revealed that the saturated magnetization of the Fe3O4-chitosan nanoparticles reached 21.5 emu g-1 and the nanoparticles showed the characteristics of superparamagnetism

19

Preparation and characterization of superparamagnetic graphene oxide nanohybrids anchored with Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

Highlights: • A new method for fabrication of GPO–Fe3O4 nanostructured hybrid was demonstrated. • The FT-IR analysis of nanohybrid shows infrared peaks characteristic of amide link. • EDX spectrum shows intense peaks for Iron along with carbon and oxygen peaks. • SEM images confirm the presence of Fe3O4 nanoparticles on the GPO surface. • This nanohybrid is a potential material for electromagnetic devices and biomedicine. -- Abstract: We describe a novel method for the preparation of a graphene oxide (GPO) – magnetic nanoparticle (Fe3O4) (GPO–Fe3O4) nanostructured hybrids by a simple and effective method. In this method, the fabrication of multi-component nanostructure system involves covalent attachment of GPO with Fe3O4 through dopamine (do) (GPO–do-Fe3O4). Optical microscopy (OM), ultraviolet spectroscopy (UV), Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to demonstrate the successful attachment of Fe3O4 to GPO. It was found that the fabricated nanohybrid shows superparamagnetic behavior and allows rapid separation under an external-magnetic field. The FT-IR analysis of GPO–do-Fe3O4 nanohybrid shows infrared (IR) peaks characteristic of amide (-CO-NH-) link on the surface of GPO. TGA analysis clearly shows two major stages of thermal degradation, different from the pattern of observed for dopamine coated Fe3O4 surface. An EDX spectrum of GPO–do-Fe3O4 shows intense peaks for Iron (Fe) along with carbon and oxygen peaks. SEM images further support the FT-IR and TGA results and confirm the presence of Fe3O4 on GPO surface. Thus, the resultant GPO–do-Fe3O4 nanohybrid system carries both electrical and magnetic properties, which are important for applications ranging from electro-magnetic devices to biomedicine

20

Solid phase extraction of magnetic carbon doped Fe3O4 nanoparticles.  

Science.gov (United States)

Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole-dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process. PMID:24342532

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

2014-01-17

 
 
 
 
21

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

22

Preparation, characterization and SRXPS study of polyvinyl alcohol modified Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

In this study, Fe3O4 nanoparticles were coated with PVA to synthesize PVA-Fe3O4 complex, which were characterized by transmission electron microscopy(TEM),thermo gravimetric(TG) analysis, UV-vis spectra,zeta potentials and ICP-MS, in terms of the physicochemical properties, while surface constituents, structures and chemical bonds of the modified and unmodified nanoparticles were characterized with synchrotron radiation X-ray photoelectron spectroscopy(SRXPS), for exploring modification mechanism of the PVA-Fe3O4. The results indicate that after PVA modification, the suspension stability of Fe3O4 nanoparticles in water and cellular uptake capability were significantly improved compared with unmodified Fe3O4. The SRXPS analysis reveals that the hydroxy groups on the surface of Fe3O4 nanoparticles and PVA were combined by hydrogen bond to consist a stable system, which would be beneficial to the biomedical applications of Fe3O4 nanoparticles. (authors)

23

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

Science.gov (United States)

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

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

2013-11-01

24

1, 3-dipolar cycloaddition as a general route for functionalization of Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

Triazole formation by 1, 3-dipolar cycloaddition reactions has been used to functionalize the surface of Fe3O4 nanoparticles. Fe3O4 particle samples with diameters around 22 nm were synthesized without any additional stabilizer, and were then treated with silane coupling agent to react with propargyl acid. The alkynyl group on the Fe3O4 surface provides better conjugation efficiency with azide derivative molecules, which led to their attachment through the formation of a 1, 2, 3-triazole ring

25

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

Science.gov (United States)

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.

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

2014-09-01

26

Pharmacokinetic parameters and tissue distribution of magnetic Fe3O4 nanoparticles in mice  

Directory of Open Access Journals (Sweden)

Full Text Available Jun Wang1, Yue Chen1, Baoan Chen1, Jiahua Ding1, Guohua Xia1, Chong Gao1, Jian Cheng1, Nan Jin1, Ying Zhou1, Xiaomao Li1, Meng Tang2, Xue Mei Wang21Department of Hematology, Zhongda Hospital, Clinical Medical School, Southeast University, Nanjing, People’s Republic of China; 1Department of Physics, University of Saarland, D-266041 Saarbruechen, Germany; 2National Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, People’s Republic of ChinaBackground: This study explored the pharmacokinetic parameters and tissue distribution of magnetic iron oxide nanoparticles (Fe3O4 MNPs in imprinting control region (ICR mice.Methods: The Fe3O4 MNPs were synthesized by chemical coprecipitation, and their morphology and appearance were observed by transmission electron microscopy. ICR mice were divided into a control group and a Fe3O4 MNP-treated group. Probable target organs in ICR mice were observed, and the pharmacokinetic parameters and biodistribution of Fe3O4 MNPs in tissues were identified using atomic absorption spectrophotometry.Results: Fe3O4 MNPs were spherical with a well distributed particle diameter, and were distributed widely in various target organs and tissues including the heart, liver, spleen, lungs, kidneys, brain, stomach, small intestine, and bone marrow. The majority of Fe3O4 MNPs were distributed to the liver and the spleen. Fe3O4 MNP levels in brain tissue were higher in the Fe3O4 MNP-treated group than in the control group, indicating that Fe3O4 MNPs can penetrate the blood–brain barrier.Conclusion: These results suggest that the distribution of Fe3O4 MNPs was mostly in the liver and spleen, so the curative effect of these compounds could be more pronounced for liver tumors. Furthermore, Fe3O4 MNPs might be used as drug carriers to overcome physiologic barriers.Keywords: magnetic nanoparticles, Fe3O4, tissue distribution, mice

Jun Wang

2010-10-01

27

Magnetic field synthesis of Fe3O4 nanoparticles used as a precursor of ferrofluids  

International Nuclear Information System (INIS)

Methods to synthesize magnetic Fe3O4 nanoparticles and to modify the nanoparticle surface are presented in this paper. In these methods, Fe3O4 nanoparticles were prepared by co-precipitation, and the aging of nanoparticles was improved by applied magnetic field. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Thereafter, to enhance the compatibility between nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticle surface. FT-IR, XRD, transmission electron microscopy (TEM), and thermogravimetry (TG) were used to characterize the resultant sample. The testing results indicated that the polyacrylic acid chains have been covalently bonded to the surface of magnetic Fe3O4 nanoparticles. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface-modified Fe3O4 nanoparticles were investigated. Moreover, the Fe3O4-g-PAA hybrid nanoparticles were dispersed in water to form ferrofluids (FFs). The obtained FFs were characterized by UV-vis spectrophotometer, Gouy magnetic balance and laser particle-size analyzer. The testing results showed that the high-concentration FF had excellent stability, with high susceptibility and high saturation magnetization. The rheological properties of the FFs were also investigated using a rotating rheometer

28

Composite Photothermal Platform of Polypyrrole-Enveloped Fe3O4 Nanoparticle Self-Assembled Superstructures.  

Science.gov (United States)

Photothermal nanoplatforms with small size, low cost, multifunctionality, good biocompatibility and in particular biodegradability are greatly desired in the exploration of novel diagnostic and therapeutic methodologies. Despite Fe3O4 nanoparticles (NPs) have been approved as safe clinical agents, the low molar extinction coefficient and subsequent poor photothermal performance shed the doubt as effective photothermal materials. In this paper, we demonstrate the fabrication of polypyrrole (PPy)-enveloped Fe3O4 NP superstructures with a spherical morphology, which leads to a 300-fold increase in the molar extinction coefficient. The basic idea is the optimization of Fe3O4 electronic structures. By controlling the self-assembly of Fe3O4 NPs, the diameters of the superstructures are tuned from 32 to 64 nm. This significantly enhances the indirect transition and magnetic coupling of Fe ions, thus increasing the molar extinction coefficient of Fe3O4 NPs from 3.65 × 10(6) to 1.31 × 10(8) M(-1) cm(-1) at 808 nm. The envelopment of Fe3O4 superstructures with conductive PPy shell introduces additional electrons in the Fe3O4 oscillation system, and therewith further enhances the molar extinction coefficient to 1.12 × 10(9) M(-1) cm(-1). As a result, the photothermal performance is greatly improved. Primary cell experiments indicate that PPy-enveloped Fe3O4 NP superstructures are low toxic, and capable to kill Hela cells under near-infrared laser irradiation. Owing to the low cost, good biocompatibility and biodegradability, the PPy-enveloped Fe3O4 NP superstructures are promising photothermal platform for establishing novel diagnostic and therapeutic methods. PMID:25134068

Zhang, Xue; Xu, Xiaowei; Li, Tingting; Lin, Min; Lin, Xiaoying; Zhang, Hao; Sun, Hongchen; Yang, Bai

2014-08-27

29

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

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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.

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

2012-06-01

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

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Background The objective of this study was to evaluate the synthesis and biocompatibility of Fe3O4 nanoparticles and investigate their therapeutic effects when combined with magnetic fluid hyperthermia on cultured MCF-7 cancer cells. Methods Magnetic Fe3O4 nanoparticles were prepared using a coprecipitation method. The appearance, structure, phase composition, functional groups, surface charge, magnetic susceptibility, and release in vitro were characterized by transmission electron microscopy, x-ray diffraction, scanning electron microscopy-energy dispersive x-ray spectroscopy, and a vibrating sample magnetometer. Blood toxicity, in vitro toxicity, and genotoxicity were investigated. Therapeutic effects were evaluated by MTT [3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide] and flow cytometry assays. Results Transmission electron microscopy revealed that the shapes of the Fe3O4 nanoparticles were approximately spherical, with diameters of about 26.1 ± 5.2 nm. Only the spinel phase was indicated in a comparison of the x-ray diffraction data with Joint Corporation of Powder Diffraction Standards (JCPDS) X-ray powder diffraction files. The O-to-Fe ratio of the Fe3O4 was determined by scanning electron microscopy-energy dispersive x-ray spectroscopy elemental analysis, and approximated pure Fe3O4. The vibrating sample magnetometer hysteresis loop suggested that the Fe3O4 nanoparticles were superparamagnetic at room temperature. MTT experiments showed that the toxicity of the material in mouse fibroblast (L-929) cell lines was between Grade 0 to Grade 1, and that the material lacked hemolysis activity. The acute toxicity (LD50) was 8.39 g/kg. Micronucleus testing showed no genotoxic effects. Pathomorphology and blood biochemistry testing demonstrated that the Fe3O4 nanoparticles had no effect on the main organs and blood biochemistry in a rabbit model. MTT and flow cytometry assays revealed that Fe3O4 nano magnetofluid thermotherapy inhibited MCF-7 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. PMID:23028225

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

2012-01-01

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Multifunctional magnetic Fe3O4 nanoparticles combined with chemotherapy and hyperthermia to overcome multidrug resistance  

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Full Text Available Yanyan Ren1,2,*, Haijun Zhang1,2,*, Baoan Chen1, Jian Cheng1, Xiaohui Cai1, Ran Liu1, Guohua Xia1, Weiwei Wu1, Shuai Wang1, Jiahua Ding1, Chong Gao1, Jun Wang1, Wen Bao1, Lei Wang1, Liang Tian1, Huihui Song1, Xuemei Wang1,2 1Department of Hematology and Oncology, Key Medical Discipline, Jiangsu Province, Zhongda Hospital, and Faculty of Oncology, Medical School, Nanjing, 2State Key Laboratory of Bioelectronics, Southeast University, Nanjing, People's Republic of China*These authors contributed equally to this workBackground: Multidrug resistance in cancer is a major obstacle for clinical therapeutics, and is the reason for 90% of treatment failures. This study investigated the efficiency of novel multifunctional Fe3O4 magnetic nanoparticles (Fe3O4-MNP combined with chemotherapy and hyperthermia for overcoming multidrug resistance in an in vivo model of leukemia.Methods: Nude mice with tumor xenografts were randomly divided into a control group, and the treatment groups were allocated to receive daunorubicin, 5-bromotetrandrine (5-BrTet and daunorubicin, Fe3O4-MNP, and Fe3O4-MNP coloaded with daunorubicin and 5-bromotetrandrine (Fe3O4-MNP-DNR-5-BrTet, with hyperthermia in an alternating magnetic field. We investigated tumor volume and pathology, as well as P-glycoprotein, Bcl-2, Bax, and caspase-3 protein expression to elucidate the effect of multimodal treatment on overcoming multidrug resistance.Results: Fe3O4-MNP played a role in increasing tumor temperature during hyperthermia. Tumors became significantly smaller, and apoptosis of cells was observed in both the Fe3O4-MNP and Fe3O4-MNP-DNR-5-BrTet groups, especially in the Fe3O4-MNP-DNR-5-BrTet group, while tumor volumes in the other groups had increased after treatment for 12 days. Furthermore, Fe3O4-MNP-DNR-5-BrTet with hyperthermia noticeably decreased P-glycoprotein and Bcl-2 expression, and markedly increased Bax and caspase-3 expression.Conclusion: Fe3O4-MNP-DNR-5-BrTet with hyperthermia may be a potential approach for reversal of multidrug resistance in the treatment of leukemia.Keywords: magnetic nanoparticles, daunorubicin, 5-bromotetrandrine, multidrug resistance, hyperthermia

Ren Y

2012-05-01

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Adsorption of uranium ions from aqueous solution by amine-group functionalized magnetic Fe3O4 nanoparticle  

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The magnetic Fe3O4 nanoparticle was functionalized by covalently grafting amine group with (3-aminopropyl) trimethoxy silane, and the Fe3O4-NH2 nanoparticle and the Fe3O4 nanoparticle were characterized by Fourier transform infrared, and X-ray diffraction. And the results indicated the amine-group was immobilized successfully on the surface of Fe3O4. The adsorption behavior of uranium from aqueous solution by the Fe3O4 nanoparticle and the Fe3O4-NH2 nanoparticle was investigated using batch experiments. The pH of initial aqueous solution at 5.0 and 6.0 were in favour of adsorption of uranium, and the adsorption percentage of uranium by the Fe3O4 nanoparticle and the Fe3O4-NH2 nanoparticle were 81.2 and 95.6 %, respectively. In addition, the adsorption of uranium ions could be well-described by the Langmuir, Freundlich isotherms and pseudo-second kinetic models. The monolayer adsorption maximum capacity of the Fe3O4 nanoparticle and the Fe3O4-NH2 nanoparticle were 85.35 and 268.49 mg/g at 298.15 K, respectively, which indicate the adsorption capacity the Fe3O4 nanoparticle was improved by amine functionalization. (author)

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Preparation and characterization of PVPI-coated Fe3O4 nanoparticles as an MRI contrast agent  

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Polyvinylpyrrolidone-iodine (PVPI)-coated Fe3O4 nanoparticles were prepared by using inverse chemical co-precipitation method, in which the PVPI serves as a stabilizer and dispersant. The wide angle X-ray diffraction (WAXD) 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 the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FTIR) results suggested that PVPI interacted with Fe3O4 via its carbonyl groups. Results of superconducting quantum interference device (SQUID) indicated prepared Fe3O4 nanoparticles exhibited superparamagnetic behavior and high saturation magnetization. T2-weighted MRI images of PVPI-coated Fe3O4 nanoparticles showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticles concentration in water at room temperature. These results indicated that the PVPI-coated Fe3O4 nanoparticles had great potential for application in MRI as a T2 contrast agent. - Highlights: • PVPI-coated Fe3O4 nanoparticles were prepared using inverse co-precipitation method. • Resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. • Prepared Fe3O4 nanoparticles exhibited superparamagnetic behavior. • T2-weighted MRI images of PVPI-coated Fe3O4 nanoparticles were obtained

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Synthesis and characterization of Fe3O4 nanoparticles coated with fucan polysaccharides  

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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.

Silva, V. A. J.; Andrade, P. L.; Silva, M. P. C.; Bustamante D., A.; De Los Santos Valladares, Luis; Albino Aguiar, J.

2013-10-01

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Effects of Fe3O4 Magnetic Nanoparticles on A549 Cells  

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Full Text Available Fe3O4 magnetic nanoparticles (MgNPs-Fe3O4 are widely used in medical applications, including magnetic resonance imaging, drug delivery, and in hyperthermia. However, the same properties that aid their utility in the clinic may potentially induce toxicity. Therefore, the purpose of this study was to investigate the cytotoxicity and genotoxicity of MgNPs-Fe3O4 in A549 human lung epithelial cells. MgNPs-Fe3O4 caused cell membrane damage, as assessed by the release of lactate dehydrogenase (LDH, only at a high concentration (100 ?g/mL; a lower concentration (10 ?g/mL increased the production of reactive oxygen species, increased oxidative damage to DNA, and decreased the level of reduced glutathione. MgNPs-Fe3O4 caused a dose-dependent increase in the CD44+ fraction of A549 cells. MgNPs-Fe3O4 induced the expression of heme oxygenase-1 at a concentration of 1 ?g/mL, and in a dose-dependent manner. Despite these effects, MgNPs-Fe3O4 had minimal effect on cell viability and elicited only a small increase in the number of cells undergoing apoptosis. Together, these data suggest that MgNPs-Fe3O4 exert little or no cytotoxicity until a high exposure level (100 ?g/mL is reached. This dissociation between elevated indices of cell damage and a small effect on cell viability warrants further study.

Hiroshi Kasai

2013-07-01

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

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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.

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

2014-01-01

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

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

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

2014-08-01

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Fe3O4 nanoparticles: protein-mediated crystalline magnetic superstructures  

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The synthesis of magnetic, monodisperse nanoparticles has attracted great interest in nanoelectronics and nanomedicine. Here we report the fabrication of pure magnetite nanoparticles, less than ten nanometers in size, using the cage-shaped protein apoferritin (Fe3O4–ferritin). Crystallizable proteins were obtained through careful successive separation methods, including a magnetic chromatography that enabled the effective separation of proteins, including a Fe3O4 nanoparticle (7.9 ± 0.8 nm), from empty ones. Macroscopic protein crystals allowed the fabrication of three-dimensional arrays of Fe3O4 nanoparticles with interparticle gaps controlled by dehydration, decreasing their magnetic susceptibilities and increasing their blocking temperatures through enhanced dipole–dipole interactions. (paper)

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Fe3O4 nanoparticles: protein-mediated crystalline magnetic superstructures  

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The synthesis of magnetic, monodisperse nanoparticles has attracted great interest in nanoelectronics and nanomedicine. Here we report the fabrication of pure magnetite nanoparticles, less than ten nanometers in size, using the cage-shaped protein apoferritin (Fe3O4-ferritin). Crystallizable proteins were obtained through careful successive separation methods, including a magnetic chromatography that enabled the effective separation of proteins, including a Fe3O4 nanoparticle (7.9 ± 0.8 nm), from empty ones. Macroscopic protein crystals allowed the fabrication of three-dimensional arrays of Fe3O4 nanoparticles with interparticle gaps controlled by dehydration, decreasing their magnetic susceptibilities and increasing their blocking temperatures through enhanced dipole-dipole interactions.

Okuda, Mitsuhiro; Eloi, Jean-Charles; Jones, Sarah E. Ward; Sarua, Andrei; Richardson, Robert M.; Schwarzacher, Walther

2012-10-01

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Single source preparation of superparamagnetic Fe3O4 nanoparticles by simple cyclic microwave approach  

International Nuclear Information System (INIS)

Graphical abstract: - Highlights: • Superparamagnetic Fe3O4 nanoparticles were synthesized in high yield. • PEG-200 was applied as both solvent and reductive agent. • Single source synthesis of Fe3O4 was performed. • Nontoxic materials and surfactant were used in current investigation. • Reaction time and temperature significantly decreased in current experiment. - Abstract: Polyol mediated process was applied for the synthesis of Fe3O4 nanoparticles under microwave irradiation. By combination of polyol medium and microwave irradiation different advantages including low reaction time, low consumption of energy, and simplicity were achieved. Different parameters affecting on products including microwave irradiation power, reaction time, reactants concentration, and solvent were changed to reach the optimum condition for synthesis of Fe3O4 nanoparticles. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR) spectra, and vibrating sample magnetometer (VSM). Facile preparation and separation are important features of this route. This work has provided a general, simple, and effective method to control the composition and morphology of Fe3O4 nanoparticles in nonaqueous solution, which will be important for inorganic synthesis methodolog

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

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The magnetite (Fe3O4) nanoparticles were prepared by coprecipitation of Fe3+ and Fe2+ with an aqueous NaOH solution. The Fe3O4/polyaniline (PANI) magnetic composite nanoparticles with a core-shell structure with a diameter of 30-50 nm were prepared via an in situ polymerization of aniline in an aqueous solution containing the Fe3O4 magnetic fluid. The inductive heat property of Fe3O4/PANI composite nanoparticles in an alternating current (ac) magnetic field was investigated. The potential of Fe3O4/PANI nanoparticles was evaluated for localized hyperthermia treatment of cancers. The saturation magnetization, Ms, and coercivity, Hc, are 50.05 emu g-1 and 137 Oe for Fe3O4 nanoparticles and 26.34 emu g-1 and 0 Oe for Fe3O4/PANI composite nanoparticles, respectively. Exposed in the ac magnetic field for 29 min, the temperatures of physiological saline suspensions containing Fe3O4 nanoparticles or Fe3O4/PANI composite nanoparticles are 63.6 °C and 52.4 °C, respectively. The Fe3O4/PANI composite nanoparticles would be useful as good thermoseeds for localized hyperthermia treatment of cancers.

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

2006-12-01

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Preparation and application of core–shell Fe3O4/polythiophene nanoparticles  

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The Fe3O4/polythiophene nanoparticles, possessing core–shell structure, were prepared by two-step method. In the first step, the Fe3O4 particles were synthesized via co-precipitation of FeCl3 and FeSO4, using the NH3·H2O and N2H4·H2O as precipitant system. In the second step, the thiophene adsorbed and polymerized on the surface of the Fe3O4 in the solvent of chloroform. Raman, FTIR, EDS, XRD, TEM, Zeta potential measurement and TG-SDTA were employed to characterize the composition and structure of the products. The results showed that the Fe3O4/polythiophene nanoparticles were successfully synthesized with good dispersion and stable core–shell structure, provided with average particle size of approximately 20 nm, in which the diameter of Fe3O4 core was approximately 14 nm and the thickness of polythiophene shell was approximately 3–4 nm. Then, the nanoparticles were added into alkyd varnish to prepare a composite coating. The neutral salt spray test, paraffin control test and mechanical test were carried out to identify the properties of the composite coating. It was found that the composite coating had good performances of anticorrosion and paraffin controlling when the mass fraction of the nanoparticles was 0.8–1 wt% in alkyd varnish. As a multifunctional material, the Femultifunctional material, the Fe3O4/polythiophene nanoparticles can be used in the internal coating of pipeline and have great potential application in crude oil pipeline transportation.

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Magnetic nanoparticles of Fe3O4 enhance docetaxel-induced prostate cancer cell death  

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Full Text Available Akiko Sato,1 Naoki Itcho,1 Hitoshi Ishiguro,2,3 Daiki Okamoto,1 Naohito Kobayashi,4 Kazuaki Kawai,5 Hiroshi Kasai,5 Daisuke Kurioka,1 Hiroji Uemura,2 Yoshinobu Kubota,2 Masatoshi Watanabe11Laboratory for Medical Engineering, Division of Materials Science and Chemical Engineering, Graduate School of Engineering, Yokohama National University, Yokohama, Japan; 2Department of Urology, Yokohama City University Graduate School of Medicine, Yokohama, Japan; 3Photocatalyst Group, Kanagawa Academy of Science and Technology, Kawasaki, Japan; 4Department of Molecular Pathology, Yokohama City University Graduate School of Medicine, Yokohama, Japan; 5Department of Environmental Oncology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Kitakyushu, JapanAbstract: Docetaxel (DTX is one of the most important anticancer drugs; however, the severity of its adverse effects detracts from its practical use in the clinic. Magnetic nanoparticles of Fe3O4 (MgNPs-Fe3O4 can enhance the delivery and efficacy of anticancer drugs. We investigated the effects of MgNPs-Fe3O4 or DTX alone, and in combination with prostate cancer cell growth in vitro, as well as with the mechanism underlying the cytotoxic effects. MgNPs-Fe3O4 caused dose-dependent increases in reactive oxygen species levels in DU145, PC-3, and LNCaP cells; 8-hydroxydeoxyguanosine levels were also elevated. MgNPs-Fe3O4 alone reduced the viability of LNCaP and PC-3 cells; however, MgNPs-Fe3O4 enhanced the cytotoxic effect of a low dose of DTX in all three cell lines. MgNPs-Fe3O4 also augmented the percentage of DU145 cells undergoing apoptosis following treatment with low dose DTX. Expression of nuclear transcription factor ?B in DU145 was not affected by MgNPs-Fe3O4 or DTX alone; however, combined treatment suppressed nuclear transcription factor ?B expression. These findings offer the possibility that MgNPs-Fe3O4–low dose DTX combination therapy may be effective in treating prostate cancer with limited adverse effects.Keywords: prostate cancer, magnetic nanoparticles, docetaxel, reactive oxidative species

Sato A

2013-08-01

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Encapsulated Fe3O4 nanoparticles with silica thin layer as an anode material for lithium secondary batteries  

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Fe3O4 nanoparticles were coated with a SiO2 layer by using a modified sol-gel method. The synthetic procedures for Fe3O4 nanoparticles encapsulated with a SiO2 layer (SiO2-Fe3O4) consist of three consecutive steps: (i) fabrication of Fe3O4 by the co-precipitation method, (ii) stabilization of Fe3O4 with citrate as a capping agent, which is used to prevent particles from aggregating, and (iii) silica encapsulation by a modified sol-gel reaction. Based on the experimental range, SiO2-Fe3O4 exhibited higher cyclic performance than the intrinsic one. The reversible capacity of Fe3O4 with SiO2 at the first cycle was 363 mA h g-1 and the remaining discharge capacity was 321 mA h g-1 after the 30th cycle.

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Green synthesis of soya bean sprouts-mediated superparamagnetic Fe3O4 nanoparticles  

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Superparamagnetic Fe3O4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe3O4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe3O4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe3O4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature (TB) of 150 K and saturation magnetization of 37.1 emu/g.

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

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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

Chen DZ

2012-09-01

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Chromium (VI) reduction in aqueous solutions by Fe3O4-stabilized Fe0 nanoparticles  

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This paper describes the use of highly reactive magnetite (Fe3O4) nanoparticles-stabilized Fe0 nanocomposites for the reduction and mitigation of hexavalent chromium Cr(VI) species in aqueous solutions. Higher proportions of Fe3O4 in the nanocomposites could increase the rate of Cr(VI) reduction. In the absence of magnetite, the Cr(VI) mitigation rate was just 51.4% after 60 min of reaction, while with an initial Fe3O4 mass loading of 3 g l-1, the Cr(VI) mitigation rate was nearly 100% after 60 min. The optimal ratio of Fe3O4:Fe0 for the mitigation of Cr(VI) was found to be 40:1. Otherwise, solution pHs significantly affected the rate of Cr(VI) reduction, with reactions occurring more rapidly under acidic or neutral than basic conditions. It is hypothesized that the high efficiency of the Fe3O4 nanoparticles-stabilized Fe0 nanocomposites for Cr(VI) reduction was a direct result of the attachment of Fe0 nanoparticles to the surface of magnetite, which prevents the aggregation of nano-Fe0, moreover, the electron transfer during the reduction process most likely takes place via Fe0 nanoparticles that are located at the magnetite octahedral sites, which are versatile redox centers as they can accommodate both Fe(III) and Fe(II), and this will promote the reduction of Cr(VI). Cr(VI) reduction is coupled with nano-Fe0 oxidation. Nano-Fe0 particles are located at the magnetite octahedral sites. Ions of Fe(II) and Fe(III) accommodated by magnetite octahedral sites are products of nano-Fe0 oxidation. Therefore, Cr(VI) reduction is mediated either by nano-Fe0 (direct reduction) or Fe(II) species (indirect reduction). Additionally, catalytic Cr(VI) reduction by molecular H2 (or atomic H) is possible.

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One-step hydrothermal synthesis of magnetic Fe3O4 nanoparticles immobilized on polyamide fabric  

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A thin film of nanosized Fe3O4 particles prepared by hydrothermal method was immobilized on the surface of polyamide 6 fiber using ferric trichloride and ferrous chloride as the precursor, N,N-dimethyl formamide as the swelling agent and sodium dodecyl sulfate as the dispersant agent. The morphology, crystalline phase, thermal stability, magnetization properties and chemical structure of polyamide 6 fabric before and after treatments were characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS) techniques. The tensile properties and abrasion resistance were also measured. It was found that the inverse cubic spinel phase of Fe3O4 nanoparticles with an average size 50 nm were synthesized, and synchronously grafted onto polyamide fiber surface. As compared with the original fabric, the onset decomposition temperature of the Fe3O4-coated fabric decreased slightly. The saturation magnetization was measured to be 3.8 emu/g at temperature of 300 K. The tensile properties were enhanced to some extent mainly due to the fabric shrinkage. The abrasion resistance of the Fe3O4-coated fabric behaved well.

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One-step hydrothermal synthesis of magnetic Fe3O4 nanoparticles immobilized on polyamide fabric  

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A thin film of nanosized Fe3O4 particles prepared by hydrothermal method was immobilized on the surface of polyamide 6 fiber using ferric trichloride and ferrous chloride as the precursor, N,N-dimethyl formamide as the swelling agent and sodium dodecyl sulfate as the dispersant agent. The morphology, crystalline phase, thermal stability, magnetization properties and chemical structure of polyamide 6 fabric before and after treatments were characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS) techniques. The tensile properties and abrasion resistance were also measured. It was found that the inverse cubic spinel phase of Fe3O4 nanoparticles with an average size 50 nm were synthesized, and synchronously grafted onto polyamide fiber surface. As compared with the original fabric, the onset decomposition temperature of the Fe3O4-coated fabric decreased slightly. The saturation magnetization was measured to be 3.8 emu/g at temperature of 300 K. The tensile properties were enhanced to some extent mainly due to the fabric shrinkage. The abrasion resistance of the Fe3O4-coated fabric behaved well.

Zhang, Hui; Zhu, Guoqing

2012-03-01

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Competing reactions of selected atmospheric gases on Fe3O4 nanoparticles surfaces.  

Science.gov (United States)

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

Eltouny, N; Ariya, Parisa A

2014-10-01

51

Simple solvothermal synthesis of hydrophobic magnetic monodispersed Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

Graphical abstract: A facile method to produce monodispersed magnetite nanoparticles is based on the solvothermal reaction of iron acetylacetonate (Fe(acac)3) decomposition. The sizes ranged from 7 to 12 nm, which could be controlled by adjusting the volume ratio of oleylamine to n-hexane. Display Omitted Highlights: ? The solvethermal reaction of Fe(acac)3 decomposition was carried out at mild temperature in the presence of oleylamine and n-hexane. ? The size of nanocrystals is controlled by adjusting the volume ratio of oleylamine to n-hexane. ? The low-boiling-point solvent n-hexane offered autogenous pressure parameter after gasified in the reaction temperature. ? The as prepared hydrophobic monodisperse Fe3O4 NPs can be used to prepare the magnetic micelles for future biomedical applications. -- Abstract: A new solvothermal method is proposed for the preparation of Fe3O4 nanoparticles (NPs) from iron acetylacetonate in the presence of oleylamine and n-hexane. The products are characterized by X-ray powder diffraction, infrared (IR) spectroscopy, transmission electron microscopy, thermogravimetry/differential thermogravimetry (TG/DTG) analysis, and vibrating sample magnetometery. The new procedure yields superparamagnetic monodispersed Fe3O4 particles with sizes ranging from 7 nm to 12 nm. The nanocrystal sizes are controlled by adjusting the volume ratio of oleylamine to n-hexane. IR and TG/DTG analyses indicate that the oleylamine molecules, as stabilizers, are adsorbed on the surface of Fe3O4 NPs as bilayer adsorption models. The surface adsorption quantities of oleylamine on 7.5 and 10.4 nm-diameter Fe3O4 NPs are 18% and 11%, respectively. The hydrophobic surface of the obtained nanocrystals is passivated by adsorbed organic solvent molecules. These molecules provide stability against agglomeration, enable solubility in nonpolar solvents, and allow the formation of magnetic polymer micelles.

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Synthesis and characterization of environment friendly and multifunctional Fe3O4 magnetic nanoparticles.  

Science.gov (United States)

In this study, the size-uniform (5-6 nm), nearly spherical, and well-dispersed aqueous Fe3o4 magnetic nanoparticles were prepared by an improved chemical coprecipitation method. The DDAT-terminated (S-1-Dodecyl-S'-(alpha,alpha'-dimethyl-alpha"-acetic acid) trithiocarbonate) polymethacrylic (PMA-DDAT) was chosen as the apt surfactant, and the terminal DDAT can be used as a high efficient RAFT chain-transfer agent for further functionalization. Then, the functionalized Fe3O4 reacted with 4-amino-2,2,6,6-tetramethyl-piperidine-oxyl (4-NH2-TEMPO) to give the spin labeling magnetic nanoparticles. Finally, the multifunctional MNPs was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), Fourier transform infrared spectrometer (FT-IR), and vibrating-sample magnetometer (VSM). The obtained highly water-soluble, superparamagnetic, and multifunctional magnetic nanoparticles should find potential applications in biomedical research. PMID:22755003

Zhao, Zijun; Zhao, Hongli; Yu, Ronghua; Yuan, Huihui; Zhu, Xiang; Lan, Minbo

2012-03-01

53

Fe3O4 nanoparticles embedded in carbon-framework as anode material for high performance lithium-ion batteries  

International Nuclear Information System (INIS)

Highlights: ? Fe3O4 nanoparticles are embedded in the three-dimensional carbon-framework. ? Carbon layers and Fe3O4 nanoparticles bulid a special micro-nanostructure. ? Carbon-framework favors fast electrons transportation during the charge/discharge process. ? Carbon-framework improves the cyclic stability of the composite. ? Fe3O4/C composite show higher capacity retention in comparison with that of Fe3O4 nanoparticles. - Abstract: Fe3O4/C composites have been prepared by sucrose calcining with Fe3O4 particles obtained from ferrous oxalate decomposition. The scanning electron microscopy (SEM) images show that Fe3O4 nanoparticles (Fe3O4 NPS) with average size of 200 nm are embedded in the three-dimensional (3D) carbon-framework. As an anode material for rechargeable lithium-ion batteries, the Fe3O4/C composite delivers a reversible capacity of 773 mAh g?1 at a current density of 924 mA g?1 after 200 cycles, higher than that of the bare Fe3O4 NPS which only retain a capacity of 350 mAh g?1. When the current density rises to 1848 mA g?1, Fe3O4/C material still remains 670 mAh g?1 even after 400 cycles. The enhanced high-rate performance can be attributed to can be attributed to the 3D carbon-framework, which improves the electric conductivity, relaxes the strain stress and prevents the aggregation of Fe3O4 particles during the charge/discharge process.

54

Formation of multifunctional Fe3O4/Au composite nanoparticles for dual-mode MR/CT imaging applications  

Science.gov (United States)

Recent advances with iron oxide/gold (Fe3O4/Au) composite nanoparticles (CNPs) in dual-modality magnetic resonance (MR) and computed tomography (CT) imaging applications are reviewed. The synthesis and assembly of “dumbbelllike” and “core/shell” Fe3O4/Au CNPs is introduced. Potential applications of some developed Fe3O4/Au CNPs as contrast agents for dual-mode MR/CT imaging applications are described in detail.

Hu, Yong; Li, Jing-Chao; Shen, Ming-Wu; Shi, Xiang-Yang

2014-07-01

55

Interactions in ?-Fe2O3 and Fe3O4 nanoparticle systems  

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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.

Laha, S. S.; Tackett, R. J.; Lawes, G.

2014-09-01

56

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

Science.gov (United States)

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.

Sun, Minmin; Zhu, Aimei; Zhang, Qiugen; Liu, Qinglin

2014-11-01

57

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

Science.gov (United States)

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.

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

2013-06-01

58

Controlled synthesis and self-assembly of dendrite patterns of Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

A method for the growth and self-assembly of Fe3O4 nanoparticles that is template assisted, as well as gas diffusion and surface tension controlled, has been developed at room temperature. Well-defined dendrite patterns of Fe3O4 nanoparticles were obtained upon ion (Fe3+/Fe2+) entrapment in a polyethylene glycol solution followed by NH3 gas exposure on the surface of an aqueous solution on the glass substrate. During the formation of Fe3O4 nanoparticles, the diffusion of volatile NH3 limits the hydrolysis rate of the molecular precursor and catalyzes slow formation. The template and surface tension also provided significant driving forces to promote the formation of dendrite patterns and influence the nature of the pattern. The Fe3+/Fe2+ concentration was varied in order to see the affects on the template molecular weight. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and SQUID measurements were used to characterize the final product. The derived patterned structure can be tailored by a simple combination of the physical and chemical procedure, which provides a new opportunity for obtaining a controllable pattern of nanoparticles.

59

Alcohol dependent production of Fe3O4 and CoFe2O4 nanoparticles.  

Science.gov (United States)

Commonly available alcohols of varying lengths and degree of branching were used to synthesize iron oxide, Fe3O4, and cobalt iron oxide, CoFe2O4, nanoparticles by means of a simple solvothermal decomposition of iron (III) acetylacetonates and cobalt (II) acetylacetonates. Depending on the solvent employed resulting Fe3O4 and CoFe2O4 nanoparticles ranged in size from approximately 5-16 nm and approximately 4-8 nm, respectively. All alcohols utilized resulted in the formation of nanoparticles with a spinel crystal structure, with the exception of methanol. Use of tert-butanol and phenol resulted in nearly spherical agglomerations of individual nanoparticles ranging between 100-250 nm. The resulting structures and morphologies of all samples were confirmed by X-ray diffraction and electron microscopy. Mass specific moments are reported based on SQUID magnetometry, and ranged from 57.5(5)-76.4(3) emu/g for Fe3O4 and 47.7(7)-67.0(4) emu/g CoFe2O4. PMID:23862521

Yocum, Brandon J; Ekiert, Thomas F; Alexander, Max D; O'Malley, Matthew J

2013-06-01

60

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

Directory of Open Access Journals (Sweden)

Full Text Available Yuntao Li1,2, Jing Liu1, Yuejiao Zhong3, Jia Zhang1, Ziyu Wang1, Li Wang1, Yanli An1, Mei Lin1, Zhiqiang Gao2, Dongsheng Zhang11School of Medicine, Southeast University, Nanjing, Jiangsu Province, People's Republic of China; 2Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, People's Republic of China; 3Jiangsu Cancer Hospital and Jiangsu Institute of Cancer Research, Nanjing, Jiangsu Province, People's Republic of ChinaPurpose: This research was conducted to assess the biocompatibility of the core-shell Fe3O4@Au composite magnetic nanoparticles (MNPs, which have potential application in tumor hyperthermia. Methods: Fe3O4@Au composite MNPs with core-shell structure were synthesized by reduction of Au3+ in the presence of Fe3O4-MNPs prepared by improved co-precipitation. Cytotoxicity assay, hemolysis test, micronucleus (MN assay, and detection of acute toxicity in mice and beagle dogs were then carried out.Results: The result of cytotoxicity assay showed that the toxicity grade of this material on mouse fibroblast cell line (L-929 was classified as grade 1, which belongs to no cytotoxicity. Hemolysis rates showed 0.278%, 0.232%, and 0.197%, far less than 5%, after treatment with different concentrations of Fe3O4@Au composite MNPs. In the MN assay, there was no significant difference in MN formation rates between the experimental groups and negative control (P > 0.05, but there was a significant difference between the experimental groups and the positive control (P < 0.05. The median lethal dose of the Fe3O4@Au composite MNPs after intraperitoneal administration in mice was 8.39 g/kg, and the 95% confidence interval was 6.58-10.72 g/kg, suggesting that these nanoparticles have a wide safety margin. Acute toxicity testing in beagle dogs also showed no significant difference in body weight between the treatment groups at 1, 2, 3, and 4 weeks after liver injection and no behavioral changes. Furthermore, blood parameters, autopsy, and histopathological studies in the experimental group showed no significant difference compared with the control group.Conclusion: The results indicate that Fe3O4@Au composite MNPs appear to be highly biocompatible and safe nanoparticles that are suitable for further application in tumor hyperthermia. Keywords: toxicity, hyperthermia, core-shell

Li Y

2011-11-01

 
 
 
 
61

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

Science.gov (United States)

The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (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.

Almeida, Trevor P.; Muxworthy, Adrian R.; Williams, Wyn; Kasama, Takeshi; Dunin-Borkowski, Rafal E.

2014-06-01

62

Folate-conjugated luminescent Fe3O4 nanoparticles for magnetic hyperthermia  

Science.gov (United States)

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

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

2014-04-01

63

Composite multifunctional nanostructures based on ZnO tetrapods and superparamagnetic Fe3O4 nanoparticles  

Science.gov (United States)

A nanocomposite material is obtained by coupling superparamagnetic magnetite nanoparticles (Fe3O4 NP) and vapor phase grown zinc oxide nanostructures with ‘tetrapod’ morphology (ZnO TP). The aim is the creation of a multifunctional material which retains the attractive features of ZnO (e.g. surface reactivity, strong UV emission, piezoelectricity) together with added magnetism. Structural, morphological, optical, magnetic and functional characterization are performed. In particular, the high saturation magnetization of Fe3O4 NP (above 50 A m2 kg-1), the strong UV luminescence and the enhanced photocatalytic activity of coupled nanostructures are discussed. Thus the nanocomposite turns out to be suitable for applications in energy harvesting and conversion, gas- and bio-sensing, bio-medicine and filter-free photocatalysis.

Villani, M.; Rimoldi, T.; Calestani, D.; Lazzarini, L.; Chiesi, V.; Casoli, F.; Albertini, F.; Zappettini, A.

2013-04-01

64

Synthesis and surface properties of magnetite (Fe3O4) nanoparticles infiltrated into porous silicon template  

Science.gov (United States)

The synthesis and surface properties of a composite material consisting of porous silicon/magnetite nanoparticles (PSi/Fe3O4 NPs) are demonstrated. PSi layers with intermediate pore size (?100 nm) are prepared by electrochemical porosification of n-type Si wafer in a hydrofluoric acid-containing oxidizing agent and surfactant. The intrinsically luminescent PSi templates are infiltrated with ferromagnetic Fe3O4 NPs grown by a simple hydrothermal approach with average sizes ranging from 8 to 30 nm. The photoluminescence intensity of magnetic nanocomposite was enhanced after Fe3O4 loading, probably due to the recombination of photoexcited carriers within the nanocrystallites. Magnetization measurement for the nanocomposites indicated that the magnetic nanoparticles retain their ferromagnetic characteristic at room temperature. The nanocomposites have been characterized by various techniques including, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and magnetic measurements. The biocompatibility of both components and the ability to tailor the magnetic properties of the composite might be useful for magnetic and biomedical applications.

Harraz, Farid A.

2013-12-01

65

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: ? b>3O4. - 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.

66

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

International Nuclear Information System (INIS)

To prepare dispersed Fe3O4 magnetic nanoparticles (MNPs), we adopt a co-precipitation method and consider surfactant amount, stirring speed, dispersion mode, and molar ratio of Fe3+/Fe2+. Via transmission electronic microscopy and X-ray diffractometry, we characterize the dispersibility and size of the products and determine the appropriate values of experimental parameters. The stirring speed is 1000 rpm in titration. There is simultaneous ultrasonic vibration and mechanical stirring in the titration and surface coating processes. The surfactant amount of oleic acid is 1.2 ml for molar ratios of Fe3+/Fe2+ as 1.7:1, 1.8:1, and 1.9:1. The average diameters of these Fe3O4 MNPs are 11 nm, and the ratios of saturation magnetization for these MNPs to that of bulk magnetite range from 45% to 65%, with remanent magnetization close to zero and low coercivity. Above all, the linear birefringence and dichroism measurements of the kerosene-based ferrofluid (FF) samples are investigated by a Stokes polarimeter. The influences of particle size distribution and magnetization in the birefringence and dichroism measurements of FFs are discussed. - Highlights: ? Dispersed Fe3O4 magnetic nanoparticles (MNPs) are produced by a co-precipitation method. ? Simultaneous ultrasonic vibration and mechanical stirring are used in titration and coating. ? Diameters of Fe3O4 MNPs are determined as 11 nm with maximum magnetization as 54.27 emu/g. ? Birefringence and dichroism of ferrofluids are obtained by a Stokes polarimeter successfully

67

Fast removal of malachite green dye using novel superparamagnetic sodium alginate-coated Fe3O4 nanoparticles.  

Science.gov (United States)

In this study, superparamagnetic sodium alginate-coated Fe3O4 nanoparticles (Alg-Fe3O4) as a novel magnetic adsorbent were prepared by in situ coprecipitation method, in which Fe3O4 nanoparticles were precipitated from FeCl3 and FeCl2 under alkaline medium in the presence of sodium alginate. The Alg-Fe3O4 nanoparticles were used for removal of malachite green (MG) from aqueous solutions using batch adsorption technique. The characterization of synthesized nanoparticles was performed using XRD, FTIR, TEM, TGA and vibrating sample magnetometer (VSM) techniques. FTIR analysis of synthesized nanoparticles provided the evidence that sodium alginate was successfully coated on the surface of Fe3O4 nanoparticles. The FT-IR and TGA characterization showed that the Alg-Fe3O4 nanoparticles contained about 14% (w/w) of sodium alginate. Moreover, TEM analysis indicated that the average diameter of the Alg-Fe3O4 nanoparticles was about 12nm. The effects of adsorbent dosage, pH and temperature were investigated on the adsorption properties of MG onto Alg-Fe3O4 nanoparticles. The equilibrium adsorption data were modeled using the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 47.84mg/g. The kinetics of adsorption of MG onto Alg-Fe3O4 nanoparticles were investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption of MG onto nanoparticles followed pseudo-second-order kinetic model. PMID:24875322

Mohammadi, Abbas; Daemi, Hamed; Barikani, Mehdi

2014-08-01

68

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

Science.gov (United States)

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 magnetic properties of the two nanopowders and the corresponding nanocomposites were measured in the 10 K-300 K temperature range. Magnetic measurements are shown here to be able to give unambiguous information on single-particle properties such as particle size and magnetic anisotropy as well as on nanoparticle aggregation and interparticle interaction. A comparison between the size distribution functions obtained from magnetic measurements and from TEM images shows that figures estimated from properly analyzed magnetic measurements are very close to the actual values. In addition, the present analysis allows us to determine the value of the effective magnetic anisotropy and to estimate the anisotropy contribution from the surface. The Field-cooled/zero field cooled curves reveal a high degree of particle aggregation in the Fe3O4 nanopowder, which is partially reduced by silica coating and strongly decreased by dissolution in the host polymer. In all considered materials, the nanoparticles are magnetically interacting, the interaction strength being a function of nanoparticle environment and being the lowest in the nanocomposite containing bare, well-separate Fe3O4 particles. All samples behave as interacting superparamagnetic materials instead of ideal superparamagnets and follow the corresponding scaling law.

Allia, P.; Barrera, G.; Tiberto, P.; Nardi, T.; Leterrier, Y.; Sangermano, M.

2014-09-01

69

Synthesis and characterization of Fe3O4 nanoparticles with perspectives in biomedical applications  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

2014-06-01

70

Preparation and characterization of PVPI-coated Fe3O4 nanoparticles as an MRI contrast agent  

Science.gov (United States)

Polyvinylpyrrolidone-iodine (PVPI)-coated Fe3O4 nanoparticles were prepared by using inverse chemical co-precipitation method, in which the PVPI serves as a stabilizer and dispersant. The wide angle X-ray diffraction (WAXD) 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 the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FTIR) results suggested that PVPI interacted with Fe3O4 via its carbonyl groups. Results of superconducting quantum interference device (SQUID) indicated prepared Fe3O4 nanoparticles exhibited superparamagnetic behavior and high saturation magnetization. T2-weighted MRI images of PVPI-coated Fe3O4 nanoparticles showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticles concentration in water at room temperature. These results indicated that the PVPI-coated Fe3O4 nanoparticles had great potential for application in MRI as a T2 contrast agent.

Wang, Guangshuo; Chang, Ying; Wang, Ling; Wei, Zhiyong; Kang, Jianyun; Sang, Lin; Dong, Xufeng; Chen, Guangyi; Wang, Hong; Qi, Min

2013-08-01

71

Functionalized Fe3O4-Au superparamagnetic nanoparticles: in vitro bioactivity  

International Nuclear Information System (INIS)

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe3O4-Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10–15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe3O4-Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cea higher level of accumulation in the cells for glucose conjugated nanoparticles. (paper)

72

Functionalized Fe3O4@Au superparamagnetic nanoparticles: in vitro bioactivity  

Science.gov (United States)

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe3O4@Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10-15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe3O4@Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cells for glucose conjugated nanoparticles.

Salado, J.; Insausti, M.; Lezama, L.; Gil de Muro, I.; Moros, M.; Pelaz, B.; Grazu, V.; de la Fuente, J. M.; Rojo, T.

2012-08-01

73

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

Directory of Open Access Journals (Sweden)

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

Dorniani D

2012-11-01

74

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

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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.

Chittor Raghuraman

2010-12-01

75

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

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

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

2012-01-01

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Electrical and Magnetic Properties of Polymer Electrolyte PVA.LiOH Dispersed by Fe3O4 Nanoparticles  

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Nanocomposite magnetic polymer electrolyte based on poly (vinyl alcohol) (PVA) with lithium hydroxide (LiOH) dispersed by magnetite (Fe3O4) nanoparticle as inorganic filler were prepared by using an in-situ method. Ions carriers were inserted during the growth of the nanoparticles that had been contributed by a precursor. The effect upon the addition of Fe3O4 nanoparticles on the ionic conductivity of the composite polymer electrolytes was investigated, and it was proven that the ionic conductivity had been enhanced. Maximum conductivity was obtained upon addition of Fe3O4 nanoparticles, i.e. 1.81×10-3S.cm-1. The magnetic properties of nanocomposite magnetic polymer electrolyte were observed by magnetic susceptibility studies. The magnetic susceptibility data revealed that polymer electrolyte PVA.LiOH dispersed by Fe3O4 nanoparticle was found predominantly ferrimagnetism.

Aji, Mahardika Prasetya; Rahmawati; Masturi; Bijaksana, Satria; Khairurrijal; Abdullah, Mikrajuddin

2011-12-01

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Comment on 'Preparation and antibacterial activity of Fe3O4-Ag nanoparticles'  

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The fabrication of nanocomposite materials with a metal oxide-nobel metal structure represents a challenge both from the theoretical and experimental points of view. This challenge is connected with a complicated mechanism of formation of these nanocomposite materials. In the paper by Gong et al (2007 Nanotechnology 18 285604), the authors tried to solve this problem but the suggested mechanism is rather improbable. This improbability derived from the found discrepancy in the material balance of reactants/products. Therefore this comment is devoted to evaluation of this discrepancy of the Fe3O4-Ag nanoparticle preparation and suggestion of another possible mechanism. (comment)

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COMMENT: Comment on 'Preparation and antibacterial activity of Fe3O4@Ag nanoparticles'  

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The fabrication of nanocomposite materials with a metal-oxide@nobel-metal structure represents a challenge both from the theoretical and experimental points of view. This challenge is connected with a complicated mechanism of formation of these nanocomposite materials. In the paper by Gong et al (2007 Nanotechnology 18 285604), the authors tried to solve this problem but the suggested mechanism is rather improbable. This improbability derived from the found discrepancy in the material balance of reactants/products. Therefore this comment is devoted to evaluation of this discrepancy of the Fe3O4@Ag nanoparticle preparation and suggestion of another possible mechanism.

Kvítek, Libor; Soukupova, Jana

2009-01-01

79

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

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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.

80

Interface composition between Fe3O4 nanoparticles and GaAs for spintronic applications  

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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.

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

2014-08-01

 
 
 
 
81

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

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

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

2014-06-01

82

Carbon-encapsulated Fe3O4 nanoparticles as a high-rate lithium ion battery anode material.  

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A facile and scalable in situ synthesis strategy is developed to fabricate carbon-encapsulated Fe3O4 nanoparticles homogeneously embedded in two-dimensional (2D) porous graphitic carbon nanosheets (Fe3O4@C@PGC nanosheets) as a durable high-rate lithium ion battery anode material. With assistance of the surface of NaCl particles, 2D Fe@C@PGC nanosheets can be in situ synthesized by using the Fe(NO3)3·9H2O and C6H12O6 as the metal and carbon precursor, respectively. After annealing under air, the Fe@C@PGC nanosheets can be converted to Fe3O4@C@PGC nanosheets, in which Fe3O4 nanoparticles (?18.2 nm) coated with conformal and thin onion-like carbon shells are homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of less than 30 nm. In the constructed architecture, the thin carbon shells can avoid the direct exposure of encapsulated Fe3O4 to the electrolyte and preserve the structural and interfacial stabilization of Fe3O4 nanoparticles. Meanwhile, the flexible and conductive PGC nanosheets can accommodate the mechanical stress induced by the volume change of embedded Fe3O4@C nanoparticles as well as inhibit the aggregation of Fe3O4 nanoparticles and thus maintain the structural and electrical integrity of the Fe3O4@C@PGC electrode during the lithiation/delithiation processes. As a result, this Fe3O4@C@PGC electrode exhibits superhigh rate capability (858, 587, and 311 mAh/g at 5, 10, and 20 C, respectively, 1 C = 1 A/g) and extremely excellent cycling performance at high rates (only 3.47% capacity loss after 350 cycles at a high rate of 10 C), which is the best one ever reported for an Fe3O4-based electrode including various nanostructured Fe3O4 anode materials, composite electrodes, etc. PMID:23614734

He, Chunnian; Wu, Shan; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun

2013-05-28

83

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

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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.

Mukherjee Joyeeta

2012-11-01

84

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

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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.

Yazdi MH

2012-08-01

85

Fast defluorination and removal of norfloxacin by alginate/Fe@Fe3O4 core/shell structured nanoparticles.  

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Alginate-Fe(2+)/Fe(3+) polymer coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@ALG/Fe MNPs) with core/shell structure are prepared and used as heterogeneous Fenton nanocatalyst to degrade norfloxacin (NOF). The Fenton-like process based on Fe(3)O(4)@ALG/Fe shows much higher efficiency on NOF degradation. Compared with Fe(3)O(4) nanoparticle-H(2)O(2) system, NOF degradation in Fe(3)O(4)@AlG/Fe-H(2)O(2) system can be conducted in a wide pH range (pH 3.5-6.5) and independent on temperature. With 0.98 mM H(2)O(2) and 0.4 g L(-1) Fe(3)O(4)@ALG/Fe, 100% of NOF and 90% of TOC is removed within 60 min, and the fluorine element in NOF molecule changes into F(-) ions within 1 min, indicating that NOF degradation in this Fenton-like reaction is performed through direct defluorination pathway. XPS analysis shows that TOC removal in reaction solution mainly results from the adsorption of NOF degradation intermediates on catalyst. Due to the paramagneticity and high saturation magnetization of Fe(3)O(4)@ALG/Fe, the used catalyst with adsorbed NOF intermediate is collected from aqueous solution by applying an external magnetic field, leading to complete removal of NOF from water samples. As being composed of inorganic materials and biopolymer, Fe(3)O(4)@ALG/Fe MNPs are robust, thermo-stable, nontoxic and environmentally friendly. These attractive features endow Fe(3)O(4)@ALG/Fe as a potent Fenton-like catalyst for fluoroquinolones degradation. PMID:22658830

Niu, Hongyun; Dizhang; Meng, Zhaofu; Cai, Yaqi

2012-08-15

86

Linear birefringence and dichroism in citric acid coated Fe3O4 magnetic nanoparticles  

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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.

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

2014-12-01

87

Magnetic Behaviour and Heating Effect of Fe3O4 Ferrofluids Composed of Monodisperse Nanoparticles  

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Fe3O4 ferrofluids containing monodisperse Fe3O4 nanoparticles with different diameters of 8, 12, 16 and 18 nm are prepared by using high-temperature solution phase reaction. The particles have single crystal structures with narrow size distributions. At room temperature, the 8-nm ferrofluid shows superparamagnetic behaviour, whereas the others display hysteresis properties and the coercivity increases with the increasing particle size. The spin glass-like behaviour and cusps near 190 K are observed on all ferrofluids according to the temperature variation of field-cooled (FC) and zero-field-cooled (ZFC) magnetization measurements. The cusps are found to be associated with the freezing point of the solvent. As a comparison, the ferrofluids are dried and the FC and ZFC magnetization curves of powdery samples are also investigated. It is found that the blocking temperatures for the powdery samples are higher than those for their corresponding ferrofluids. Moreover, the size dependent heating effect of the ferrofluids is also investigated in ac magnetic field with a frequency of 55 kHz and amplitude of 200 Oe.

Zhang, Li-Ying; Dou, Yong-Hua; Zhang, Ling; Gu, Hong-Chen

2007-02-01

88

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

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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

Echeverria, Coro; Mijangos, Carmen

2011-07-01

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Magnetic nanoparticle of Fe3O4 and 5-bromotetrandrin interact synergistically to induce apoptosis by daunorubicin in leukemia cells  

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Full Text Available Baoan Chen1*, Jian Cheng1*, Mingfang Shen1, Feng Gao1, Wenlin Xu2, et al1Department of Hematology;2Department of Hematology, The Affiliated People’s Hospital, Jiangsu University, Zhenjiang, P.R China, et al *These authors have contributed equally to this work.Abstract: Apoptosis is a common pathway that finally mediated the killing functions of anticancer drugs, which is an important cause of multidrug resistance (MDR. The aim of this study was to investigate the potential benefit of combination therapy with magnetic nanoparticle of Fe3O4 (MNP(Fe3O4 and 5-bromotetrandrin (BrTet. Analysis of the apoptosis percentage showed that combination of daunorubicin (DNR with either MNP(Fe3O4 or BrTet exerted a potent cytotoxic effect on K562/A02 cells, while MNP(Fe3O4 and BrTet cotreatment can synergistically enhance DNR-induced apoptosis. Importantly, we confirmed that the distinct synergism effect of that composite on reverse multidrug resistance may owe to the regulation of various proliferative and antiapoptotic gene products, including P53 and caspase-3. Thus our in vitro data strongly suggests a potential clinical application of MNP(Fe3O4 and BrTet combination on CML.Keywords: K562/A02 leukemic cells, multidrug resistance, magnetic nanoparticle of Fe3O4, 5-bromotetrandrine, apoptosis, P53, caspase-3

Baoan Chen

2009-03-01

90

Functionalization of PEGylated Fe3O4 magnetic nanoparticles with tetraphosphonate cavitand for biomedical application  

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In this contribution, Fe3O4 magnetic nanoparticles (MNPs) have been functionalized with a tetraphosphonate cavitand receptor (Tiiii), capable of complexing N-monomethylated species with high selectivity, and polyethylene glycol (PEG) via click-chemistry. The grafting process is based on MNP pre-functionalization with a bifunctional phosphonic linker, 10-undecynylphosphonic acid, anchored on an iron surface through the phosphonic group. The Tiiii cavitand and the PEG modified with azide moieties have then been bonded to the resulting alkyne-functionalized MNPs through a ``click'' reaction. Each reaction step has been monitored by using X-ray photoelectron and FTIR spectroscopies. PEG and Tiiii functionalized MNPs have been able to load N-methyl ammonium salts such as the antitumor drug procarbazine hydrochloride and the neurotransmitter epinephrine hydrochloride and release them as free bases. In addition, the introduction of PEG moieties promoted biocompatibility of functionalized MNPs, thus allowing their use in biological environments.

Tudisco, C.; Bertani, F.; Cambria, M. T.; Sinatra, F.; Fantechi, E.; Innocenti, C.; Sangregorio, C.; Dalcanale, E.; Condorelli, G. G.

2013-11-01

91

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

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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

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

2012-10-01

92

A novel platform of hemoglobin on core-shell structurally Fe3O4-Au nanoparticles and its direct electrochemistry  

International Nuclear Information System (INIS)

en peroxide, oxygen and trichloroacetic acid. The possible functions of Fe3O4 core and Au shell as a novel platform for achieving Hb direct electrochemistry were also discussed, respectively. - Abstract: A novel platform, which hemoglobin (Hb) was immobilized on core-shell structurally Fe3O4/Au nanoparticles (simplified as Fe3O4-Au NPs) modified glassy carbon electrode (GCE), has been developed for fabricating the third biosensors. Fe3O4-Au NPs, characterized using transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive spectra (EDS), were coated onto GCE mediated by chitosan so as to provide larger surface area for anchoring Hb. The thermodynamics, dynamics and catalysis properties of Hb immobilized on Fe3O4-Au NPs were discussed by UV-visible spectrum (UV-vis), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance technique (EQCM) and cyclic voltammetry (CV). The electrochemical parameters of Hb on Fe3O4-Au NPs modified GCE were further carefully calculated with the results of the effective working area as 3.61 cm2, the surface coverage concentration (?) as 1.07 x 10-12 mol cm-2, the electron-transfer rate constant (Ks) as 1.03 s-1, the number of electron transferred (n) as 1.20 and the standard entropy of the immobilized Hb (?S0') as calculated to be -104.1 J mol-1 K-1. The electrocatalytic behaviors of the immobilized Hb on Fe3O4-Au NPs were applied for the determination of hydrogen peroxide (H2O2), oxygen (O2) and trichloroacetic acid (TCA). The possible functions of Fe3O4 core and Au shell as a novel platform for achieving Hb direct electrochemistry were discussed, respectively.

93

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

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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.

Yuan, Muzhaozi

94

Tailoring biocompatible Fe3O4 nanoparticles for applications to magnetic hyperthermia  

Science.gov (United States)

Magnetite based nanoparticles functionalized with different ligands have been obtained by optimization of two synthetic methods. Gold surrounded Fe3O4 nanoparticles capped with oleic acid and oleylamine were achieved by thermal decomposition of metallo-organic precursors. By this way nanoparticles with perfectly defined size within 3.5 nm to 7 nm in diameter and organic content from 16.1% to 40.9 % were obtained. Precipitation of iron(II) chloride in basic solution yield magnetite nanoparticles between 20 and 40 nm with contents of organic ligands of 3 - 12 %. The samples have been characterized by X-ray diffraction, transmission electron microscopy and thermogravimetric measurements. A complete magnetic study has been performed by means of a SQUID magnetometer and electron magnetic resonance (EMR), showing the influence of capping covering on the superparamagnetic behaviour. The citotoxicity and interaction with HeLa cells was evaluated for some of the preparations. Finally, the specific absorption rate (SAR) was calculated to compare the efficiency of heating each sample for the various applied magnetic fields.

Insausti, Maite; Salado, Javier; Castellanos, Idoia; Lezama, Luis; Gil de Muro, Izaskun; de la Fuente, Jesús M.; Garayo, Eneko; Plazaola, Fernando; Rojo, Teófilo

2012-03-01

95

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

96

Use of hydroxypropyl-?-cyclodextrin/polyethylene glycol 400, modified Fe3O4 nanoparticles for congo red removal.  

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Fe3O4 nanoparticles were modified with Hydroxypropyl-?-cyclodextrin (HP-?-CD) and Polyethylene glycol 400 (PEG400) by a facile one-pot homogeneous precipitation method, and were used as a novel nano-adsorbent for the removal of congo red (CR) from aqueous solutions. The polymer-modified composites were characterized by FTIR, TEM, TGA, XRD and VSM, and showed excellent adsorption efficiency for CR. The value of the maximum adsorption capacity calculated according to the Langmuir isotherm model were 1.895g/g, which are much high and about 19 times that of Fe3O4 nanoparticles. Desorption study further indicates the good regeneration ability of the nanocomposites. The results suggest that the HP-?-CD/PEG400-modified Fe3O4 nanoparticles is a promising adsorbent for CR removal from aqueous solutions, and it is easily recycled owing to its large specific surface area and unique magnetic responsiveness. PMID:24333392

Yu, Lan; Xue, Weihua; Cui, Lei; Xing, Wen; Cao, Xinli; Li, Hongyu

2014-03-01

97

Multifunctional luminomagnetic FePt-Fe3O4/SiO2/Rhodamine B/SiO2 nanoparticles with high magnetic emanation for biomedical applications  

International Nuclear Information System (INIS)

Multifunctional luminomagnetic nanoparticles with average particle diameter around 34 nm and enhanced magnetic properties are reported. FePt-Fe3O4 magnetic nuclei with 6.0 ± 0.7 nm in a core–shell nanostructure were synthesized combining the modified polyol and seed-mediated growth processes, coated with silica by reverse micelle route and annealed. Individual silica-coated magnetic core resulted in a mixture of hard and soft magnetic nanostructured material with superparamagnetic behavior and enhanced magnetic emanation. Luminescent dye Rhodamine B (RhB) was incorporated onto the nanoparticle surface followed by coating with an outer silica shell in a layer-by-layer structure. The bifunctional luminomagnetic nanoparticles of FePt-Fe3O4/SiO2/RhB/SiO2 present high-water dispersibility, colloidal stability, and hydrophilic surface with isoelectric point of 2.7. The superparamagnetic behavior was preserved with blocking temperature of 40 K and the saturation magnetization of the final product equal 64.3 emu g?1 was around ten times higher than observed for nanoparticles using pure magnetite core synthesized in the same conditions. Inner and outer silica layers minimize luminescence quenching processes due to avoid contact between dye and both magnetic core and solvent, respectively, resulting in a stable emission for, at least, 1 h. These properties allied with the possibility to use differed with the possibility to use different dye compounds gives a potential bifunctional nanosensor for biomedical applications.

98

Degradation of methylene blue with H2O2 activated by peroxidase-like Fe3O4 magnetic nanoparticles.  

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Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) were successfully prepared through an advanced reverse co-precipitation method under the assistance of ultrasound irradiation. The structure and size distribution were characterized by X-ray powder diffraction (XRD), laser particle size analyzer (LPSA), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The magnetic properties of Fe3O4 nanoparticles were measured by the vibrating sample magnetometer (VSM). Such Fe3O4 MNPs were used as a peroxidase mimetic to remove the dye pollutant methylene blue (MB) in the presence of H2O2. Some important reaction parameters were optimized to improve the degradation of MB. It was observed that the degradation efficiency of 10 mg L(-1) MB was above 96% over 0.62 g L(-1) Fe3O4 MNPs within 0.30 mmol L(-1) H2O2 at pH 4.85 and temperature 25 degrees C in 15 min, being superior to the previous reports. PMID:21770106

Jiang, Jizhou; Zou, Jing; Zhu, Lihua; Huang, Lei; Jiang, Haipeng; Zhang, Yuanxiao

2011-06-01

99

Electromagnetic characteristics of manganese oxide-coated Fe3O4 nanoparticles at 2-18 GHz  

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The dielectric and magnetic properties of manganese oxide-coated Fe3O4 nanoparticles (NPs) were measured by the transmission/reflection method in 2-18 GHz. MnOx-coated Fe3O4 NPs were prepared by sol-gel method followed by heat-treating at 300, 400, and 500 °C, respectively. The heat-treated powders were then used as magnetic fillers and added to an epoxy resin to prepare MnOx-coated Fe3O4 composites for the complex permittivity (?'-j??) and permeability (?'-j??) measurements. After the sol-gel process, the coating of manganese oxide (mixture of major Mn2O3 and minor Mn3O4) reduced the value of ?'. The lower the heat-treating temperature, the larger the decrease in ?'. The relative decrease in ?', compared with uncoated Fe3O4 nanoparticles, is 28.7, 23.5, and 20.0% for coated MnOx heat-treated at 300, 400, and 500 °C, respectively, while the relative decrease in ?? is 74.1, 68.8, and 65.2%, respectively. In the present study, MnOx-coated Fe3O4 exhibited a significant decrease in dielectric loss tangent of ˜100% compared to that of uncoated NPs and can be of practical use for microwave components.

Yang, R. B.; Liang, W. F.; Lin, C. K.

2011-04-01

100

A covalently attached film based on poly(methacrylic acid)-capped Fe3O4 nanoparticles  

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Poly(methacrylic acid) (PMAA)-capped Fe3O4 nanoparticles were prepared by coprecipitation with PMAA in aqueous solution. Fe3O4 nanoparticles were further assembled with 2-nitro-N-methyl-4-diazonium-formaldehyde resin (NDR) to form a photosensitive precursor film, by virtue of the coulombic attraction between the negatively charged PMAA surface capping agent and the cationic polyelectrolyte of NDR. Covalent bonds were formed under ultraviolet irradiation. As a result of polymer capping of the nanoparticles and covalent linkage, a highly stable multilayer structure was formed. Transmission electron micrographs and selected area electron diffraction pattern revealed the Fe3O4 nanoparticles to be approximately 8 nm in diameter with a cubic phase structure. X-Ray photoelectron spectroscopy provided evidence for the presence of Fe3O4 nanoparticles and NDR within the ultrathin films. The UV-visible spectroscopy and atomic force microscopy measurements supported the improvement of the stability of the film, which became impervious to polar solvents when the linkages between the nanoparticles and polymer changed from ionic bonds to covalent bonds

 
 
 
 
101

Polyaniline shell cross-linked Fe3O4 magnetic nanoparticles for heat activated killing of cancer cells.  

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Superparamagnetic Fe3O4 nanoparticles are appealing materials for heat activated killing of cancer cells. Here, we report a novel method to enhance the heat activated killing of cancer cells under an AC magnetic field (AMF) by introducing a polyaniline impregnated shell onto the surface of Fe3O4 nanoparticles. These polyaniline shell cross-linked magnetic nanoparticles (PSMN) were prepared by in situ polymerization of aniline hydrochloride on the surface of carboxyl PEGylated Fe3O4 nanoparticles. XRD and TEM analyses revealed the formation of single phase inverse spinel Fe3O4 nanoparticles of a size of about 10 nm. The successful growth of the polyaniline shell on the surface of carboxyl PEGylated magnetic nanoparticles (CPMN) is evident from FTIR spectra, DLS, TGA, zeta-potential and magnetic measurements. Both CPMN and PSMN show good colloidal stability, superparamagnetic behavior at room temperature and excellent heating efficacy under AMF. It has been observed that the heating efficacy of PSMN under AMF was slightly reduced as compared to that of CPMN. The enhanced toxicity of PSMN to cancer cells under AMF suggests their strong potential for magnetic hyperthermia. Furthermore, PSMN shows high loading affinity for an anticancer drug (doxorubicin), its sustained release and substantial internalization in tumor cells. PMID:24948377

Rana, Suman; Jadhav, Neena V; Barick, K C; Pandey, B N; Hassan, P A

2014-08-28

102

Fe3O4/Au magnetic nanoparticle amplification strategies for ultrasensitive electrochemical immunoassay of alfa-fetoprotein  

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Full Text Available Ning Gan1*, Haijuan Jin1*, Tianhua Li1, Lei Zheng21The State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering, Ningbo University, Ningbo, 2Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, People's Republic of China *Both authors contributed equally to this workBackground: The purpose of this study was to devise a novel electrochemical immunosensor for ultrasensitive detection of alfa-fetoprotein based on Fe3O4/Au nanoparticles as a carrier using a multienzyme amplification strategy.Methods and results: Greatly enhanced sensitivity was achieved using bioconjugates containing horseradish peroxidase (HRP and a secondary antibody (Ab2 linked to Fe3O4/Au nanoparticles (Fe3O4/Au-HRP-Ab2 at a high HRP/Ab2 ratio. After a sandwich immunoreaction, the Fe3O4/Au-HRP-Ab2 captured on the electrode surface produced an amplified electrocatalytic response by reduction of enzymatically oxidized hydroquinone in the presence of hydrogen peroxide. The high content of HRP in the Fe3O4/Au-HRP-Ab2 could greatly amplify the electrochemical signal. Under optimal conditions, the reduction current increased with increasing alfa-fetoprotein concentration in the sample, and exhibited a dynamic range of 0.005–10 ng/mL with a detection limit of 3 pg/mL.Conclusion: The amplified immunoassay developed in this work shows good precision, acceptable stability, and reproducibility, and can be used for detection of alfa-fetoprotein in real samples, so provides a potential alternative tool for detection of protein in the laboratory. Furthermore, this immunosensor could be regenerated by simply using an external magnetic field.Keywords: Fe3O4/Au nanoparticles, alfa-fetoprotein, sandwich immunoassay, electrochemical immunosensor

Gan N

2011-12-01

103

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

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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

P. Alimard

2013-04-01

104

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

105

Magnetic photocatalysts with a p-n junction: Fe3O4 nanoparticle and FeWO4 nanowire heterostructures.  

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Magnetic n-type semiconductor Fe3O4 nanoparticle and p-type semiconductor FeWO4 nanowire heterostructures were successfully synthesized without any surfactants or templates via a facile one-step hydrothermal process at 160 °C. The heterojunction structure and morphology were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Magnetic measurements indicated the coexistence of ferrimagnetic behavior of Fe3O4 and weak antiferromagnetic behavior of FeWO4. The degradation of methylene blue (MB) under UV-Visible light irradiation was studied as a model experiment to evaluate the catalytic activity of the Fe3O4/FeWO4 heterostructure p-n junctions. The decomposition efficiency was 97.1% after one hour UV-Visible irradiation. This magnetic photocatalyst can be easily recovered from the solution using a permanent magnet and redispersed by removing the magnet. PMID:25201551

Cao, Xuan; Chen, Yan; Jiao, Shihui; Fang, Zhenxing; Xu, Man; Liu, Xu; Li, Lu; Pang, Guangsheng; Feng, Shouhua

2014-10-01

106

Photoelectron diffraction study of Rh nanoparticles growth on Fe3O4/Pd(111) ultrathin film  

International Nuclear Information System (INIS)

Metallic nanoparticles (NPs) supported on oxides thin films are commonly used as model catalysts for studies of heterogeneous catalysis. Several 4d and 5d metal NPs (for example, Pd, Pt and Au) grown on alumina, ceria and titania have shown strong metal support interaction (SMSI), for instance the encapsulation of the NPs by the oxide. The SMSI plays an important role in catalysis and is very dependent on the support oxide used. The present work investigates the growth mechanism and atomic structure of Rh NPs supported on epitaxial magnetite Fe3O4(111) ultrathin films prepared on Pd(111) using the Molecular Beam Epitaxy (MBE) technique. The iron oxide and the Rh NPs were characterized using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction and photoelectron diffraction (PED). The combined XPS and PED results indicate that Rh NPs are metallic, cover approximately 20 % of the iron oxide surface and show height distribution ranging 3–5 ML (monolayers) with essentially a bulk fcc structure.

107

Biocompatible PEGylated Fe3O4 Nanoparticles as Photothermal Agents for Near-Infrared Light Modulated Cancer Therapy  

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Full Text Available In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for near-infrared light mediated cancer therapy in vitro. Via a facile one-pot solvothermal method, well-defined PEGylated magnetic nanoparticles (PEG–Fe3O4 were prepared with cheap inhesion as a first step. Due to the successful coating of PEG molecules on the surface of PEG–Fe3O4, these nanoparticles exhibited excellent dispersibility and dissolvability in physiological condition. Cytotoxicity based on MTT assays indicated these nanoparticles revealed high biocompatibility and low toxicity towards both Hela cells and C6 cells. After near-infrared (NIR laser irradiation, the viabilities of C6 cells were effectively suppressed when incubated with the NIR laser activated PEG–Fe3O4. In addition, detailed photothermal anti-cancer efficacy was evaluated via visual microscope images, demonstrating that our PEG–Fe3O4 were promising for photothermal therapy of cancer cells.

Gang Yuan

2014-10-01

108

Biocompatible PEGylated Fe3O4 Nanoparticles as Photothermal Agents for Near-Infrared Light Modulated Cancer Therapy  

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In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for near-infrared light mediated cancer therapy in vitro. Via a facile one-pot solvothermal method, well-defined PEGylated magnetic nanoparticles (PEG–Fe3O4) were prepared with cheap inhesion as a first step. Due to the successful coating of PEG molecules on the surface of PEG–Fe3O4, these nanoparticles exhibited excellent dispersibility and dissolvability in physiological condition. Cytotoxicity based on MTT assays indicated these nanoparticles revealed high biocompatibility and low toxicity towards both Hela cells and C6 cells. After near-infrared (NIR) laser irradiation, the viabilities of C6 cells were effectively suppressed when incubated with the NIR laser activated PEG–Fe3O4. In addition, detailed photothermal anti-cancer efficacy was evaluated via visual microscope images, demonstrating that our PEG–Fe3O4 were promising for photothermal therapy of cancer cells. PMID:25329618

Yuan, Gang; Yuan, Yongjie; Xu, Kan; Luo, Qi

2014-01-01

109

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)

110

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

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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.

Cunha, C.; Panseri, S.; Iannazzo, D.; Piperno, A.; Pistone, A.; Fazio, M.; Russo, A.; Marcacci, M.; Galvagno, S.

2012-11-01

111

Novel magnetic Fe3O4-C nanoparticles as adsorbents for removal of organic dyes from aqueous solution  

International Nuclear Information System (INIS)

Highlights: ? In this work, novel magnetic Fe3O4-C nanoparticles have been synthesized and employed as high efficient adsorbent for removal cationic dyes from polluted water. ? While up to now, little study is done on adsorption of dyes by the Fe3O4-C nanoparticles. ? Hence, here we provide a simply and environment friendly method for removal of cationic dyes or other pollutants from water. - Abstract: The magnetic Fe3O4/C core-shell nanoparticles have been synthesized by a simple strategy and used as adsorbents for removal of organic dyes from aqueous solution. The resulting products are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectra and Fourier transform infrared spectra (FTIR). Adsorption performances of the nanomaterial adsorbents are tested with removal of methylene blue (MB) and cresol red (CR) from aqueous solution. The effects of solution pH value, adsorption time and capacity of the nanocomposites have been fully investigated. The results reveal that the nanospheres can be easily manipulated by an external magnetic field with high separation efficiency. In addition, the process is clean and safe for purifying water pollution. The prepared Fe3O4/C complex nanomaterials could thus be used as promising adsorbents for the remove organic dyes, ebents for the remove organic dyes, especially, cationic dye, from polluted water.

112

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

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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. PMID:25123943

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

2015-01-25

113

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

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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.

Lunge, Sneha; Singh, Shripal; Sinha, Amalendu

2014-04-01

114

Preparation, characterization and application of Fe3O4/ZnO core/shell magnetic nanoparticles  

International Nuclear Information System (INIS)

Fe3O4 magnetic nanoparticles (MNPs) were synthesized by a co-precipitation method. The phase purity was confirmed by X-ray powder diffraction (XRD) analysis. The crystal size was found to be 10 nm from transmission electron microscopy (TEM). It is evidenced that the surface of Fe3O4 MNPs was modified by sodium citrate. The Fe3O4/ZnO core/shell MNPs were obtained by coating the MNPs with direct precipitation using zinc acetate and ammonium carbonate. The precursor was firstly dried and then calcined at 350 deg. C. The antioxidation tests indicated that the core/shell MNPs give better antioxidation than that of the Fe3O4 MNPs. The photocatalytic degradation of methyl orange revealed that the core/shell MNPs have higher photocatalytic activity than that of the ZnO nanoparticles. Separation of the core/shell MNPs from the aqueous suspension using a magnet provides an easy way to recycle the core/shell MNPs. After four-time recycling, the photocatalytic degradation percentage of the core/shell MNPs is about 70%

115

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

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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.

Jung Kyoo Lee

2013-09-01

116

Mapping the subcellular localization of Fe3O4@TiO2 nanoparticles by X-ray Fluorescence Microscopy  

International Nuclear Information System (INIS)

The targeted delivery of Fe3O4@TiO2 nanoparticles to cancer cells is an important step in their development as nanomedicines. We have synthesized nanoparticles that can bind the Epidermal Growth Factor Receptor, a cell surface protein that is overexpressed in many epithelial type cancers. In order to study the subcellular distribution of these nanoparticles, we have utilized the sub-micron resolution of X-ray Fluorescence Microscopy to map the location of Fe3O4@TiO2 NPs and other trace metal elements within HeLa cervical cancer cells. Here we demonstrate how the higher resolution of the newly installed Bionanoprobe at the Advanced Photon Source at Argonne National Laboratory can greatly improve our ability to distinguish intracellular nanoparticles and their spatial relationship with subcellular compartments

117

Nanocomposite materials based on ZnO and Fe3O4 nanoparticles in a polymer martix  

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The techniques of sample synthesis of four types (the original liquid-phase dispersions of ZnO nanoparticles (NPs) and Fe3O4 NPs, solid nanocomposites ZnO-high-density polyethylene (HDPE) and Fe3O4-HDPE) have been developed. The dispersion of ZnO NPs was obtained by alkaline hydrolysis of zinc acetate potassium hydroxide in isopropyl alcohol. The dispersion of Fe3O4 NPs was prepared via the reaction of aqueous solutions of the iron salts (FeCl2 and FeCl3). After removal of impurity ions the dispersions were introduced into HDPE. A comparative analysis of the characteristics and properties of ZnO and Fe3O4 NPs in the original dispersions and in the polyethylene matrices was carried out by a complex of structural and physical methods (X-ray and electron diffraction, transmission and scanning electron microscopy, X-ray small-angle scattering, photoluminescence, electron magnetic resonance).

Zaporozhets, M. A.; Rustamova, C. G.; Timoshenko, N. S.; Nikolaichik, V. I.; Dembo, K. A.; Savilov, S. V.; Khodos, I. I.; Avilov, A. S.; Gubin, S. P.

2012-02-01

118

Magnetic photocatalysts with a p-n junction: Fe3O4 nanoparticle and FeWO4 nanowire heterostructures  

Science.gov (United States)

Magnetic n-type semiconductor Fe3O4 nanoparticle and p-type semiconductor FeWO4 nanowire heterostructures were successfully synthesized without any surfactants or templates via a facile one-step hydrothermal process at 160 °C. The heterojunction structure and morphology were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Magnetic measurements indicated the coexistence of ferrimagnetic behavior of Fe3O4 and weak antiferromagnetic behavior of FeWO4. The degradation of methylene blue (MB) under UV-Visible light irradiation was studied as a model experiment to evaluate the catalytic activity of the Fe3O4/FeWO4 heterostructure p-n junctions. The decomposition efficiency was 97.1% after one hour UV-Visible irradiation. This magnetic photocatalyst can be easily recovered from the solution using a permanent magnet and redispersed by removing the magnet.Magnetic n-type semiconductor Fe3O4 nanoparticle and p-type semiconductor FeWO4 nanowire heterostructures were successfully synthesized without any surfactants or templates via a facile one-step hydrothermal process at 160 °C. The heterojunction structure and morphology were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Magnetic measurements indicated the coexistence of ferrimagnetic behavior of Fe3O4 and weak antiferromagnetic behavior of FeWO4. The degradation of methylene blue (MB) under UV-Visible light irradiation was studied as a model experiment to evaluate the catalytic activity of the Fe3O4/FeWO4 heterostructure p-n junctions. The decomposition efficiency was 97.1% after one hour UV-Visible irradiation. This magnetic photocatalyst can be easily recovered from the solution using a permanent magnet and redispersed by removing the magnet. Electronic supplementary information (ESI) available: The equation used to calculate the energy band gap, XRD data of the products with various pH values, the SEM image of Fe3O4/FeWO4, and the TEM image of FeWO4 nanowires. See DOI: 10.1039/c4nr03729d

Cao, Xuan; Chen, Yan; Jiao, Shihui; Fang, Zhenxing; Xu, Man; Liu, Xu; Li, Lu; Pang, Guangsheng; Feng, Shouhua

2014-10-01

119

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

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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.

Venkateswarlu, Sada; Natesh Kumar, B.; Prasad, C. H.; Venkateswarlu, P.; Jyothi, N. V. V.

2014-09-01

120

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

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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

Zhi Jiang

2009-04-01

 
 
 
 
121

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

Science.gov (United States)

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.

Shieh, Dar-Bin; Su, Chia-Hao; Chang, Fong-Yu; Wu, Ya-Na; Su, Wu-Chou; Hwu, Jih Ru; Chen, Jyh-Horng; Yeh, Chen-Sheng

2006-08-01

122

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

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The removal of Ni(II) from aqueous solution by magnetic nanoparticles prepared and impregnated onto tea waste (Fe(3)O(4)-TW) from agriculture biomass was investigated. Magnetic nanoparticles (Fe(3)O(4)) were prepared by chemical precipitation of a Fe(2+) and Fe(3+) salts from aqueous solution by ammonia solution. These magnetic nanoparticles of the adsorbent Fe(3)O(4) 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 1.90×10(-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, Q°, was found to be (38.3)mgg(-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. PMID:21146294

Panneerselvam, P; Morad, Norhashimah; Tan, Kah Aik

2011-02-15

123

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

Directory of Open Access Journals (Sweden)

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

Ma P

2012-09-01

124

Activated carbon/Fe(3)O(4) nanoparticle composite: fabrication, methyl orange removal and regeneration by hydrogen peroxide.  

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In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe(3)O(4) nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe(3)O(4) nanoparticles, were fabricated by a modified impregnation method using HNO(3) as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO(3) (powdered activated carbon modified by HNO(3)) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe(3)O(4) nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide. PMID:21840037

Do, Manh Huy; Phan, Ngoc Hoa; Nguyen, Thi Dung; Pham, Thi Thu Suong; Nguyen, Van Khoa; Vu, Thi Thuy Trang; Nguyen, Thi Kim Phuong

2011-11-01

125

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

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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.

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

2014-12-01

126

Synthesis of monodisperse Fe3O4 nanoparticles by optimized sonochemical method using mono(ethylene glycol) (MEG).  

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In this study, we successfully synthesized monodisperse magnetite nanoparticles (NPs) (Fe3O4) by sonochemical method using mono (ethylene glycol) (MEG) as a modifier of the reaction environment and found that MEG could be a good candidate to prevent oxidation and toxicity in sonochemical synthesis. The microstructure and size distribution of the Fe3O4 NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. It revealed that the NPs prepared by MEG assisted sonochemical method show a smaller average size and better monodispersity compared to conventional sonochemical method. Due the the reduced average size and uniform size distribution nature of the NPs, it also showed good superparamagnetic properties with very low coercivity less than 0.5 Oe. PMID:21449463

Phong, Le Van; Hung, Tran Quang; Son, Vo Thanh; Kim, Sarah; Jeong, Jun-Ho; Kim, CheolGi; Jeong, Jong-Ryul

2011-03-01

127

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

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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.

128

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

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

129

Rapid and highly efficient preconcentration of Eu(III) by core-shell structured Fe3O4@humic acid magnetic nanoparticles.  

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In this study, humic acid-coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@HA MNPs) were synthesized using a chemical coprecipitation method and characterized in detail. The XRD analysis results showed that HA coating did not change the phase of Fe(3)O(4) cores. The TEM image suggested that Fe(3)O(4)@HA MNPs had nearly uniform size without the observation of aggregation. The Fe(3)O(4)@HA MNPs were stable in solution and could be easily separated from aqueous solution using a magnetic separation method. A batch technique was adopted to investigate the removal efficiency of Fe(3)O(4)@HA MNPs toward Eu(III) under various environmental conditions. The kinetic process of Eu(III) sorption on Fe(3)O(4)@HA MNPs reached equilibrium within complexation. The sorption isotherm agreed well with the Langmuir model, having a maximum sorption capacity of 6.95 × 10(-5) mol g(-1). The leaching test showed that the Eu(III)-loaded Fe(3)O(4)@HA colloids were capable to maintain high thermodynamic stability for long aging times. The findings herein suggested that Fe(3)O(4)@HA MNPs could be potentially used as a highly effective material for the enrichment and preconcentration of radionuclide Eu(III) or other trivalent lanthanides/actinides in geological repositories or in nuclear waste management. PMID:23182180

Yang, Shitong; Zong, Pengfei; Ren, Xuemei; Wang, Qi; Wang, Xiangke

2012-12-01

130

Modified properties of Fe3O4 nanoparticles on incorporation of optically active ZnSe  

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A facile two-steps method for preparation of the Fe3O4/ZnSe nanocomposite at room temperature has been reported. The prepared samples were characterized by XRD, SQUID VSM, Mössbauer, UV-vis and Photoluminescence (PL) spectroscopy. Zero-field-cooled (ZFC) and field-cooled (FC) measurements show irreversibility up to room temperature and a superparamagnetic blocked state below 250 K. Mössbauer spectra at RT shows typical relaxed sextet pattern with a superparamagnetic doublet. PL spectra show strong near band edge emission and some weak peaks related to different defects levels.

Roychowdhury, A.; Das, A.; Pati, S. P.; Kumar, S.; Das, D.

2014-04-01

131

A study on the magnetic and photoluminescence properties of Eu(n+) and Sm3+ doped Fe3O4 nanoparticles.  

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In this paper, Eu(n+), Sm3+ doped Fe3O4 nanoparticles were prepared via solvothermal method, in which Ferric chloride is used as the iron source, and anhydrous EuCl3, SmCl3 as doping source. Eu, Sm valence in doped Fe3O4 nanoparticles, and effects of Eu, Sm doping amount on their structure, morphology, magnetic properties and PL properties were discussed. The results show, the Eu ions had doped Fe3O4 nanoparticles in the mixed-valence state, when the Eu and Sm doping amount were increased, the doped Fe3O4 nanoparticles changed from hollow nanospheres into spherical particles, and finally changed into uniform cube-shaped particles with 13 nm in diameter. Moreover, the doping sites for doping ions in doped Fe3O4 nanoparticles were discussed from Rietveld analysis of XRD pattern of the doped Fe3O4 nanoparticles. And the changes of the magnetic and PL properties with the doping amount were further discussed. It was found that higher Sm(3+)-doping amount led to stronger magnetic dipole transitions, while the Eu(n+)-doping amount had little effect on the magnetic dipole transitions, thus resulting in different changes in their saturation magnetization with doping amount. PMID:22905509

Huan, Weiwei; Cheng, Chao; Yang, Yuxiang; Yuan, Hongming; Li, Yongxia

2012-06-01

132

Hierarchically Porous MnO2 Microspheres Doped with Homogeneously Distributed Fe3O4 Nanoparticles for Supercapacitors.  

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Hierarchically porous yet densely packed MnO2 microspheres doped with Fe3O4 nanoparticles are synthesized via a one-step and low-cost ultrasound assisted method. The scalable synthesis is based on Fe(2+) and ultrasound assisted nucleation and growth at a constant temperature in a range of 25-70 °C. Single-crystalline Fe3O4 particles of 3-5 nm in diameter are homogeneously distributed throughout the spheres and none are on the surface. A systematic optimization of reaction parameters results in isolated, porous, and uniform Fe3O4-MnO2 composite spheres. The spheres' average diameter is dependent on the temperature, and thus is controllable in a range of 0.7-1.28 ?m. The involved growth mechanism is discussed. The specific capacitance is optimized at an Fe/Mn atomic ratio of r = 0.075 to be 448 F/g at a scan rate of 5 mV/s, which is nearly 1.5 times that of the extremely high reported value for MnO2 nanostructures (309 F/g). Especially, such a structure allows significantly improved stability at high charging rates. The composite has a capacitance of 367.4 F/g at a high scan rate of 100 mV/s, which is 82% of that at 5 mV/s. Also, it has an excellent cycling performance with a capacitance retention of 76% after 5000 charge/discharge cycles at 5 A/g. PMID:25255299

Zhu, Jian; Tang, Shaochun; Xie, Hao; Dai, Yuming; Meng, Xiangkang

2014-10-22

133

Effect of natural Fe3O4 nanoparticles on structural and optical properties of Er3+ doped tellurite glass  

International Nuclear Information System (INIS)

Control doping of magnetic nanoparticles and its influence on optical and structural properties of tellurite glass is important from device perspectives. Natural Fe3O4 nanoparticles obtained by extracting and ball milling iron sand, are incorporated in the Er3+ doped tellurite glasses having composition (80?x)TeO2·xFe3O4·18ZnO·1Li2O·1Er2O3 (0?x?1.5) in mol% by melt quenching method at 850 °C. X-Ray diffraction spectra confirms the presence of iron nanoparticles with estimated sizes 18–70 nm and an amorphous structure of the samples. Thermal and optical characterizations are made using diffential thermal analysis, ultraviolet–visible and photoluminescence spectrocopies. It is found that the presence of nanoparticles changes color and thermal stability of the glasses, which is proved by increasing thermal stability factor from 118 to 132 °C. Absorption spectra consist of six peaks corresponding to different transition from ground state to the excited states in which the quench of the peak associated with 4F1/2 is attributed to the effect nanoparticles. Moreover, the shift in the absorption edge from ?400 to ?500 nm indicates a significant decrease of the optical energy band gap for both direct and indirect allowed transitions and a decrease in the Urbach energy as much as 0.116 eV is observed. The room temperature down-conversion lture down-conversion luminescence spectra obtained under 500 nm excitation exhibit two strong peaks related to excited states 4S3/2 and 4F9/2 of Er3+ ions in the absence of nanoparticles. Furthermore, embedding nanoparticles into the glass not only make the peaks weaker but the second peak completely disappears. Interestingly, the emission bands of the Er3+ ion are quenched as concentration of the magnetic nanoparticles is increased.

134

Covalent TiO(2)/pectin microspheres with Fe(3)O(4) nanoparticles for magnetic field-modulated drug delivery.  

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Covalent TiO(2)-co-pectin microspheres containing Fe(3)O(4) nanoparticles were developed through an ultrasound-induced crosslinking/polymerization reaction between the glycidyl methacrylate from vinyl groups in TiO(2) and in pectin. ?-potentials became less negative in the nanostructured microspheres, caused by the presence of both inorganic particles in the negatively charged pectin. The nanostructured pectin microspheres showed an amoxicillin release rate slower than that of pure pectin microspheres. The proposed microspheres were found to be a sustained release system of amoxicillin in the acid medium. Furthermore, the antibiotic release may be modulated by exposition of the microspheres to a remote magnetic field. In practical terms, the nanostructured microspheres could deliver a larger proportion of their initial load to specific site of action. The cytotoxic concentrations for 50% of VERO cells (CC(50)), calculated as the concentration required to reduce cell viability by 50% after 72h of incubation, for pectin-only microspheres and nanostructured pectin microspheres were 217.7±6.5 and 121.5±4.9?gmL(-1), respectively. The obtained CC(50) values indicated acceptable cytotoxic levels for an incubation period of 72h, showing that the pectin microspheres have a great pharmacological potential for uses in biological environments, even after the introduction of both Fe(3)O(4) and TiO(2). PMID:24565898

da Silva, Elisangela P; Sitta, Danielly L A; Fragal, Vanessa H; Cellet, Thelma S P; Mauricio, Marcos R; Garcia, Francielle P; Nakamura, Celso V; Guilherme, Marcos R; Rubira, Adley F; Kunita, Marcos H

2014-06-01

135

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

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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.

Li, Yabin; Yan, Yuerong; Ming, Hai; Zheng, Junwei

2014-06-01

136

The induction of maturation on dendritic cells by TiO2 and Fe(3)O(4)@TiO(2) nanoparticles via NF-?B signaling pathway.  

Science.gov (United States)

Nanomaterials are increasingly used in many fields, including drug vectors and vaccine formulation. In this study, nano-TiO(2) and magnetic Fe(3)O(4)@TiO(2) were synthesized and their abilities to activate dendritic cells were investigated. The signaling pathway involved in their effects on the cellular functions was also explored. First, nano-TiO(2) and Fe(3)O(4)@TiO(2) were prepared with diameters of 82nm and 63nm, and zeta potentials of 41.5mV and 30.2mV, respectively. The magnetic property of Fe(3)O(4)@TiO(2) was detected to be 12.9emu/g. Both kinds of nanoparticles were proved to have good biocompatibility in vitro. Second, the exposure of nano-TiO2 and Fe(3)O(4)@TiO(2)caused an increased expression of TNF-?, CD86 and CD80, and besides, Fe(3)O(4)@TiO(2)showed a certain up-regulation on MHC-II. The cellular uptake of Ovalbumin on BMDCs could be strongly improved by nano-TiO2 and Fe(3)O(4)@TiO(2)as detected via flow cytometer and confocal observation. Further investigation revealed that nano-TiO(2) and Fe(3)O(4)@TiO(2)significantly increased the NF-?B expression in the nucleus, indicating that the NF-?B signaling pathway was involved in the dendritic cell maturation. Our results suggested that nano-TiO(2) and Fe(3)O(4)@TiO(2)may function as a useful vector to promote vaccine delivery in immune cells, and Fe(3)O(4)@TiO(2)provided a possibility to deliver and track vaccines via its magnetofection. PMID:24863229

Zhu, Rongrong; Zhu, Yanjing; Zhang, Min; Xiao, Yu; Du, Xiling; Liu, Hui; Wang, Shilong

2014-06-01

137

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

138

Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction.  

Science.gov (United States)

A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4?nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine. PMID:25354532

Brollo, Maria Eugênia F; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J A; Pirota, Kleber R; Knobel, Marcelo

2014-01-01

139

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

Science.gov (United States)

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.

Dehghani, Z.; Iranizad, E. Saievar

2014-02-01

140

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

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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.

Yong Seok Kim

2014-01-01

 
 
 
 
141

Chitosan-coated ferrite (Fe3O4) nanoparticles as a T2 contrast agent for magnetic resonance imaging  

International Nuclear Information System (INIS)

Iron oxide (Fe3O4) nanoparticles coated with biocompatible chitosan were synthesized for use as an MRI (magnetic resonance imaging) contrast agent. The coating was performed simultaneously with the synthesis of the ferrite nanoparticles. A dynamic light-scattering spectrometer (DLS) and a transmission electron microscope (TEM) were used to measure the average diameter of the coated nanoparticles, which was 67.0 nm. Fourier transform infrared (FT-IR) measurements showed strong bonding of the chitosan molecules to the surfaces of the ferrite nanoparticles. The spin-lattice (T1) and the spin-spin (T2) relaxation times of the nuclear spins (hydrogen protons) in aqueous solutions of various concentrations of coated ferrite nanoparticles were determined using a nuclear magnetic resonance (NMR) spectrometer. Using these data, we found that the T1 and the T2 relaxivities of the nuclear spins in aqueous solutions of ferrite nanoparticles were 0.00291 and 0.0691 ppm-1sec-1, respectively. In particular, the value of the T2 relaxivity was much larger than that of the commercial contrast agent GD-DTPA (gadolinium diethylenetriamine penta-acetic acid). A 31.7% intensity loss in the T2 image of a rabbit liver was observed after injecting the aqueous solution of coated nanoparticles into the rabbit, which shows that our coated ferrite nanoparticles can be used as a T2 MRI contrast agent.

142

Reversal of multidrug resistance by cisplatin-loaded magnetic Fe3O4 nanoparticles in A549/DDP lung cancer cells in vitro and in vivo  

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Full Text Available Ke Li,1 Baoan Chen,1,2 Lin Xu,3 Jifeng Feng,3 Guohua Xia,1,2 Jian Cheng,1,2 Jun Wang,1,2 Feng Gao,1,2 Xuemei Wang,41Department of Hematology, Key Medical Disciplines of Jiangsu Province, Zhongda Hospital, Medical School, Southeast University, Nanjing, 2Faculty of Oncology, Medical School, Southeast University, Nanjing, 3Department of Thoracic Surgery, Jiangsu Province Cancer Hospital, Jiangsu Province, 4State Key Laboratory of Bioelectronics, Southeast University, Nanjing, People’s Republic of ChinaAbstract: The purpose of this study was to explore whether magnetic Fe3O4 nanoparticles (Fe3O4-MNP loaded with cisplatin (Fe3O4-MNP-DDP can reverse DDP resistance in lung cancer cells and to investigate mechanisms of multidrug resistance in vitro and in vivo. MTT assay showed that DDP inhibited both A549 cells and DDP-resistant A549 cells in a time-dependent and dose-dependent manner, and that this inhibition was enhanced by Fe3O4-MNP. An increased rate of apoptosis was detected in the Fe3O4-MNP-DDP group compared with a control group and the Fe3O4-MNP group by flow cytometry, and typical morphologic features of apoptosis were confirmed by confocal microscopy. Accumulation of intracellular DDP in the Fe3O4-MNP-DDP group was greater than that in the DDP group by inductively coupled plasma mass spectrometry. Further, lower levels of multidrug resistance-associated protein-1, lung resistance-related protein, Akt, and Bad, and higher levels of caspase-3 genes and proteins, were demonstrated by reverse transcriptase polymerase chain reaction and Western blotting in the presence of Fe3O4-MNP-DDP. We also demonstrated that Fe3O4-MNP enhanced the effect of DDP on tumor growth in BALB/c nude mice bearing DDP-resistant human A549 xenografts by decreasing localization of lung resistance-related protein and Ki-67 immunoreactivity in cells. There were no apparent signs of toxicity in the animals. Overall, these findings suggest potential clinical application of Fe3O4-MNP-DDP to increase cytotoxicity in lung tumor xenografts.Keywords: Fe3O4, nanoparticles, multidrug resistance, reversal, DDP-resistant A549 cells, cisplatin

Li K

2013-05-01

143

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

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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

Akbarzadeh A

2012-02-01

144

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)

145

Preparation and characterization of magnetic nanoparticles containing Fe3O4-dextran- anti-?-human chorionic gonadotropin, a new generation choriocarcinoma-specific gene vector  

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Full Text Available Cai Jingting1,2, Liu Huining1, Zhang Yi11Department of Obstetrics and Gynecology, Xiangya Hospital, Central South University, Changsha, Hunan, People’s Republic of China; 2Department of Gynecological Oncology, Hunan Tumor Hospital, Changsha, Hunan, People’s Republic of ChinaObjective: To evaluate the feasibility of using magnetic iron oxide (Fe3O4-dextran-anti-?-human chorionic gonadotropin (HCG nanoparticles as a gene vector for cellular transfections.Study design: Fe3O4-dextran-anti-?-HCG nanoparticles were synthesized by chemical coprecipitation. The configuration, diameter, and iron content of the nanoparticles were detected by transmission electron microscopy (TEM, light scatter, and atomic absorption spectrophotometry. A3-(4,5-dimethylthiahiazo(-z-y1-3,5-di-phenytetrazoliumromide assay was used to evaluate the cytotoxicity of Fe3O4-dextran-anti-?-HCG nanoparticles. Enzyme-linked immunosorbent assay and indirect immunofluorescence were used to evaluate immunoreactivity. The efficiency of absorbing DNA and resisting deoxyribonuclease I (DNase I digestion when bound to Fe3O4-dextran-anti-?-HCG nanoparticles was examined by agarose gel electrophoresis. The ability of Fe3O4-dextran-anti-?-HCG nanoparticles to absorb heparanase antisense oligodeoxynucleotides (AS-ODN nanoparticles in different cell lines was evaluated by flow cytometry. The tissue distribution of heparanase AS-ODN magnetic nanoparticles in choriocarcinoma tumors transplanted in nude mice was detected by atomic absorption spectrophotometry.Results: TEM demonstrated that the shape of nanoparticles is irregular. Light scatter revealed nanoparticles with a mean diameter of 75.5 nm and an iron content of 37.5 µg/mL. No cytotoxicity was observed when the concentration of Fe3O4-dextran-anti-?-HCG nanoparticles was <37.5 µg/mL. Fe3O4-dextran nanoparticles have a satisfactory potential to combine with ?-HCG antibody. Agarose gel electrophoresis analysis of binding experiments showed that after treatment with sodium periodate, Fe3O4-dextran-anti-?-HCG nanoparticles have a satisfactory potential to absorb DNA, and the protection experiment showed that nanoparticles can effectively protect DNA from DNase I digestion. Aldehyde Fe3O4-dextran-anti-?-HCG nanoparticles can transfect reporter genes, and the transfection efficiency of these nanoparticles is greater than that of liposomes (P <0.05. Fe3O4-dextran-anti-?-HCG nanoparticles can concentrate in choriocarcinoma cells and in transplanted choriocarcinoma tumors.Conclusions: The results confirm that Fe3O4-dextran-anti-?-HCG nanoparticles have potential as a secure, effective, and choriocarcinoma-specific targeting gene vector.Keywords: magnetic nanoparticles, Fe3O4-dextran-anti-?-HCG, choriocarcinoma, targeting vector, gene vector

Cai Jingting

2011-02-01

146

The synthesis and characterization of monodispersed chitosan-coated Fe3O4 nanoparticles via a facile one-step solvothermal process for adsorption of bovine serum albumin  

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Preparation of magnetic nanoparticles coated with chitosan (CS-coated Fe3O4 NPs) in one step by the solvothermal method in the presence of different amounts of added chitosan is reported here. The magnetic property of the obtained magnetic composite nanoparticles was confirmed by X-ray diffraction (XRD) and magnetic measurements (VSM). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allowed the identification of spherical nanoparticles with about 150 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy (FTIR) demonstrated that CS-coated Fe3O4 NPs were obtained. Chitosan content in the obtained nanocomposites was estimated by thermogravimetric analysis (TGA). The adsorption properties of the CS-coated Fe3O4 NPs for bovine serum albumin (BSA) were investigated under different concentrations of BSA. Compared with naked Fe3O4 nanoparticles, the CS-coated Fe3O4 NPs showed a higher BSA adsorption capacity (96.5 mg/g) and a fast adsorption rate (45 min) in aqueous solutions. This work demonstrates that the prepared magnetic nanoparticles have promising applications in enzyme and protein immobilization. PMID:24994954

2014-01-01

147

One-step synthesis of monodisperse, water-soluble ultra-small Fe3O4 nanoparticles for potential bio-application  

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We report that ultra-small, monodisperse, water-dispersible magnetite (Fe3O4) nanoparticles can be synthesized by a facile one-pot approach using trisodium citrate as crystal grain growth inhibitor and stabilizer in polyol solution. The resultant Fe3O4 nanoparticles exhibit an excellent long-term colloidal stability in various buffer solutions without any modification. They are also superparamagnetic at room temperature and their magnetic property relies heavily on their size. Due to the low magnetization and good water-dispersibility, the 1.9 nm-sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 1.415 mM-1 s-1, r2 = 2.87 mM-1 s-1), demonstrating that they can be efficient T1 contrast agents. On the other hand, because of the excellent magnetic responsivity, the 13.8 nm-sized Fe3O4 nanoparticles can be readily modified with nitrilotriacetic acid and used to separate the protein simply with the assistance of a magnet. In addition, these Fe3O4 nanoparticles may be useful in other fields, such as hyperthermia treatment of cancer and targeted drug delivery based on their size-dependent magnetic property and excellent stability.

Shen, Li-Hua; Bao, Jian-Feng; Wang, Dong; Wang, Yi-Xiao; Chen, Zhi-Wei; Ren, Lei; Zhou, Xi; Ke, Xue-Bin; Chen, Min; Yang, An-Qi

2013-02-01

148

Interaction of iron oxide Fe3O4 nanoparticles and alveolar macrophages in vivo.  

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Aqueous suspension of magnetite nanoparticles with primary diameter of 10 nm were intratracheally administered into rat lungs. In 24 h, cells were isolated from bronchoalveolar lavage and examined under a transmission electron microscope. Alveolar macrophages demonstrated ability to actively uptake single nanoparticles and small aggregates composed of such particles, which then formed larger conglomerates inside fused phagosomes. Some of these mature phagosomes shed the membrane and free nanoparticles closely interacted with nuclear membrane and with cristae and mitochondrial membranes thereby inflicting pronounced damage to these intracellular structures. The loss of primary lysosomes can be viewed as indirect evidence attesting to the role played by diffusion of lysosomal hydrolytic enzymes in the final destruction of the alveolar macrophages provoked by nanoparticles. PMID:22803151

Katsnelson, B A; Privalova, L I; Sutunkova, M P; Tulakina, L G; Pichugova, S V; Beykin, J B; Khodos, M J

2012-03-01

149

A remote-activated shape memory polymer network employing vinyl-capped Fe3O4 nanoparticles as netpoints for durable performance  

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A new type of shape memory polymer (SMP) employing vinyl-capped Fe3O4 nanoparticles as netpoints that determine the permanent shape for remote activation has been presented. The new design effectively prevents the nanoparticles from moving and re-aggregating in a polymer matrix and guarantees the stability of the SMP networks when a high temperature and external stress are applied. Therefore, durable shape memory performance is obtained during the programmed deformation-recovery processes. Meanwhile, a homogeneous distribution of vinyl-capped Fe3O4 nanoparticles achieves uniform heat generation and heat transfer in the alternating magnetic field. Consequently, the novel remote-activated SMP also exhibits a fast magnetic responsiveness compared to the SMPs physically dispersed with Fe3O4 nanoparticles.

Xia, Shuang; Li, Xingjian; Wang, Yaru; Pan, Yi; Zheng, Zhaohui; Ding, Xiaobin; Peng, Yuxing

2014-08-01

150

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

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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.

151

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

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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

152

Surface anisotropy of a Fe 3O 4 nanoparticle: A simulation approach  

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On the basis of a three-dimensional classical Heisenberg model with nearest magnetic neighbor interactions, and using a Monte Carlo-Metropolis dynamics, we study the magnetic behavior of a 5 nm diameter magnetite nanoparticle as a function of temperature. The nanoparticle is built by taken into account the inverse spinel structure of a stoichiometric magnetite, the valence of the iron ions (Fe 3+A, Fe 3+B, Fe 2+B where A and B stand for tetrahedral and octahedral sites, respectively) as well as the different involved coordination numbers and superexchange integrals. The employed Hamiltonian includes coupling interactions between Fe ions through the integrals JAA, JAB and JBB, a Néel's surface anisotropy term applied to surface ions, and cubic magnetocrystalline anisotropy for those ions belonging to the core of the nanoparticle. Results reveal a strong influence of surface anisotropy, depending on its sign and magnitude, upon the total magnetization at low temperatures. Such results, which are summarized in a proposal of phase diagram, reveal the onset of spin structures different from a single-domain state. Differences in the thermal behavior respect to a bulk magnetite are also addressed and discussed.

Mazo-Zuluaga, J.; Restrepo, J.; Mejía-López, J.

2007-09-01

153

Enhanced Magnetism of Fe3O4 Nanoparticles with Ga Doping  

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Magnetic (Ga{sub x}Fe{sub 1-x}){sub 3}O{sub 4} nanoparticles with 5%-33% gallium doping (x = 0.05-0.33) were measured using x-ray absorption spectroscopy and x-ray magnetic circular dichroism to determine that the Ga dopant is substituting for Fe{sub 3+} as Ga{sub 3+} in the tetrahedral A-site of the spinel structure, resulting in an overall increase in the total moment of the material. Frequency-dependent alternating-current magnetic susceptibility measurements showed these particles to be weakly interacting with a reduction of the cubic anisotropy energy term with Ga concentration. The element-specific dichroism spectra show that the average Fe moment is observed to increase with Ga concentration, a result consistent with the replacement of A-site Fe by Ga.

Pool, V. L.; Klem, M. T.; Chorney, C. L.; Arenholz, E.; Idzerda, Y.U.

2010-10-22

154

Synthesis and characterization of L10 FePt nanoparticles from Pt-Fe3O4 core-shell nanoparticles  

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Pt/Fe3O4 core-shell nanoparticles have been prepared by a modified polyol method. Pt nanoparticles were first prepared via the reduction of Pt(acac)2 by polyethylene glycol-200 (PEG-200), and layers of iron oxide were subsequently deposited on the surface of Pt nanoparticles by the thermal decomposition of Fe(acac)3. The nanoparticles were characterized by XRD and HR-TEM. The as-prepared Pt/Fe3O4 nanoparticles have a chemically disordered FCC structure and transformed into chemically ordered fct structure after annealing in reducing atmosphere (4% H2, 96% Ar) at 700 deg C. The ordered fct FePt phase has high magnetic anisotropy with coercivity reaching 7.5 kOe at room temperature and 9.3 kOe at 10 K

155

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

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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.

2010-06-01

156

Developing Fe3O4 nanoparticles into an efficient multimodality imaging and therapeutic probe  

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A rapid ligand-exchange method was developed to transfer high quality hydrophobic magnetite nanocrystals into water-soluble NPs by using protocatechuic acid as a ligand via homogenous reaction. After ligand exchange, the magnetite nanocrystals not only exhibited outstanding stability in water, but also maintained high crystallinity and saturation magnetization. Cell viability experiments demonstrated good biocompatibility of the NPs. For 12 nm magnetite nanoparticles (NPs), the small hydrodynamic size of 14 nm enabled a high T1 relaxivity of 17.8 mM-1 s-1 while high saturation magnetization of 77.8 emu g-1 enabled the NPs to exhibit a high T2 relaxivity of 220 mM-1 s-1 in MRI phantom experiments. In vivo MR imaging experiments further confirmed that the NPs were eminent T1 and T2 contrast agents. Moreover, the high quality NPs can be used as excellent magnetic heating agents under an alternating magnetic field. With all those features, including multimodality imaging and magnetic hyperthermia, the NPs can be used as single compound multifunctional agents for various biomedical applications, especially for cancer diagnosis and therapy.

Hao, Rui; Yu, Jing; Ge, Zigang; Zhao, Lingyun; Sheng, Fugeng; Xu, Lili; Li, Gongjie; Hou, Yanglong

2013-11-01

157

Novel electrochemical sensor based on N-doped carbon nanotubes and Fe3O4 nanoparticles: simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.  

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A new modified electrode based on N-doped carbon nanotubes functionalized with Fe3O4 nanoparticles (Fe3O4@CNT-N) has been prepared and applied on the simultaneous electrochemical determination of small biomolecules such as dopamine (DA), uric acid (UA) and ascorbic acid (AA) using voltammetric methods. The unique properties of CNT-N and Fe3O4 nanoparticles individually and the synergetic effect between them led to an improved electrocatalytic activity toward the oxidation of AA, DA and UA. The overlapping anodic peaks of these three biomolecules could be resolved from each other due to their lower oxidation potentials and enhanced oxidation currents when using the Fe3O4@CNT-N modified electrode. The linear response ranges for the square wave voltammetric determination of AA, DA and UA were 5-235, 2.5-65 and 2.5-85?moldm(-3) with detection limit (S/N=3) of 0.24, 0.050 and 0.047?moldm(-3), respectively. These results show that Fe3O4@CNT-N nanocomposite is a promising candidate of cutting-edge electrode materials for electrocatalytic applications. PMID:25086716

Fernandes, Diana M; Costa, Marta; Pereira, Clara; Bachiller-Baeza, Belén; Rodríguez-Ramos, Inmaculada; Guerrero-Ruiz, Antonio; Freire, Cristina

2014-10-15

158

Facile one-pot synthesis of Fe3O4@Au composite nanoparticles for dual-mode MR/CT imaging applications.  

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A facile one-pot hydrothermal approach to synthesizing Fe3O4@Au composite nanoparticles (CNPs) for dual-mode magnetic resonance (MR) and computed tomography (CT) imaging applications is reported. In this work, polyethyleneimine (PEI) partially modified with poly(ethylene glycol) monomethyl ether (mPEG) was used as a stabilizer to form gold NPs (mPEG-PEI.NH2-Au NPs) with the assistance of sodium borohydride reduction. The mPEG-PEI.NH2-Au NPs were then mixed with iron(II) salt in a basic aqueous solution followed by treatment under an elevated temperature and pressure. This hydrothermal process led to the formation of Fe3O4@Au-mPEG-PEI.NH2 CNPs. The remaining PEI amine groups were finally acetylated to reduce the surface positive charge of the CNPs. The formed Fe3O4@Au-mPEG-PEI.NHAc (Fe3O4@Au) CNPs were characterized via different techniques. The combined in vitro cell viability assay, cell morphology observation, flow cytometry, and hemolysis assay data show that the formed Fe3O4@Au CNPs are noncytotoxic and hemocompatible in the given concentration range. MR and CT imaging data reveal that the formed Fe3O4@Au CNPs have a relatively high r2 relaxivity (146.07 mM(-1) s(-1)) and good X-ray attenuation property, which enables their uses as contrast agents for MR imaging of mouse liver and CT imaging of rat liver and aorta. The Fe3O4@Au CNPs developed via the facile one-pot approach may have promising potential for the dual-mode MR/CT imaging of different biological systems. PMID:24063810

Li, Jingchao; Zheng, Linfeng; Cai, Hongdong; Sun, Wenjie; Shen, Mingwu; Zhang, Guixiang; Shi, Xiangyang

2013-10-23

159

Antitumor efficacy of DMSA modified Fe3O4 magnetic nanoparticles combined with arsenic trioxide and adriamycin in Raji cells.  

Science.gov (United States)

The objective of the present study was to investigate the anticancer efficacy of dimercaptosuccinic acid modified iron oxide (DMSA-Fe3O4) magnetic nanoparticles (MNPs) combined with arsenic trioxide (As2O3) and doxorubicin (ADM) in non-Hodgkin's lymphoma (NHL) cell line (Raji cells). The growth inhibition rate of Raji cells was determined by MTT assay. Characteristics of DMSA-Fe3O4 MNPs and distribution of nanoparticles taken up by Raji cells were observed under a transmission electron microscopy (TEM). Further, apoptosis of cells and intracellular concentration of ADM were detected by flow cytometry (FCM). DAPI staining was used to view apoptotic cellular morphology. Subsequently, transcription and protein expression levels of bcl-2, NFKB, survivin, bax, p53 and caspase-3 were determined by reverse transciptase polymerase chain reaction (RT-PCR) and Western blotting analysis, respectively. The results of MTT assay indicated that the inhibition of Raji cells by the combined form of ADM and As2O3 was significantly higher than either ADM or As2O3 alone. However, ADM-As2O3 MNPs proved superior over all other groups. TEM observation revealed that the majority of MNPs were quasi-spherical with an average diameter of about 18 nm and the MNPs taken up by cells were located in the endosome vesicles of cytoplasm. The apoptotic rate and accumulation of intracellular ADM in ADM-As2O3 MNPs group were significantly higher than those in control, ADM, As2O3 and ADM+As2O3, groups. In addition, DAPI staining of Raji cells from ADM-As,O3 MNPs group clearly exhibited more morphological changes (severe structural alterations) than other groups. Moreover, transcription and protein expression of bcl-2, NFKB, survivin, bax, p53 and caspase-3 of Raji cells were regulated at the most remarkable extent in ADM-As2O3, MNPs group as compared with other groups. These findings suggest that the antitumor efficacy of the combination of novel ADM-As2O3, MNPs on Raji cells would be a promising strategy for lymphoma therapy. PMID:24738333

Cai, Xiaohui; Cai, Xiaohui; Wang, Chunling; Chen, Baoan; Hua, Weijun; Shen, Fei; Yu, Liang; He, Zhengmei; Shi, Yuye; Chen, Yue; Xia, Guohua; Bao, Wen; Zhang, Yu; Wang, Xuemei

2014-02-01

160

Magnetic properties of variable-sized Fe3O4 nanoparticles synthesized from non-aqueous homogeneous solutions of polyols  

International Nuclear Information System (INIS)

The magnetic behaviour of well-dispersed monodisperse Fe3O4 nanoparticles with sizes varying between 6.6 and 17.8 nm prepared in a non-aqueous medium was investigated. The smaller nanocrystals exhibit superparamagnetism with the blocking temperatures increasing with the particle size, whereas the biggest particles are ferromagnetic at room temperature. The saturation magnetization values are slightly smaller than that of the bulk material, suggesting the existence of a disordered spin configuration on their surface. The thickness of the magnetically inert shell was estimated from the size variation of the magnetization at 1.9 A. The dipole-dipole interactions between the particles were tuned by changing the interparticle distances, e.g. by diluting the nanopowders in a non-magnetic matrix at concentrations ranging from 0.25 to 100 wt%. As the strength of the interactions is decreased with dilution, the energy barrier is substantially lowered; this will induce a drastic decrease of both the blocking temperatures and the coercivity with decreasing concentration of the nanoparticles

 
 
 
 
161

Removal of sulfonamide antibiotics by oriented immobilized laccase on Fe3O4 nanoparticles with natural mediators.  

Science.gov (United States)

A novel strategy was applied in the oriented immobilization of laccase from Echinodontium taxodii on concanavalin A-activated Fe3O4 nanoparticles (GAMNs-Con A) based on laccase surface analysis. These nanoparticles showed higher enzyme loading and activity recovery compared with conventional covalent binding. Along with the improvement in thermal and operational stabilities, the oriented immobilized laccase (GAMNs-Con A-L) exhibited higher substrate affinity than free laccase. Free laccase and GAMNs-Con A-L were then applied in the removal of sulfonamide antibiotics (SAs). Although both free and immobilized laccase resulted in the rapid removal of SAs, GAMNs-Con A-L showed a higher removal rate of SAs compared with the free counterpart in the presence of S-type compounds present in lignin structure. Syringic acid mediated the fastest removal efficiency of SAs among S-type compounds and resulted in an almost complete removal of these substances after incubation for 5min. The oxidation products of SAs were identified via LC-ESI(+)-MS. The results suggested the transformation of SAs and S-type compounds were catalyzed by laccase, resulting in the formation of cross-coupled products. PMID:25064257

Shi, Lili; Ma, Fuying; Han, Yuling; Zhang, Xiaoyu; Yu, Hongbo

2014-08-30

162

Inhibition of choriocarcinoma by Fe3O4-dextran-anti-ß-human chorionic gonadotropin nanoparticles containing antisense oligodeoxynucleotide of heparanase  

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Full Text Available Liu Huining,1 Zhang Yi,1 Tang Dihong,2 Pan Yifeng,3 Xia Man,2 Yang Ting,2 Cai Jingting1,2 1Department of Obstetrics and Gynecology, Xiangya Hospital, 2Department of Gynecological Oncology, Hunan Provincial Tumor Hospital, 3National Hepatobiliary and Enteric Surgery Research Center, Central South University, Changsha, Hunan, People's Republic of China Objective: To observe the influence of Fe3O4-dextran-anti-ß-human chorionic gonadotropin (HCG carrying heparanase (Hpa antisense oligodeoxynucleotide (ASODN, via the invasion, proliferation, and Hpa expression of JEG-3 cell lines and inhibitory effect of transplanted choriocarcinoma tumor growth. Methods: The different abilities of invasion and proliferation between transfected JEG-3 and untransfected JEG-3 were measured by Matrigel invasion assay and 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay in vitro. The effect of Hpa ASODN transfection on the expression of Hpa mRNA and protein was measured by reverse-transcription polymerase chain reaction and Western blot. The transplanted choriocarcinoma tumors were taken out to calculate the inhibitory effect on tumor growth of Hpa ASODN. Results: In this study, we found that: (1 the invasive ability of JEG-3 cells was inhibited sufficiently (P < 0.05 after JEG-3 cells were transfected by Fe3O4-dextran-anti-?HCG carrying Hpa ASODN; (2 after JEG-3 cells were transfected by Fe3O4-dextran-anti-?HCG carrying Hpa ASODN at 48 and 72 hours, the proliferative ability of JEG-3 cells was inhibited sufficiently (P < 0.05; (3 the expression of Hpa mRNA and protein in JEG-3 cells was inhibited efficiently after JEG-3 cells were transfected by Fe3O4-dextran-anti-?HCG carrying Hpa ASODN (P < 0.05; and (4 Fe3O4-dextran-anti-?HCG carrying Hpa ASODN had an inhibitory effect on the transplanted choriocarcinoma tumor growth (P < 0.05 and was harmless on nude mice. Conclusion: Fe3O4-dextran-anti-?HCG carrying Hpa ASODN weakened the invasive and proliferative ability of choriocarcinoma, with a significant inhibitory effect on the transplanted choriocarcinoma tumor. Therefore, Fe3O4-dextran-anti-?HCG carrying Hpa ASODN is an effective gene therapy, and Fe3O4-dextran-anti-?HCG nanoparticles are a harmless and effective gene vector. Keywords: heparanase, antisense oligodeoxynucleotide, Fe3O4-dextran-anti-?HCG nanoparticles, choriocarcinoma, invasive ability

Huining L

2013-11-01

163

Synthesis of Fe3O4@phenol formaldehyde resin core-shell nanospheres loaded with Au nanoparticles as magnetic FRET nanoprobes for detection of thiols in living cells.  

Science.gov (United States)

A magnetic, sensitive, and selective fluorescence resonance energy transfer (FRET) probe for detection of thiols in living cells was designed and prepared. The FRET probe consists of an Fe(3)O(4) core, a green-luminescent phenol formaldehyde resin (PFR) shell, and Au nanoparticles (NPs) as FRET quenching agent on the surface of the PFR shell. The Fe(3)O(4) NPs were used as the core and coated with green-luminescent PFR nanoshells by a simple hydrothermal approach. Au NPs were then loaded onto the surface of the PFR shell by electric charge absorption between Fe(3)O(4)@PFR and Au NPs after modifying the Fe(3)O(4)@PFR nanocomposites with polymers to alter the charge of the PFR shell. Thus, a FRET probe can be designed on the basis of the quenching effect of Au NPs on the fluorescence of Fe(3)O(4)@PFR nanocomposites. This magnetic and sensitive FRET probe was used to detect three kinds of primary biological thiols (glutathione, homocysteine, and cysteine) in cells. Such a multifunctional fluorescent probe shows advantages of strong magnetism for sample separation, sensitive response for sample detection, and low toxicity without injury to cellular components. PMID:22190410

Yang, Ping; Xu, Qi-Zhi; Jin, Sheng-Yu; Zhao, Yang; Lu, Yang; Xu, Xue-Wei; Yu, Shu-Hong

2012-01-23

164

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

Science.gov (United States)

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.

Shen, Xiaofang; Wang, Qin; Chen, WenLing; Pang, Yuehong

2014-10-01

165

Correlating material-specific layers and magnetic distributions within onion-like Fe 3 O 4 /MnO/ ?- Mn2 O3 core/shell nanoparticles  

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The magnetic responses of two nanoparticle systems comprised of Fe3 O 4/??Mn2O3 (soft ferrimagnetic, FM/hard FM) and Fe3O4/MnO/??Mn2 O3 (soft FM / antiferromagnetic, AFM/hard FM) are compared, where the MnO serves to physically decouple the FM layers. Variation in the temperature and applied field allows for Small Angle Neutron Scattering (SANS) measurements of the magnetic moments both parallel and perpendicular to an applied field. Data for the bilayer particle indicate that the grade...

Krycka, K. L.

2013-01-01

166

Efficient purification of ginkgolic acids from Ginkgo biloba leaves by selective adsorption on Fe3O4 magnetic nanoparticles.  

Science.gov (United States)

Ginkgolic acids (GAs; anacardic acids; 6-alkylsalicylic acids) are both unwanted constituents in standardized Ginkgo biloba (Ginkgo) extracts and desirable constituents for pharmacological assays. Thus, for the quality control of Ginkgo extracts, the availability of pure GAs is important. In this investigation, inexpensive and easily prepared Fe3O4 magnetic nanoparticles (MNPs) in methanol were used to selectively adsorb GAs from crude petroleum ether extracts of Ginkgo leaves in the presence of various lipids including other alkylphenols (cardanols and cardols). The adsorption capacity of the MNPs is high, at 4-5% (w/w). The moiety responsible for the adsorption is the salicylic acid group, which binds strongly to Fe(III). Desorption with acidified methanol gave an extract with a GA content of 73%. This could be further separated by preparative HPLC on a C8 column. In total, eight different GAs were captured by MNPs. The MNP adsorption step can replace more traditional column chromatography and liquid-liquid extraction steps and is superior in terms of solvent consumption, selectivity, labor, and energy consumption. MNPs might become an efficient separation technique for selected high-value phytochemicals that contain a salicylic acid moiety. PMID:24484321

Li, Renkai; Shen, Yao; Zhang, Xiaojuan; Ma, Ming; Chen, Bo; van Beek, Teris A

2014-03-28

167

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

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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.

Latorre Sa?nchez, Marcos; Primo Arnau, Ana Maria; Garci?a Go?mez, Hermenegildo

2012-01-01

168

Radical induced degradation of acetaminophen with Fe3O4 magnetic nanoparticles as heterogeneous activator of peroxymonosulfate.  

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Magnetic nano-scaled particles Fe3O4 were studied for the activation of peroxymonosulfate (PMS) to generate active radicals for degradation of acetaminophen (APAP) in water. The Fe3O4 MNPs were found to effectively catalyze PMS for removal of APAP, and the reactions well followed a pseudo-first-order kinetics pattern (R(2)>0.95). Within 120min, approximately 75% of 10ppm APAP was accomplished by 0.2mM PMS in the presence of 0.8g/L Fe3O4 MNPs with little Fe(3+) leaching (TBA) and ethanol (EtOH); (2) directly from the electron paramagnetic resonance (ESR) tests with 0.1M 5,5-dimethyl-1-pyrrolidine N-oxide (DMPO). Plausible mechanisms on the radical generation from Fe3O4 MNP activation of PMS are proposed based on the results of radical identification tests and XPS analysis. It appeared that Fe(2+)Fe(3+) on the catalyst surface was responsible for the radical generation. The results demonstrated that Fe3O4 MNPs activated PMS is a promising technology for water pollution caused by contaminants such as pharmaceuticals. PMID:24929305

Tan, Chaoqun; Gao, Naiyun; Deng, Yang; Deng, Jing; Zhou, Shiqing; Li, Jun; Xin, Xiaoyan

2014-07-15

169

Self-assembly and graft polymerization route to Monodispersed Fe3O4@SiO2--polyaniline core-shell composite nanoparticles: physical properties.  

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This study describes the synthesis of monodispersed core-shell composites of silica-modified magnetic nanoparticles and conducting polyaniline by self-assembly and graft polymerization. Magnetic ferrite nanoparticles (Fe3O4) were prepared by coprecipitation of Fe+2 and Fe+3 ions in alkaline solution, and then silananized. The silanation of magnetic particles (Fe3O4@SiO2) was carried out using 3-bromopropyltrichlorosilane (BPTS) as the coupling agent. FT-IR spectra indicated the presence of Fe--O--Si chemical bonds in Fe3O4@SiO2. Core-shell type nanocomposites (Fe3O4@SiO2/PANI) were prepared by grafting polyaniline (PANI) on the surface of silanized magnetic particles through surface initiated in-situ chemical oxidative graft polymerization. The nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform infrared (FTIR) spectra, UV-visible spectroscopy, photoluminescence (PL) spectra, electrical conductivity and magnetic characteristics. HRTEM images of the nanocomposites revealed that the silica-modified magnetic particles made up the core while PANI made up the shell. The XPS spectrum revealed the presence of silica in the composites, and the XRD results showed that the composites were more crystalline than pure PANI. PL spectra show that composites exhibit photoluminescent property. Conductivity of the composites (6.2 to 9.4 x 10(-2) S/cm) was higher than that of pristine PANI (3.7 x 10(-3) S/cm). The nanocomposites exhibited superparamagnetism. Formation mechanism of the core-shell structured nanocomposites and the effect of modified magnetic nanoparticles on the electro-magnetic properties of the Fe3O4@SiO2/PANI nanocomposites are also investigated. This method provides a new strategy for the generation of multi-functional nanocomposites that composed of other conducting polymers and metal nanoparticles. PMID:19198281

Reddy, Kakarla Raghava; Lee, Kwang-Pill; Kim, Ju Young; Lee, Youngil

2008-11-01

170

Ferromagnetic resonance and ac conductivity of a polymer composite of Fe3O4 and Fe3C nanoparticles dispersed in a graphite matrix  

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Ferromagnetic resonance (FMR) and ac conductivity have been applied to study a polymer composite containing as filler a binary mixture of magnetite (Fe3O4) and cementite (Fe3C) nanoparticles (30-50nm) dispersed in a diamagnetic carbon matrix, which was synthesized by the carburization of nanocrystalline iron. Ac conductivity measurements showed thermally activated behavior involving a range of activation energies and power law frequency dependence at high frequencies similar to conducting polymer composites randomly filled with metal particles. Ferromagnetic resonance measurements revealed a relatively narrow FMR line at high temperatures indicating the presence of ferromagnetic nanoparticles, where thermal fluctuations and interparticle interactions determine the FMR temperature variation. An abrupt change of the FMR spectra was observed at T Fe3O4 nanoparticles, where the concurrent skin depth variation unveils the FMR of large magnetite conglomerates and thus allows discriminating their contribution from relatively isolated nanoparticles.

Guskos, N.; Anagnostakis, E. A.; Likodimos, V.; Bodziony, T.; Typek, J.; Maryniak, M.; Narkiewicz, U.; Kucharewicz, I.; Waplak, S.

2005-01-01

171

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

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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

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

2014-08-01

172

Characteristics of magnetic labeling on liver tumors with anti-alpha-fetoprotein-mediated Fe3O4 magnetic nanoparticles  

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Full Text Available Kai-Wen Huang,1 Jen-Jie Chieh,2 Herng-Er Horng,2 Chin-Yih Hong,3 Hong-Chang Yang41Department of Surgery and Hepatitis Research Center, National Taiwan University Hospital, Taipei, 2Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 3Graduate Institute of Biomedical Engineering, National Chung Hsing University, Taichung, 4Department of Physics, National Taiwan University, Taipei, TaiwanAbstract: For preoperative and intraoperative detection of tumor distribution, numerous multimodal contrast agents, such as magnetic nanoparticles (MNPs with several examination indicators, are currently in development. However, complex materials, configuration, and cost are required for multimodal contrast agents, accompanied by a high possibility of toxicity and low popularity in clinics. Nevertheless, the magnetic labeling of MNPs using bioprobes should be feasible not only in preoperative magnetic resonance imaging (MRI, but also in intraoperative examination based on other magnetic properties. In this study, anti-alpha-fetoprotein (AFP-mediated Fe3O4 MNPs, injected into mice with liver tumors, were used to examine the characteristics of magnetic labeling. Using MRI and scanning superconducting-quantum-interference-device biosusceptometry (SSB, based on alternating current (AC susceptibility, the magnetic labeling occurred significantly on the first day post-injection of anti-AFP magnetic fluid (MF, and then decreased over time. However, for both MF without antibodies and an anti-carcinoembryonic antigen MF, no magnetic labeling occured on the first day of their respective post-injection. The favorable agreement indicates that magnetic labeling possesses two magnetic characteristics: distortion of the imaging field and AC susceptibility. In addition, the results of the biopsy tests, anti-AFP staining, and Prussian blue staining show the same dynamics as those of magnetic methodologies and prove that bound MNPs on tumor tissue are rotatable by an AC magnetic field to express AC susceptibility. Therefore, with the simple configuration of antibody-mediated MNPs, magnetic labeling is also feasible for intraoperative examinations using SSB with high mobility and sensitivity.Keywords: alpha-fetoprotein, magnetic resonance imaging, scanning SQUID biosusceptometry

Huang KW

2012-06-01

173

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

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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.

Yuen, Clement; Liu, Quan

2014-03-01

174

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)

175

Synthesis of sulfonic acid-functionalized Fe3O4@C nanoparticles as magnetically recyclable solid acid catalysts for acetalization reaction.  

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The Fe3O4@C core-shell magnetic nanoparticles with an average size of about 190 nm were synthesized via a one-pot solvothermal process using ferrocene as a single reactant. The sulfonic acid-functionalized Fe3O4@C magnetic nanoparticles were obtained by grafting the sulfonic groups on the surface of Fe3O4@C nanoparticles to produce magnetically recyclable solid acid catalysts. The as-prepared products were characterized by X-ray diffraction and transmission electron microscopy. The catalytic performance of the as-prepared catalysts was examined through the condensation reaction of benzaldehyde and ethylene glycol. The results showed that the catalysts exhibited high catalytic activity with a conversion rate of 88.3% under mild conditions. Furthermore, catalysts with a magnetization saturation of 53.5 emu g(-1) at room temperature were easily separated from the reaction mixture by using a 0.2 T permanent magnet and were reused 8 times without any significant decrease in catalytic activity. PMID:24178624

Zheng, Fang-Cai; Chen, Qian-Wang; Hu, Lin; Yan, Nan; Kong, Xiang-Kai

2014-01-21

176

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-12-15

177

Characterization of Fe3O4/SiO2/Gd2O(CO3)2 core/shell/shell nanoparticles as T1 and T2 dual mode MRI contrast agent.  

Science.gov (United States)

Core/shell/shell structured Fe3O4/SiO2/Gd2O(CO3)2 nanoparticles were successfully synthesized. Their properties as a new type of T1-T2 dual model contrast agent for magnetic resonance imaging were investigated. Due to the introduce of a separating SiO2 layer, the magnetic coupling between Gd2O(CO3)2 and Fe3O4 could be modulated by the thickness of SiO2 layer and produce appropriate T1 and T2 signal. Additionally, the existence of Gd(3+) enhances the transverse relaxivity of Fe3O4 possibly because of the magnetic coupling between Gd(3+) and Fe3O4. The Fe3O4/SiO2/Gd2O(CO3)2 nanoparticles exhibit good biocompatibility, showing great potential for biomedical applications. PMID:25281156

Yang, Meicheng; Gao, Lipeng; Liu, Kai; Luo, Chunhua; Wang, Yiting; Yu, Lei; Peng, Hui; Zhang, Wen

2015-01-01

178

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.

179

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

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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

Wang C

2012-02-01

180

An Ultrasensitive Electrochemiluminescence Immunoassay for Carbohydrate Antigen 19-9 in Serum Based on Antibody Labeled Fe3O4 Nanoparticles as Capture Probes and Graphene/CdTe Quantum Dot Bionanoconjugates as Signal Amplifiers  

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The CdTe quantum dots (QDs), graphene nanocomposite (CdTe-G) and dextran–Fe3O4 magnetic nanoparticles have been synthesized for developing an ultrasensitive electrochemiluminescence (ECL) immunoassay for Carcinoembryonic antigen 19-9 (CA 19-9) in serums. Firstly, the capture probes (CA 19-9 Ab1/Fe3O4) for enriching CA 19-9 were synthesized by immobilizing the CA 19-9’s first antibody (CA 19-9 Ab1) on magnetic nanoparticles (dextran-Fe3O4). Secondly, the signal probes (CA 19-9 Ab2/CdTe-G),...

Ning Gan; Jing Zhou; Ping Xiong; Tianhua Li; Shan Jiang; Yuting Cao; Qianli Jiang

2013-01-01

 
 
 
 
181

Manufacture of IRDye800CW-coupled Fe3O4 nanoparticles and their applications in cell labeling and in vivo imaging  

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Full Text Available Abstract Background In recent years, near-infrared fluorescence (NIRF-labeled iron nanoparticles have been synthesized and applied in a number of applications, including the labeling of human cells for monitoring the engraftment process, imaging tumors, sensoring the in vivo molecular environment surrounding nanoparticles and tracing their in vivo biodistribution. These studies demonstrate that NIRF-labeled iron nanoparticles provide an efficient probe for cell labeling. Furthermore, the in vivo imaging studies show excellent performance of the NIR fluorophores. However, there is a limited selection of NIRF-labeled iron nanoparticles with an optimal wavelength for imaging around 800 nm, where tissue autofluorescence is minimal. Therefore, it is necessary to develop additional alternative NIRF-labeled iron nanoparticles for application in this area. Results This study manufactured 12-nm DMSA-coated Fe3O4 nanoparticles labeled with a near-infrared fluorophore, IRDye800CW (excitation/emission, 774/789 nm, to investigate their applicability in cell labeling and in vivo imaging. The mouse macrophage RAW264.7 was labeled with IRDye800CW-labeled Fe3O4 nanoparticles at concentrations of 20, 30, 40, 50, 60, 80 and 100 ?g/ml for 24 h. The results revealed that the cells were efficiently labeled by the nanoparticles, without any significant effect on cell viability. The nanoparticles were injected into the mouse via the tail vein, at dosages of 2 or 5 mg/kg body weight, and the mouse was discontinuously imaged for 24 h. The results demonstrated that the nanoparticles gradually accumulated in liver and kidney regions following injection, reaching maximum concentrations at 6 h post-injection, following which they were gradually removed from these regions. After tracing the nanoparticles throughout the body it was revealed that they mainly distributed in three organs, the liver, spleen and kidney. Real-time live-body imaging effectively reported the dynamic process of the biodistribution and clearance of the nanoparticles in vivo. Conclusion IRDye800CW-labeled Fe3O4 nanoparticles provide an effective probe for cell-labeling and in vivo imaging.

Chen Zhongping

2010-10-01

182

Magnetic-Fe/Fe3O4-nanoparticle-bound SN38 as carboxylesterase-cleavable prodrug for the delivery to tumors within monocytes/macrophages  

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The targeted delivery of therapeutics to the tumor site is highly desirable in cancer treatment, because it is capable of minimizing collateral damage. Herein, we report the synthesis of a nanoplatform, which is composed of a 15 ± 1 nm diameter core/shell Fe/Fe3O4 magnetic nanoparticles (MNPs) and the topoisomerase I blocker SN38 bound to the surface of the MNPs via a carboxylesterase cleavable linker. This nanoplatform demonstrated high heating ability (SAR = 522 ± 40 W/g) in an AC-magneti...

Wang, Hongwang; Shrestha, Tej B.; Basel, Matthew T.; Dani, Raj Kumar; Seo, Gwi-moon; Balivada, Sivasai; Pyle, Marla M.; Prock, Heidy; Koper, Olga B.; Thapa, Prem S.; Moore, David; Li, Ping; Chikan, Viktor; Troyer, Deryl L.; Bossmann, Stefan H.

2012-01-01

183

Synthesis and characterization of Mn0.5Zn0.5Fe2O4 and Fe3O4 nanoparticle ferrofluids for thermo-electric conversion  

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Ferrofluids containing nanoparticles of Mn 0.5Zn0.5Fe2O4 (MZ5) and Fe3O4 (magnetite) have been examined as potential thermal transport media and energy harvesting materials. The ferrofluids were synthesized by chemical co-precipitation and characterized by EDX to determine composition and by TEM to determine particle size and agglomeration. A range of particle coatings and carrier fluids were used to complete the fluid preparation. Commercially available ferrofluids were tested in custom buil...

Sansom, Christopher L.; Jones, Paul M.; Dorey, Robert A.; Beck, C.; Stanhope-bosumpim, A.; Peterson, J.

2013-01-01

184

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)

185

Immobilized transferrin Fe3O4@SiO2 nanoparticle with high doxorubicin loading for dual-targeted tumor drug delivery  

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Full Text Available Wence Ding, Lin GuoKey Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, People's Republic of ChinaAbstract: Transferrin (Tf was immobilized onto Fe3O4@SiO2 nanoparticles with high doxorubicin (DOX loading (TfDMP, for dual targeting of cancer, by chemically coupling both Tf and DOX with dual-function magnetic nanoparticles (DMPs using a multi-armed crosslinker, poly-L-glutamic acid. With high trapping efficiency for magnetic targeting, TfDMP exhibits a Tf receptor-targeting function. Moreover, the DOX loading percentage of TfDMP is high, and can be controlled by adjusting the reactant ratio. TfDMP presents a narrow size distribution, and is sensitive to pH for drug release. Compared with DOX-coupled DMP without Tf modification (DDMP, TfDMP exhibits enhanced uptake by Tf receptor-expressing tumor cells, and displays stronger cancer cell cytotoxicity. This study provides an efficient method for the dual-targeted delivery of therapeutic agents to tumors, with controlled low carrier toxicity and high efficiency.Keywords: transferrin, Fe3O4@SiO2, nanoparticle, doxorubicin, targeted tumor

Ding W

2013-12-01

186

Peroxidase-like activity of Fe3O4@carbon nanoparticles enhances ascorbic acid-induced oxidative stress and selective damage to PC-3 prostate cancer cells.  

Science.gov (United States)

Ascorbic acid (AA) is capable of inhibiting cancer cell growth by perturbing the normal redox state of cells and causing toxic effects through the generation of abundant reactive-oxygen species (ROS). However, the clinical utility of AA at a tolerable dosage is plagued by a relatively low in vivo efficacy. This study describes the development of a peroxidase-like composite nanoparticle for use in an AA-mediated therapeutic strategy. On the basis of a high-throughput, one-pot solvothermal approach, Fe3O4@C nanoparticles (NPs) were synthesized and then modified with folic acid (FA) on the surface. Particular focus is concentrated on the assessment of peroxidase-like catalytic activity by a chromogenic reaction in the presence of H2O2. The carbon shell of Fe3O4@C NPs contains partially graphitized carbon and thus facilitates electron transfer in the catalytic decomposition of H2O2, leading to the production of highly reactive hydroxyl radicals. Along with magnetic responsiveness and receptor-binding specificity, the intrinsic peroxidase-like catalytic activity of Fe3O4@C-FA NPs pronouncedly promotes AA-induced oxidative stress in cancer cells and optimizes the ROS-mediated antineoplastic efficacy of exogenous AA. In vitro experiments using human prostate cancer PC-3 cells demonstrate that Fe3O4@C-FA NPs serve as a peroxidase mimic to create hydroxyl radicals from endogenous H2O2 that is yielded in response to exogenous AA via an oxidative stress process. The usage of a dual agent leads to the enhanced cytotoxicity of PC-3 cells, and, because of the synergistic effect of NPs, the administrated dosage of AA is reduced markedly. However, because normal cells (HEK 293T cells) appear to have a higher capacity to cope with additionally generated ROS than cancer cells, the NP-AA combination shows little damage in this case, proving that selective killing of cancer cells could be achieved owing to preferential accumulation of ROS in cancer cells. A possible ROS-mediated mechanism is discussed to elucidate the pharmaceutical profile of the NP-AA agent. In general, this foundational study reveals that the peroxidase-like nanomaterials are applicable for modulating oxidative stress for the selective treatment of cancer cells by generating a high level of endogenous ROS. PMID:24199694

An, Qiao; Sun, Chuanyu; Li, Dian; Xu, Ke; Guo, Jia; Wang, Changchun

2013-12-26

187

Magnetic solid-phase extraction based on diphenyl functionalization of Fe3O4 magnetic nanoparticles for the determination of polycyclic aromatic hydrocarbons in urine samples.  

Science.gov (United States)

Superparamagnetic Fe(3)O(4) diphenyl nanoparticles were prepared according to a solvothernal procedure and characterized by X-ray diffraction, infrared spectroscopy, surface area measurements, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The magnetic phases present in the nanoparticle samples were analyzed by thermomagnetic analysis and the samples' magnetic properties were studied by vibrating sample magnetometry. The resulting nanoparticles having an average diameter of 200 nm were then used as solid-phase extraction sorbent for the determination of polycyclic aromatic hydrocarbons in urine samples. Method validation proved the feasibility of the developed beads for the quantitation of the investigated analytes at trace levels obtaining lower limit of quantitation values in the ng/l range. A good precision with coefficients of variations always lower than 15% was obtained. Finally, the superior extraction performance of the synthesized nanoparticles with respect to commercially available beads was proved. PMID:22364670

Bianchi, F; Chiesi, V; Casoli, F; Luches, P; Nasi, L; Careri, M; Mangia, A

2012-03-30

188

Correlating material-specific layers and magnetic distributions within onion-like Fe3O4/MnO/?-Mn2O3 core/shell nanoparticles  

Science.gov (United States)

The magnetic responses of two nanoparticle systems comprised of Fe3O4/?-Mn2O3 (soft ferrimagnetic, FM/hard FM) and Fe3O4/MnO/?-Mn2O3 (soft FM/antiferromagnetic, AFM/hard FM) are compared, where the MnO serves to physically decouple the FM layers. Variation in the temperature and applied field allows for Small Angle Neutron Scattering (SANS) measurements of the magnetic moments both parallel and perpendicular to an applied field. Data for the bilayer particle indicate that the graded ferrimagnetic layers are coupled and respond to the field as a single unit. For the trilayer nanoparticles, magnetometry suggests a Curie temperature (TC) ? 40 K for the outer ?-Mn2O3 component, yet SANS reveals an increase in the magnetization associated with outer layer that is perpendicular to the applied field above TC during magnetic reversal. This result suggests that the ?-Mn2O3 magnetically reorients relative to the applied field as the temperature is increased above 40 K.

Krycka, K. L.; Borchers, J. A.; Laver, M.; Salazar-Alvarez, G.; López-Ortega, A.; Estrader, M.; Suriñach, S.; Baró, M. D.; Sort, J.; Nogués, J.

2013-05-01

189

Synthesis and characterization of Mn0.5Zn0.5Fe2O4 and Fe3O4 nanoparticle ferrofluids for thermo-electric conversion  

International Nuclear Information System (INIS)

Ferrofluids containing nanoparticles of Mn0.5Zn0.5Fe2O4 (MZ5) and Fe3O4 (magnetite) have been examined as potential thermal transport media and energy harvesting materials. The ferrofluids were synthesized by chemical co-precipitation and characterized by EDX to determine composition and by TEM to determine particle size and agglomeration. A range of particle coatings and carrier fluids were used to complete the fluid preparation. Commercially available ferrofluids were tested in custom built rigs to demonstrate both thermal pumping (for waste heat removal applications) and power induction (for power conversion and energy harvesting applications). The results indicate that simple ferrofluids possess the necessary properties to remove waste heat, either into thermal storage or for conversion to electrical power. - Highlights: ? The synthesis of nanoparticle ferrofluids based on Mn0.5Zn0.5Fe2O4 and Fe3O4 is reported. ? The thermal properties of the ferrofluids creates a novel pump with no moving parts. ? Thermal energy harvesting for conversion into electrical power is demonstrated

190

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

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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.

Huan Liu

2013-11-01

191

Magnetically assisted solid phase extraction using Fe3O4 nanoparticles combined with enhanced spectrofluorimetric detection for aflatoxin M1 determination in milk samples.  

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A novel, facile and inexpensive solid phase extraction (SPE) method using ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol grafted Fe(3)O(4) nanoparticles coupled with spectrofluorimetric detection was proposed for determination of aflatoxin M1 (AFM1) in liquid milk samples. The method uses the advantage fluorescence enhancement by ?-cyclodexterin complexation of AFM1 in 12% (v/v) acetonitrile-water and the remarkable properties of Fe(3)O(4) nanoparticles namely high surface area and strong magnetization were utilized to achieve high enrichment factor (57) and satisfactory extraction recoveries (91-102%) using only 100 mg of magnetic adsorbent. Furthermore, fast separation time of about 15 min avoids many time-consuming column-passing procedures of conventional SPE. The main factors affecting extraction efficiency including pH value, desorption conditions, extraction/desorption time, sample volume, and adsorbent amount were evaluated and optimized. Under the optimal conditions, a wide linear range of 0.04-8 ng mL(-1) with a low detection limit of 0.015 ng mL(-1) was obtained. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method. PMID:25127653

Taherimaslak, Zohreh; Amoli-Diva, Mitra; Allahyary, Mehdi; Pourghazi, Kamyar

2014-09-01

192

Gold nanoparticles on mesoporous SiO(2)-coated magnetic Fe(3)O(4)spheres: a magnetically separatable catalyst with good thermal stability.  

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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. PMID:24252995

Liu, Huan; Lin, Chao; Ma, Zhen; Yu, Hongbo; Zhou, Shenghu

2013-01-01

193

Multifunctional Fe3O4@P(St/MAA)@chitosan@Au core/shell nanoparticles for dual imaging and photothermal therapy.  

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Merging different components into a single nanoparticle can exhibit profound impact on various biomedical applications including diagnostics, imaging, and therapy. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated that gold nanoshells on polystyrene spheres have potential in photohermal therapy. Here, we report a facile and green strategy to synthesize a multifunctional nanocomposite with Fe3O4 core coated gold nanoshells as dual imaging probes and photothermal agents. The as-prepared nanoparticles exhibit well-defined structure and excellent physical properties such as magnetic and plasmonic activities. Therefore, they were applied as contrast agents in magnetic resonance imaging (MRI) and dark field imaging (DFI). Besides, we demonstrated their potential application in photothermal therapy. Moreover, the obtained multifunctional nanoparticles have shown excellent biocompatibility for their low cytotoxicity and hemolyticity. PMID:23683167

Wang, Xuandong; Liu, Huiyu; Chen, Dong; Meng, Xianwei; Liu, Tianlong; Fu, Changhui; Hao, Nanjing; Zhang, Yanqi; Wu, Xiaoli; Ren, Jun; Tang, Fangqiong

2013-06-12

194

The magnetic proximity effect in a ferrimagnetic Fe3O4 core/ferrimagnetic ?-Mn2O3 shell nanoparticle system  

International Nuclear Information System (INIS)

We report the magnetic proximity effect in a ferrimagnetic Fe3O4 core/ferrimagnetic ?-Mn2O3 shell nanoparticle system, in terms of an enhancement of the Curie temperature (Tc) of the ?-Mn2O3 shell (?66 K) compared to its bulk value (?40 K), and the presence of magnetic ordering in its so-called paramagnetic region (i.e. above 66 K). The ferrimagnetic nature of both core and shell has been found from a neutron diffraction study. The origin of these two features of the magnetic proximity effect has been ascribed to the proximity of the ?-Mn2O3 shell with a high-Tc Fe3O4 core (?858 K in bulk form) and an interface exchange coupling between core and shell. Interestingly, we did not observe any exchange bias effect, which has been interpreted as a signature of a weak interface exchange coupling between core and shell. The present study brings out the importance of the relative strength of the interface coupling in governing the simultaneous occurrence of the magnetic proximity effect and the exchange bias phenomenon in a single system. (paper)

195

Rapid and high-throughput determination of endogenous cytokinins in Oryza sativa by bare Fe3O4 nanoparticles-based magnetic solid-phase extraction.  

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A rapid method was developed for determination of endogenous cytokinins (CKs) based on magnetic solid-phase extraction (MSPE) followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We illustrated the hydrophilic character of bare Fe3O4 nanoparticles that were directly used as a MSPE sorbent for rapid enrichment of endogenous CKs from complex plant extract. To the best of our knowledge, this is the first report of bare Fe3O4 directly used as efficient extraction sorbent to enrich target CKs based on hydrophilic interaction. Under the optimized conditions, a rapid, sensitive and high-throughput method for the determination of 16 CKs was established by combination of MSPE with UPLC-MS/MS. Good linearity was obtained with correlation coefficients (r) from 0.9902 to 0.9998. The limits of detection (LODs) and quantification (LOQs) ranged from 1.2 pg mL(-1) to 391.3 pg mL(-1) and 4.1 pg mL(-1) to 1304.3 pg mL(-1), respectively. 16 CKs could be successfully determined in spiked sample with 80.6-117.3% recoveries and the relative standard deviations (RSDs) were less than 16.6%. Finally, 10 endogenous CKs were successfully quantified in 50mg Oryza sativa sample using the developed MSPE-UPLC-MS/MS method. PMID:24685168

Cai, Bao-Dong; Zhu, Jiu-Xia; Gao, Qiang; Luo, Dan; Yuan, Bi-Feng; Feng, Yu-Qi

2014-05-01

196

Bifunctional polydopamine@Fe3O4 core–shell nanoparticles for electrochemical determination of lead(II) and cadmium(II)  

International Nuclear Information System (INIS)

Highlights: •The bifunctional nanocomposites were synthesized. •A modified magnetic glassy carbon electrode was fabricated. •The electrode was used for the selective detection of Pb2+ and Cd2+ ions. •The proposed sensor features a wider linear range and higher sensitivity. -- Abstract: The present paper has focused on the potential application of the bifunctional polydopamine@Fe3O4 core–shell nanoparticles for development of a simple, stable and highly selective electrochemical method for metal ions monitoring in real samples. The electrochemical method is based on electrochemical preconcentration/reduction of metal ions onto a polydopamine@Fe3O4 modified magnetic glassy carbon electrode at ?1.1 V (versus SCE) in 0.1 M pH 5.0 acetate solution containing Pb2+ and Cd2+ during 160 s, followed by subsequent anodic stripping. The proposed method has been demonstrated highly selective and sensitive detection of Pb2+ and Cd2+, with the calculated detection limits of 1.4 × 10?11 M and 9.2 × 10?11 M. Under the optimized conditions, the square wave anodic stripping voltammetry response of the modified electrode to Pb2+ (or Cd2+) shows a linear concentration range of 5.0–600 nM (or 20–590 nM) with a correlation coefficient of 0.997 (or 0.994). Further, the proposed method has been performed to successfully detect Pb2+ and Cd2+ in aqueous effluent

197

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

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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. PMID:25318051

Khandanlou, Roshanak; Ahmad, Mansor B; Shameli, Kamyar; Saki, Elnaz; Kalantari, Katayoon

2014-01-01

198

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

Science.gov (United States)

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. PMID:25318051

Khandanlou, Roshanak; Ahmad, Mansor B.; Shameli, Kamyar; Saki, Elnaz; Kalantari, Katayoon

2014-01-01

199

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

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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.

Roshanak Khandanlou

2014-10-01

200

Paclitaxel-Fe3O4 nanoparticles inhibit growth of CD138–  CD34– tumor stem-like cells in multiple myeloma-bearing mice  

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Full Text Available Cuiping Yang,1,3,* Jing Wang,2,* Dengyu Chen,1,* Junsong Chen,1 Fei Xiong,4 Hongyi Zhang,1 Yunxia Zhang,2 Ning Gu,4 Jun Dou11Department of Pathogenic Biology and Immunology, Medical School, 2Department of Gynecology and Obstetrics, Zhongda Hospital, Southeast University, Nanjing, 3Department of Pathogenic Biology and Immunology, School of Basic Medicine, Jiangxi University of Traditional Chinese Medicine, Nanchang, 4School of Biological Science and Medical Engineering, Southeast University, Nanjing, People’s Republic of China*These authors contributed equally to this workBackground: There is growing evidence that CD138– CD34– cells may actually be tumor stem cells responsible for initiation and relapse of multiple myeloma. However, effective drugs targeted at CD138– CD34– tumor stem cells are yet to be developed. The purpose of this study was to investigate the inhibitory effect of paclitaxel-loaded Fe3O4 nanoparticles (PTX-NPs on CD138– CD34– tumor stem cells in multiple myeloma-bearing mice.Methods: CD138– CD34– cells were isolated from a human U266 multiple myeloma cell line using an immune magnetic bead sorting method and then subcutaneously injected into mice with nonobese diabetic/severe combined immunodeficiency to develop a multiple myeloma-bearing mouse model. The mice were treated with Fe3O4 nanoparticles 2 mg/kg, paclitaxel 4.8 mg/kg, and PTX-NPs 0.64 mg/kg for 2 weeks. Tumor growth, pathological changes, serum and urinary interleukin-6 levels, and molecular expression of caspase-3, caspase-8, and caspase-9 were evaluated.Results: CD138– CD34– cells were found to have tumor stem cell characteristics. All the mice developed tumors in 40 days after injection of 1 × 106 CD138– CD34– tumor stem cells. Tumor growth in mice treated with PTX-NPs was significantly inhibited compared with the controls (P <  0.005, and the groups that received nanoparticles alone (P < 0.005 or paclitaxel alone (P < 0.05. In addition, the PTX-NPs markedly inhibited interleukin-6 secretion, increased caspase-8, caspase-9, and caspase-3 expression, and induced apoptosis of tumor cells in the treated mice.Conclusion: PTX-NPs proved to be a potent anticancer treatment strategy that may contribute to targeted therapy for multiple myeloma tumor stem cells in future clinical trials.Keywords: multiple myeloma, tumor stem cells, Fe3O4 nanoparticles, paclitaxel

Yang C

2013-04-01

 
 
 
 
201

Immobilized transferrin Fe3O4@SiO2 nanoparticle with high doxorubicin loading for dual-targeted tumor drug delivery.  

Science.gov (United States)

Transferrin (Tf) was immobilized onto Fe3O4@SiO2 nanoparticles with high doxorubicin (DOX) loading (TfDMP), for dual targeting of cancer, by chemically coupling both Tf and DOX with dual-function magnetic nanoparticles (DMPs) using a multi-armed crosslinker, poly-L-glutamic acid. With high trapping efficiency for magnetic targeting, TfDMP exhibits a Tf receptor-targeting function. Moreover, the DOX loading percentage of TfDMP is high, and can be controlled by adjusting the reactant ratio. TfDMP presents a narrow size distribution, and is sensitive to pH for drug release. Compared with DOX-coupled DMP without Tf modification (DDMP), TfDMP exhibits enhanced uptake by Tf receptor-expressing tumor cells, and displays stronger cancer cell cytotoxicity. This study provides an efficient method for the dual-targeted delivery of therapeutic agents to tumors, with controlled low carrier toxicity and high efficiency. PMID:24348038

Ding, Wence; Guo, Lin

2013-01-01

202

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.

203

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.

204

Silica supported Fe(3)O(4) magnetic nanoparticles for magnetic solid-phase extraction and magnetic in-tube solid-phase microextraction: application to organophosphorous compounds.  

Science.gov (United States)

This work demonstrates the application of silica supported Fe3O4 nanoparticles as sorbent phase for magnetic solid-phase extraction (MSPE) and magnetic on-line in-tube solid-phase microextraction (Magnetic-IT-SPME) combined with capillary liquid chromatography-diode array detection (CapLC-DAD) to determine organophosphorous compounds (OPs) at trace level. In MSPE, magnetism is used as separation tool while in Magnetic-IT-SPME, the application of an external magnetic field gave rise to a significant improvement of the adsorption of OPs on the sorbent phase. Extraction efficiency, analysis time, reproducibility and sensitivity have been compared. This work showed that Magnetic-IT-SPME can be extended to OPs with successful results in terms of simplicity, speed, extraction efficiency and limit of detection. Finally, wastewater samples were analysed to determine OPs at nanograms per litre. PMID:24105458

Moliner-Martinez, Y; Vitta, Yosmery; Prima-Garcia, Helena; González-Fuenzalida, R A; Ribera, Antonio; Campíns-Falcó, P; Coronado, Eugenio

2014-03-01

205

Study on synthesis of poly(GMA)-grafted Fe3O4/SiOX magnetic nanoparticles using atom transfer radical polymerization and their application for lipase immobilization  

International Nuclear Information System (INIS)

Functionalized superparamagnetic particles were prepared by atom transfer radical polymerization of glycidyl methacrylate onto the surface of modified Fe3O4/SiOX nanoparticles. The obtained particles were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). Candida rugosa lipase was covalently immobilized on the magnetic particles in mild condition via covalent binding with a higher activity recovery. The resulting immobilized lipase had better resistance to pH and temperature inactivation in comparison to free lipase, the adaptive pH and temperature ranges of lipase were widened, and it exhibited good thermal stability and reusability.

206

Reduction of hematite with ethanol to produce magnetic nanoparticles of Fe3O4, Fe1-xO or Fe0 coated with carbon  

International Nuclear Information System (INIS)

The production of magnetic nanoparticles of Fe3O4 or Fe0 coated with carbon and carbon nanotubes was investigated by the reduction of hematite with ethanol in a Temperature Programmed Reaction up to 950 deg. C. XRD and Moessbauer measurements showed after reaction at 350 deg. C the partial reduction of hematite to magnetite. At 600 deg. C the hematite is completely reduced to magnetite (59%), wuestite (39%) and metallic iron (7%). At higher temperatures, carbide and metallic iron are the only phases present. TG weight losses suggested the formation of 3-56 wt.% carbon deposits after reaction with ethanol. It was observed by SEM images a high concentration of nanometric carbon filaments on the material surface. BET analyses showed a slight increase in the surface area after reaction. These materials have potential application as catalyst support and removal of spilled oil contaminants.

207

Ultrasound assisted the green synthesis of 2-amino-4H-chromene derivatives catalyzed by Fe3O4-functionalized nanoparticles with chitosan as a novel and reusable magnetic catalyst.  

Science.gov (United States)

Fe3O4 nanoparticles were prepared by chemical coprecipitation method. Subsequently immobilization of chitosan on Fe3O4 nanoparticles was accomplished and afforded magnetic Fe3O4-chitosan nanoparticles. Synthesized nanoparticles was found to be a magnetic and heterogeneous catalyst for a one-pot and efficient synthesis of 2-amino-4H-chromenes by condensation of aldehydes with malononitrile and resorcinol under ultrasound irradiation as an ecofriendly method. This convenient procedure allowed us to achieve products under ultrasound irradiation in short time and excellent yield without using of harmful catalyst. The present method will permit a further increase of the diversity within the 2-amino-4H-chromene family. PMID:24835021

Safari, Javad; Javadian, Leila

2015-01-01

208

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

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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.

Roozbeh Hushiarian

2014-04-01

209

Facile and solvent-free routes for the synthesis of size-controllable Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

Magnetite nanoparticles are one of the most important materials that are widely used in both medically diagnostic and therapeutic research. In this paper, we present some facile and non-toxic synthetic approaches for size-controllable preparations of magnetite nanoparticles, which are appropriate for biomedical applications, namely (i) co-precipitation; (ii) reduction–precipitation and (iii) oxidation–precipitation. Magnetic characterizations of the obtained nanoparticles have been studied and discussed. The oxidation precipitation route was chosen for investigation of the dependence of kinetic driven activation energy and that of coercive force on particle size (and temperature) during the course of the reaction. The structural–magnetic behavior was also correlated. Being solvent and surfactant-free, these methods are advantageous for synthesis and further functionalization towards biomedical applications

210

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 elffraction (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.

211

Controlling anisotropic drug diffusion in lipid-Fe3O4 nanoparticle hybrid mesophases by magnetic alignment.  

Science.gov (United States)

We present a new strategy to control the anisotropic diffusion of hydrophilic drugs in lyotropic liquid crystals via the dispersion of magnetic nanoparticles in the mesophase, followed by reorientation of the mesophase domains via an external magnetic field. We select a lipid reverse hexagonal phase doped with magnetic iron oxide nanoparticles and glucose and caffeine as model hybrid mesophase and hydrophilic drugs, respectively. Upon cooling through the disorder-order phase transition of the hexagonal phase and under exposure to an external moderate magnetic field (1.1 T), both the nanoparticles and the hexagonal domains align with their columnar axes along the field direction. As a result, the water nanochannels of the inverted hexagonal domains also align parallel to the field direction, leading to a drug diffusion coefficient parallel to the field direction much larger than what was measured perpendicularly: in the case of glucose, for example, this difference in diffusion coefficients approaches 1 order of magnitude. Drug diffusion of the unaligned reverse hexagonal phase, which consists of randomly distributed domains, shows values in between the parallel and transversal diffusion values. This study shows that modifying the overall alignment of anisotropic mesophases via moderate external fields is a valuable means to control the corresponding transport tensor of the mesophase and demonstrates that the orientation of the domains plays an important role in the diffusion process of foreign hydrophilic molecules. PMID:23302008

Vallooran, Jijo J; Negrini, Renata; Mezzenga, Raffaele

2013-01-29

212

Magnetic poly epsilon-caprolactone nanoparticles containing Fe3O4 and gemcitabine enhance anti-tumor effect in pancreatic cancer xenograft mouse model.  

Science.gov (United States)

We prepared magnetic (Fe(3)O(4)) poly epsilon-caprolactone (PCL) nanoparticles (mean diameter 164 +/- 3 nm) containing an anticancer drug (gemcitabine) using emulsion-diffusion method in order to develop more efficient drug delivery for cancer treatment. Nanoparticles were smooth, well individualized and homogeneous in size. The values of magnetizations for the magnetic PCL nanoparticles were observed around 10.2 emu/g at 2000 Oe magnetic field intensity and showed super-paramagnetic property. In case of the drug, the drug loading contents was 18.6% and entrapment efficiency was 52.2%. The anti-tumor effects caused by these particles were examined using nude mice bearing subcutaneous human pancreatic adenocarcinoma cells (HPAC) in vivo. We divided that these mice were randomly assigned to one of five treatment groups for experimental contrast. The antitumor effect was showed with 15-fold higher dose when compared to free gemcitabine. From the result, the magnetic PCL nanoparticles may provide a therapeutic benefit by delivering drugs efficiently to magnetically targeted tumor tissues, thus achieving safe and successful anti-tumor effects with low toxicity. PMID:17613663

Gang, Jingu; Park, Seong-Bae; Hyung, Woochan; Choi, Eric H; Wen, Jing; Kim, Han-Soo; Shul, Young-Gun; Haam, Seungjoo; Song, Si Young

2007-07-01

213

Magneto-transport study of magnetite (Fe3O4) nanoparticles between Au nanogap electrodes on surface-oxidized Si substrate  

International Nuclear Information System (INIS)

We have studied the magneto-transport of magnetite (Fe3O4) nanoparticles (MNPs) between Au nanogap electrodes (ANGEs) on surface-oxidized Si substrate. The MNP sizes are approximately 40 nm and the 100 nm thick magnetite thin film (which is formed of the MNP aggregation) was prepared between and around the ANGEs by use of the RF reactive magnetron sputtering method. The distance between the ANGEs and the bridge width of the ANGEs are approximately 50 nm and 1.5 ?m, respectively. The ANGEs were produced by the tilted-angle-deposition method. The optical microscope, scanning electron microscope and atomic force microscope were used to observe the sample surface structure and morphology. To investigate the crystal structure and crystallinity of the MNPs, the X-ray diffraction measurement was performed. The electrical resistance and magneto-resistance ratio of the MNPs between the ANGEs were measured as a function of temperature. The magneto-transport mechanism is discussed on the basis of the spin dependent transport. -- Highlights: ? Between Au nanogap electrodes, magnetite nanoparticle aggregation was prepared. ? Magnetite nanoparticle aggregation was produced by the RF magnetron sputtering method. ? Resistivity and magnetoresistance of magnetite nanoparticle aggregation were measured. ? We propose the tunneling magneto-resistance model due to amorphous-like grain boundaries. ? The model explains temperature dependence on resistivity and magneto-resistance

214

PLLA- Fe3O4 nanocomposites  

Science.gov (United States)

In the present work magnetite nanoparticules and PLLA- Fe3O4 nanocomposites were prepared by high frequency ultrasound. The influence of pH on nanoparticle size was studied, showing that the particle size decreased as the pH increased. In the composites an interaction between the magnetite nanoparticles and the PLLA matrix was observed by FTIR. Magnetic properties were studied using a VSM, and a superparamegnetic behavior was observed for magnetite nanoparticles, but for the composite a magnetic attenuation was observed due to the polymeric matrix.

Albano, Carmen; Gonzalez, Gema; Naranjo, Claudio

2012-07-01

215

Magnetic nanofibers with core (Fe3O4 nanoparticle suspension)/sheath (poly ethylene terephthalate) structure fabricated by coaxial electrospinning  

International Nuclear Information System (INIS)

One-dimensional magnetic nanostructures have recently attracted much attention because of their intriguing properties that are not realized by their bulk or particle form. These nanostructures are potentially useful for the application to ultrahigh-density data storages, sensors and bulletproof vest. The magnetic particles in magnetic nanofibers of blend types cannot fully align along the external magnetic field because magnetic particles are arrested in solid polymer matrix. To improve the mobility of magnetic particles, we used magneto-rheological fluid (MRF), which has the good mobility and dispersibility. Superparamagnetic core/sheath composite nanofibers were obtained with MRF and poly (ethylene terephthalate) (PET) solution via a coaxial electrospinning technique. Coaxial electrospinning is suited for fabricating core/sheath nanofibers encapsulating MRF materials within a polymer sheath. The magnetic nanoparticles in MRF were dispersed within core part of the nanofibers. The core/sheath magnetic composite nanofibers exhibited superparamagnetic behavior at room temperature and the magnetic nanoparticles in MRF well responded to an applied magnetic field. Also, the mechanical properties of the nanofiber were improved in the magnetic field. This study aimed to fabricate core/sheath magnetic composite nanofibers using coaxial electrospinning and characterize the magnetic as well as mechanical properties of composite nanofibers. - Highlights: ? The composite nanofirs. - Highlights: ? The composite nanofibers including the MRF and PET. ? The fabrication of core/sheath structured nanofibers using coaxial electrospinning. ? Superparamagnetic composite nanofibers.

216

Extraction of Genomic DNA Using Magnetic Nanoparticles (Fe3O4 as a Solid-Phase Support  

Directory of Open Access Journals (Sweden)

Full Text Available Magnetic separation technology, using magnetic particles, is quick and easy method for sensitive and reliable captures of specific proteins, genetic material and other biomolecules. The current paper describes a universal genomic DNA extraction method optimized in our laboratory using magnetic nanoparticles as a solid phase adsorbent. The yields of the isolated DNA with magnetic method were higher or equivalent to the conventional procedures in all the samples tested. Additionally, the magnetic method takes less than 15 minutes to extract DNA as against several hours taken by conventional protocols. Furthermore, the isolated DNA was found to function satisfactorily in PCR amplification and restriction endonuclease digestion. The developed procedure is simple, quick, cheap, robust and does not require the use of organic solvents or sophisticated equipments; thereby making it more amenable to automation.

Z. M. Saiyed

2007-01-01

217

One-step hydrothermal synthesis of highly water-soluble secondary structural Fe3O4 nanoparticles  

Science.gov (United States)

Magnetite nanoparticles (MNPs) were prepared using the ferric acetylacetonate as the sole iron source in a facile hydrothermal route, while poly(acrylic acid) (PAA) was chosen as the stabilizer via one-step functionalized MNPs for better hydrophilic properties. The orthogonal was used in the paper for the experimental parameters optimization, including the solvent, the reaction time, the amount of stabilizer and the presynthesis. The obtained highly water dispersible MNPs with uniform size from about 50 to about 100 nm was individually composed of many monodisperse magnetite crystallites approximately 6 nm in size. And the MNPs show high magnetic properties, whose magnetite content was up to 76.76% and the saturation magnetization was 39.0 emu/g. Later the formation mechanism of MNPs was also discussed. Thus the MNPs proved to be very promising for biomedical applications.

Yang, Xiwen; Jiang, Wei; Liu, Li; Chen, Binghua; Wu, Shixi; Sun, Danping; Li, Fengsheng

2012-07-01

218

Kinetics of elimination and distribution in blood and liver of biocompatible ferrofluids based on Fe3O4 nanoparticles: An EPR and XRF study  

International Nuclear Information System (INIS)

In this study, we evaluated the biodistribution and the elimination kinetics of a biocompatible magnetic fluid, EndoremTM, based on dextran-coated Fe3O4 nanoparticles endovenously injected into Winstar rats. The iron content in blood and liver samples was recorded using electron paramagnetic resonance (EPR) and X-ray fluorescence (XRF) techniques. The EPR line intensity at g = 2.1 was found to be proportional to the concentration of magnetic nanoparticles and the best temperature for spectra acquisition was 298 K. Both EPR and XRF analysis indicated that the maximum concentration of iron in the liver occurred 95 min after the ferrofluid administration. The half-life of the magnetic nanoparticles (MNP) in the blood was (11.6 ± 0.6) min measured by EPR and (12.6 ± 0.6) min determined by XRF. These results indicate that both EPR and XRF are very useful and appropriate techniques for the study of kinetics of ferrofluid elimination and biodistribution after its administration into the organism

219

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.

220

One-step hydrothermal synthesis of highly water-soluble secondary structural Fe3O4 nanoparticles  

International Nuclear Information System (INIS)

Magnetite nanoparticles (MNPs) were prepared using the ferric acetylacetonate as the sole iron source in a facile hydrothermal route, while poly(acrylic acid) (PAA) was chosen as the stabilizer via one-step functionalized MNPs for better hydrophilic properties. The orthogonal was used in the paper for the experimental parameters optimization, including the solvent, the reaction time, the amount of stabilizer and the presynthesis. The obtained highly water dispersible MNPs with uniform size from about 50 to about 100 nm was individually composed of many monodisperse magnetite crystallites approximately 6 nm in size. And the MNPs show high magnetic properties, whose magnetite content was up to 76.76% and the saturation magnetization was 39.0 emu/g. Later the formation mechanism of MNPs was also discussed. Thus the MNPs proved to be very promising for biomedical applications. - Highlights: ? MNPs are prepared in a low-temperature hydrothermal synthesis procedure. ? Synthesis of MNPs is hybridized with their in situ surface functionalization. ? Each of the secondary structural MNPs is composed of monodisperse primary particles. ? The resulting MNPs show good magnetic properties combining that of primary one. ? The size of MNPs is controllable and the mechanism is elaborated.

 
 
 
 
221

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

CERN Document Server

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...

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

2014-01-01

222

Fe3O4@ionic liquid@methyl orange nanoparticles as a novel nano-adsorbent for magnetic solid-phase extraction of polycyclic aromatic hydrocarbons in environmental water samples.  

Science.gov (United States)

A novel nano-adsorbent, Fe3O4@ionic liquid@methyl orange nanoparticles (Fe3O4@IL@MO NPs), was prepared for magnetic solid-phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. The Fe3O4@IL@MO NPs were synthesized by self-assembly of the ionic liquid 1-octadecyl-3-methylimidazolium bromide (C18mimBr) and methyl orange (MO) onto the surface of Fe3O4 silica magnetic nanoparticles, as confirmed by infrared spectroscopy, ultraviolet-visible spectroscopy and superconducting quantum interface device magnetometer. The extraction performance of Fe3O4@IL@MO NPs as a nano-adsorbent was evaluated by using five PAHs, fluorene (FLu), anthracene (AnT), pyrene (Pyr), benzo(a)anthracene (BaA) and benzo(a)pyrene (BaP) as model analytes. Under the optimum conditions, detection limits in the range of 0.1-2 ng/L were obtained by high performance liquid chromatography-fluorescence detection (HPLC-FLD). This method has been successfully applied for the determination of PAHs in environmental water samples by using the MSPE-HPLC-FLD. The recoveries for the five PAHs tested in spiked real water samples were in the range of 80.4-104.0% with relative standard deviations ranging from 2.3 to 4.9%. PMID:24401423

Liu, Xiaofei; Lu, Xin; Huang, Yong; Liu, Chengwei; Zhao, Shulin

2014-02-01

223

Effect of embedding Fe3O4 nanoparticles in silica spheres on the optical transmission properties of three-dimensional magnetic photonic crystals  

Science.gov (United States)

Magnetic and optical properties of three-dimensional fcc-structured magnetic photonic crystals (MPCs), consisting of SiO2 spheres, in the size range 260-680 nm, embedded with 0-6.4 wt % Fe3O4 nanoparticles have been investigated. In the wide spatial angle transmission spectra for these crystals at normal incidence of light in the UV-visible range, five photonic band gaps (PBGs) due to Bragg diffraction from different crystal planes have been observed. The Bragg wavelengths (?B) of PBGs in both the nonmagnetic and MPCs of the same structure are found to depend linearly on the sphere size. From the slope of this linear function the calculated effective refractive index is found to increase with the concentration of the magnetite nanoparticles in the MPCs, and is consistent with the result calculated from the average dielectric constant. We also find ?B of PBGs are dependent on the angle of the incidence of the light. Furthermore, for small angles this angular dependency is more strongly dependent on the polarization of incident light for MPCs than for the non-MPCs. Thus, magnetic nanocomposite PCs can be designed to incorporate additional functionality in the development of potential magneto-optical devices.

Fang, Mei; Volotinen, Tarja T.; Kulkarni, S. K.; Belova, Lyubov; Rao, K. V.

2010-11-01

224

Variable blocking temperature of a porous silicon/Fe3O4 composite due to different interactions of the magnetic nanoparticles  

Science.gov (United States)

In the frame of this work, the aim was to create a superparamagnetic nanocomposite system with a maximized magnetic moment when magnetized by an external field and a blocking temperature far below room temperature. For this purpose, iron oxide nanoparticles of 3.8-, 5- and 8-nm size have been infiltrated into the pores of porous silicon. To fabricate tailored magnetic properties of the system, the particle size and the magnetic interactions among the particles play a crucial role. Different concentrations of the particles dispersed in hexane have been used for the infiltration to vary the blocking temperature T B, which indicates the transition between the superparamagnetic behavior and blocked state. T B is not only dependent on the particle size but also on the magnetic interactions between them, which can be varied by the particle-particle distance. Thus, a modification of the pore loading on the one hand and of the porous silicon morphology on the other hand results in a composite material with a desired blocking temperature. Because both materials, the mesoporous silicon matrices as well as the Fe3O4 nanoparticles, offer low toxicity, the system is a promising candidate for biomedical applications.

Rumpf, Klemens; Granitzer, Petra; Morales, Puerto M.; Poelt, Peter; Reissner, Michael

2012-08-01

225

Fe3O4/Au nanoparticles/lignin modified microspheres as effectual surface enhanced Raman scattering (SERS) substrates for highly selective and sensitive detection of 2,4,6-trinitrotoluene (TNT).  

Science.gov (United States)

A new lignin modified hybrid microsphere, comprising poly(styrene-co-acrylic acid) core and magnetite (Fe3O4)/Au nanoparticle (NP) shell, was proposed here for the selective and highly sensitive detection and removal of 2,4,6-trinitrotoluene (TNT) explosives based on surface enhanced Raman scattering (SERS) and electrochemical detection methods. The presence of lignin and the highly packed layer of Fe3O4/AuNPs as a magnetic collector and metal enhancer for SERS signals allowed for the detection of TNT below 1 pM. PMID:23515305

Mahmoud, Khaled A; Zourob, Mohammed

2013-05-01

226

Magneto-transport study of magnetite (Fe3O4) nanoparticles between Au nanogap electrodes on surface-oxidized Si substrate  

Science.gov (United States)

We have studied the magneto-transport of magnetite (Fe3O4) nanoparticles (MNPs) between Au nanogap electrodes (ANGEs) on surface-oxidized Si substrate. The MNP sizes are approximately 40 nm and the 100 nm thick magnetite thin film (which is formed of the MNP aggregation) was prepared between and around the ANGEs by use of the RF reactive magnetron sputtering method. The distance between the ANGEs and the bridge width of the ANGEs are approximately 50 nm and 1.5 ?m, respectively. The ANGEs were produced by the tilted-angle-deposition method. The optical microscope, scanning electron microscope and atomic force microscope were used to observe the sample surface structure and morphology. To investigate the crystal structure and crystallinity of the MNPs, the X-ray diffraction measurement was performed. The electrical resistance and magneto-resistance ratio of the MNPs between the ANGEs were measured as a function of temperature. The magneto-transport mechanism is discussed on the basis of the spin dependent transport.

Kobori, H.; Takata, N.; Fukutome, N.; Yamasaki, A.; Sugimura, A.; Taniguchi, T.; Horie, T.; Naitoh, Y.; Shimizu, T.

2013-04-01

227

Aluminium hydroxide stabilised MnFe2O4 and Fe3O4 nanoparticles as dual-modality contrasts agent for MRI and PET imaging  

Science.gov (United States)

Magnetic nanoparticles (NPs) MnFe2O4 and Fe3O4 were stabilised by depositing an Al(OH)3 layer via a hydrolysis process. The particles displayed excellent colloidal stability in water and a high affinity to [18F]-fluoride and bisphosphonate groups. A high radiolabeling efficiency, 97% for 18F-fluoride and 100% for 64Cu-bisphosphonate conjugate, was achieved by simply incubating NPs with radioactivity solution at room temperature for 5 min. The properties of particles were strongly dependant on the thickness and hardness of the Al(OH)3 layer which could in turn be controlled by the hydrolysis method. The application of these Al(OH)3 coated magnetic NPs in molecular imaging has been further explored. The results demonstrated that these NPs are potential candidates as dual modal probes for MR and PET. In vivo PET imaging showed a slow release of 18F from NPs, but no sign of efflux of 64Cu. PMID:24768194

Cui, Xianjin; Belo, Salome; Kruger, Dirk; Yan, Yong; de Rosales, Rafael T.M.; Jauregui-Osoro, Maite; Ye, Haitao; Su, Shi; Mathe, Domokos; Kovacs, Noemi; Horvath, Ildiko; Semjeni, Mariann; Sunassee, Kavitha; Szigeti, Krisztian; Green, Mark A.; Blower, Philip J.

2014-01-01

228

Core-shell Fe3O4-Au magnetic nanoparticles based nonenzymatic ultrasensitive electrochemiluminescence immunosensor using quantum dots functionalized graphene sheet as labels.  

Science.gov (United States)

In this paper, a novel, low-cost electrochemiluminescence (ECL) immunosensor using core-shell Fe3O4-Au magnetic nanoparticles (AuMNPs) as the carriers of the primary antibody of carbohydrate antigen 125 (CA125) was designed. Graphene sheet (GS) with property of good conductivity and large surface area was a captivating candidate to amplify ECL signal. We successively synthesized functionalized GS by loading large amounts of quantum dots (QDs) onto the poly (diallyldimethyl-ammonium chloride) (PDDA) coated graphene sheet (P-GS@QDs) via self-assembly electrostatic reactions, which were used to label secondary antibodies. The ECL immunosensors coupled with a microfluidic strategy exhibited a wide detection range (0.005-50 U mL(-1)) and a low detection limit (1.2 mU mL(-1)) with the help of an external magnetic field to gather immunosensors. The method was evaluated with clinical serum sample, receiving good correlation with results from commercially available analytical procedure. PMID:23498695

Liu, Weiyan; Zhang, Yan; Ge, Shenguang; Song, Xianrang; Huang, Jiadong; Yan, Mei; Yu, Jinghua

2013-04-01

229

Fe3O4 magnetic nanoparticle peroxidase mimetic-based colorimetric assay for the rapid detection of organophosphorus pesticide and nerve agent.  

Science.gov (United States)

Rapid and sensitive detection methods are in urgent demand for the screening of extensively used organophosphorus pesticides and highly toxic nerve agents for their neurotoxicity. In this study, we developed a novel Fe(3)O(4) magnetic nanoparticle (MNP) peroxidase mimetic-based colorimetric method for the rapid detection of organophosphorus pesticides and nerve agents. The detection assay is composed of MNPs, acetylcholinesterase (AChE), and choline oxidase (CHO). The enzymes AChE and CHO catalyze the formation of H(2)O(2) in the presence of acetylcholine, which then activates MNPs to catalyze the oxidation of colorimetric substrates to produce a color reaction. After incubation with the organophosphorus neurotoxins, the enzymatic activity of AChE was inhibited and produced less H(2)O(2), resulting in a decreased catalytic oxidation of colorimetric substrates over MNP peroxidase mimetics, accompanied by a drop in color intensity. Three organophosphorus compounds were tested on the assay: acephate and methyl-paraoxon as representative organophosphorus pesticides and the nerve agent Sarin. The novel assay displayed substantial color change after incubation in organophosphorus neurotoxins in a concentration-dependent manner. As low as 1 nM Sarin, 10 nM methyl-paraoxon, and 5 ?M acephate are easily detected by the novel assay. In conclusion, by employing the peroxidase-mimicking activity of MNPs, the developed colorimetric assay has the potential of becoming a screening tool for the rapid and sensitive assessment of the neurotoxicity of an overwhelming number of organophosphate compounds. PMID:23153113

Liang, Minmin; Fan, Kelong; Pan, Yong; Jiang, Hui; Wang, Fei; Yang, Dongling; Lu, Di; Feng, Jing; Zhao, Jianjun; Yang, Liu; Yan, Xiyun

2013-01-01

230

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)

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 

Echevarria-Uraga JJ

2012-05-01

231

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.

232

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

233

Visual test of subparts per billion-level copper(ii) by Fe3O4 magnetic nanoparticle-based solid phase extraction coupled with a functionalized gold nanoparticle probe  

Science.gov (United States)

By combining Fe3O4 magnetic nanoparticle-based solid phase extraction with a gold nanoparticle-based visual test, a novel method was developed for the field assay of Cu(ii) in environmental water at subparts per billion-levels within 30 min. When a 200 mL water sample was treated with 12.5 mg L-1 Fe3O4 nanoparticles by the proposed procedure, the detection limit with the naked eye was 0.2 ?g L-1 Cu(ii). The proposed method is very specific to Cu(ii), with tolerance against at least 100-fold amounts of other environmentally relevant metal ions except for Hg(ii) (25-fold), and was successfully applied to the detection of trace Cu(ii) in tap water, river water, and treated wastewater, and results agreed well with that determined by inductively coupled plasma-mass spectrometry (ICP-MS).By combining Fe3O4 magnetic nanoparticle-based solid phase extraction with a gold nanoparticle-based visual test, a novel method was developed for the field assay of Cu(ii) in environmental water at subparts per billion-levels within 30 min. When a 200 mL water sample was treated with 12.5 mg L-1 Fe3O4 nanoparticles by the proposed procedure, the detection limit with the naked eye was 0.2 ?g L-1 Cu(ii). The proposed method is very specific to Cu(ii), with tolerance against at least 100-fold amounts of other environmentally relevant metal ions except for Hg(ii) (25-fold), and was successfully applied to the detection of trace Cu(ii) in tap water, river water, and treated wastewater, and results agreed well with that determined by inductively coupled plasma-mass spectrometry (ICP-MS). Electronic supplementary information (ESI) available: Experimental details, synthesis, and characterization of Cys-AuNPs and Fe3O4 NPs, magnetic-solid phase extraction and colorimetric test procedures, and effects of parameters on the extraction efficiency. See DOI: 10.1039/c2nr31753b

Tan, Zhi-Qiang; Liu, Jing-Fu; Jiang, Gui-Bin

2012-10-01

234

Sulfonic acid-functionalized silica-coated magnetic nanoparticles as an efficient reusable catalyst for the synthesis of 1-substituted 1H-tetrazoles under solvent-free conditions.  

Science.gov (United States)

Regarding green chemistry goals, silica-coated magnetite nanoparticles open up a new avenue to introduce a very useful and efficient system for facilitating catalyst recovery in different organic reactions. Therefore, in this paper the preparation of sulfonic acid-functionalized silica-coated magnetic nanoparticles with core-shell structure (Fe3O4@silica sulfonic acid) is presented by using Fe3O4 spheres as the core and silica sulfonic acid nanoparticles as the shell. The catalyst was characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis, dynamic light scattering, thermogravimetric analysis and vibrating sample magnetometry. Nanocatalyst can be recovered using an external magnet and reused for subsequent reactions 6 times without noticeable deterioration in catalytic activity. PMID:25030453

Naeimi, Hossein; Mohamadabadi, Samaneh

2014-09-14

235

Silica-coated iron-oxide nanoparticles synthesized as a T2 contrast agent for magnetic resonance imaging by using the reverse micelle method  

International Nuclear Information System (INIS)

We synthesized iron-oxide (Fe3O4) nanoparticles by using the reverse micelle method and coated them with biocompatible silica. The coated nanoparticles were found to be spherical in the TEM images and showed a uniform size distribution with an average diameter of 10 nm. The T1 and the T2 relaxation times of hydrogen protons in aqueous solutions with various concentrations of silica-coated nanoparticles were determined by using a magnetic resonance (MR) scanner. We found that the T2 relaxivity was much larger than the T1 relaxivity for the nanoparticle contrast agent, which reflected the fact that the T2 relaxation was mainly influenced by outer sphere processes. The T2 relaxivity was found to be 15 times larger than that for the commercial Gd-DTPA-BMA contrast agent. This result demonstrates that silica-coated iron oxide nanoparticles are applicable as a T2 agent in magnetic resonance imaging.

236

Mixed hemimicelles solid-phase extraction based on ionic liquid-coated Fe3O4/SiO2 nanoparticles for the determination of flavonoids in bio-matrix samples coupled with high performance liquid chromatography.  

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A novel magnetic solid-phase extraction (MSPE) method based on mixed hemimicelles of room temperature ionic liquids (RTILs) coated Fe3O4/SiO2 nanoparticles (NPs) was developed for simultaneous extraction of trace amounts of flavonoids in bio-matrix samples. A comparative study on the use of RTILs (C16mimBr) and CTAB-coated Fe3O4/SiO2 NPs as sorbents was presented. Owing to bigger adsorption amounts for analytes, RTILs-coated Fe3O4/SiO2 NPs was selected as MSPE materials and three analytes luteolin, quercetin and kaempferol can be quantitatively extracted and simultaneously determined coupled with high performance liquid chromatography (HPLC) in urine samples. No interferences were caused by proteins or endogenous compounds. Good linearity (R(2)>0.9993) for all calibration curves was obtained, and the limits of detection (LOD) for luteolin, quercetin and kaempferol were 0.10 ng/mL, 0.50 ng/mL and 0.20 ng/mL in urine samples, respectively. Satisfactory recoveries (93.5-97.6%, 90.1-95.4% and 93.3-96.6% for luteolin, quercetin and kaempferol) in biological matrices were achieved. It was notable that while using a small amount of Fe3O4/SiO2 NPs (4.0 mg) and C16mimBr (1.0 mg), satisfactory preconcentration factors and extraction recoveries for the three flavonoids were obtained. To the best of our knowledge, this is the first time a mixed hemimicelles MSPE method based on RTILs and Fe3O4/SiO2 NPs magnetic separation has ever been used for pretreatment of complex biological samples. PMID:24290172

He, Huan; Yuan, Danhua; Gao, Zhanqi; Xiao, Deli; He, Hua; Dai, Hao; Peng, Jun; Li, Nan

2014-01-10

237

Synthesis and characterization of sintering-resistant silica-encapsulated Fe3O4 magnetic nanoparticles active for oxidation and chemical looping combustion  

International Nuclear Information System (INIS)

A nanocomposite catalyst composed of ferromagnetic magnetite cores (15.5 ± 2.0 nm) and silica shells with a thickness of 4.5 ± 1.0 nm (Fe3O4-SiO2) was prepared by a two-step microemulsion-based synthesis. X-ray photoelectron spectroscopy and Raman spectroscopy after oxidation support the presence of a stable Fe3O4 core and a surface phase of ?-Fe2O3. The nanocomposite structure exhibited 100% conversion of CO in oxygen at a residence time of 0.1 s at 310 deg. C. When pre-oxidized, the Fe3O4-SiO2 catalyst is shown to be a suitable solid oxygen carrier for chemical looping combustion of methane at 700 deg. C. The nanocomposites retain their magnetism following the reaction which provides the potential for use of magnetic separation and capture in moving bed reactor applications. The core magnetite within the silica shell is resistant to sintering and a bulk phase transition to temperatures as high as 700 deg. C. These catalysts can be of use in applications of high temperature applications where catalyst recovery by magnetic separation may be required.

238

Chitosan and O-carboxymethyl chitosan modified Fe3O4 for hyperthermic treatment  

International Nuclear Information System (INIS)

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

239

Fe3O4/Au/Fe3O4 nanoflowers exhibiting tunable saturation magnetization and enhanced bioconjugation.  

Science.gov (United States)

Composite nanoparticles have proved to be promising in a wide range of biotechnological applications. In this paper, we report on a facile method to synthesize novel Fe(3)O(4)/Au/Fe(3)O(4) nanoparticles (nanoflowers) that integrate hybrid components and surface types. We demonstrate that relative to conventional nanoparticles with core/shell configuration, such nanoflowers not only retain their surface plasmon property but also allow for 170% increase in the saturation magnetization and 23% increase in the conjugation efficiency due to the synergistic co-operation between the hierarchical structures. Moreover, we demonstrate that the magnetic properties of such composite nanoparticles can be tuned by controlling the size of additional petals (Fe(3)O(4) phase). These novel building blocks could open up novel and exciting vistas in nanomedicine for broad applications such as biosensing, cancer diagnostics and therapeutics, targeted delivery, and imaging. PMID:22193883

Hui, Wenli; Shi, Feng; Yan, Kunping; Peng, Mingli; Cheng, Xiao; Luo, Yanling; Chen, Xuemei; Roy, V A L; Cui, Yali; Wang, Zuankai

2012-02-01

240

Sol-gel NiFe2O4 nanoparticles: Effect of the silica coating  

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NiFe2O4 and NiFe2O4-SiO2 nanoparticles were synthesized by a sol-gel method using citric acid as fuel, giving rise its combustion to the crystallization of the spinel phase. Different synthesis conditions were analyzed with the aim of obtaining stoichiometric NiFe2O4 nanoparticles. The spinel structure in the calcined nanoparticles (400 °C, 2 h) was evaluated by x-ray diffraction. Their nanometer size (mean diameters around 10-15 nm) was confirmed through electron microscopy (field emission scanning electron microscopy and transmission electron microscopy). Rietveld refinement indicates the existence of a small percentage of NiO and Fe3O4 phases and a certain degree of structural disorder. The main effect of the silica coating is to enhance the disorder effects and prevent the crystalline growth after post-annealing treatments. Due to the small particle size, the nanoparticles display characteristic superparamagnetic behaviour and surface effects associated to a spin-glass like state: i.e., reduction in the saturation magnetization values and splitting of the zero field cooled (ZFC)-field cooled (FC) high field magnetization curves. The fitting of the field dependence of the ZFC-FC irreversibility temperatures to the Almeida—Thouless equation confirms the spin-glass nature of the detected magnetic phenomena. Exchange bias effects (shifts in the FC hysteresis loops) detected below the estimated freezing temperature support the spin-glass nature of the spin disorder effects.

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

2012-05-01

 
 
 
 
241

Removal of hexavalent chromium ions by Yarrowia lipolytica cells modified with phyto-inspired Fe0/Fe3O4 nanoparticles  

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The removal of hexavalent chromium [Cr (VI)], an important ground water pollutant by phyto-inspired Fe0/Fe3O4 nanocomposite-modified cells of Yarrowia lipolytica (NCIM 3589 and NCIM 3590), was investigated. Electron microscopy and magnetometer studies indicated an effective modification of yeast cell surfaces by the nanocomposites. The effect of pH, temperature, agitation speed, contact time and initial metal ion concentration on the removal of Cr (VI) was determined. The specific uptake values at pH 2.0 were 186.32 ± 3.17 and 137.31 ± 4.53 mg g- 1 for NCIM 3589 and NCIM 3590, respectively, when 1000 mg L- 1 of metal ion concentrations were used. The equilibrium data fitted to Scatchard, Langmuir and linearized Freundlich models suggesting that adsorption played a role in the removal of Cr (VI) ions. The surface modified yeast cells displayed higher values of Langmuir and Scatchard coefficients than the unmodified cells indicating that the former were more efficient in Cr (VI) removal. The enhanced detoxification of Cr (VI) ions by this composite material could be attributed to the reductive power of the Fe0/Fe3O4 nanocomposites as well the yeast cell surface functional groups.

Rao, Ashit; Bankar, Ashok; Kumar, Ameeta Ravi; Gosavi, Suresh; Zinjarde, Smita

2013-03-01

242

Fabrication of Fe3O4@SiO2@TiO2 nanoparticles supported by graphene oxide sheets for the repeated adsorption and photocatalytic degradation of rhodamine B under UV irradiation.  

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A quaternary nanocomposite Fe3O4@SiO2@TiO2/graphene oxide (GO) was for the first time successfully synthesized in this work for the repeated use in simultaneous adsorption and photocatalytic degradation of aromatically structured chemical pollutants. The resulting sample was characterized by TEM, XRD, FTIR, TG-DTG, XPS, PL, and VSM. Its photocatalytic activity was evaluated in the photocatalytic degradation of rhodamine B (RhB) under high-pressure mercury lamp irradiation. The results showed that about 63% of RhB was absorbed onto the prepared Fe3O4@SiO2@TiO2/GO nanocomposites by just 30 minute mixing, and after 120 min high-pressure mercury lamp irradiation, about 92.03% of RhB was converted. The photocatalytic degradation followed pseudo first-order reaction with an apparent rate constant of 0.0136 min(-1). Compared with the Fe3O4@SiO2@TiO2 nanoparticles, it exhibits an excellent ability to adsorb aromatic compounds via ?-? stacking and a higher photocatalytic activity due to the presence of GO. In addition, the synthesized nanomaterial exhibited good magnetic response and the reusability study suggested that the prepared nanocomposites were stable enough and maintained high degradation rate and catalyst recovery even after five cycles, verifying their potential application in water purification. PMID:25087943

Chen, Fenghua; Yan, Fufeng; Chen, Qingtao; Wang, Yongwei; Han, Lifeng; Chen, Zhijun; Fang, Shaoming

2014-09-28

243

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.

244

An Ultrasensitive Electrochemiluminescence Immunoassay for Carbohydrate Antigen 19-9 in Serum Based on Antibody Labeled Fe3O4 Nanoparticles as Capture Probes and Graphene/CdTe Quantum Dot Bionanoconjugates as Signal Amplifiers  

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The CdTe quantum dots (QDs), graphene nanocomposite (CdTe-G) and dextran–Fe3O4 magnetic nanoparticles have been synthesized for developing an ultrasensitive electrochemiluminescence (ECL) immunoassay for Carcinoembryonic antigen 19-9 (CA 19-9) in serums. Firstly, the capture probes (CA 19-9 Ab1/Fe3O4) for enriching CA 19-9 were synthesized by immobilizing the CA 19-9’s first antibody (CA 19-9 Ab1) on magnetic nanoparticles (dextran-Fe3O4). Secondly, the signal probes (CA 19-9 Ab2/CdTe-G), which can emit an ECL signal, were formed by attaching the secondary CA 19-9 antibody (CA 19-9 Ab2) to the surface of the CdTe-G. Thirdly, the above two probes were used for conjugating with a serial of CA 19-9 concentrations. Graphene can immobilize dozens of CdTe QDs on their surface, which can emit stronger ECL intensity than CdTe QDs. Based on the amplified signal, ultrasensitive antigen detection can be realized. Under the optimal conditions, the ECL signal depended linearly on the logarithm of CA 19-9 concentration from 0.005 to 100 pg/mL, and the detection limit was 0.002 pg/mL. Finally, five samples of human serum were tested, and the results were compared with a time-resolved fluorescence assay (TRFA). The novel immunoassay provides a stable, specific and highly sensitive immunoassay protocol for tumor marker detection at very low levels, which can be applied in early diagnosis of tumor. PMID:23685872

Gan, Ning; Zhou, Jing; Xiong, Ping; Li, Tianhua; Jiang, Shan; Cao, Yuting; Jiang, Qianli

2013-01-01

245

An Ultrasensitive Electrochemiluminescence Immunoassay for Carbohydrate Antigen 19-9 in Serum Based on Antibody Labeled Fe3O4 Nanoparticles as Capture Probes and Graphene/CdTe Quantum Dot Bionanoconjugates as Signal Amplifiers  

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Full Text Available The CdTe quantum dots (QDs, graphene nanocomposite (CdTe-G and dextran–Fe3O4 magnetic nanoparticles have been synthesized for developing an ultrasensitive electrochemiluminescence (ECL immunoassay for Carcinoembryonic antigen 19-9 (CA 19-9 in serums. Firstly, the capture probes (CA 19-9 Ab1/Fe3O4 for enriching CA 19-9 were synthesized by immobilizing the CA 19-9’s first antibody (CA 19-9 Ab1 on magnetic nanoparticles (dextran-Fe3O4. Secondly, the signal probes (CA 19-9 Ab2/CdTe-G, which can emit an ECL signal, were formed by attaching the secondary CA 19-9 antibody (CA 19-9 Ab2 to the surface of the CdTe-G. Thirdly, the above two probes were used for conjugating with a serial of CA 19-9 concentrations. Graphene can immobilize dozens of CdTe QDs on their surface, which can emit stronger ECL intensity than CdTe QDs. Based on the amplified signal, ultrasensitive antigen detection can be realized. Under the optimal conditions, the ECL signal depended linearly on the logarithm of CA 19-9 concentration from 0.005 to 100 pg/mL, and the detection limit was 0.002 pg/mL. Finally, five samples of human serum were tested, and the results were compared with a time-resolved fluorescence assay (TRFA. The novel immunoassay provides a stable, specific and highly sensitive immunoassay protocol for tumor marker detection at very low levels, which can be applied in early diagnosis of tumor.

Ning Gan

2013-05-01

246

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

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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.

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

247

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

248

Age modulates Fe3O4 nanoparticles liver toxicity: dose-dependent decrease in mitochondrial respiratory chain complexes activities and coupling in middle-aged as compared to young rats.  

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We examined the effects of iron oxide nanoparticles (IONPs) on mitochondrial respiratory chain complexes activities and mitochondrial coupling in young (3 months) and middle-aged (18 months) rat liver, organ largely involved in body iron detoxification. Isolated liver mitochondria were extracted using differential centrifugations. Maximal oxidative capacities (V(max), complexes I, III, and IV activities), V(succ) (complexes II, III, and IV activities), and V tmpd, (complex IV activity), together with mitochondrial coupling (V(max)/V0) were determined in controls conditions and after exposure to 250, 300, and 350 ? g/ml Fe3O4 in young and middle-aged rats. In young liver mitochondria, exposure to IONPs did not alter mitochondrial function. In contrast, IONPs dose-dependently impaired all complexes of the mitochondrial respiratory chain in middle-aged rat liver: V(max) (from 30 ± 1.6 to 17.9 ± 1.5; P < 0.001), V(succ) (from 33.9 ± 1.7 to 24.3 ± 1.0; P < 0.01), V(tmpd) (from 43.0 ± 1.6 to 26.3 ± 2.2 µmol O2/min/g protein; P < 0.001) using Fe3O4 350 µg/ml. Mitochondrial coupling also decreased. Interestingly, 350 ? g/ml Fe3O4 in the form of Fe(3+) solution did not impair liver mitochondrial function in middle-aged rats. Thus, IONPs showed a specific toxicity in middle-aged rats suggesting caution when using it in old age. PMID:24949453

Baratli, Yosra; Charles, Anne-Laure; Wolff, Valérie; Ben Tahar, Lotfi; Smiri, Leila; Bouitbir, Jamal; Zoll, Joffrey; Sakly, Mohsen; Auger, Cyril; Vogel, Thomas; Abdelmelek, Hafedh; Tebourbi, Olfa; Geny, Bernard

2014-01-01

249

Surfactant-Assisted Synthesis of Fe2O3 Nanoparticles and F-Doped Carbon Modification toward an Improved Fe3O4@CFx/LiNi0.5Mn1.5O4 Battery.  

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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/LiNi0.5Mn1.5O4 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

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

2014-09-10

250

A comparative study of spinel structured Mn3O4, Co3O4 and Fe3O4 nanoparticles in catalytic oxidation of phenolic contaminants in aqueous solutions.  

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Spinel structured Mn3O4, Co3O4 and Fe3O4 nanoparticles were prepared, characterized, and tested in degradation of aqueous phenol in the presence of peroxymonosulfate. It was found that Mn3O4 and Co3O4 nanoparticles are highly effective in heterogeneous activation of peroxymonosulfate to produce sulfate radicals for phenol degradation. The activity shows an order of Mn3O4>Co3O4>Fe3O4. Mn3O4 could fast and completely remove phenol in about 20 min, at the conditions of 25 ppm phenol, 0.4 g/L catalyst, 2 g/L oxone®, and 25 °C. A pseudo first order model would fit to phenol degradation kinetics and activation energies on Mn3O4 and Co3O4 were obtained as 38.5 and 66.2 kJ/mol, respectively. In addition, Mn3O4 exhibited excellent catalytic stability in several runs, demonstrating that Mn3O4 is a promising catalyst alternative to toxic Co3O4 for water treatment. PMID:23891446

Saputra, Edy; Muhammad, Syaifullah; Sun, Hongqi; Ang, Ha-Ming; Tadé, Moses O; Wang, Shaobin

2013-10-01

251

A new route for the synthesis of graphene oxide–Fe3O4 (GO–Fe3O4) nanocomposites and their Schottky diode applications  

International Nuclear Information System (INIS)

Highlights: • Graphene Oxide (GO)–Fe3O4 nanocomposites were prepared by a novel and facile method. • The successful assembly of Fe3O4 NPs onto GO sheets was displayed by TEM. • The GO–Fe3O4 nanocomposites/p-Si junction showed good rectifying property. -- Abstract: Addressed herein is a facile method for the preparation of magnetic graphene oxide–Fe3O4 (GO–Fe3O4) nanocomposites and the rectifying properties of (GO–Fe3O4)/p-Si junction in a Schottky diode. GO–Fe3O4 nanocomposites were prepared by a novel method in which as-prepared GO sheets were decorated with the monodisperse Fe3O4 nanoparticles (NPs) in dimethylformamide/chloroform mixture via a sonication process. The successful assembly of Fe3O4 NPs onto GO sheets was displayed by transmission electron microscopy (TEM). Inductively couple plasma optical emission spectroscopy (ICP-OES) analysis of the GO–Fe3O4 nanocomposite showed that the nanocomposite consists of 20.1 wt% Fe3O4 NPs which provides a specific saturation magnetization (Ms) as 16 emu/g. The current–voltage (I–V) characteristics of the (GO–Fe3O4)/p-Si junction in a Schottky diode were studied in the temperature range of 50–350 K in the steps of 25 K. It was determined that the barrier height and ideality factor of the Au/GO–Fe3O4/p-Si/Al Schottky diode were depended on temperature as the barrier height increased while the ideality factor decreased with increasing temperature. The experimental values of barrier height and ideality factor were varied from 0.12 eV and 11.24 at 50 K to 0.76 eV and 2.49 at 350 K, respectively. The Richardson plot exhibited non-linearity at low temperatures that was attributed to the barrier inhomogeneities prevailing at the GO–Fe3O4/p-Si junction

252

Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4-Ag core-shell nanoparticles: Characterization and application  

International Nuclear Information System (INIS)

Graphical abstract: Self assembling of bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid on Fe3O4-Ag core-shell nanoparticles and application of it for solid phase extraction of PAHs. Highlights: ? A novel sorbent for magnetic solid-phase extraction of PAHs was introduced. ? Silver was coated on Fe3O4 nanoparticles (MNPs) by reduction of AgNO3 with NaBH4. ? Bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid self-assembled on silver coated MNPs. ? Size, morphology, composition and properties of the nanoparticles were characterized. ? Extraction efficiency of the sorbent was investigated by extraction of five PAHs. - Abstract: A novel sorbent for magnetic solid-phase extraction by self-assembling of organosulfur compound, (bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid), onto the silver-coated Fe3O4 nanoparticles was introduced. Due to the formation of covalent bond of S-Ag, the new coating on the silver surface was very stable and showed high thermal stability (up to 320 °C). The size, morphology, composition, and properties of the prepared nanoparticles have also been characterized and determined using scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), dynamic light scattering (DLS), Fourier transform-infrared (FT-IR) spectroscopy, and thermal gravimetric analysis (TGA). Extraction efficiency of the new sorbent was investigated by extraction ofs investigated by extraction of five polycyclic aromatic hydrocarbons (PAHs) as model compounds. The optimum extraction conditions for PAHs were obtained as of extraction time, 20 min; 50 mg sorbent from 100 mL of the sample solution, and elution with 100 ?L of 1-propanol under fierce vortex for 2 min. Under the optimal conditions, the calibration curves were obtained in the range of 0.05–100 ?g L?1 (R2 > 0.9980) and the LODs (S/N = 3) were obtained in the range of 0.02–0.10 ?g L?1. Relative standard deviations (RSDs) for intra- and inter-day precision were 2.6–4.2% and 3.6–8.3%, respectively. In addition, feasibility of the method was demonstrated with extraction and determination of PAHs from some real samples containing tap water, hookah water as well as soil samples with relative recovery of 82.4–109.0% and RSDs of 3.5–11.6%.

253

Epidermal growth factor receptor targeted nuclear delivery and high-resolution whole cell X-ray imaging of Fe3O4@TiO2 nanoparticles in cancer cells.  

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Sequestration within the cytoplasm often limits the efficacy of therapeutic nanoparticles that have specific subcellular targets. To allow for both cellular and subcellular nanoparticle delivery, we have created epidermal growth factor receptor (EGFR)-targeted Fe3O4@TiO2 nanoparticles that use the native intracellular trafficking of EGFR to improve internalization and nuclear translocation in EGFR-expressing HeLa cells. While bound to EGFR, these nanoparticles do not interfere with the interaction between EGFR and karyopherin-?, a protein that is critical for the translocation of ligand-bound EGFR to the nucleus. Thus, a portion of the EGFR-targeted nanoparticles taken up by the cells also reaches cell nuclei. We were able to track nanoparticle accumulation in cells by flow cytometry and nanoparticle subcellular distribution by confocal fluorescent microscopy indirectly, using fluorescently labeled nanoparticles. More importantly, we imaged and quantified intracellular nanoparticles directly, by their elemental signatures, using X-ray fluorescence microscopy at the Bionanoprobe, the first instrument of its kind in the world. The Bionanoprobe can focus hard X-rays down to a 30 nm spot size to map the positions of chemical elements tomographically within whole frozen-hydrated cells. Finally, we show that photoactivation of targeted nanoparticles in cell nuclei, dependent on successful EGFR nuclear accumulation, induces significantly more double-stranded DNA breaks than photoactivation of nanoparticles that remain exclusively in the cytoplasm. PMID:24219664

Yuan, Ye; Chen, Si; Paunesku, Tatjana; Gleber, Sophie Charlotte; Liu, William C; Doty, Caroline B; Mak, Rachel; Deng, Junjing; Jin, Qiaoling; Lai, Barry; Brister, Keith; Flachenecker, Claus; Jacobsen, Chris; Vogt, Stefan; Woloschak, Gayle E

2013-12-23

254

Preparation of C18-functionalized Fe3O4@SiO2 core-shell magnetic nanoparticles for extraction and determination of phthalic acid esters in Chinese herb preparations.  

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The extraction and determination of phthalic acid esters (PAEs) residue in Chinese herbal preparations (CHP) by C18-functionalized magnetic nanoparticles (C18-FS-MNP) has been firstly performed. It was synthesized through coating Fe3O4 nanoparticles with sodium silicate, followed by freeze-drying technique and then modified with C18 groups. C18-FS-MNPs prepared via freeze-drying technique were superior to those particles prepared via common vacuum drying method in terms of dispersion and extraction recovery. C18-FS-MNPs demonstrated obvious enrichment effect for four model PAEs and 478-627-fold enrichment factors were obtained. The limit of detection was <1.89ng/mL and relative standard deviation was ranging from 3.7 to 5.8%. It was successfully applied for determination of trace PAEs residue in CHP with good recoveries. PMID:25213260

Guo, Bize; Ji, Shunli; Zhang, Feifang; Yang, Bingcheng; Gu, Jiangping; Liang, Xinmiao

2014-11-01

255

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)

metric 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.

256

Fabrication and characterization of superparamagnetic and thermoresponsive hydrogels based on oleic-acid-coated Fe 3O 4 nanoparticles, hexa(ethylene glycol) methyl ether methacrylate and 2-(acetoacetoxy)ethyl methacrylate  

Science.gov (United States)

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·Fe 3O 4). 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 (Fe 3O 4). Deswelling kinetic studies that were carried out at ˜60 °C 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.

Papaphilippou, Petri C.; Pourgouris, Antonis; Marinica, Oana; Taculescu, Alina; Athanasopoulos, George I.; Vekas, Ladislau; Krasia-Christoforou, Theodora

2011-03-01

257

A simple method to synthesize modified Fe3O4 for the removal of organic pollutants on water surface  

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In this article, a simple, economic and environment-friendly approach is explored to prepare Fe3O4 nanoparticles by using air oxidation at room temperature. Furthermore, the Fe3O4 magnetic nanoparticles (MNPs) have been modified with sodium oleate successfully to form super-hydrophobic surfaces. The alkali source played an important role in controlling the morphologies of Fe3O4 MNPs. Either Fe3O4 MNPs or sodium oleate modified Fe3O4 MNPs possessed good magnetic property, and the as-prepared modified Fe3O4 nanoparticles are both hydrophobic and lipophilic. Therefore, Fe3O4/sodium oleate could be dispersed stable in the oil medium and have been applied in the cleanup engine oil from the water surface. It will open up a potential and broad application in wastewater treatment.

Zhu, Ling; Li, Chuanhao; Wang, Juan; Zhang, Hui; Zhang, Jian; Shen, Yuhua; Li, Cun; Wang, Cuiping; Xie, Anjian

2012-06-01

258

Preparation and Cytotoxic Evaluation of Magnetite (Fe3O4) Nanoparticles on Breast Cancer Cells and its Combinatory Effects with Doxorubicin used in Hyperthermia  

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Background Magnetic nanoparticles in a variable magnetic field are able to produce heat. This heat (42-45°C) has more selective effect on fast dividing cancer cells than normal tissues. Methods In this work magnetite nanoparticles have been prepared via co-precipitation and phase identification was performed by powder x-ray diffraction (XRD). Magnetic parameters of the prepared nanoparticles were measured by a Vibrating Sample Magnetometer (VSM). A sensitive thermometer has been used to measure the increase of temperature in the presence of an alternating magnetic field. To evaluate the cytotoxicity of nanoparticles, the suspended magnetite nanoparticles in liquid paraffin, doxorubicin and a mixture of both were added to the MDA-MB-468 cells in separate 15 ml tubes and left either in the RT or in the magnetic field for 30 min. Cell survival was measured by trypan blue exclusion assay and flow cytometer. Particle size distribution of the nanoparticles was homogeneous with a mean particles size of 10 nm. A 15°C temperature increase was achieved in presence of an AC magnetic field after 15 min irradiation. Results Biological results showed that magnetite nanoparticles alone were not cytotoxic at RT, while in the alternative magnetic filed more than 50% of cells were dead. Doxorubicin alone was not cytotoxic during 30 min, but in combination with magnetite more than 80% of the cells were killed. Conclusion It could be concluded that doxorubicin and magnetite nanoparticles in an AC magnetic field had combinatory effects against cells. PMID:23799178

Sadeghi-Aliabadi, Hojjat; Mozaffari, Morteza; Behdadfar, Behshid; Raesizadeh, Maryam; Zarkesh-Esfahani, Hamid

2013-01-01

259

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

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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.

Doppalapudi Swathi

2014-06-01

260

Anomalous magnetic properties of nanoparticles arising from defect structures: topotaxial oxidation of Fe(1-x)O|Fe(3-?)O4 core|shell nanocubes to single-phase particles.  

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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 Fe(1-x)O|Fe(3-?)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 development of antiphase boundaries. Dark-field transmission electron microscopy and powder X-ray diffraction concur that, as the oxidation proceeds, the interfacial strain is released as the Fe(1-x)O core is removed but that the antiphase boundaries remain. The antiphase boundaries result in anomalous magnetic behavior, that is, a reduced saturation magnetization and exchange bias effects in single-phase nanoparticles. Our results indicate that internal defects play an important role in dictating the magnetic properties of iron oxide nanoparticles. PMID:23899269

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

2013-08-27

 
 
 
 
261

Microwave-assisted silica coating and photocatalytic activities of ZnO nanoparticles  

International Nuclear Information System (INIS)

A new and rapid method for silica coating of ZnO nanoparticles by the simple microwave irradiation technique is reported. Silica-coated ZnO nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. The FT-IR spectra and XPS clearly confirmed the silica coating on ZnO nanoparticles. The results of XPS analysis showed that the elements in the coating at the surface of the ZnO nanoparticles were Zn, O and Si. HR-TEM micrographs revealed a continuous and uniform dense silica coating layer of about 3 nm in thickness on the surface of ZnO nanoparticles. In addition, the silica coating on the ZnO nanoparticles was confirmed by the agreement in the zeta potential of the silica-coated ZnO nanoparticles with that of SiO2. The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution showed that silica coating effectively reduced the photocatalytic activity of ZnO nanoparticles. Silica-coated ZnO nanoparticles showed excellent UV shielding ability and visible light transparency

262

Fabrication of fluorescent magnetic Fe3O4@ZnS nanocomposites.  

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A novel Fe3O4@ZnS nanomaterial with fluorescent and superparamagnetic properties has been successfully fabricated via TOPO-TOP synthesis with an additional coordinating component (OAm). The adsorption of OAm on the preformed magnetite nanoparticles, which were prepared in phenyl ether with oleic acid and oleyl amine, played an essential role in directing the structure of the Fe3O4@ZnS composites. The obtained materials were characterized by FTIR, TEM, XRD, X-ray photoelectron spectroscopy (XPS), UV-vis, fluorescence spectrophotometer and VSM. The results indicated that the Fe3O4 nanoparticles were successfully combined with ZnS and the coating of ZnS can be controlled by adjusting the molar ratio of Fe3O4 to ZnS. The saturation magnetization values of Fe3O4, Fe3O4@ZnS (1:2) and Fe3O4@ZnS (1:5) nanoparticles are 57.0 emu g(-1), 44.4 emu g(-1) and 34.2 emu g(-1), respectively at 300 K and the nanocomposites exhibit better fluorescence without evident quenching. The combined magnetic and fluorescent properties endow the nanocomposites with great potential applications in "nano-conveyer-belt" platform technology for drug targeting, bioseparation, diagnostic analysis and so on. PMID:24757979

Liu, Li; Jiang, Wei; Yao, Lei; Yang, Xi-Wen; Chen, Bin-Hua; Wu, Shi-Xi; Li, Feng-Sheng

2014-07-01

263

Magneto-dielectric properties of polymer- Fe3O4 nanocomposites  

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The aim of this research is to elucidate the size effect of magnetic nanoparticles on the resultant magneto-dielectric properties of polymer nanocomposites at radio frequencies. The block copolymer of [styrene-b-ethylene/butylene-b-styrene] (SEBS) was utilized as a matrix for the templating of magnetic nanoparticles. Surfactant-modified iron oxide ( Fe3O4) nanoparticles of various sizes were successfully synthesized by a seed-mediated growth method. The surfactant prevented Fe3O4 aggregation and provided compatibility with the polymer matrix. The nucleation and growth of Fe3O4 nanoparticles was controlled by changing the concentration ratio of surfactant to iron-precursor. The free iron ions present during synthesis are the major factor contributing to the growth of larger particles. The Fe3O4 nanoparticle critical size for superparamagnetic to ferrimagnetic transition was determined to be near 30 nm at room temperature. The dielectric permittivity (?r) of the polymer composite increased with increasing amount of Fe3O4 doping, and was not influenced by nanoparticle size. However, the magnetic permeability ( ?r) of the composites was significantly influenced by the size of Fe3O4 nanoparticles templated within the block copolymer matrix due to thermal energy fluctuations from the nanoparticle surroundings.

Yang, Ta-I.; Brown, Rene N. C.; Kempel, Leo C.; Kofinas, Peter

264

A multifunctional biphasic suspension of mesoporous silica encapsulated with YVO4:Eu3+ and Fe3O4 nanoparticles: synergistic effect towards cancer therapy and imaging  

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Polyol mediated synthesized luminescent YVO4:Eu3+ nanoparticles (NPs) have been encapsulated in mesoporous silica nanoparticles (MSNs) using the sol-gel process. X-ray diffraction and Fourier transform infrared spectroscopy along with transmission electron microscopy confirm the encapsulation of the YVO4:Eu3+ NPs in the SiO2 matrix. N2 adsorption/desorption analysis confirms the mesoporous nature of the MSNs and YVO4:Eu3+-MSNs. No significant quenching of the YVO4:Eu3+ luminescence is observed for YVO4:Eu3+-MSNs. This nanocomposite has been tested as a potential drug carrier. Efficient loading of doxorubicin hydrochloride (DOX), a typical anticancer drug, is observed which reaches up to 93% in 8 mg ml-1 of YVO4:Eu3+-MSNs. pH sensitive release of DOX is observed, with 54% release for pH 4.3 and 31% in a physiological environment (pH 7.4). Both MSNs and YVO4:Eu3+-MSNs nanocomposites do not show accountable toxicity to two cell lines, i.e. HeLa and MCF-7. However, as desired, toxicity is observed when cells are incubated with DOX loaded YVO4:Eu3+-MSNs. Laser scanning confocal microscopy images confirm the uptake of the nanocomposite in both cell lines. The morphology of the cells (MCF-7) changes after incubation with DOX loaded YVO4:Eu3+-MSNs, indicating an interaction of DOX with the cells. More cytotoxicity to both cell lines with ˜90% killing is observed due to the synergistic effect of magnetic fluid hyperthermia and chemotherapy using a biphasic suspension of superparamagnetic iron oxide magnetic nanoparticles and DOX loaded YVO4:Eu3+-MSNs. In addition, an AC magnetic field triggers an enhanced drug release.

Shanta Singh, N.; Kulkarni, Hrishikesh; Pradhan, Lina; Bahadur, D.

2013-02-01

265

A multifunctional biphasic suspension of mesoporous silica encapsulated with YVO4:Eu3+ and Fe3O4 nanoparticles: synergistic effect towards cancer therapy and imaging.  

Science.gov (United States)

Polyol mediated synthesized luminescent YVO(4):Eu(3+) nanoparticles (NPs) have been encapsulated in mesoporous silica nanoparticles (MSNs) using the sol-gel process. X-ray diffraction and Fourier transform infrared spectroscopy along with transmission electron microscopy confirm the encapsulation of the YVO(4):Eu(3+) NPs in the SiO(2) matrix. N(2) adsorption/desorption analysis confirms the mesoporous nature of the MSNs and YVO(4):Eu(3+)-MSNs. No significant quenching of the YVO(4):Eu(3+) luminescence is observed for YVO(4):Eu(3+)-MSNs. This nanocomposite has been tested as a potential drug carrier. Efficient loading of doxorubicin hydrochloride (DOX), a typical anticancer drug, is observed which reaches up to 93% in 8 mg ml(-1) of YVO(4):Eu(3+)-MSNs. pH sensitive release of DOX is observed, with 54% release for pH 4.3 and 31% in a physiological environment (pH 7.4). Both MSNs and YVO(4):Eu(3+)-MSNs nanocomposites do not show accountable toxicity to two cell lines, i.e. HeLa and MCF-7. However, as desired, toxicity is observed when cells are incubated with DOX loaded YVO(4):Eu(3+)-MSNs. Laser scanning confocal microscopy images confirm the uptake of the nanocomposite in both cell lines. The morphology of the cells (MCF-7) changes after incubation with DOX loaded YVO(4):Eu(3+)-MSNs, indicating an interaction of DOX with the cells. More cytotoxicity to both cell lines with ?90% killing is observed due to the synergistic effect of magnetic fluid hyperthermia and chemotherapy using a biphasic suspension of superparamagnetic iron oxide magnetic nanoparticles and DOX loaded YVO(4):Eu(3+)-MSNs. In addition, an AC magnetic field triggers an enhanced drug release. PMID:23324398

Shanta Singh, N; Kulkarni, Hrishikesh; Pradhan, Lina; Bahadur, D

2013-02-15

266

Phase Transformation in Silica-Coated FePt Nanoparticles  

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The A1 to L10 phase transformation has been examined in silica-coated FePt particles. The nanoparticles were synthesized by reduction of platinum acetylacetonate (Pt (acac) 2) followed by thermal decomposition of iron pentacarbonyl (Fe(CO)5) in the presence of oleic acid (OA) and oleyl amine (OY) as surfactants at low temperature ^[1]. The monodispersed FePt nanoparticles, with a size of 5.8 nm were then coated with silica (SiO2) shells ^[2] . The thickness of the silica shell could be controlled between 7.5-25 nm. The coated particles were subjected to thermal processing at 800 C for various amounts of times. No significant sintering was observed up to 2 hours of annealing for the shell thickness of 15.0 nm. In some silica-coated samples an increase in the particle size was observed after annealing. Selected Area Diffraction analysis and magnetic measurements showed the development of ordered L10 structure. Coercivity values up to 15 kOe at 7K are obtained. The phase transformation is currently being examined in other samples annealed at different times and temperatures and the results will be reported.1.Levent Colak and George C. Hadjipanayis, Nanotechnology 19 (2008) 235703.2.M. Aslam, L. Fu, S. Li, Vinayak P. Dravid, Journal of Colloid and Interface Science 290 (2005) 444--449.

Colak, Levent; Hadjipanayis, George

2009-03-01

267

Photoemission Study of Fe3O4  

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Photoemission experiment was carried out on a (100) surface of Fe3O4 at room temperature, for the incident photon energies between 30.5 and 140 eV, and the results were compared with the band structure calculated by APW method (J. Phys. Soc. Jpn. 53 (1984) 312). Peaks due to the Fe(3d)-O(2p) valence band, O(2s) band, Fe(3p) band and Auger electrons were observed. Valence band emission starts from the Fermi level indicating that Fe3O4 is a “metal”, not an “insulator with electron diffusion”. Several peaks are distinguished in angle-resolved normal emission spectra in the valence band region. Other peaks are broad and do not show any structure. As a whole, applicability of the calculated band structure is proved. Resonant enhancement of photoemission is observed near the Fe(3p) core excitation region. Two subsidiary peaks at 7.5 and 11 eV are tentatively assigned to satellites due to a singlet and a triplet hole pair, respectively. Correlation energy between 3d electrons is estimated from the satellite position and the kinetic energy of Auger electrons.

Shiratori, Kiiti; Suga, Shigemasa; Taniguchi, Masaki; Soda, Kazuo; Kimura, Shigeyuki; Yanase, Akira

1986-02-01

268

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 revebute to the excellent life and high reversible capacity of the battery when they are used as an anode of a lithium-ion battery.

269

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

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

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

2014-02-01

270

Hollow superparamagnetic PLGA/Fe3O4 composite microspheres for lysozyme adsorption.  

Science.gov (United States)

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

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

2014-02-28

271

Heterogeneous Fenton degradation of bisphenol A catalyzed by efficient adsorptive Fe3O4/GO nanocomposites.  

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A new method for the degradation of bisphenol A (BPA) in aqueous solution was developed. The oxidative degradation characteristics of BPA in a heterogeneous Fenton reaction catalyzed by Fe3O4/graphite oxide (GO) were studied. Transmission electron microscopic images showed that the Fe3O4 nanoparticles were evenly distributed and were ?6 nm in diameter. Experimental results suggested that BPA conversion was affected by several factors, such as the loading amount of Fe3O4/GO, pH, and initial H2O2 concentration. In the system with 1.0 g L(-1) of Fe3O4/GO and 20 mmol L(-1) of H2O2, almost 90% of BPA (20 mg L(-1)) was degraded within 6 h at pH 6.0. Based on the degradation products identified by GC-MS, the degradation pathways of BPA were proposed. In addition, the reused catalyst Fe3O4/GO still retained its catalytic activity after three cycles, indicating that Fe3O4/GO had good stability and reusability. These results demonstrated that the heterogeneous Fenton reaction catalyzed by Fe3O4/GO is a promising advanced oxidation technology for the treatment of wastewater containing BPA. PMID:24627203

Hua, Zulin; Ma, Wenqiang; Bai, Xue; Feng, Ranran; Yu, Lu; Zhang, Xiaoyuan; Dai, Zhangyan

2014-06-01

272

Application of nanosized Fe3O4 in anticancer drug carriers with target-orientation and sustained-release properties  

International Nuclear Information System (INIS)

The purpose of this study was to prepare human serum albumin (HSA) microspheres with Fe3O4 magnetic nanoparticles for tumor target therapy. Fe3O4 was obtained by liquid-phase coprecipitation; HSA-coated magnetic particles were attained by solidification at high temperature. The result was that nanosized Fe3O4 is a cubic crystal by XRD and the average size is 18.7 nm; the average size of HSA-coated magnetic particles is 341 nm. Fe3O4 magnetic nanoparticles coated with HSA can be used for targeted-drug carriers with target-orientation and sustained-release properties

273

Solid phase extraction of trace amounts of silver, cadmium, copper, mercury, and lead in various food samples based on ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol coated Fe3O4 nanoparticles.  

Science.gov (United States)

Extraction, pre-concentration, and determination of trace amounts of silver, cadmium, copper, mercury, and lead from some food samples were investigated by magnetic solid phase extraction using Fe3O4 nanoparticles coated with 3-(trimethoxysilyl)-1-propanethiol and modified with ethylene glycol bis-mercaptoacetate as a new adsorbent. SEM, X-ray diffraction, and FT-IR were used to characterise the adsorbent. Metal ions were measured using ICP-OES, except for mercury, which was determined by CV-AAS method. Various factors affecting the extraction and desorption of target metal ions were investigated. 1 mL of 1 mol/L HCl and 5% thiourea was used as eluent. The detection limits of 0.07, 0.06, 0.09, 0.01, and 0.08 ng/mL were obtained for silver, cadmium, copper, mercury, and lead with enrichment factors of 240, 294, 297, 291, and 236, respectively. The method was used for determination of target metal ions in rice, canned tuna fish, and tea leaves. PMID:24423536

Mashhadizadeh, Mohammad Hossein; Amoli-Diva, Mitra; Shapouri, Mahmoud Reza; Afruzi, Hossein

2014-05-15

274

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

275

Synthesis and characterization of Fe3O4-C-Ag nanocomposites and their antibacterial performance  

International Nuclear Information System (INIS)

We synthesized Fe3O4-C-Ag nanocomposites through a combination of solvothermal, hydrothermal, and chemical redox reactions. Characterization of the resulting samples by X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning and transmission electron microscopy, and magnetic measurement is reported. Compared to Fe3O4-Ag nanocomposites, the Fe3O4-C-Ag nanocomposites showed enhanced antibacterial activity. The Fe3O4-C-Ag nanocomposites were able to almost entirely prevent growth of Escherichia coli when the concentration of Ag nanoparticles was 10 ?g/mL. Antibacterial activity of the Fe3O4-C-Ag nanocomposites was maintained for more than 40 h at 37 deg. C. The intermediate carbon layer not only protects magnetic core, but also improves the dispersion and antibacterial activity of the silver nanoparticles. The magnetic core can be used to control the specific location of the antibacterial agent (via external magnetic field) and to recycle the residual silver nanoparticles. The Fe3O4-C-Ag nanocomposites will have potential uses in many fields as catalysts, absorbents, and bifunctional magnetic-optical materials.

276

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.

277

Nonlinear optical and optical limiting properties of graphene oxide–Fe3O4 hybrid material  

International Nuclear Information System (INIS)

The nonlinear optical (NLO) and optical limiting properties of a graphene oxide hybrid material coordinated with Fe3O4 nanoparticles (GO–Fe3O4) were studied by using the Z-scan technique at 532 nm in the nanosecond and picosecond regimes. Results show that GO–Fe3O4 exhibits enhanced NLO and optical limiting properties in comparison with the pristine GO in the nanosecond regime. Compared with fullerene (C60) in toluene at different concentrations, GO–Fe3O4 exhibits a weaker optical limiting effect than C60 at high concentration, but shows a stronger optical limiting effect than C60 at low concentration in the high input fluence region

278

Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4@Ag core@shell nanoparticles: characterization and application.  

Science.gov (United States)

A novel sorbent for magnetic solid-phase extraction by self-assembling of organosulfur compound, (bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid), onto the silver-coated Fe(3)O(4) nanoparticles was introduced. Due to the formation of covalent bond of S-Ag, the new coating on the silver surface was very stable and showed high thermal stability (up to 320°C). The size, morphology, composition, and properties of the prepared nanoparticles have also been characterized and determined using scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), dynamic light scattering (DLS), Fourier transform-infrared (FT-IR) spectroscopy, and thermal gravimetric analysis (TGA). Extraction efficiency of the new sorbent was investigated by extraction of five polycyclic aromatic hydrocarbons (PAHs) as model compounds. The optimum extraction conditions for PAHs were obtained as of extraction time, 20 min; 50 mg sorbent from 100 mL of the sample solution, and elution with 100 ?L of 1-propanol under fierce vortex for 2 min. Under the optimal conditions, the calibration curves were obtained in the range of 0.05-100 ?g L(-1) (R(2)>0.9980) and the LODs (S/N=3) were obtained in the range of 0.02-0.10 ?g L(-1). Relative standard deviations (RSDs) for intra- and inter-day precision were 2.6-4.2% and 3.6-8.3%, respectively. In addition, feasibility of the method was demonstrated with extraction and determination of PAHs from some real samples containing tap water, hookah water as well as soil samples with relative recovery of 82.4-109.0% and RSDs of 3.5-11.6%. PMID:23176735

Tahmasebi, Elham; Yamini, Yadollah

2012-12-01

279

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

International Nuclear Information System (INIS)

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

280

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

Science.gov (United States)

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

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

2011-06-01

 
 
 
 
281

A dual mode targeting probe for distinguishing HER2-positive breast cancer cells using silica-coated fluorescent magnetic nanoparticles  

International Nuclear Information System (INIS)

We report a composite nanoprobe based on silica-coated magnetic nanoparticles (NPs) for distinguishing breast cancers at different HER2 statuses. The nanoprobe has a core–shell structure, with Fe3O4 NPs as the magnetic core and dye-embedded silica as the fluorescent shell, whose average size is about 150 nm. Besides, the outmost surfaces of the probes were modified with specific antibodies to endow the probe with a targeting ability. With such a structure, the nanoprobe can accomplish dual mode targeting of human breast cancer cells based on fluorescence and magnetic resonance imaging (MRI). In the experiments, three human breast cancer cell lines were used to test the targeting ability of the nanoprobe. Specifically, SKBR3 cells with a high HER2 expression level were used as the model target cells, while MCF7 cells with a lower HER2 expression levels and HER2-negative MDA-MB-231 cells were used as the controls. Both the fluorescence and MRI imaging results confirmed that the nanoprobe can distinguish three cancer cell lines with different HER2 expression levels. With the dual mode imaging and specific targeting properties, we anticipate that the presented nanoprobe may have a great potential in the diagnosis and treatment of cancerous diseases

282

Structural and functional investigation of graphene oxide-Fe3O4 nanocomposites for the heterogeneous Fenton-like reaction  

Science.gov (United States)

Graphene oxide-iron oxide (GO-Fe3O4) nanocomposites were synthesised by co-precipitating iron salts onto GO sheets in basic solution. The results showed that formation of two distinct structures was dependent upon the GO loading. The first structure corresponds to a low GO loading up to 10 wt%, associated with the beneficial intercalation of GO within Fe3O4 nanoparticles and resulting in higher surface area up to 409 m2 g-1. High GO loading beyond 10 wt% led to the aggregation of Fe3O4 nanoparticles and the undesirable stacking of GO sheets. The presence of strong interfacial interactions (Fe-O-C bonds) between both components at low GO loading lead to 20% higher degradation of Acid Orange 7 than the Fe3O4 nanoparticles in heterogeneous Fenton-like reaction. This behaviour was attributed to synergistic structural and functional effect of the combined GO and Fe3O4 nanoparticles.

Zubir, Nor Aida; Yacou, Christelle; Motuzas, Julius; Zhang, Xiwang; Diniz da Costa, João C.

2014-04-01

283

Facile methods for synthesis of core-shell structured and heterostructured Fe3O4@Au nanocomposites  

Science.gov (United States)

Two different reaction strategies designed for core-shell structured and heterostructured Fe3O4@Au nanocomposites utilizing 50 nm polyethyleneimine coated magnetite as seeds are presented aiming at diverse applications. The polyethylenimine (PEI) coated Fe3O4 nanoparticles were firstly used as seeds to carry out the synthesis of both core-shell structured and heterostructured Fe3O4@Au nanocomposites. Results show that these two structures combined the merits of both gold and Fe3O4 nanoparticles. What is more, the distinct morphology offers diverse applications: the shell of dense gold nanoparticles coating in the core-shell structure dominates the further surface functionalization while the heterostructure offers the particles with two distinct surfaces and functionalities due to different surfactant molecules on the surface of Fe3O4 and Au nanoparticles. Furthermore, the synthesis methods presented in this paper also suggested new ways to the synthesis of multifunctional nanostructures.

Lou, Lei; Yu, Ke; Zhang, Zhengli; Huang, Rong; Wang, Yiting; Zhu, Ziqiang

2012-09-01

284

Synthesis and characterization of Fe3O4 magnetic nanofluid  

Directory of Open Access Journals (Sweden)

Full Text Available 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.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.

Javier A Lopez

2010-06-01

285

Synthesis and characterization of Fe3O4 magnetic nanofluid  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: English Abstract in spanish 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.

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

286

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.

287

Fe3O4/reduced graphene oxide nanocomposite as high performance anode for lithium ion batteries  

International Nuclear Information System (INIS)

Highlights: ? Fe3O4/graphene composite is fabricated by interface reaction and in situ reduction. ? The method leads to well-organized flexible interleaved structure. ? The interface reaction is benefit to ensure strong interfacial interaction. ? The nanocomposite shows high reversible capacity and super long cycling stability - Abstract: Fe3O4/reduced graphene oxide (Fe3O4/RGO) nanocomposite was prepared by a facile interface reaction and subsequent in situ reduction process. The electrochemical performances of the as-prepared Fe3O4/RGO nanocomposite were evaluated in coin-type cells. It delivers high reversible capacity of 1025 mAh g?1 at 100 mA g?1 after 50 cycles and outstanding cycle stability. Even after 800 cycles at various rates from 100 to 4000 mA g?1, the capacity still retains 959.4 mAh g?1 at 100 mA g?1. A transmission electron microscopy image has shown the flexible interleaved structure of nanocomposite, and the interface reaction is also benefit to ensure strong interfacial interaction between Fe3O4 nanoparticles (50 nm) and RGO nanosheets. The designed structure plays key role in improving electrochemical performance. The Fe3O4/RGO nanocomposite with super long cycling life will be an ideal candidate of anode material for lithium ion batteries.ium ion batteries.

288

Fabrication and estimation of Au-coated Fe3O4 nanocomposite powders for the separation and purification of biomolecules  

International Nuclear Information System (INIS)

Au and Fe3O4 nanoparticles were prepared by reduction and coprecipitation methods. The Au/Fe3O4 nanocomposite particles were prepared through the control of the surface charges, and glutathione (GSH) of a thiol group was used as a biomolecule. GSH immobilization onto Au/Fe3O4 was accomplished by simply mixing process. The nanoparticles were characterized by UV-vis spectroscopy: X-ray diffraction, transmission electron microscopy and vibrating sample magnetometry. The amount of immobilized GSH on the Au/Fe3O4 increased with increasing amount of coated Au nanoparticles. The possibility of Au/Fe3O4 nanocomposite particles for the application to the separation and purification of biomolecules by magnetic field was confirmed

289

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.

290

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.

291

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)

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

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

2013-04-15

292

Mössbauer evidence of 57Fe3O4 based ferrofluid biodegradation in the brain  

Science.gov (United States)

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

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

2014-04-01

293

Polymide/Fe3O4-carbonized Membranes for Gas Separation  

Directory of Open Access Journals (Sweden)

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.

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

2010-07-01

294

Mössbauer study of a Fe3O4/PMMA nanocomposite synthesized by sonochemistry  

Science.gov (United States)

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.

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

2014-01-01

295

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

Directory of Open Access Journals (Sweden)

Full Text Available Katayoon Kalantari,1 Mansor Bin Ahmad,1,* Kamyar Shameli,1,2,* Roshanak Khandanlou11Department of Chemistry, Universiti Putra Malaysia, Serdang, Malaysia; 2Nanotechnology and Advance Materials Department, Materials and Energy Research Center, Karaj, Alborz, Karaj, Iran*These authors contributed equally to this workAbstract: The aim of this research was to synthesize and develop a new method for the preparation of iron oxide (Fe3O4 nanoparticles on talc layers using an environmentally friendly process. The Fe3O4 magnetic nanoparticles were synthesized using the chemical co-precipitation method on the exterior surface layer of talc mineral as a solid substrate. Ferric chloride, ferrous chloride, and sodium hydroxide were used as the Fe3O4 precursor and reducing agent in talc. The talc was suspended in deionized water, and then ferrous and ferric ions were added to this solution and stirred. After the absorption of ions on the exterior surface of talc layers, the ions were reduced with sodium hydroxide. The reaction was carried out under a nonoxidizing oxygen-free environment. There were not many changes in the interlamellar space limits (d-spacing = 0.94–0.93 nm; therefore, Fe3O4 nanoparticles formed on the exterior surface of talc, with an average size of 1.95–2.59 nm in diameter. Nanoparticles were characterized using different methods, including powder X-ray diffraction, transmission electron microscopy, emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. These talc/Fe3O4 nanocomposites may have potential applications in the chemical and biological industries.Keywords: nanocomposites, Fe3O4 nanoparticles, talc, powder X-ray diffraction, scanning electron microscopy

Kalantari K

2013-05-01

296

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

Science.gov (United States)

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

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

2014-05-01

297

Hydrothermal synthesis of carbon nanotube/cubic Fe3O4 nanocomposite for enhanced performance supercapacitor electrode material  

International Nuclear Information System (INIS)

Graphical abstract: First, the acid treated CNTs were used as support substrate. Then cubic Fe3O4 nanoparticles directly anchored on the surfaces of CNTs as supercapacitor electrode material by an easy and cost effective hydrothermal method. Results showed that the composite has superior capacitive performance with a maximum specific capacitance of 119 F/g. -- Highlights: • The acid treated CNTs were used as conductive substrate materials. • Cubic Fe3O4 nanoparticles directly grew onto surfaces of CNTs preventing the agglomeration of Fe3O4. • The loose structure improves the contact between the electrode and the electrolyte. • Results showed that this composite has good electrochemical property. -- Abstract: Carbon nanotube/Fe3O4 (CNT/Fe3O4) nanocomposite with well-dispersed Fe3O4 nano-cubes inlaid on the surfaces of carbon nanotubes, was synthesized through an easy and efficient hydrothermal method. The electrochemical behaviors of the nanocomposite were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry in 6 M KOH electrolyte. Results demonstrated that CNT as the supporting material could significantly improve the supercapacitor (SC) performance of the CNT/Fe3O4 composite. Comparing with pure Fe3O4, the resulting composite exhibited improved specific capacitances of 117.2 F/g at 10 mA/cm2 (3 times than that of pure Fe3O4), excellent cyclic stability and a maximum energy density of 16.2 Wh/kg. The much improved electrochemical performances could be attributed to the good conductivity of CNTs as well as the anchored Fe3O4 particles on the CNTs

298

Solvothermal in situ synthesis of Fe3O4-multi-walled carbon nanotubes with enhanced heterogeneous Fenton-like activity  

International Nuclear Information System (INIS)

Graphical abstract: After purification, the multi-wall carbon nanotubes (MWCNTs) act as seeds for Fe3O4 nanoparticles heterogeneous nucleation. The Fe3O4 nanoparticles with diameter range of 4.2–10.0 nm synthesized in situ on the MWCNTs under solvothermal condition. The formed nano Fe3O4-MWCNTs decolorized the Acid Orange II effectively via Fenton-like reaction. Highlights: ? The amount of water tunes size and size distribution of the Fe3O4 nanoparticles (FNs). ? FNs are homogeneously coated on the multi-walled carbon nanotubes (MWCNTs). ? FNs have diameters in the range of 4.2–10.0 nm, average grain size of 7.4 nm. ? Fe3O4-MWCNTs are used as a Fenton-like catalyst to decompose Acid Orange II. ? Fe3O4-MWCNTs displayed a higher activity than nanometer-size Fe3O4. -- Abstract: Fe3O4-multi-walled carbon nanotubes (Fe3O4-MWCNTs) hybrid materials were synthesized by a solvothermal process using acid treated MWCNTs and iron acetylacetonate in a mixed solution of ethylene glycol and ultrapure water. The materials were characterized using X-ray powder diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. The results showed that a small amount of water in the synthesis system played a role in controlling crystal phase formation, size of Fe3O4, and the homogeneous distribution of the Fe3O4 nanoparticles deposited on the MWCNTs. The Fe3O4 nanoparticles had diameters in the range of 4.2–10.0 nm. They displayed good superparamagnetism at room temperature and their magnetization was influenced by the reaction conditions. They were used as a Fenton-like catalyst to decompose Acid Orange II and displayed a higher activity than nanometer-size Fe3O4.

299

Preparation of Fe3O4 with high specific surface area and improved capacitance as a supercapacitor.  

Science.gov (United States)

Here, we report for the first time a facile ultrasonic synthesis of Fe3O4 nanoparticles using FeCl3 and the organic solvent ethanolamine (ETA). The intermediate of the ETA-Fe(II) complex produces Fe3O4 after hydrolysis and hydrothermal treatment. The moderate reduction of ETA and ultrasound play an important role in the synthesis of superfine Fe3O4 particles with a very high specific surface area (165.05 m(2) g(-1)). The Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), high-resolution transmission electron microscopy (HRTEM), and ultraviolet-visible absorption spectroscopy (UV-vis). Fe3O4 as an electrode material was fabricated into a supercapacitor and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements. The as-synthesized Fe3O4 exhibits remarkable pseudocapacitive activities including high specific capacitance (207.7 F g(-1) at 0.4 A g(-1)), good rate capability (90.4 F g(-1) at 10 A g(-1)), and excellent cycling stability (retention 100% after 2000 cycles). This novel synthetic route towards Fe3O4 is a convenient and potential way of producing a secondary energy material which is expected to be applicable in the synthesis of other metal oxide nanoparticles. PMID:23512007

Wang, Lu; Ji, Hongmei; Wang, Shasha; Kong, Lijuan; Jiang, Xuefan; Yang, Gang

2013-05-01

300

Synthesis of Fe3O4 nanocrystals using hydrothermal approach  

Science.gov (United States)

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.

Ahmadi, Shideh; Chia, Chin-Hua; Zakaria, Sarani; Saeedfar, Kasra; Asim, Nilofar

2012-12-01

 
 
 
 
301

Preparation of Fe3O4Spherical Nanoporous Particles Facilitated by Polyethylene Glycol 4000  

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Full Text Available 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 surface area of 87.5 m2/g. Magnetization measurement and Mössbauer spectrum indicate that these particles are nearly superparamagnetic at room temperature. It is found that the morphology of the products is greatly influenced by polyethylene glycol concentration and the polymerization degree of polyethylene glycol. Polyethylene glycol molecules are believed to facilitate the formation of the spherical assembly.

Wang Li-Li

2009-01-01

302

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 thhis material showed better performances than original CeO2 nanoparticles.

303

Silica coating of CeO 2 nanoparticles by a fast microwave irradiation method  

Science.gov (United States)

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 CeO 2 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 CeO 2 nanoparticles surface through Ce-O-Si chemical bonds. The coating extent was increased with increasing in TEOS loading and surface characteristics of coated CeO 2 nanoparticles with high silica extents showed similar electrokinetic behavior to SiO 2 particles. The high resolution transmission electron microscope (HR-TEM) images also showed that SiO 2 coated the cubic shaped CeO 2 nanoparticles as thin uniform layers (5 nm). The catalytic activities of non-coated and silica coated CeO 2 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 CeO 2 nanoparticles were evaluated by UV-vis spectroscopic analyses. These analytical results indicated that silica coated CeO 2 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 CeO 2 nanoparticles.

Siddiquey, Iqbal Ahmed; Furusawa, Takeshi; Hoshi, Yu-ichiro; Ukaji, Emi; Kurayama, Fumio; Sato, Masahide; Suzuki, Noboru

2008-12-01

304

Size dependent electromagnetic properties of Fe3O4 nanospheres  

Science.gov (United States)

Different-sized Fe3O4 nanospheres (from ?30 nm to ?100 nm) were prepared via a solvent-thermal route by controlling the content of FeCl3rad 6H2O in the synthesis. The crystalline structure, surface morphology and magnetic properties of obtained Fe3O4 nanospheres were systematically characterized. Additionally, the complex permittivity and permeability were measured to simulate the electromagnetic absorption of different-sized Fe3O4 nanospheres from 0.5 to 15 GHz. The results indicated that the Fe3O4 nanospheres with an average size of ?65 nm exhibited the strongest magnetic properties (saturation magnetization of 89.24 emu/g) and electromagnetic absorption (reflection loss of -30.37 dB at 9.68 GHz).

Jia, Kun; Zhang, Jiandong; Huang, Xu; Liu, Xiaobo

2014-10-01

305

Synthesis of Fe3O4 magnetic fluid used for magnetic resonance imaging and hyperthermia  

International Nuclear Information System (INIS)

Fe3O4 magnetic nanoparticles were prepared by co-precipitation from FeSO4.7H2O and FeCl3.6H2O aqueous solutions using NaOH as precipitating reagent. The nanoparticles have an average size of 12 nm and exhibit superparamagnetism at room temperature. The nanoparticles were used to prepare a water-based magnetic fluid using oleic acid and Tween 80 as surfactants. The stability and magnetic properties of the magnetic fluid were characterized by Gouy magnetic balance. The experimental results imply that the hydrophilic block of Tween 80 can make the Fe3O4 nanoparticles suspending in water stable even after dilution and autoclaving. The magnetic fluid demonstrates excellent stability and fast magneto-temperature response, which can be used both in magnetic resonance imaging and magnetic fluid hyperthermia. - Highlights: ? Fe3O4 magnetic fluid (MF) was prepared by co-precipitation without protection gas and using NaOH as co-precipitation agent. ? Tween 80 was employed as the second layer surfactant. ? Hydrophilic ends of Tween 80 were exposed outside making the Fe3O4 MNPs suspending in water stably. ? Prepared MF can be used both in magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH).

306

Enhanced interfacial polarization relaxation effect on microwave absorption properties of submicron-sized hollow Fe3O4 hemispheres  

Science.gov (United States)

Bowl-like Fe3O4 hemispheres with a hollow structure have been synthesized with an average outer diameter of 250 nm and a shell thickness of 80 nm using tiny ˜25 nm Fe3O4 nanoparticles. The complex permittivity, complex permeability and reflection loss of the samples in weight percentages of 60% of the hollow Fe3O4 hemispheres were studied by using an Agilent E5071 C vector network analyzer in the frequency range of 2-18 GHz. Results show that as-prepared samples exhibit improved microwave absorbing properties compared with our previously reported ball-like Fe3O4 microspheres and Fe3O4 hemispheres/r-GO composites. Two Cole-Cole semicircles reveal that there are dual dielectric relaxation losses: one is interfacial polarization relaxation, the other is dipolar relaxation. X-ray photoelectron and Fourier transform infrared spectra of the products calcinated at different temperatures reveal the enhanced interfacial polarization relaxation effect due to the higher concentration of Fe2+ ions in the surface layer and increased interfaces among the Fe3O4 nanoparticles that form the submicron-sized hollow Fe3O4 hemispheres. In addition, the fitted results of complex permeability demonstrate that the magnetic loss is mainly caused by the Kittel natural resonance.

Zou, Jianping; Wang, Zhongzhu; Yan, Manqing; Bi, Hong

2014-07-01

307

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

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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.

Xiao Qi

2009-01-01

308

In situ XANES studies of TiO 2/Fe 3O 4@C during photocatalytic degradation of trichloroethylene  

Science.gov (United States)

Mainly anatase and Fe 3O 4 in the magnetic photocatalysts (TiO 2 on Fe 3O 4@C core-shell nanoparticles (TiO 2/Fe 3O 4@C)) are observed by X-ray powder diffraction (XRD) spectroscopy. The Ti K-edge least-square fitted XANES spectra of the TiO 2/Fe 3O 4@C photocatalyst indicate that the main titanium species are nanosize TiO 2 (9 nm) (77%) and bulky TiO 2 (23%). Speciation of titanium in the TiO 2/Fe 3O 4@C during photocatalytic degradation of 100 ppm of trichloroethylene (TCE) has also been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. TiO 2 is not perturbed during the course of photocatalysis. However, it is worth to note that during photocatalytic degradation of TCE, about 33% of FeO and 67% of Fe 3O 4 are observed in the photocatalyst. It seems that the carbon layer on the TiO 2/Fe 3O 4@C photocatalysts can reduce the possibility for photoexcited electron-hole recombination as usually found on the relatively narrow bandgap of ferric oxide during photocatalysis.

Hsu, T.-F.; Hsiung, T.-L.; Wang, James; Huang, C.-H.; Paul Wang, H.

2010-07-01

309

In situ XANES studies of TiO2/Fe3O4-C during photocatalytic degradation of trichloroethylene  

International Nuclear Information System (INIS)

Mainly anatase and Fe3O4 in the magnetic photocatalysts (TiO2 on Fe3O4-C core-shell nanoparticles (TiO2/Fe3O4-C)) are observed by X-ray powder diffraction (XRD) spectroscopy. The Ti K-edge least-square fitted XANES spectra of the TiO2/Fe3O4-C photocatalyst indicate that the main titanium species are nanosize TiO2 (9 nm) (77%) and bulky TiO2 (23%). Speciation of titanium in the TiO2/Fe3O4-C during photocatalytic degradation of 100 ppm of trichloroethylene (TCE) has also been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. TiO2 is not perturbed during the course of photocatalysis. However, it is worth to note that during photocatalytic degradation of TCE, about 33% of FeO and 67% of Fe3O4 are observed in the photocatalyst. It seems that the carbon layer on the TiO2/Fe3O4-C photocatalysts can reduce the possibility for photoexcited electron-hole recombination as usually found on the relatively narrow bandgap of ferric oxide during photocatalysis.

310

Magnetocapacidad en nanopartículas de Fe3O4 y NiFe2O4  

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Full Text Available 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 Stöber 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 Fe3O4@SiO2 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 Catalán in which the combination of Maxwell-Wagner effects and magnetoresistance promote the appearance of stronger magnetocapacitive effects.Hemos preparado nanopartículas magnéticas de NiFe2O4 (?? 6 nm y Fe3O4 (?? 30 nm mediante el método de síntesis solvotermal; además estas últimas han sido recubiertas con una capa de SiO2 de unos 5 nm de espesor mediante el método de Stöber. Al estudiar el comportamiento dieléctrico en función de la frecuencia, temperatura y campo magnético aplicado, observamos un comportamiento magnetocapacitivo (MC a temperatura ambiente y bajo un campo magnético moderado (H= 0.5 T que es especialmente importante en el caso de las nanopartículas de Fe3O4 (MC? 6%. Por su parte las muestras de NiFe2O4 y Fe3O4@SiO2 presentan efectos magnetocapacitivos menores: MC? 2% y MC? 1%, respectivamente. Estos valores de MC, que son considerablemente superiores a los descritos hasta el momento para otras nanopartículas magnéticas, corroboran la predicción teórica de Catalán de que la combinación de efecto Maxwell-Wagner con efectos magnetorresitivos potencian la aparición de fenómenos magnetocapacitivos.

Mira, J.

2010-02-01

311

Localization and scintigraphy vizualization of nanocomposite based on 99mTc-phosphate with Fe3O4 and KCl nanoparticles under radiofrequency hyperthermia on animal tumor Walker-256  

International Nuclear Information System (INIS)

A comparative experimental study of the localization under the influence of constant magnetic fields and local radio frequency moderate hyperthermia for the scintigraphic imaging of malignant Walker-256 carcinosarcoma tumors by conventional 99mTc-phosphate and nanocomposite based on 99mTc-phosphate with Fe3O4 and KCl is performed. It is shown that, after the introduction of conventional 99mTc-phosphate to animals from control group, no tumor is visualized. After the introduction of nanocomposite, we observed the accumulation and the visualization of radiopharmaceuticals in the tumor with diffusion-uneven distribution. Accumulation of nanocomposite in the projection of a tumor as compared with control animals increased by more than 2 times.

312

Spherical polystyrene-supported nano-Fe3O4 of high capacity and low-field separation for arsenate removal from water  

International Nuclear Information System (INIS)

Highlights: ? Nano-Fe3O4 was coated onto polystyrene (PS) beads to obtain PS-Fe3O4 for arsenate removal from water. ? PS-Fe3O4 exhibited higher capacity and faster kinetics for arsenate adsorption than Fe3O4. ? PS-Fe3O4 can be effectively separated from water under a low magnetic field (3O4 can be employed for multiple uses after regeneration with alkaline solution. - Abstract: Fe3O4 is a promising material for arsenic sequestration due to its specific affinity toward arsenic and feasible magnetic separation. How to further increase its adsorption capacity while maintain its low-field separation is an interesting but challenging task. In this study nano-Fe3O4 was successfully coated onto the outer surface of polystyrene (PS) beads of 350–400 nm in diameter by the hetero-coacervation method, and the resulting composite PS-Fe3O4 was characterized using transmission electron microscope (TEM), X-ray powder diffraction (XRD), and electrophoresis measurement (EM). Its adsorption toward arsenate was investigated as a function of solution pH, arsenic concentration, contact time, and coexisting anions. The maximum adsorption capacity of PS-Fe3O4 was 139.3 mg/g Fe3O4, 77.7% greater than that of bulky Fe3O4. More attractively, it can be readily separated from water under a low magnetic field (3O4 can be effectively regenerated by NaOH solution, and the regenerated composite beads could be employed for repeated use without significant capacity loss, indicating that nano-Fe3O4 was steadily coated onto the surface of PS beads. Generally, PS beads could be employed as a promising host to fabricate efficient composites originated from Fe3O4 or other nanoparticles for environmental remediation.

313

High rate capability and long cycle stability Fe3O4–graphene nanocomposite as anode material for lithium ion batteries  

International Nuclear Information System (INIS)

Highlights: ? Fabrication of graphene and Fe3O4 nanocomposite for lithium ion batteries anode. ? In situ synthesis method leads to small particle size. ? Small particle size results in fine and strong interfacial interaction. ? The nanocomposite shows high rate capability and super long cycling stability. - Abstract: We developed one-spot in situ synthesis method to form nanocomposite of reduced graphene oxide (RGO) sheets with Fe3O4 nanoparticles for lithium ion battery applications. A transmission electron microscopy image has shown that the as-formed Fe3O4 nanoparticles are about 10 nm in average size, and uniformly anchor on RGO sheets as spacers to keep the neighboring sheets separated. The Fe3O4–RGO nanocomposite exhibits improved rate capability of 436 mA h g?1 at 2400 mA g?1. It delivers a high capacity of 1188 mA h g?1 at 100 mA g?1 after 1000 cycles of charge and discharge at various rates from 100 to 6000 mA g?1, indicating outstanding cycle stability. The improved electrochemical performance can be attributed to the important interfacial interaction between small-sized Fe3O4 nanoparticles and ultrathin RGO nanosheets, and suggests that Fe3O4–RGO nanocomposite with superior performance will be a promising anode material for lithium ion batteries.ion batteries.

314

Sensing behavior study of silica-coated Ag nanoparticles deposited on glassy carbon toward nitrobenzene  

International Nuclear Information System (INIS)

In this study, we report the synthesis and characterization of silica-coated silver core/shell nanostructures (NSs) and their sensing behavior when deposited on glassy carbon (GC) electrode for nitrobenzene (NB) detection. Synthesized silica-coated silver core/shell NSs were characterized for their chemical, structural and morphological properties. TEM analysis confirmed that the silica-coated silver nanoparticles (size ?200 nm) are spherical in shape and the core diameter is ?38 nm. FT-IR spectra also confirmed the coating of silica on the surface of silver nanoparticles. Cyclic voltammetry studies of NB with silica-coated silver core–shell nanoparticles-modified GC electrodes revealed two cathodic peaks at ?0.74 V (C1) and ?0.34 V (C2) along with two anodic peaks at ?0.64 V (A1) and ?0.2 V (A2). Enhanced cathodic peak current (C1, IP) of the core–shell NSs-modified electrode is observed relative to bare and silica-modified electrodes. Amperometric studies revealed a very high current sensitivity (114 nA/nM) and linearly dependent reduction current with NB amount in the low concentration range and a detection limit of 25 nM. Moreover, the core–shell NSs-modified electrode showed good reproducibility and selectivity toward NB in the presence of many cationic, anionic, and organic interferents.

315

Sensing behavior study of silica-coated Ag nanoparticles deposited on glassy carbon toward nitrobenzene  

Energy Technology Data Exchange (ETDEWEB)

In this study, we report the synthesis and characterization of silica-coated silver core/shell nanostructures (NSs) and their sensing behavior when deposited on glassy carbon (GC) electrode for nitrobenzene (NB) detection. Synthesized silica-coated silver core/shell NSs were characterized for their chemical, structural and morphological properties. TEM analysis confirmed that the silica-coated silver nanoparticles (size {approx}200 nm) are spherical in shape and the core diameter is {approx}38 nm. FT-IR spectra also confirmed the coating of silica on the surface of silver nanoparticles. Cyclic voltammetry studies of NB with silica-coated silver core-shell nanoparticles-modified GC electrodes revealed two cathodic peaks at -0.74 V (C{sub 1}) and -0.34 V (C{sub 2}) along with two anodic peaks at -0.64 V (A{sub 1}) and -0.2 V (A{sub 2}). Enhanced cathodic peak current (C{sub 1}, I{sub P}) of the core-shell NSs-modified electrode is observed relative to bare and silica-modified electrodes. Amperometric studies revealed a very high current sensitivity (114 nA/nM) and linearly dependent reduction current with NB amount in the low concentration range and a detection limit of 25 nM. Moreover, the core-shell NSs-modified electrode showed good reproducibility and selectivity toward NB in the presence of many cationic, anionic, and organic interferents.

Devi, Pooja; Reddy, Pramod [CSIR, Sector-30C, Central Scientific Instruments Organization (India); Arora, Swati [Shri Mata Vaishno Devi University (India); Singh, Suman; Ghanshyam, C.; Singla, M. L., E-mail: singla_min@yahoo.co.in [CSIR, Sector-30C, Central Scientific Instruments Organization (India)

2012-10-15

316

Nanoarchitectured Fe3O4 array electrode and its excellent lithium storage performance  

International Nuclear Information System (INIS)

Fe3O4 nanoparticles were deposited electrochemically on an array of Cu nanoribbons and used as the anode for lithium ion batteries. The three-dimensional (3D) nanostructure of the Fe3O4 anode was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Galvanostatic cycling tests revealed that the 3D nanostructured Fe3O4 anode exhibited a superior performance. Reversible capacity was measured as high as 870 mAh g?1 after 280 cycles (at a current density of 385 mA g?1, 0.42 C) and also shown an excellent rate capability that was determined at 231 mAh g?1 under the rate of 8000 mA g?1 (?9 C). The superior performance of the 3D nanostructured Fe3O4 electrode has been attributed to its peculiar structure, which allows one-dimensional electron transport on the array, as well as to the decrease in interparticle contact resistance.

317

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

318

Effect of silica shell thickness of Fe3O4–SiOx core–shell nanostructures on MRI contrast  

International Nuclear Information System (INIS)

Core–shell magnetic nanostructures (MNS) such as Fe3O4–SiOx, are being explored for their potential applications in biomedicine, such as a T2 (dark) contrast enhancement agent in magnetic resonance imaging (MRI). Herein, we present the effect of silica shell thickness on its r2 relaxivity in MRI as it relates to other physical parameters. In this effort initially, monodispersed Fe3O4 MNS (nominally 9 nm size) were synthesized in organic phase via a simple chemical decomposition method. To study effect of shell thickness of silica of Fe3O4–SiOx core shell on r2 relaxivity, the reverse micro-emulsion process was used to form silica coating of 5, 10 and 13 nm of silica shell around the MNS, while polyhedral oligomeric silsesquioxane was used to form very thin layer on the surface of MNS; synthesized nanostructures were characterized by transmission electron microscopy (TEM) and high resolution TEM (HRTEM), superconducting quantum interference device magnetometry and MRI. Our observation suggests that, with increase in thickness of silica shell in Fe3O4–SiOx core–shell nanostructure, r2 relaxivity decreases. The decrease in relaxivity could be attributed to increased distance between water molecules and magnetic core followed by change in the difference in Larmor frequencies (??) of water moleculesencies (??) of water molecules. These results provide a rational basis for optimization of SiOx-coated MNS for biomedical applications.

319

Highly luminescent silica-coated ZnO nanoparticles dispersed in an aqueous medium  

International Nuclear Information System (INIS)

Highly luminescent silica-coated ZnO nanoparticles dispersed in an aqueous medium were synthesized using the sol-gel process. The samples prepared at various temperatures exhibited an emission peak at around 480 nm (blue color) and a quantum efficiency of 60% at maximum by the quantum confinement effect of ZnO nanoparticles, with diameters ranging from 3.1 to 3.5 nm, under ultraviolet excitation. No degradation of the quantum efficiencies and no peak shifting in the emission spectra were observed for 7 days following the preparation, which indicated no growth of ZnO nanoparticles in the aqueous medium. - Research highlights: ? Highly luminescent silica-coated ZnO nanoparticles can be dispersed in an aqueous medium. ? The prepared samples exhibited an emission peak at around 480 nm (blue color). ? The quantum efficiency was 60% at maximum by ultraviolet excitation. ? No degradation of the PL properties was observed for 7 days following the preparation.