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Sample records for fe3o4 polymer composites

  1. Core-Shell Ferromagnetic Nanorod Based on Amine Polymer Composite (Fe3O4@DAPF) for Fast Removal of Pb(II) from Aqueous Solutions.

    PubMed

    Venkateswarlu, Sada; Yoon, Minyoung

    2015-11-18

    Heavy metal ion removal from wastewater constitutes an important issue in the water treatment industry. Although a variety of nanomaterials have been developed for heavy metal removal via adsorption, the adsorption capacity, removal efficiency, and material recyclability still remain a challenge. Here, we present novel Fe3O4@DAPF core-shell ferromagnetic nanorods (CSFMNRs) for the removal of Pb(II) from aqueous solutions; they were prepared by the facile surface modification of twin-like ferromagnetic Fe3O4 nanorods using a 2,3-diaminophenol and formaldehyde (DAPF)-based polymer. The crystallinity and structure of the Fe3O4 nanorods were confirmed via X-ray diffraction (XRD). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed the core-shell morphology and composition of the materials. Pb(II) removal using the prepared Fe3O4@DAPF CSFMNRs was assessed, and comparable adsorption capacities (83.3 mg g(-1)) to the largest value were demonstrated. A thermodynamic study of the adsorption clearly indicated that the adsorption was exothermic and spontaneous. Due to the ferromagnetic properties with a high saturation magnetization value (56.1 emu g(-1)) of the nanorods, the nanorods exhibited excellent reusability with one of the fastest recovery times (25 s) among reported materials. Therefore, the Fe3O4@DAPF CSFMNRs can serve as recyclable adsorbent materials and as an alternative to commonly used sorbent materials for the rapid removal of heavy metals from aqueous solutions.

  2. Magnetite (Fe3O4)-filled carbon nanofibers as electro-conducting/superparamagnetic nanohybrids and their multifunctional polymer composites

    NASA Astrophysics Data System (ADS)

    Das, Arindam; Raffi, Muhammad; Megaridis, Constantine; Fragouli, Despina; Innocenti, Claudia; Athanassiou, Athanassia

    2015-01-01

    A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe3O4 nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields.

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

    NASA Astrophysics Data System (ADS)

    Koc, Kenan; Alveroglu, Esra

    2015-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

    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 <81K (ΔT⩽1K) coinciding with a sharp anomaly resolved in the temperature derivative of the ac conductivity. This behavior is attributed to the Verwey transition of 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. Polymer (PDMS-Fe3O4) magneto-dielectric substrate for a MIMO antenna array

    NASA Astrophysics Data System (ADS)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Kamarudin, Muhammad Ramlee

    2016-01-01

    This paper presents the design of a 2 × 4 multiple-input multiple-output (MIMO) antenna array fabricated on a nanocomposite magneto-dielectric polymer substrate. The 10-nm iron oxide (Fe3O4) nanoparticles and polydimethylsiloxane (PDMS) composite is used as substrate to enhance the performance of a MIMO antenna array. The measured results showed up to 40.8 % enhancement in terms of bandwidth, 9.95 dB gain, and 57 % of radiation efficiency. Furthermore, it is found that the proposed magneto-dielectric (PDMS-Fe3O4) composite substrate provides excellent MIMO parameters such as correlation coefficient, diversity gain, and mutual coupling. The prototype of the proposed antenna is transparent, flexible, lightweight, and resistant against dust and corrosion. Measured results indicate that the proposed antenna is suitable for WLAN and ultra-wideband biomedical applications within frequency range of 5.33-7.70 GHz.

  8. Synthesis of montmorillonite/Fe3O4-OTAB composite capable of using as anisotropic nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Li, Yingjun; Wang, Shanqiang; Zhou, Yuanlin

    2017-04-01

    The high hydrophobic magnetic montmorillonite (MMT) nanoparticles were synthesized in two solvents (deionized water and ethanol) by using octadecyl trimethylammonium bromide (OTAB) as intercalating agent and Fe3O4 as magnetic nanoparticles. The obtained samples were characterized by FTIR, XRD, EDS, SEM, VSM. When Fe3O4 was loaded before OTAB on MMT, the sample prepared in deionized water exhibited better adsorption than that prepared in ethanol. The order of Fe3O4 and CTAB introduction had great effect on the hydrophobicity, magnetism, and adsorption. Compared with OTAB-MMT-Fe3O4, Fe3O4-MMT-OTAB possessed higher hydrophobicity and higher magnetic response. The contact angle of Fe3O4-MMT-OTAB could reach 84.80° and Fe3O4-MMT-OTAB possessed higher Ms (9.25 emu/g) than OTAB-MMT-Fe3O4 (6.72 emu/g) dose. Fe3O4-MMT-OTAB will become a promising candidate of anisotropic nano-filled powder in polymers by using low magnetic field to obtain the orientation, based on its above excellent properties.

  9. [Study on preparation of composite nano-scale Fe3O4 for phosphorus control].

    PubMed

    Li, Lei; Pan, Gang; Chen, Hao

    2010-03-01

    Composite nano-scale Fe3O4 particles were prepared in sodium carboxymethyl cellulose (CMC) solution by the oxidation deposition method. The adsorptions of phosphorus by micro-scale Fe3O4 and composite nano-scale Fe3O4 were investigated in water and soil, and the role of cellulase in the adsorption of composite nano-scale Fe3O4 was studied. Kinetic tests indicated that the equilibrium adsorption capacity of phosphorous on the composite nano-scale Fe3O4 (2.1 mg/g) was less than that of micro-scale Fe3O4 (3.2 mg/g). When cellulase was added to the solution of composite nano-scale Fe3O4 to degrade CMC, the removal rate of P by the nanoparticles (86%) was enhanced to the same level as the microparticles (90%). In the column tests, when the composite nano-scale Fe3O4 suspension was introduced in the downflow mode through the soil column, 72% of Fe3O4 penetrated through the soil bed under gravity. In contrast, the micro-scale Fe3O4 failed to pass through the soil column. The retention rate of P was 45% in the soil column when treated by the CMC-stabilized nanoparticles, in comparison with only 30% for the untreated soil column, however it could be improved to 74% in the soil column when treated by both the CMC-stabilized nanoparticles and cellulase, which degraded CMC after the nanoparticles were delivered into the soil.

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

    DOE PAGES

    David C. Bock; Takeuchi, Kenneth J.; Pelliccione, Christopher J.; ...

    2016-04-20

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

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

    NASA Astrophysics Data System (ADS)

    Oh, Ilgeun; Kim, Myeongjin; Kim, Jooheon

    2015-02-01

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

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

    PubMed

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

    2016-06-01

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

  13. Bioinspired 2D-Carbon Flakes and Fe3O4 Nanoparticles Composite for Arsenite Removal.

    PubMed

    Venkateswarlu, Sada; Lee, Daeho; Yoon, Minyoung

    2016-09-14

    Development of carbon-based materials has received tremendous attention owing to their multifunctional properties. Biomaterials often serve as an inspiration for the preparation of new carbon materials. Herein, we present a facile synthesis of a new bioinspired graphene oxide-like 2D-carbon flake (CF) using a natural resource, waste onion sheathing (Allium cepa). The 2D-CF was further decorated with crystalline Fe3O4 nanoparticles for applications. Superparamagnetic Fe3O4 nanoparticles (7 nm) were well-dispersed on the surface of the 2D-CF, which was characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, Raman spectrometry, and transmission electron microscopy. Batch As(III) adsorption experiments showed that aqueous arsenic ions strongly adsorbed to the Fe3O4@2D-CF composite. The adsorption capacity of the Fe3O4@2D-CF composite for As(III) was 57.47 mg g(-1). The synergetic effect of both graphene oxide-like 2D-CF and Fe3O4 nanoparticles aided in excellent As(III) adsorption. An As(III) ion adsorption kinetics study showed that adsorption was very fast at the initial stage, and equilibrium was reached within 60 min following a pseudo-second-order rate model. Owing to the excellent superparamagnetic properties (52.6 emu g(-1)), the Fe3O4@2D-CF composite exhibited superb reusability with the shortest recovery time (28 s) among reported materials. This study indicated that Fe3O4@2D-CF composites can be used for practical applications as a global economic material for future generations.

  14. Hydrothermal synthesis of magnetic Fe3O4/graphene composites with good electromagnetic microwave absorbing performances

    NASA Astrophysics Data System (ADS)

    Zhu, Lingyu; Zeng, Xiaojun; Li, Xiaopan; Yang, B.; Yu, Ronghai

    2017-03-01

    The Fe3O4 sub-microspheres have been embedded uniformly into the reduced graphene oxide (rGO) to form a new-type Fe3O4/rGO composites through a one-pot solvothermal method. The dielectric properties for these magnetic Fe3O4/rGO composites can be greatly tuned by their different rGO additions. A good impedance matching from the balanced dielectric and magnetic loss is achieved in the Fe3O4/rGO composites with 4 wt% rGO addition, which dominates their excellent microwave absorbing performances including the minimum reflection loss (RL) value of -45 dB at a frequency of 8.96 GHz with a sample thickness of 3.5 mm and an effective absorption bandwidth of 3.2 GHz (below -10 dB) superior to those of the most magnetic materials and carbon-based composites. The controlled Fe3O4/rGO composite structure also exhibits high chemical stability and low density, which shows great potential application in high-performance electromagnetic microwave-absorbing materials.

  15. Synthesis of electromagnetic functionalized Fe3O4 microspheres/polyaniline composites by two-step oxidative polymerization.

    PubMed

    Cui, Chenkui; Du, Yunchen; Li, Tianhao; Zheng, Xiaoying; Wang, Xiaohong; Han, Xijiang; Xu, Ping

    2012-08-09

    Composites consisting of Fe(3)O(4) microspheres (FMS) and polyaniline (PANI), FMS/PANI, have been successfully prepared through a two-step oxidative polymerization of aniline monomers in the presence of Fe(3)O(4) microspheres. In our two-step polymerization technique, Fe(3+) and ammonium persulfate (APS) are used as the oxidants in each step. It is discovered that the two-step oxidative process plays a dominant role in the morphology of these composites: aniline oligomers oxidized by Fe(3+) are mainly produced in the first stage, and "egg-like" PANI aggregates are obtained in the second stage. It can be found that embedding Fe(3)O(4) microspheres in the polymer matrixes will not only modulate the complex permittivity but also produce magnetic resonance and loss in the composites. Therefore, the characteristic impedance and reflection loss of these composites are greatly improved. Especially, the composite with equal amount of FMS and PANI, FMS/PANI(50), displays very strong reflection loss over a wide frequency range that can be manipulated by the absorber thickness. More importantly, the composites prepared from the two-step chemical oxidative polymerization using hierarchical magnetic materials have better microwave absorption and environmental stability as compared with those composites from Fe(3)O(4) nanoparticles, one-step oxidative polymerization, and physical mixture. We believe the two-step oxidative polymerization technique can be a novel route for the design and preparation of lightweight and highly effective microwave absorbers in the future.

  16. Synthesis and Characterization of the Graphene-Fe3O4 Hybrid Composite.

    PubMed

    Myekhlai, Munkhshur; Lee, Taejin; Lee, Sinil; Kim, Junhyo; Kang, Donghoon; Noh, Jungpil; Huh, Sunchul; Chung, Hanshik; Jeong, Hyomin

    2015-03-01

    Graphene and iron oxide composites have attracted huge attention in the fields of nanoelectronics and nanodevices due to their superior magnetic and electric characteristics. However, their synthesis methods are composed of many steps and use toxic chemical reactants. Accordingly, in this study, a GN-Fe3O4 NP hybrid composite was prepared using an eco-friendly and facile method. Its morphological and structural characteristics were then investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffractometer and UV-visible spectroscopy. The results indicated that the GN structures as well as Fe3O4 NPs were significantly associated with the composite of GN-Fe3O4 NPs.

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

    PubMed

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

    2015-07-15

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

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

    PubMed

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

    2013-11-13

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

  19. Controllable synthesis and characterization of Fe3O4/Au composite nanoparticles

    NASA Astrophysics Data System (ADS)

    Xing, Yan; Jin, Yan-Yan; Si, Jian-Chao; Peng, Ming-Li; Wang, Xiao-Fang; Chen, Chao; Cui, Ya-Li

    2015-04-01

    Fe3O4/Au composite nanoparticles (GoldMag NPs) have received considerable attention because of their advantageous properties arisen from both individual Au and Fe3O4 nanoparticles. Many efforts have been devoted to the synthesis of these composite nanoparticles. Herein, GoldMag NPs were reported to be synthesized by two-step method. Fe3O4 nanoparticles were prepared by co-precipitation and modified by the citric acid, and then citric acid-coated Fe3O4 nanoparticles were used as seeds in sodium citrate solution to reduce the HAuCl4. The size of obtained nanoparticles was geared from 25 to 300 nm by controlling the concentration of reactants. The GoldMag NPs were characterized by UV-vis spectrometer, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The GoldMag NPs showed good superparamagnetism at room temperature and were well dispersed in water with surface plasmon resonance absorption peak varied from 538 nm to 570 nm.

  20. Composites of aminodextran-coated Fe3O4 nanoparticles and graphene oxide for cellular magnetic resonance imaging.

    PubMed

    Chen, Weihong; Yi, Peiwei; Zhang, Yi; Zhang, Liming; Deng, Zongwu; Zhang, Zhijun

    2011-10-01

    Formation of composites of dextran-coated Fe(3)O(4) nanoparticles (NPs) and graphene oxide (Fe(3)O(4)-GO) and their application as T(2)-weighted contrast agent for efficient cellular magnetic resonance imaging (MRI) are reported. Aminodextran (AMD) was first synthesized by coupling reaction of carboxymethyldextran with butanediamine, which was then chemically conjugated to meso-2,3-dimercaptosuccinnic acid-modified Fe(3)O(4) NPs. Next, the AMD-coated Fe(3)O(4) NPs were anchored onto GO sheets via formation of amide bond in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC). It is found that the Fe(3)O(4)-GO composites possess good physiological stability and low cytotoxicity. Prussian Blue staining analysis indicates that the Fe(3)O(4)-GO nanocomposites can be internalized efficiently by HeLa cells, depending on the concentration of the composites incubated with the cells. Furthermore, compared with the isolated Fe(3)O(4) NPs, the Fe(3)O(4)-GO composites show significantly enhanced cellular MRI, being capable of detecting cells at the iron concentration of 5 μg mL(-1) with cell density of 2 × 10(5) cells mL(-1), and at the iron concentration of 20 μg mL(-1) with cell density of 1000 cells mL(-1).

  1. Synthesis of one-dimensional Fe3O4@C composites from catalytic pyrolysis of waste polypropylene.

    PubMed

    Kong, Qinghong; Zhang, Junhao; Liu, Hong; Zhang, Yunlong; Zhang, Xiaoning

    2012-10-01

    A simple catalytic pyrolysis route was developed to prepare one-dimensional Fe3O4@C composites using waste polypropylene as carbon resource, in which the Fe3O4 nanoparticles were self-assembled to necklace-shaped structures. The products were characterized by means of X-ray power diffraction (XRD), Raman spectra, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results indicate that the diameter of chains is about 550 nm, the size of Fe3O4 particles is ranging from 200 to 500 nm, and the thickness of carbon shells is about 150 nm. The magnetic measurement at room temperature indicates that the value of saturation magnetization (22.0 emu/g) and coercivity (171.7 Oe) is different from that of bare Fe3O4 nanoparticles and bulk Fe3O4 due to the different carbon content, dipolar interactions, size and morphology of the products.

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

    PubMed

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

    2016-01-01

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

  3. Removal of nitrate and phosphate using chitosan/Al2O3/Fe3O4 composite nanofibrous adsorbent: Comparison with chitosan/Al2O3/Fe3O4 beads.

    PubMed

    Bozorgpour, Farahnaz; Ramandi, Hossein Fasih; Jafari, Pooya; Samadi, Saman; Yazd, Shabnam Sharif; Aliabadi, Majid

    2016-12-01

    In the present study the chitosan/Al2O3/Fe3O4 composite nanofibrous adsorbent was prepared by electrospinning process and its application for the removal of nitrate and phosphate were compared with chitosan/Al2O3/Fe3O4 composite bead adsorbent. The influence of Al2O3/Fe3O4 composite content, pH, contact time, nitrate and phosphate initial concentrations and temperature on the nitrate and phosphate sorption using synthesized bead and nanofibrous adsorbents was investigated in a single system. The reusability of chitosan/Al2O3/Fe3O4 composite beads and nanofibers after five sorption-desorption cycles were carried out. The Box-Behnken design was used to investigate the interaction effects of adsorbent dosage, nitrate and phosphate initial concentrations on the nitrate and phosphate removal efficiency. The pseudo-second-order kinetic model and known Freundlich and Langmuir isotherm models were used to describe the kinetic and equilibrium data of nitrate and phosphate sorption using chitosan/Al2O3/Fe3O4 composite beads and nanofibers. The influence of other anions including chloride, fluoride and sulphate on the sorption efficiency of nitrate and phosphate was examined. The obtained results revealed the higher potential of chitosan/Al2O3/Fe3O4 composite nanofibers for nitrate and phosphate compared with chitosan/Al2O3/Fe3O4 composite beads.

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

    PubMed

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

    2016-03-09

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  6. One-step preparation of Fe3O4/Pd@polypyrrole composites with enhanced catalytic activity and stability.

    PubMed

    Zhang, Hui; Liu, Yang; Wu, Jie; Xin, Baifu

    2016-08-15

    Core/shell Fe3O4/Pd@polypyrrole (PPy) composites with a Fe3O4 core and a PPy shell embedding Pd nanoparticles were prepared in one-step. The diameter of highly dispersed Pd nanoparticles was as small as 2.9nm owing to coordination interaction generated between Pd(2+) ions and amino groups on PPy chains. The outer PPy shell was only 6.8nm: on one hand, the coverage was beneficial to improving the stability of resulting composites; on the other hand, the shell was thin enough to permit free contact between embedding Pd nanoparticles and reactants. Additionally, the as-prepared Fe3O4/Pd@PPy composites displayed good magnetic separation property due to incorporation of Fe3O4 nanospheres. Based on above merits, they served as suitable catalyst candidates. Their catalytic performance and reusability were evaluated by reduction of 4-nitrophenol with sodium borohydride as reducing agent. Compared with traditional Fe3O4/Pd composites, Fe3O4/Pd@PPy composites not only showed superior catalytic activity; but also exhibited much better stability in successive cycling tests.

  7. Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

    SciTech Connect

    Sun, Weixing; Sun, Wuzhu; Kessler, Michael R; Bowler, Nicola; Dennis, Kevin W; McCallum, R William; Li, Qi; Tan, Xiaoli

    2013-02-22

    SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 ?C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.

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

    PubMed

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

    2013-01-18

    A superparamagnetic reduced graphene oxide-Fe(3)O(4) hybrid composite (rGO-Fe(3)O(4)) was prepared via a facile and straightforward method through the solvothermal reaction of iron (III) acetylacetonate (Fe(acac)(3)) and graphene oxide (GO) in ethylenediamine (EDA) and water. By this method, chemical reduction of GO as well as the formation of Fe(3)O(4) nanoparticles (NPs) can be achieved in one step. The Fe(3)O(4) NPs are firmly deposited on the surfaces of rGO, avoiding their reassembly to graphite. The rGO sheets prevent the agglomeration of Fe(3)O(4) NPs and enable a uniform dispersion of these metal oxide particles. The size distribution and coverage density of Fe(3)O(4) NPs deposited on rGO can be controlled by varying the initial mass ratio of GO and iron precursor, Fe(acac)(3). With an initial mass ratio of GO and Fe(acac)(3) of 5:5, the surfaces of rGO sheets are densely covered by spherical Fe(3)O(4) NPs with an average size of 19.9 nm. The magnetic-functionalized rGO hybrid exhibits a good magnetic property and the specific saturation magnetization (M(s)) is 13.2 emu g(-1). The adsorption test of methylene blue from aqueous solution demonstrates the potential application of this rGO-Fe(3)O(4) hybrid composite in removing organic dyes from polluted water.

  9. Microwave absorption properties and mechanism for hollow Fe3 O4 nanosphere composites

    NASA Astrophysics Data System (ADS)

    Li, Z. W.; Yang, Z. H.

    2015-08-01

    Hollow Fe3 O4 nanospheres with the diameter of 450 nm and the wall thickness of 80 nm are prepared using the Ostwald ripening process. The composites filled with the hollow nanospheres of 60 wt% have good high-frequency and absorption properties. In RL-f curves, two absorption frequencies are found, which have their origins in quarter-wavelength resonator and magnetic resonance, respectively. Based on the quarter-wavelength resonator model, the calculated fA1 and RLA1 are in a good agreement with the observed values. Due to the overlap of the two absorptions, the frequency band is expanded. The composite with light weight of the density of 2.71 g/cm3 has bandwidth WP of 65% with return loss RL ≤ - 10 dB at thickness of 0.3 cm for EM absorption or attenuation applications.

  10. Highly stable and magnetically separable alginate/Fe3O4 composite for the removal of strontium (Sr) from seawater.

    PubMed

    Hong, Hye-Jin; Jeong, Hyeon Su; Kim, Byoung-Gyu; Hong, Jeongsik; Park, In-Su; Ryu, Taegong; Chung, Kang-Sup; Kim, Hyuncheol; Ryu, Jungho

    2016-12-01

    In this study, a highly stable alginate/Fe3O4 composite was synthesized, and systematically investigated for the practical application of strontium (Sr) removal in complex media, such as seawater and radioactive wastewater. To overcome the drawbacks of the use of alginate microspheres, high contents of alginic acid and Fe3O4 were used to provide a more rigid structure with little swelling and facile separation, respectively. The synthesized composite was optimized for particle sizes of <400 μm and 1% content of Fe3O4. The alginate/Fe3O4 composite showed excellent Sr uptake (≈400.0 mg/g) and exhibited outstanding selectivity for Sr among various cations (Na, Mg, Ca and K). However, in diluted Sr condition (50 mg/L), Ca significantly affected Sr adsorption, resulting in a decrease of Kd value from 3.7 to 2.4 at the 0.01 M Ca. The alginate/Fe3O4 composite could be completely regenerated using 0.1 M HCl and CaCl2. In real seawater spiked with 50 mg/L of Sr, the alginate/Fe3O4 composite showed 12.5 mg/g of Sr uptake, despite the highly concentrated ions in seawater. The adsorption experiment for radio-active (90)Sr revealed a removal efficiency of 67% in real seawater, demonstrating the reliability of the alginate/Fe3O4 composite.

  11. Generalized green synthesis of Fe3O4/Ag composites with excellent SERS activity and their application in fungicide detection

    NASA Astrophysics Data System (ADS)

    Guo, Hongyan; Zhao, Aiwu; Wang, Rujing; Wang, Dapeng; Wang, Liusan; Gao, Qian; Sun, Henghui; Li, Lei; He, Qinye

    2015-12-01

    This paper reports the generalized green synthesis of a series of Fe3O4/Ag composites by magnetron sputtering method. The amounts of silver nanoparticles located on the hollow Fe3O4 magnetic nanoparticles can be tuned by controlling the sputtering time. The surfaces of Fe3O4/Ag composites are rough with high density and numerous Ag nanogaps (which can serve as Raman active hot spots to amplify the Raman signal), providing the sound reliability and reproducibility of Raman detection. With p-aminothiophenol and Rhodamine 6G (R6G) for probe molecules, the surface-enhanced Raman scattering (SERS) properties of these Fe3O4/Ag composites were studied. It was found that the SERS signal reached the maximum with the sputtering time of 130 s, indicating that this compound had most hot spots. In this paper, we used the composite with the strongest SERS signal for thiram detection, and the detection limit can reach 5 × 10-7 mol/L (about 0.012 ppm), which is lower than the maximal residue limit of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency. The Fe3O4/Ag composites are readily available, easy to carry, and show great potential for applications in universal SERS substrates in practical SERS detection.

  12. Fabrication, structure, and properties of Fe3O4@C encapsulated with YVO4:Eu3+ composites

    NASA Astrophysics Data System (ADS)

    Shi, Jianhui; Tong, Lizhu; Liu, Deming; Yang, Hua

    2012-03-01

    The use of carbon shells offers many advantages in surface coating or surface modification due to their surface with activated carboxyl and carbonyl groups. In this study, the Fe3O4@C@YVO4:Eu3+ composites were prepared through a simple sol-gel process. Reactive carbon interlayer was introduced as a key component, which separates lanthanide-based luminescent component from the magnetite, more importantly, it effectively prevent oxidation of the Fe3O4 core during the whole preparation process. The morphology, structure, magnetic, and luminescent properties of the composites were characterized by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, X-ray photoelectron spectra, VSM, and photoluminescent spectrophotometer. As a result, the Fe3O4@C/YVO4:Eu3+ composites with well-crystallized and core-shell structure were prepared and the YVO4:Eu3+ luminescent layer decorating the Fe3O4@C core-shell microspheres are about 10 nm. In addition, the Fe3O4@C@YVO4:Eu3+ composites have the excellent magnetic and luminescent properties, which allow them great potential for bioapplications such as magnetic bioseparation, magnetic resonance imaging, and drug/gene delivery.

  13. Synthesis of composite magnetic nanoparticles Fe3O4 with alendronate for osteoporosis treatment

    PubMed Central

    Lee, Ming-Song; Su, Chao-Ming; Yeh, Jih-Chao; Wu, Pei-Ru; Tsai, Tien-Yao; Lou, Shyh-Liang

    2016-01-01

    Osteoporosis is a result of imbalance between bone formation by osteoblasts and resorption by osteoclasts (OCs). In the present study, we investigated the potential of limiting the aggravation of osteoporosis by reducing the activity of OCs through thermolysis. The proposed method is to synthesize bisphosphonate (Bis)-conjugated iron (II, III) oxide (Fe3O4) nanoparticles and incorporate them into OCs. The cells should be subsequently exposed to radiofrequency (RF) to induce thermolysis. In this study, particles of Fe3O4 were first synthesized by chemical co-precipitation and then coated with dextran (Dex). The Dex/Fe3O4 particles were then conjugated with Bis to form Bis/Dex/Fe3O4. Transmission electron microscopy revealed that the average diameter of the Bis/Dex/Fe3O4 particles was ~20 nm. All three kinds of nanoparticles were found to have cubic inverse spinel structure of Fe3O4 by the X-ray diffraction analysis. Fourier transform infrared spectroscopy confirmed that the Dex/Fe3O4 and Bis/Dex/Fe3O4 nanoparticles possessed their respective Dex and Bis functional groups, while a superconducting quantum interference device magnetometer measured the magnetic moment to be 24.5 emu. In addition, the Bis/Dex/Fe3O4 nanoparticles were fully dispersed in double-distilled water. Osteoblasts and OCs were individually cultured with the nanoparticles, and an MTT assay revealed that they were non-cytotoxic. An RF system (42 kHz and 450 A) was used to raise the temperature of the nanoparticles for 20 minutes, and the thermal effect was found to be sufficient to destroy OCs. Furthermore, in vivo studies verified that nanoparticles were indeed magnetic resonance imaging contrast agents and that they accumulated after being injected into the body of rats. In conclusion, we developed a water-dispersible magnetic nanoparticle that had RF-induced thermogenic properties, and the results indicated that the Bis/Dex/Fe3O4 nanoparticle had the potential for controlling osteoporosis. PMID

  14. Photodarkening effect and optical properties of a nanocomposite material polymer/Fe3O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Laikhtman, A.; Harea, D.; Axelevitch, A.; Meshalkin, A.

    2016-02-01

    Materials with combined ferroelectric and ferromagnetic properties or magneto-electric coupling effects are promising candidates for information technology, photosensoring, and device fabrication. Preparation and characterization of multiferroic materials in which ferroelectricity and ferromagnetism coexist attracted much interest in research for functionalized materials and devices. They present a possibility to electrically control magnetic memory devices and, conversely, magnetically manipulate electric devices. In this work we considered Fe3O4 magnetic nanoparticles with and without a protective SiO2/TiO2 double-layer coating embedded into the carbazole-based, namely, polyepoxypropylcarbazole (PEPC) thin (500 nm) film. Optical characterization of the PEPC films was performed using light irradiation in the UV/VIS and NIR ranges. A shift in the optical absorption edge toward a higher wavelength region of the spectrum took place for all irradiated samples: the polymer film, as well as for the samples with Fe3O4 and Fe3O4/SiO2/TiO2 nanoparticles inside of the polymer matrix. We suggest that changes in the UV/VIS/NIR spectra took place as a function of the degree of structural changes and stabilizing of the atomic matrix, as well as due to change in the values of the refractive index following irradiation, calculated from the spectral data. In such a way photo-structural modifications induced by the UV irradiation and the implantation of the magnetic nanoparticles make these materials perspective for optical recording media. We conclude, therefore, that Fe3O4 and Fe3O4/SiO2/TiO2 nanoparticles considerably affect the optical properties of the PEPC thin film, and result in the enhancement of the photodarkening effect following the UV irradiation.

  15. Magnetic and microstructural properties of Fe3O4-coated Fe powder soft magnetic composites

    NASA Astrophysics Data System (ADS)

    Jo Sunday, Katie; Hanejko, Francis G.; Taheri, Mitra L.

    2017-02-01

    Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and possess high melting temperatures, thus providing adequate electrical barriers between metallic particles. In this work, iron powder was coated with Fe3O4 particles via mechanical milling, then compacted and cured in an inert gas environment. We find density and coercivity to improve with increasing temperatures; however, core loss greatly increases, which is attributed to the formation of a more conductive iron-oxide phase and less resistive Fe volume. Our work begins to exemplify the unique qualities and potential for ferrite-based coatings using traditional powder metallurgy techniques and higher curing temperatures for electromagnetic devices.

  16. Efficient reduced graphene oxide grafted porous Fe3O4 composite as a high performance anode material for Li-ion batteries.

    PubMed

    Bhuvaneswari, Subramani; Pratheeksha, Parakandy Muzhikara; Anandan, Srinivasan; Rangappa, Dinesh; Gopalan, Raghavan; Rao, Tata Narasinga

    2014-03-21

    Here, we report facile fabrication of Fe3O4-reduced graphene oxide (Fe3O4-RGO) composite by a novel approach, i.e., microwave assisted combustion synthesis of porous Fe3O4 particles followed by decoration of Fe3O4 by RGO. The characterization studies of Fe3O4-RGO composite demonstrate formation of face centered cubic hexagonal crystalline Fe3O4, and homogeneous grafting of Fe3O4 particles by RGO. The nitrogen adsorption-desorption isotherm shows presence of a porous structure with a surface area and a pore volume of 81.67 m(2) g(-1), and 0.106 cm(3) g(-1) respectively. Raman spectroscopic studies of Fe3O4-RGO composite confirm the existence of graphitic carbon. Electrochemical studies reveal that the composite exhibits high reversible Li-ion storage capacity with enhanced cycle life and high coulombic efficiency. The Fe3O4-RGO composite showed a reversible capacity ∼612, 543, and ∼446 mA h g(-1) at current rates of 1 C, 3 C and 5 C, respectively, with a coulombic efficiency of 98% after 50 cycles, which is higher than graphite, and Fe3O4-carbon composite. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4-RGO composite during the starting and subsequent cycles. The results emphasize the importance of our strategy which exhibited promising electrochemical performance in terms of high capacity retention and good cycling stability. The synergistic properties, (i) improved ionic diffusion by porous Fe3O4 particles with a high surface area and pore volume, and (ii) increased electronic conductivity by RGO grafting attributed to the excellent electrochemical performance of Fe3O4, which make this material attractive to use as anode materials for lithium ion storage.

  17. Chemical synthesis of Fe/Fe3O4 core-shell composites with enhanced soft magnetic performances

    NASA Astrophysics Data System (ADS)

    Yang, Bai; Li, Xiaopan; Yang, Xueying; Yu, Ronghai

    2017-04-01

    The large-grain Fe/Fe3O4 composite particles with average size of about 1.2 μm have been fabricated by a facile one-step solvothermal method. The formation of high-purity Fe3O4 as the shells (90.14 wt%) and α-Fe as the cores (9.86 wt%) in the Fe/Fe3O4 composites leads to their high saturation magnetization of 119.6 A m2 Kg-1. Very low coercivity of 30 Oe is obtained in the composites due to their uniform cubic-shaped morphologies. Compared with Fe-based nanosized particles, these micron-sized magnetic Fe/Fe3O4 composites exhibit high air stability and good compactibility with high compressed density of 5.9 g cm-3. The fully compacted sample shows good soft magnetic properties including high magnetic induction B1.2k (H=1200 A/m) of 540 mT and good frequency-dependent magnetic properties with operating frequency up to 50 MHz superior to those of the most traditional soft magnetic ferrites, which promotes their potential applications in high-frequency and high-power magnetic devices.

  18. Magnetic recoverable Fe3O4-TiO2:Eu composite nanoparticles with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Stefan, M.; Leostean, C.; Pana, O.; Toloman, D.; Popa, A.; Perhaita, I.; Senilă, M.; Marincas, O.; Barbu-Tudoran, L.

    2016-12-01

    This work refers to the influence of Eu doping on the morphologic, structural and compositional properties of magnetic separable Fe3O4-TiO2 composite nanoparticles with photocatalytic activity. In this respect, Fe3O4-TiO2:Eu nanocomposites were prepared by seed mediated growth of TiO2:Eu through a sol-gel method onto preformed magnetite resulted from co-precipitation method. Different Eu concentration precursors were used for doping. The thermal behavior and the conversion of precursors into corresponding Fe3O4-TiO2:Eu composite nanoparticles were evidenced by FT-IR spectra and thermal analysis. The XRD, XPS and HRTEM investigations results indicate that nanocomposites contain besides Fe3O4-TiO2:Eu some amounts of iron titanate. Formation of FeTiO3 is suppressed by the increase of Eu doping level. Magnetic studies also indicated that nanocomposite exhibit superparamagnetic behavior at room temperature. The large surface area and mesoporous structure of magnetic nanocomposite were confirmed by the surface area (BET) and porosity measurements. It was demonstrated that the composite nanoparticles exhibit good photocatalytic activity toward the degradation of RhB solution and they can be used as efficient and conveniently recoverable photocatalyst.

  19. Synthesis and characterization of Fe3O4@SiO2 magnetic composite nanoparticles by a one-pot process

    NASA Astrophysics Data System (ADS)

    Zhang, Le; Shao, Hui-ping; Zheng, Hang; Lin, Tao; Guo, Zhi-meng

    2016-09-01

    Fe3O4@SiO2 core-shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core-shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder (34.85 A·m2·kg-1) was markedly lower than that of the Fe3O4 powder (79.55 A·m2·kg-1), which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.

  20. Facile preparation of magnetic mesoporous Fe3O4/C/Cu composites as high performance Fenton-like catalysts

    NASA Astrophysics Data System (ADS)

    Li, Keyan; Zhao, Yongqin; Janik, Michael J.; Song, Chunshan; Guo, Xinwen

    2017-02-01

    Fe-Cu composites with different compositions and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation. γ-Fe2O3/CuO and α-Fe2O3/CuO were obtained by calcining the Fe and Cu tartrates under air atmosphere at 350 °C and 500 °C, respectively, while Fe3O4/C/Cu was obtained by calcining the tartrate precursor under N2 atmosphere at 500 °C. The Fe3O4/C/Cu composite possessed mesoporous structure and large surface area up to 133 m2 g-1. The Fenton catalytic performance of Fe3O4/C/Cu composite was closely related to the Fe/Cu molar ratio, and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity. Cu inclusion reduced Fe3+ to Fe2+, which accelerated the Fe3+/Fe2+ cycles and favored H2O2 decomposition to produce more hydroxyl radicals for methylene blue (MB) oxidation. Due to the photo-reduction of Fe3+ and Cu2+, the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe3O4/C/Cu-H2O2 system, and MB (100 mg L-1) was nearly removed within 60 min. The Fe3O4/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field. Compared with conventional methods for mesoporous composite construction, the thermolysis method using mixed metal tartrates as precursors has the advantages of easy preparation and low cost. This strategy provides a facile, cheap and green method for the synthesis of mesoporous composites as excellent Fenton-like catalysts, without any additional reductants or organic surfactants.

  1. Synthesis of magnetic and lightweight hollow microspheres/polyaniline/Fe 3 O 4 composite in one-step method

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Qin; Wang, Wei; Pang, Jianfeng; Zhai, Jianping

    2011-09-01

    After hollow microspheres (HM) were surface modified, a layer of electromagnetic polyaniline/Fe3O4 composite (PAN/Fe3O4) was successfully grafted onto the surface of the self-assembled monolayer coated HM, resulting in HM/PAN/Fe3O4 composites. In this approach, γ-aminopropyltriethoxy silane was adopted to form a well-coating monolayer with amino groups for the graft polymerization of aniline, which played an important role in fabricating the core-shell structure. FeCl3 was used as the oxidant not only for aniline to form PAN, but also for FeCl2 to prepare the magnets. The structure, morphologies, and magnetic properties of the as-prepared samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The results indicated that the HM/PAN/Fe3O4 composites possess low density (ρ < 1.0 g/cm3), controllable morphology, and good magnetic properties at room temperature (saturation magnetization Ms = 8.32 emu g-1 and coercive force Hc ≈ 0).

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  3. Ultrasensitive electrochemical detection of DNA hybridization using Au/Fe3O4 magnetic composites combined with silver enhancement.

    PubMed

    Bai, Yu-Hui; Li, Jin-Yi; Xu, Jing-Juan; Chen, Hong-Yuan

    2010-07-01

    A novel method is described for the highly effective amplifying electrochemical response of DNA based on oligonucleotides functionalized with Au/Fe(3)O(4) nanocomposites by the aid of silver (Ag) enhancement. Via electrostatic layer-by-layer (LBL) assembly, the prepared Fe(3)O(4) nanoparticles form nano-clusters coated with a bilayer composed of polystyrene sulfonate sodium salt (PSS) and poly(diallyldimethylammonium chloride) (PDDA), which are in favor of adsorbing lots of gold nanoparticles (AuNPs) on the surface. The application of magnetic Fe(3)O(4) made the procedures much more simple, convenient and feasible. The resulting composites were then used as labels via the Au-S bond for the DNA hybridization, followed by catalytic deposition of silver on the gold tags. Such an assay is then combined with a sensitive anodic stripping voltammetry (ASV) measurement of multiple silver nanoparticle tracers. A 27-mer sequence DNA target is detected at a glassy carbon (GC) electrode with a detection limit down to ca. 100 aM, which is 800 times lower than that obtained using gold nanoparticles only as labels in the control experiments. This Fe(3)O(4)/PSS/PDDA/Au composite offers a great promising future for the ultrasensitive detection of other biorecognition events.

  4. Composite multifunctional nanostructures based on ZnO tetrapods and superparamagnetic Fe3O4 nanoparticles.

    PubMed

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

    2013-04-05

    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 m(2) 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.

  5. A facile synthesis of Fe3O4-charcoal composite for the sorption of a hazardous dye from aquatic environment.

    PubMed

    Ahmed, Md Juned K; Ahmaruzzaman, M

    2015-11-01

    Herein, we synthesized Fe3O4-charcoal composite using chemical precipitation technique and utilized it for the sorption of methylene blue from aqueous solution. The synthesized composite was characterized by Infra-red spectroscopy, N2 adsorption-desorption isotherm, X-ray diffraction, selected area electron diffraction, transmission electron microscopy, and vibrating sample magnetometer. The composite depicts absorption bands conforming to Fe-O, -OH, CO, and C-O vibrations. The composite was mesoporous in nature with a surface area of 387.30 m(2) g(-1). The observed diffraction planes correspond to face-centered cubic Fe3O4 and disordered graphitic carbon. The spherical Fe3O4 particles (average diameter ∼13.8 nm) were uniformly distributed in the carbon matrix of the charcoal. The saturation and remanent magnetizations demonstrate its potential for magnetic separation and reuse. The composite showed dye sorption capacities of 97.49 mg g(-1) and 90.85 mg g(-1) in batch and fixed-bed system. Pseudo-second order kinetics and Temkin isotherm best represented the sorption data. The sorption process was endothermic, spontaneous, and administered by electrostatic, π-π dispersive interactions, film, and intraparticle diffusion. Microwave irradiations followed by methanol elution regenerated the dye-loaded composite with nearly no loss in sorption capacity. The recovery of energy and potential utilization of bottom ash enhances the prospective of Fe3O4-charcoal composite for industrial applications.

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

    PubMed

    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

    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.

  7. The Influence of Nano-Fe3O4 on the Microstructure and Mechanical Properties of Cementitious Composites

    NASA Astrophysics Data System (ADS)

    Sikora, Pawel; Horszczaruk, Elzbieta; Cendrowski, Krzysztof; Mijowska, Ewa

    2016-04-01

    In the last decade, nanotechnology has been gathering a spectacular amount of attention in the field of building materials. The incorporation of nanosized particles in a small amount to the building materials can influence their properties significantly. And it can contribute to the creation of novel and sustainable structures. In this work, the effect of nano-Fe3O4 as an admixture (from 1 to 5 wt.% in mass of the cement) on the mechanical and microstructural properties of cementitious composites has been characterised. The study showed that Fe3O4 nanoparticles acted as a filler which improved the microstructure of a cementitious composite and reduced its total porosity, thus increasing the density of the composite. The presence of nanomagnetite did not affect the main hydration products and the rate of cement hydration. In addition, the samples containing nanomagnetite exhibited compressive strength improvement (up to 20 %). The study showed that 3 wt.% of nano-Fe3O4 in the cementitious composite was the optimal amount to improve both its mechanical and microstructural properties.

  8. Highly efficient surface enhanced Raman scattering with ZnS@Fe3O4@Ag composite structures as probes

    NASA Astrophysics Data System (ADS)

    Nair, Radhika V.; Siva Gummaluri, Venkata; Gayathri, P. K.; Vijayan, C.

    2017-01-01

    Development of novel composite materials with enhanced optical properties and modified surface morphology is highly significant in surface enhanced Raman spectroscopic (SERS) applications. Dielectric-plasmonic multilayer composites are found to serve this purpose due to the feasibility of tuning their plasmon resonances even to IR region, far away from electronic resonance of analyte molecules. In this work, we introduce a new composite material that can have enormous potential in sensing applications at trace level. Here we demonstrate surface enhanced Raman scattering activity of ZnS@Fe3O4@Ag composite structures using rhodamine 6G (Rh6G) dye molecule as the model analyte. The SERS substrate is prepared by coating these structures on borosilicate glass substrate. ZnS particles of size 300 nm coated successively with Fe3O4 (40 nm thick) and Ag (20 nm thick) nanoparticles are found to be capable of detecting even 10‑11 M concentration of Rh6G. Obtained results are compared with SERS activity of ZnS@Ag particles which could detect only up to 10‑8 M of Rh6G. It is observed that inclusion of Fe3O4 layer increases SERS enhancement by a factor of 102 compared to that of ZnS@Ag. SERS substrates fabricated out of ZnS@Fe3O4@Ag particles resulted in SERS enhancement factor (EF) of around 109 which is large enough for single molecule detection. Theoretical investigations on SERS activity of these structures are carried out using finite difference time domain (FDTD) method. SERS EFs obtained using FDTD are found to be in good agreement with experimental results.

  9. Effect of nanographene platelets (NGP) surface area on organic dye adsorption using Fe3O4-NGP composites

    NASA Astrophysics Data System (ADS)

    Taufik, A.; Saleh, R.

    2016-11-01

    Fe3O4-NanoGraphene Platelets (NGP) composites with different surface area were successfully synthesized using sol gel method. The inverse cubic spinel structures as well as graphitic like structure from NGP were detected using X-Ray Diffraction (XRD) Measurement, while the ferromagnetic behavior for all samples were detected using Vibrating Sample Magnetometry (VSM) measurement. The vibrational mode for all samples were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), and thermal stability for all samples were characterized using Thermogravimetric Analysis (TGA). The adsorption process were tested using methylene blue (MB) as a model of organic pollutant. The result showed that the higher NGP surface area could enhance the adsorption capacity of the samples. The kinetic model of adsorption shows that the adsorption process of Fe3O4-NGP materials followed the second order kinetic reaction. The reusability of adsorbent were also performed to analyze the stability of the adsorbent.

  10. Amphiphilic comblike polymers enhance the colloidal stability of Fe(3)O(4) nanoparticles.

    PubMed

    Kim, Myeongjin; Jung, Jaeyeon; Lee, Jonghwan; Na, Kyunga; Park, Subeom; Hyun, Jinho

    2010-03-01

    Stable colloidal dispersions of magnetite (Fe(3)O(4)) nanoparticles (MNPs) were obtained with the inclusion of an amphiphilic comblike polyethylene glycol derivative (CL-PEG) as an amphiphilic polymeric surfactant. Both the size and morphology of the resulting CL-PEG-modified MNPs could be controlled and were characterized by transmission electron microscopy (TEM). The interaction between MNPs and CL-PEG was confirmed by the presence of characteristic infrared absorption peaks, and the colloidal stability of the nanoparticle dispersion in water was evaluated by long-term observation of the dispersion using UV-visible spectroscopy. SQUID measurements confirmed the magnetization of CL-PEG-modified MNPs. The zeta potential of the CL-PEG-modified MNPs showed a dramatic conversion from positive to negative in response to the pH of the surrounding aqueous medium due to the presence of carboxyl groups at the surface. These carboxyl groups can be used to functionalize the MNPs with biomolecules for biotechnological applications. However, regardless of surface electrostatics, the flexible, hydrophilic side chains of CL-PEG-modified MNPs prevented the approach of adjacent nanoparticles, thereby resisting aggregation and resulting in a stable aqueous colloid. The cytotoxicity of MNPs and CL-PEG-modified MNPs was evaluated by a MTT assay.

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

    PubMed

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

    2015-06-01

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

  12. Fabrication of nano-Fe3O4 3D structure on carbon fibers as a microwave absorber and EMI shielding composite by modified EPD method

    NASA Astrophysics Data System (ADS)

    Gholampoor, Mahdi; Movassagh-Alanagh, Farid; Salimkhani, Hamed

    2017-02-01

    Recently, electromagnetic interference (EMI) shielding materials have absorbed a lot of attention due to a growing need for application in the area of electronic and wireless devices. In this study, a carbon-based EMI shielding composite was fabricated by electrophoretic deposition of Fe3O4 nano-particles on carbon fibers (CFs) as a 3D structure incorporated with an epoxy resin. Co-precipitation method was employed to synthesize Fe3O4 nano-particles. This as-synthesized Fe3O4 nano-powder was then successfully deposited on CFs using a modified multi-step electrophoretic deposition (EPD) method. The results of structural studies showed that the Fe3O4 nano-particles (25 nm) were successfully and uniformly deposited on CFs. The measured magnetic properties of as-synthesized Fe3O4 nano-powder and nano-Fe3O4/CFs composite showed that the saturation magnetization of bare Fe3O4 was decreased from Ms = 72.3 emu/g to Ms = 33.1 emu/g for nano-Fe3O4/CFs composite and also corecivity of Fe3O4 was increased from Hc = 4.9 Oe to Hc = 168 Oe for composite. The results of microwave absorption tests revealed that the reflection loss (RL) of an epoxy-based nano-Fe3O4/CFs composite are significantly influenced by layer thickness. The maximum RL value of -10.21 dB at 10.12 GHz with an effective absorption bandwidth about 2 GHz was obtained for the sample with the thickness of 2 mm. It also exhibited an EMI shielding performance of -23 dB for whole the frequency range of 8.2-12.4 GHz.

  13. Macroporous Fe3O4/carbon composite microspheres with a short Li+ diffusion pathway for the fast charge/discharge of lithium ion batteries.

    PubMed

    Choi, Seung Ho; Ko, You Na; Jung, Kyeong Youl; Kang, Yun Chan

    2014-08-25

    Macroporous Fe3O4/carbon composite and core-shell Fe3O4@carbon composite microspheres have been prepared by means of one-pot spray pyrolysis. The addition of polystyrene (PS) nanobeads to a spray solution containing an iron salt and poly(vinylpyrrolidone) (PVP) led to macroporous Fe3O4/carbon composite microspheres, the carbon and iron components of which are uniformly distributed over the entire composite microsphere. The pore-size distribution curve for the macroporous Fe3O4/carbon composite shows distinct peaks at around 10 and 80 nm. An electrode prepared from the macroporous Fe3O4/carbon composite microspheres showed better cycling and rate performances than an electrode formed from core-shell Fe3O4@carbon composite microspheres. The initial discharge and charge capacities of the macroporous Fe3O4/carbon composite microsphere electrode were determined to be 1258 and 908 mA h g(-1) at 2 A g(-1), respectively, and the corresponding initial coulombic efficiency was 72 %. The composite microsphere electrode cycled 500 times at 5 A g(-1) showed a high discharge capacity of 733 mA h g(-1).

  14. Synthesis for Magnetic Mesoporous Fe3O4-SiO2 Composites and Heterogeneous Fenton Degradation of Methyl Blue

    NASA Astrophysics Data System (ADS)

    Xie, Huanling; Zhang, Tengyun

    2014-12-01

    In this work, we presented a facile, one-step preparation for magnetic mesoporous Fe3O4-SiO2 composites under closely neutral conditions by an evaporation-induced self-assembly (EISA) and adding 1,3,5-TMB as co-solvent approach. The resulting samples were characterized by X-ray diffraction, N2 adsorption measurement, FT-IR and SEM. Magnetic mesoporous composites and H2O2 form heterogeneous Fenton in order to removal methylene blue as the dye wastewater model object. The catalysts showed high catalytic activity and stability in the decolorization of methlye blue.

  15. Competitive fluorescence assay for specific recognition of atrazine by magnetic molecularly imprinted polymer based on Fe3O4-chitosan.

    PubMed

    Liu, Guangyang; Li, Tengfei; Yang, Xin; She, Yongxin; Wang, Miao; Wang, Jing; Zhang, Min; Wang, Shanshan; Jin, Fen; Jin, Maojun; Shao, Hua; Jiang, Zejun; Yu, Hailong

    2016-02-10

    A novel fluorescence sensing strategy for determination of atrazine in tap water involving direct competition between atrazine and 5-(4,6-dichlorotriazinyl) aminofluorescein (5-DTAF), and which exploits magnetic molecularly imprinted polymer (MMIP), has been developed. The MMIP, based on Fe3O4-chitosan nanoparticles, was synthesized to recognize specific binding sites of atrazine. The recognition capability and selectivity of the MMIP for atrazine and other triazine herbicides was investigated. Under optimal conditions, the competitive reaction between 5-DTAF and atrazine was performed to permit quantitation. Fluorescence intensity changes at 515 nm was linearly related to the logarithm of the atrazine concentration for the range 2.32-185.4 μM. The detection limit for atrazine was 0.86μM (S/N=3) and recoveries were 77.6-115% in spiked tap water samples.

  16. A chemiluminescence biosensor based on the adsorption recognition function between Fe3O4@SiO2@GO polymers and DNA for ultrasensitive detection of DNA.

    PubMed

    Sun, Yuanling; Li, Jianbo; Wang, Yanhui; Ding, Chaofan; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

    2017-05-05

    In this work, a chemiluminescence (CL) biosensor was prepared for ultrasensitive determination of deoxyribonucleic acid (DNA) based on the adsorption recognition function between core-shell Fe3O4@SiO2 - graphene oxide (Fe3O4@SiO2@GO) polymers and DNA. The Fe3O4@SiO2@GO polymers were composed by GO and magnetite nanoparticles. And the core-shell polymers were confirmed by Scanning Electron Microscope (SEM), X-Ray Powder Diffraction (XRD) and Fourier Transform Infrared (FTIR). Then Fe3O4@SiO2@GO was modified by DNA. Based on the principle of complementary base, Fe3O4@SiO2@GO-DNA was introduced to the CL system and the selectivity, sensitivity of DNA detection was significantly improved. The adsorption properties of Fe3O4@SiO2@GO to DNA were researched through the adsorption equilibrium, adsorption kinetic and thermodynamics. Under optimized CL conditions, DNA could be assayed with the linear concentration range of 5.0×10(-12)-2.5×10(-11)mol/L. The detection limit was 1.7×10(-12)mol/L (3δ) and the relative standard deviation (RSD) was 3.1%. The biosensor was finally used for the determination of DNA in laboratory samples and recoveries ranged from 99% to 103%. The satisfactory results revealed the potential application of Fe3O4@SiO2@GO-DNA-CL biosensor in the diagnosis and the treatment of human genetic diseases.

  17. Surface modification of porous suspended ceramsite used for water treatment by activated carbon/Fe3O4 magnetic composites.

    PubMed

    Lu, Mang; Xia, Guang-Hua; Zhao, Xiao-Dong

    2013-01-01

    In this study, porous suspended ceramsite with a specific density close to that of water was prepared by high-temperature calcination using fly ash, feldspar, calcite, fired talc and kaolin as the raw materials. The ceramsite was modified by activated carbon/Fe3O4 magnetic composites. The optimum modification conditions determined by methylene blue adsorption experiment were: KOH/glucose ratio of 1.5:1, carbonization temperature of 400 degrees C, activation temperature of 850 degrees C, activation time of 1 h, and Fe3O4/KOH+glucose ratio of 1:10. The results demonstrated that the adsorption capacity of the modified ceramsite for methylene blue was significantly higher than that of the unmodified ones. The presence of the composites did not lead to significant decrease in the mechanical properties of the modified ceramsite. Moreover, the modified ceramsite showed good resistance towards acid and alkali. The modified ceramsite can be used as biocarrier and adsorbent for a wide range of contaminants in water and can subsequently be removed from the medium by a simple magnetic procedure.

  18. Monodisperse magnetizable silica composite particles from heteroaggregate of carboxylic polystyrene latex and Fe(3)O(4) nanoparticles.

    PubMed

    Lu, Ziyang; Qin, Yaqiong; Fang, Jianyong; Sun, Jing; Li, Jun; Liu, Fengqi; Yang, Wensheng

    2008-02-06

    Monodisperse magnetizable silica composite particles were prepared from heteroaggregates of carboxylic polystyrene latex and Fe(3)O(4) nanoparticles. It was found that the heteroaggregation of the carboxylic latex and Fe(3)O(4) nanoparticles is dependent on the pH of the solution. At low pH value (pH = 2-4), the aggregation proceeds effectively due to opposite charges on the surfaces of the latex and the magnetic nanoparticles. At high pH value (pH>8), no aggregation was observed due to the negative charge on both the surface of the latex and the magnetic nanoparticles. The heteroaggregate of the latex and magnetic nanoparticles was found to be stable in a wide range of pH values, due to the existence of coordination interactions at the interface of the latex and magnetic nanoparticles. After silica layer coating on the heteroaggregate by the Stöber process and removal of the latex by calcination, hollow monodisperse magnetizable silica composite particles are obtained.

  19. Efficient use of Fe metal as an electron transfer agent in a heterogeneous Fenton system based on Fe0/Fe3O4 composites.

    PubMed

    Moura, Flávia C C; Araujo, Maria Helena; Costa, Regina C C; Fabris, José D; Ardisson, José D; Macedo, Waldemar A A; Lago, Rochel M

    2005-08-01

    In this work a novel heterogeneous Fenton system based on Fe(0)/Fe3O4 composites is described. The composites with several Fe(0)/Fe3O4 ratios were prepared by two different methods, i.e. mechanical alloying of Fe(0) and Fe3O4 powders and controlled reduction of Fe3O4 with H2. Reaction studies and detailed Conversion Electron Mössbauer surface characterization of the composites Fe(0)/Fe3O4, Fe(0), Fe3O4, alpha-Fe2O3 and gamma-Fe2O3 suggested that Fe2+surf species are essential to produce an active Fenton system. Kinetic studies for the oxidation of the dye methylene blue, used as an organic model molecule, and for the peroxide decomposition suggest that the reactions proceed via HO* radicals generated from Fe2+surf species and H2O2 in a Fenton like mechanism. The increase in activity caused by the addition of Fe(0) is discussed in terms of a creation of Fe2+surf species during the preparation of the composite and by an electron transfer mechanism from Fe(0) to Fe3+surf during the Fenton reaction to regenerate the Fe2+surf active species.

  20. A novel electrochemical biosensor based on Fe3O4 nanoparticles-polyvinyl alcohol composite for sensitive detection of glucose.

    PubMed

    Sanaeifar, Niuosha; Rabiee, Mohammad; Abdolrahim, Mojgan; Tahriri, Mohammadreza; Vashaee, Daryoosh; Tayebi, Lobat

    2017-02-15

    In this research, a new electrochemical biosensor was constructed for the glucose detection. Iron oxide nanoparticles (Fe3O4) were synthesized through co-precipitation method. Polyvinyl alcohol-Fe3O4 nanocomposite was prepared by dispersing synthesized nanoparticles in the polyvinyl alcohol (PVA) solution. Glucose oxidase (GOx) was immobilized on the PVA-Fe3O4 nanocomposite via physical adsorption. The mixture of PVA, Fe3O4 nanoparticles and GOx was drop cast on a tin (Sn) electrode surface (GOx/PVA-Fe3O4/Sn). The Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD). Also, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) techniques were utilized to evaluate the PVA-Fe3O4 and GOx/PVA-Fe3O4 nanocomposites. The electrochemical performance of the modified biosensor was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Presence of Fe3O4 nanoparticles in the PVA matrix enhanced the electron transfer between enzyme and electrode surface and the immobilized GOx showed excellent catalytic characteristic toward glucose. The GOx/PVA-Fe3O4/Sn bioelectrode could measure glucose in the range from 5 × 10(-3) to 30 mM with a sensitivity of 9.36 μA mM(-1) and exhibited a lower detection limit of 8 μM at a signal-to-noise ratio of 3. The value of Michaelis-Menten constant (KM) was calculated as 1.42 mM. The modified biosensor also has good anti-interfering ability during the glucose detection, fast response (10 s), good reproducibility and satisfactory stability. Finally, the results demonstrated that the GOx/PVA-Fe3O4/Sn bioelectrode is promising in biosensor construction.

  1. Synthesis of Fe3O4-ZnS/AgInS2 composite nanoparticles using a hydrophobic interaction.

    PubMed

    Choi, Kang Sik; Bang, Bo Keuk; Bae, Pan Kee; Kim, Yong-Rok; Kim, Chang Hae

    2013-03-01

    Magnetic nanoparticles and fluorescent quantum dots (QDs) can make many effective applications in biomedical system. Here, we demonstrated one way of synthetic method and its surface modification to use for biomedical applications. Fe3O4 nanoparticles are well known as magnetic materials and its magnetic property can be used in magnetic resonance imaging (MRI), cell detection. QDs as a fluorescent probes, make cell labeling and in vivo imaging possible. ZnS/AgInS2 QDs have a lower toxicity than other QDs (CdSe, CdTe, CdS). We combined two nanoparticles by hydrophobic interaction in their ligands. The prepared fluorescent magnetic composite particles were modified with CTAB-TEOS. The surface modified composite has a low cytotoxicity and these biocompatible particles will provide many possibilities in biomedical system.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  3. Two-phase magnetoconvection flow of magnetite (Fe3O4) nanoparticles in a horizontal composite porous annulus

    NASA Astrophysics Data System (ADS)

    Abbas, Zaheer; Hasnain, Jafar

    A numerical study is performed to examine the two-phase magnetoconvection and heat transfer phenomena of Fe3O4 -kerosene nanofluid flow in a horizontal composite porous annulus with an external magnetic field. The annulus is filled with immiscible fluids flowing between two concentric cylinders. The governing equations of the flow problem are obtained using Darcy-Brinkman model. Heat transfer is analyzed in the presence of viscous and Darcian dissipation terms. The shooting method is used as a tool to solve the obtained non-linear ordinary differential equations for the velocity and temperature profiles. The velocity and temperature distributions are analyzed and discussed under the influence of involved flow parameters with the aid of graphs. It is found that both velocity and temperature of fluid are decreased with ferroparticle volume fraction. In addition to that, it is also presented that the existence of magnetic field decreases the benefit of ferrofluids in heat transfer progression.

  4. Co-assembly of CdTe and Fe3O4 with molecularly imprinted polymer for recognition and separation of endocrine disrupting chemicals

    NASA Astrophysics Data System (ADS)

    Chang, Limin; Chen, Shaona; Chu, Jia; Li, Xin

    2013-11-01

    In this study, we present a general protocol to fabricate imprinting matrix co-loaded with CdTe quantum dots and Fe3O4 nanoparticles for the recognition of endocrine disrupting chemicals (EDCs). The resultant composites were characterized by transmission electron microscopy, fluorescence spectroscopy, and energy dispersive spectroscopy. The materials have been demonstrated to be characterized with spherical shape with a saturation magnetization value of 1.7 emu g-1. Furthermore, the rebinding experiments show that the resultant materials have greater affinity and selectivity towards p-nitrophenol (model EDCs) over structurally related compounds. We believe that the effective method proposed in this work might provide a platform to prepare magnetic and fluorescent molecularly imprinted polymers for the recognition and separation of EDCs.

  5. Facile synthesis of Fe3O4/g-C3N4/HKUST-1 composites as a novel biosensor platform for ochratoxin A.

    PubMed

    Hu, Shuisheng; Ouyang, Wenjun; Guo, Longhua; Lin, Zhenyu; Jiang, Xiaohua; Qiu, Bin; Chen, Guonan

    2017-06-15

    A fluorescent biosensor for ochratoxin A was fabricated on the basis of a new nanocomposite (Fe3O4/g-C3N4/HKUST-1 composites). Fe3O4/g-C3N4/HKUST-1 was synthesized in this work for the first time, which combined HKUST-1 with g-C3N4 to improve its chemical stability. Fe3O4/g-C3N4/HKUST-1 composites have strong adsorption capacity for dye-labeled aptamer and are able to completely quench the fluorescence of the dye through the photoinduced electron transfer (PET) mechanism. In the presence of ochratoxin A (OTA), it can bind with the aptamer with high affinity, causing the releasing of the dye-labeled aptamer from the Fe3O4/g-C3N4/HKUST-1 and therefore results in the recovery of fluorescence. The fluorescence intensity of the biosensor has a linear relationship with the OTA concentration in the range of 5.0-160.0ng/mL. The LOD of sensor is 2.57ng/mL (S/N=3). This fluorescence sensor based on the Fe3O4/g-C3N4/HKUST-1 composites has been applied to detect OTA in corn with satisfying results.

  6. Sub-micron-sized polyethylenimine-modified polystyrene/Fe3O4/chitosan magnetic composites for the efficient and recyclable adsorption of Cu(II) ions

    NASA Astrophysics Data System (ADS)

    Xiao, Changwei; Liu, Xijian; Mao, Shimin; Zhang, Lijuan; Lu, Jie

    2017-02-01

    A sub-micron-sized polyethylenimine(PEI)-modified polystyrene/Fe3O4/chitosan magnetic composite (PS/Fe3O4/CS-PEI) was developed as a novel adsorbent for the removal of Cu(II) ions from aqueous solutions. The PS/Fe3O4/CS-PEI microspheres with a diameter of ∼300 nm can be highly monodisperse and conveniently separated from suspensions by a magnet due to their excellent magnetism. When the PS/Fe3O4/CS-PEI microspheres were used as an absorbent for the absorption of Cu(II) ions, the adsorption isotherms and adsorption kinetics well fitted the Langmuir model and the pseudo-second-order model, respectively. The maximum adsorption capacity was about 204.6 mg g-1, which was higher than those of other chitosan adsorbents reported recently. The adsorption was considerably fast, reaching the equilibrium within 15 min. In addition, the adsorbed Cu(II) ions could be effectively desorbed using 0.1 mol L-1 NaOH solution, and the regeneration study proved that the composite microspheres could be repeatedly utilized without significant capacity loss after six cycles. All the results demonstrated that the synthesized sub-micron-sized magnetic PS/Fe3O4/CS-PEI composites can be used as an ideal adsorbent of Cu(II) ions for environmental cleanup applications.

  7. A Facile Electrophoretic Deposition Route to the Fe3O4/CNTs/rGO Composite Electrode as a Binder-Free Anode for Lithium Ion Battery.

    PubMed

    Yang, Yang; Li, Jiaqi; Chen, Dingqiong; Zhao, Jinbao

    2016-10-12

    Fe3O4 is regarded as an attractive anode material for lithium ion batteries (LIBs) due to its high theoretical capacity, natural abundance, and low cost. However, the poor cyclic performance resulting from the low conductivity and huge volume change during cycling impedes its application. Here we have developed a facile electrophoretic deposition route to fabricate the Fe3O4/CNTs (carbon nanotubes)/rGO (reduced graphene oxide) composite electrode, simultaneously achieving material synthesis and electrode assembling. Even without binders, the adhesion and mechanical firmness of the electrode are strong enough to be used for LIB anode. In this specific structure, Fe3O4 nanoparticles (NPs) interconnected by CNTs are sandwiched by rGO layers to form a robust network with good conductivity. The resulting Fe3O4/CNTs/rGO composite electrode exhibits much improved electrochemical performance (high reversible capacity of 540 mAh g(-1) at a very high current density of 10 A g(-1), and a remarkable capacity of 1080 mAh g(-1) can be maintained after 450 cycles at 1 A g(-1)) compared with that of commercial Fe3O4 NPs electrode.

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

    NASA Astrophysics Data System (ADS)

    Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  10. Synthesis, characterization, and application of Fe3O4/Ag magnetic composites for mercury removal from water

    NASA Astrophysics Data System (ADS)

    Elhouderi, Z. A.; Beesley, D. P.; Nguyen, T. T.; Lai, P.; Sheehan, K.; Trudel, S.; Prenner, E.; Cramb, D. T.; Anikovskiy, M.

    2016-04-01

    Engineered nanocomposites (NCs) have recently emerged as materials of great scientific and technological interest. In these materials, different components are combined to yield a nanoentity with desired properties not afforded by the constituent materials. Designing novel NCs and synthetic routes that enable controlling the size and functionalities remains an active area of research. Here, we present a two-step method of synthesizing Ag-Fe3O4 NCs with tunable sizes. Unlike previously reported structures, the prepared NCs do not have a familiar core-shell architecture. Instead, small Fe3O4 nanoparticles (NPs) are embedded in a larger silver matrix. The superparamagnetic Fe3O4 NPs endow the NC with magnetic properties, enabling easy separation from solution. The degree of the NC response to an external magnetic field can be controlled by varying the concentration of Fe3O4 NPs during the synthesis. The Ag matrix serves to protect the embedded Fe3O4 NPs from degradation and can be used for further functionalization of the NCs with different sulfhydryl containing linkers. To demonstrate utility, we show how decorating the outer layer of the Ag NC with diphenyl-4,4‧-dithiol transforms the NCs into a water purifying system capable of sequestering highly toxic Hg2+ ions from solution magnetically.

  11. Synthesis and drug-loading properties of folic acid-modified superparamagnetic Fe3O4 hollow microsphere core/mesoporous SiO2 shell composite particles

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Guo, Xue; Wei, Kaiwei; Wang, Lijuan; Yang, Dandan; Lai, Lifang; Cheng, Meiling; Liu, Qi

    2014-01-01

    A drug delivery system, which not only has superparamagnetic property, higher surface area but also has targeting function, has been developed. The core/shell structural magnetic magnetite mesoporous silica microspheres with amine groups (Fe3O4-SiO2-NH2) were first fabricated by a one-pot direct co-condensation method, then folic acid-modified magnetic mesoporous silica composite microspheres (Fe3O4-SiO2-NHFA) were obtained by the bonding of the Fe3O4-SiO2-NH2 with folic acid as targeted molecule. The resultant composite microspheres were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, low temperature nitrogen adsorption-desorption, and vibrating sample magnetometer. A well-known inflammational drug ibuprofen was used as a model drug to assess the loading and releasing behavior of the composite microspheres. Fe3O4-SiO2-NHFA system exhibits magnetic properties typical for superparamagnetic material with a higher saturation magnetization value of about 41.2 emu/g and has better capacity of drug storage (32.0 %) and sustained drug-release property. So this system has potential applications in biomedical field.

  12. Potential application of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) environmental contaminants.

    PubMed

    Dos Santos Coelho, Flávia; Ardisson, José Domingos; Moura, Flávia C C; Lago, Rochel M; Murad, Enver; Fabris, José Domingos

    2008-03-01

    We describe the use of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) species in aqueous medium. The composites were prepared by simple mechanical alloying of metallic iron and magnetite in different proportions, i.e. Fe(0) 25, 50, 75 and 90wt%. While after 3h of reaction pure Fe(0) and pure Fe3O4 showed only a low reduction efficiency of 15% and 25% Cr(VI) conversion, respectively, the composites, in particular Fe(0)(25wt%)/Fe3O4, showed a remarkable activity with ca. 65% Cr(VI) conversion. Kinetic experiments showed a high reaction rate during the first 3h, which subsequently decreased strongly, probably due to a pH increase from 6 to 8. Experiments with composites based on Fe(0)/alpha-Fe2O3, Fe(0)/gamma-Fe2O3 and Fe(0)/FeOOH showed very low activities, suggesting that Fe(oct)2+ in the magnetite structure plays an important role in the reaction. Scanning and high resolution electron microscopies and Mössbauer spectra (transmission and conversion electron Mössbauer spectroscopy) indicated that the mechanical alloying process promotes a strong interaction and interface between the metallic and oxide phases, with the Fe(0) particles completely covered by Fe3O4 particles. The high efficiency of the composite Fe(0)/Fe3O4 for Cr(VI) reduction is discussed in terms of a special mechanism where an electron is transferred from Fe(0) to magnetite to reduce Fe(oct)3+ to Fe(oct)2+, which is active for Cr(VI) reduction.

  13. Synergistic effect of static magnetic field and HA-Fe3O4 magnetic composites on viability of S. aureus and E. coli bacteria.

    PubMed

    Bajpai, Indu; Balani, Kantesh; Basu, Bikramjit

    2014-04-01

    In addressing the issue of prosthetic infection, this work demonstrated the synergistic effect of the application of static magnetic field (SMF) and ferrimagnetic substrate properties on the bactericidal property in vitro. This aspect was studied using hydroxyapatite (HA)-xFe3 O4 (x=10, 20, and 40 wt.%) substrates, which have different saturation magnetization properties. During bacteria culture experiments, 100 mT SMF was applied to growth medium (with HA-xFe3 O4 substrate) in vitro for 30, 120, and 240 min. A combination of MTT assay, membrane rupture assays, live/dead assay, and fluorescence microscopic analysis showed that the bactericidal effect of SMF increases with the exposure duration as well as increasing Fe3 O4 content in biomaterial substrates. Importantly, the synergistic bactericidal effect was found to be independent of bacterial cell type, as similar qualitative trend is measured with both gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus) strains. The reduction in E. coli viability was 83% higher on HA-40 Wt % Fe3 O4 composite after 4 h exposure to SMF as compared to nonexposed control. Interestingly, any statistically significant difference in ROS was not observed in bacterial growth medium after magnetic field exposure, indicating the absence of ROS enhancement due to magnetic field. Overall, this study illustrates significant role being played by magnetic substrate compositions towards bactericidal property than by magnetic field exposure alone.

  14. The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

    DOE PAGES

    Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; ...

    2016-12-15

    In two series of magnetite (Fe3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe3O4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe3O4 composite containing the largest weight fraction ofmore » PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe3O4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

  15. Monodisperse magnetite (Fe3O4) nanoparticles modified with water soluble polymers for the diagnosis of breast cancer by MRI method

    NASA Astrophysics Data System (ADS)

    Rezayan, Ali Hossein; Mousavi, Majid; Kheirjou, Somayyeh; Amoabediny, Ghasem; Ardestani, Mehdi Shafiee; Mohammadnejad, Javad

    2016-12-01

    In this study, magnetic nanoparticles (MNPs) were synthesized via co-precipitation method. To enhance the biocompatibility and colloidal stability of the synthesized nanoparticles, they were modified with carboxyl functionalized PEG via dopamine (DPA) linker. Both modified and unmodified Fe3O4 nanoparticles exhibited super paramagnetic behavior (particle size below 20 nm). The saturation magnetization (Ms) of PEGdiacid-modified Fe3O4 was 45 emu/g, which was less than the unmodified Fe3O4 nanoparticles (70 emu/g). This difference indicated that PEGdiacid polymer was immobilized on the surface of Fe3O4 nanoparticles successfully. To evaluate the efficiency of the resulting nanoparticles as contrast agents for magnetic resonance imaging (MRI), different concentration of MNPs and different value of echo time TE were investigated. The results showed that by increasing the concentration of the nanoparticles, transverse relaxation time (T2) decreased, which subsequently resulted in MR signal enhancement. T2-weighted MR images of the different concentration of MNPs in different value of echo time TE indicated that MR signal intensity increased with increase in TE value up to 66 and then remained constant. The cytotoxicity effect of the modified and unmodified nanoparticles was evaluated in three different concentrations (12, 60 and 312 mg l-1) on MDA-MB-231 cancer cells for 24 and 48 h. In both tested time (24 and 48 h) for all three samples, the modified nanoparticles had long life time than unmodified nanoparticles. Cellular uptake of modified MNPs was 80% and reduced to 9% by the unmodified MNPs.

  16. Adsorption of methylene blue using Fe3O4/CuO/ZnO/ nanographene platelets (NGP) composites with various NGP concentration

    NASA Astrophysics Data System (ADS)

    Tju, H.; Taufik, A.; Saleh, R.

    2016-11-01

    This study will examine the use of Fe3O4/CuO/ZnO nanocomposites that have been modified by Nanographene Platelets (NGP) as an adsorbent to degrade organic dye waste Methylene Blue (MB). The nanocomposites were synthesized using the sol-gel method then combined with three variatons of NGP weight percents by simple hydrothermal method. The Fe3O4/CuO/ZnO/NGP composites were characterized using the X-Ray Diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR), Energy Dispersive X-Ray (EDX), Thermogravimetric Analysis (TGA) and Vibrating Sample Magnetometer (VSM). The composites exhibit ferromagnetic behaviour. The presence of hexagonal wurtzite of ZnO, monoclinic of CuO and cubic spinel of Fe3O4 were found in the composites. The graphitic-like structure represents the presence of the NGP in the composites. However, the addition of NGP weight percent reduces the thermal stability of the composites. The adsorption capability of the composites are analyzed by observing the degradation of organic dye Methylene Blue (MB) under dark condition. The NGP addition of 15 wt% show the best result of the composites to degrade Methylene Blue in alkaline condition. Adsorption mechanism of the composites with NGP addition tend to follow the model Langmuir adsorption kinetic models.

  17. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves.

    PubMed

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-02-23

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5-20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures.

  18. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves

    NASA Astrophysics Data System (ADS)

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-02-01

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5–20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures.

  19. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves

    PubMed Central

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-01-01

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5–20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures. PMID:26902260

  20. A Novel Nanofilm Sensor Based on Poly-(Alizarin Red)/Fe3O4 Magnetic Nanoparticles-Multiwalled Carbon Nanotubes Composite Material for Determination of Nitrite.

    PubMed

    Qu, Jianying; Dong, Ying; Yong, Wang; Lou, Tongfang; Du, Xueping; Qu, Jianhang

    2016-03-01

    Fe3O4 magnetic nanoparticles were synthesized by chemical co-precipitation with sodium citrate as surfactant and were characterized by FT-IR spectrometer, X-ray diffraction and transmission electron microscopy. A novel nitrite sensor was fabricated by electropolymerization of alizarin red on the surface of glassy carbon electrode modified with Fe3O4-multiwalled carbon nanotubes composite nanofilm. Under the optimal experimental conditions, it was showed that the proposed sensor exhibited good electrocatalytic activity to the oxidation of nitrite, and the peak current increased linearly with the nitrite concentration from 9.64 x 10(-6) mol x L(-1) to 1.30 x 10(-3) mol x L(-1) (R = 0.9976) with a detection limit of 1.19 x 10(-6) mol x L(-1) (S/N = 3). This sensor showed excellent sensitivity, wide linear range, stability and repeatability for nitrite determination with potential applications.

  1. Magnetic Fe3O4-graphene composites as targeted drug nanocarriers for pH-activated release.

    PubMed

    Fan, Xiujuan; Jiao, Guozheng; Zhao, Wei; Jin, Pengfei; Li, Xin

    2013-02-07

    A novel nanocarrier of magnetic Fe(3)O(4)-graphene nanocomposites (MGNs) was proposed as an effective drug delivery system for cancer treatment. The nanocarrier was synthesized by covalently attaching modified Fe(3)O(4) nanoparticles onto water-soluble graphene sheets via the formation of an amide bond with the aid of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide. The obtained MGNs exhibited excellent dispersibility and stability in aqueous solution and they also exhibited superparamagnetic properties with a saturation magnetization of 23.096 emu g(-1). An efficient loading of 5-fluorouracil (5-FU) on MGNs as high as 0.35 mg mg(-1) was obtained. Furthermore, the in vitro drug release of 5-FU was examined in pH 6.9 and pH 4.0 buffers at 37 °C, and showed strong pH dependence. Transmission electron microscope observations revealed that MGNs can be internalized efficiently by HepG2 cells. More importantly, the cytotoxicity evaluation shows that the resulting MGNs exhibit excellent biocompatibility. The as-prepared nanocarrier system combined the advantages of the superparamagnetic iron oxide nanoparticles and water-soluble graphene sheets, which will find many potential applications in biomedicine and biomaterials.

  2. Magnetic Fe3O4-graphene composites as targeted drug nanocarriers for pH-activated release

    NASA Astrophysics Data System (ADS)

    Fan, Xiujuan; Jiao, Guozheng; Zhao, Wei; Jin, Pengfei; Li, Xin

    2013-01-01

    A novel nanocarrier of magnetic Fe3O4-graphene nanocomposites (MGNs) was proposed as an effective drug delivery system for cancer treatment. The nanocarrier was synthesized by covalently attaching modified Fe3O4 nanoparticles onto water-soluble graphene sheets via the formation of an amide bond with the aid of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide. The obtained MGNs exhibited excellent dispersibility and stability in aqueous solution and they also exhibited superparamagnetic properties with a saturation magnetization of 23.096 emu g-1. An efficient loading of 5-fluorouracil (5-FU) on MGNs as high as 0.35 mg mg-1 was obtained. Furthermore, the in vitro drug release of 5-FU was examined in pH 6.9 and pH 4.0 buffers at 37 °C, and showed strong pH dependence. Transmission electron microscope observations revealed that MGNs can be internalized efficiently by HepG2 cells. More importantly, the cytotoxicity evaluation shows that the resulting MGNs exhibit excellent biocompatibility. The as-prepared nanocarrier system combined the advantages of the superparamagnetic iron oxide nanoparticles and water-soluble graphene sheets, which will find many potential applications in biomedicine and biomaterials.

  3. Degradation of p-Nitrophenol using magnetic Fe(0)/Fe3O4/Coke composite as a heterogeneous Fenton-like catalyst.

    PubMed

    Wan, Dong; Li, Wenbing; Wang, Guanghua; Lu, Lulu; Wei, Xiaobi

    2017-01-01

    A Coke supported Fe3O4 and Fe(0) composite (Fe(0)/Fe3O4/Coke) was prepared for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the Fenton degradation of p-Nitrophenol (p-NP). A four factor Box-Behnken design (BBD) coupled with response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely Fe(0)/Fe3O4/Coke dosage, reaction temperature, initial pH and H2O2 concentration, on the removal efficiency of p-NP. A significant quadratic model (p-value<0.0001, R(2)=0.9952) was derived using analysis of variance (ANOVA). Optimum conditions were determined to be 1.3g/L catalyst, 32°C, pH3.1 and 11.3mM H2O2. 100% of p-NP (100mg/L) conversion and 81% of COD removal were achieved after 120min of reaction time, respectively, under the optimum conditions, which agreed well with the modeling prediction. The recyclability of Fe(0)/Fe3O4/Coke was also investigated after three successive runs, in which p-NP degradation performances showed a slight difference with the first oxidation cycle with an acceptable iron leaching. Moreover, according to the main intermediate products identified by gas chromatography-mass spectrometry (GC-MS), a possible pathway of p-NP degradation was proposed based on hydrogen radicals ([H]) or hydroxyl radicals (•OH) mechanism.

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

    PubMed Central

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

    2014-01-01

    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

  5. High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

    PubMed Central

    Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

    2014-01-01

    The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

  6. Adsorption of drinking water fluoride on a micron-sized magnetic Fe3O4@Fe-Ti composite adsorbent

    NASA Astrophysics Data System (ADS)

    Zhang, Chang; Li, Yingzhen; Wang, Ting-Jie; Jiang, Yanping; Wang, Haifeng

    2016-02-01

    A micron-sized magnetic adsorbent (MMA) for fluoride removal from drinking water was prepared by spray drying and subsequent calcination of a magnetic Fe3O4@Fe-Ti core-shell nanoparticle slurry. The MMA granules had high mechanical strength and stability against water scouring, can be easily separated from the water by a magnet, and had a high selectivity for fluoride versus common co-existing ions and high fluoride removal efficiency in a wide range of initial pH of 3-11. Abundant hydroxyl groups on the MMA surface acted as the active sites for fluoride adsorption, which resulted in a high affinity of the MMA for fluoride. The pH in the adsorption process affected the adsorption significantly. At neutral initial pH, the adsorption isotherm was well fitted with the Langmuir model, and the maximum adsorption capacity reached a high value of 41.8 mg/g. At a constant pH of 3, multilayer adsorption of fluoride occurred due to the abundant positive surface charges on the MMA, and the adsorption isotherm was well fitted with the Freundlich model. The MMA had a fast adsorption rate, and adsorption equilibrium was achieved within 2 min. The adsorption kinetics followed a quasi-second order model. The regeneration of the MMA was easy and fast, and can be completed within 2 min. After 10 recycles, the fluoride removal efficiency of the MMA still remained high. These properties showed that the MMA is a promising adsorbent for fluoride removal.

  7. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres with controlled shell thickness and its releasing property for phenolphthalein.

    PubMed

    Zhang, Baoliang; Zhang, Hepeng; Fan, Xinlong; Li, Xiangjie; Yin, Dezhong; Zhang, Qiuyu

    2013-05-15

    In this work, Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) (Fe3O4/P(AA-MMA-NIPAm)) thermoresponsive magnetic composite microspheres have been prepared by controlled radical polymerization in the presence of 1,1-diphenylethene (DPE). The shell thickness of thermosensitive polymer (PNIPAm), which was on the surface of the microspheres, can be controlled by using DPE method. The morphology and thermosensitive properties of the composite microspheres, polymerization mechanism of the shell were characterized by TEM, FTIR, VSM, Laser Particle Sizer, TGA, NMR, and GPC. The microspheres with narrow particle size distribution show high saturation magnetization and superparamagnetism. The thermosensitive properties of the composite microspheres can be adjusted indirectly via controlling the addition amount of monomer (NIPAm) in the second step during controlled radical polymerization. Phenolphthalein was chosen as a model drug to investigate drug release behavior of the thermoresponsive magnetic composite microspheres with different shell thickness. Controlled drug release testing reveals that the release behavior depends on the thickness of polymer on the surface of the microspheres.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  9. Facile one-pot fabrication of nano-Fe3O4/carboxyl-functionalized baker's yeast composites and their application in methylene blue dye adsorption

    NASA Astrophysics Data System (ADS)

    Du, Zongjun; Zhang, Yue; Li, Zhengjie; Chen, Hui; Wang, Ying; Wang, Guangtu; Zou, Ping; Chen, Huaping; Zhang, Yunsong

    2017-01-01

    Nano-Fe3O4/carboxyl-functionalized baker's yeast composites (NF/CF-BYs) were prepared for the first time based on the ultrasonic cavitation assisted oxygen implosion method using single Fe2+ as iron source. The series of characterization analysis results showed that the obtained NF/CF-BYs had not only the superparamagnetic properties of nano-Fe3O4, but their surface also had plenty of functional groups (especially carboxyl groups) introduced by strong oxidization. The adsorption properties of NF/CF-BYs for methylene blue (MB) were also evaluated. The results displayed that the uptakes of NF/CF-BYs for MB were higher than that of pristine baker's yeast (P-BYs), and the adsorption process was followed by the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity of NF/CF-BYs for MB was estimated to be 141.75 mg g-1 at pH 6. The regeneration efficiency of the obtained NF/CF-BYs was attained to be more than 90%.

  10. Sonochemical synthesis of magnetic responsive Fe3O4@TMU-17-NH2 composite as sorbent for highly efficient ultrasonic-assisted denitrogenation of fossil fuel.

    PubMed

    Mirzaie, Abbas; Musabeygi, Tahereh; Afzalinia, Ahmad

    2016-08-10

    In this work, a novel magnetic responsive composite was fabricated by encapsulation of Fe3O4 nanoparticles into an amino-functionalized MOF (TMU-17-NH2) under ultrasound irradiation. The prepared materials were characterized by several techniques such as elemental analyses, PXRD, FT-IR, N2 adsorption, TGA and ICP. This composite has been applied to the adsorptive removal of nitrogen-contain compounds in model liquid fuel. The prepared composite demonstrates very good performance for the removal of NCCs. The maximum adsorption capacity of IND and QUI over prepared composite calculated 375.93 and 310.18mg·g(-1) at 25°C, respectively. The composite material is magnetically separable and reusable for several times.

  11. Removal of chromium(VI) and dye Alizarin Red S (ARS) using polymer-coated iron oxide (Fe3O4) magnetic nanoparticles by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Hanif, Sara; Shahzad, Asma

    2014-06-01

    The present research was conducted with an aim to develop such adsorbent system: polymer-coated magnetic nanoparticles which can remove heavy metal and dye from water of different concentration. Synthesis of magnetic iron oxide nanoparticles for contaminated water purification has been one of the outcomes of application of rapidly growing field of Nanotechnology in Environmental Science. In the present study, the efficiency of magnetic nanoparticles for removal of Cr(VI) and dye (alizarin) from water solutions of known concentrations were evaluated. The nanoparticles were prepared by co-precipitation method and characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Polymer-coated magnetic iron oxide nanoparticles carrying functional groups on their surface were synthesized by different methods for permanent magnet-assisted removal of heavy metal (chromium) and dye (Alizarin Red S) from water. The characterization showed that synthesized nanoparticles were in the size range of 10-50 nm. The adsorption capacities of the Fe3O4 using polyMETAC-coated particles for dye (Alizarin Red S) removal were 80-96 % and chromium 62-91 %. The chromium concentration was determined after magnetic separation using atomic absorption spectrophotometer and dye concentration was estimated with UV-visible spectrophotometer. Nanoparticles of polymer coated showed the highest removal capacity from water for metal and dye. The developed adsorbents had higher capacity for removal of heavy metal ions and dye.

  12. Synergistic Ternary Composite (Carbon/Fe3 O4 @Graphene) with Hollow Microspherical and Robust Structure for Li-Ion Storage.

    PubMed

    Li, Xingxing; Zheng, Xueying; Shao, Jie; Gao, Tian; Shi, Qiang; Qu, Qunting

    2016-01-04

    The electrode materials with hollow structure and/or graphene coating are expected to exhibit outstanding electrochemical performances in energy-storage systems. 2D graphene-wrapped hollow C/Fe3 O4 microspheres are rationally designed and fabricated by a novel facile and scalable strategy. The core@double-shell structure SPS@FeOOH@GO (SPS: sulfonated polystyrene, GO: graphene oxide) microspheres are first prepared through a simple one-pot approach and then transformed into C/Fe3 O4 @G (G: graphene) after calcination at 500 °C in Ar. During calcination, the Kirkendall effect resulting from the diffusion/reaction of SPS-derived carbon and FeOOH leads to the formation of hollow structure carbon with Fe3 O4 nanoparticles embedded in it. In the rationally constructed architecture of C/Fe3 O4 @G, the strongly coupled C/Fe3 O4 hollow microspheres are further anchored onto 2D graphene networks, achieving a strong synergetic effect between carbon, Fe3 O4 , and graphene. As an anode material of Li-ion batteries (LIBs), C/Fe3 O4 @G manifests a high reversible capacity, excellent rate behavior, and outstanding long-term cycling performance (1208 mAh g(-1) after 200 cycles at 100 mA g(-1) ).

  13. Cyclodextrin polymer/Fe3O4 nanocomposites as solid phase extraction material coupled with UV-vis spectrometry for the analysis of rutin

    NASA Astrophysics Data System (ADS)

    Gong, Aiqin; Ping, Wenhui; Wang, Jue; Zhu, Xiashi

    2014-03-01

    In this paper, carboxymethyl-hydroxypropyl-β-cyclodextrin polymer modified magnetic particles Fe3O4 (CM-HP-β-CDCP-MNPs) were prepared and applied to magnetic solid phase extraction of rutin combined with UV-visible spectrometry detection. The synthesized magnetic particles were characterized by element analysis, Fourier transform infrared spectra, thermal gravimetric analysis, and transmission electron microscopy. Several variables affecting the extraction and desorption of rutin such as pH, the amount of adsorbent, the type and volume of eluent, extraction and desorption time, and temperature were investigated. The maximum adsorption capacity was 67.0 mg g-1 for rutin with the equilibrium time of 30 min at room temperature, and the adsorbent could be reused for 10 times. A calibration curve was linear in the range of 0.05-8.00 μg mL-1 with a relative standard deviation of 2.9% (n = 5, c = 4.0 μg mL-1). The limit of detection was 7.0 ng mL-1. The interaction mechanism between the adsorbent and rutin was also studied. Feasibility of this method was validated by the analysis of rutin tablets and lotus plumule.

  14. Preparation of thermo and pH-responsive polymer@Au/Fe3O4 core/shell nanoparticles as a carrier for delivery of anticancer agent

    NASA Astrophysics Data System (ADS)

    Ghorbani, Marjan; Hamishehkar, Hamed; Arsalani, Naser; Entezami, Ali Akbar

    2015-07-01

    In this work, a thermo and pH-responsive poly- N-isopropylacrylamide-co-itaconic acid containing thiol side groups were successfully synthesized to prepare Doxorubicin-loaded polymer@Au/Fe3O4 core/shell nanoparticles (DOX-NPs). Copolymer and NPs were fully characterized by FT-IR, HNMR, photo-correlation spectroscopy, SEM, X-ray diffraction, vibrating-sample magnetometer, thermal gravimetric analysis, and UV-Vis spectroscopy. The stimuli-responsive characteristics of NPs were evaluated by in vitro release study in simulated cancerous environment. The biocompatibility and cytotoxic properties of NPs and DOX-NPs are explored by MTT method. The prepared NPs with the size of 50 nm showed paramagnetic characteristics with suitable and stable dispersion at physiological medium and high loading capacity (up to 55 %) of DOX. DOX-NPs yielded a pH- and temperature-triggered release of entrapped drugs at tumor tissue environment (59 % of DOX release) compared to physiological condition (20 % of DOX release) during 48 h. In vitro cytotoxicity studies indicated that the NPs showed no cytotoxicity on A549 cells at different amounts after incubation for 72 h confirming its suitability as a drug carrier. DOX-NPs, on the other hand, caused an efficient anticancer performance as verified by MTT assay test. It was concluded that developed NPs by us in this study may open the possibilities for targeted delivery of DOX to the cancerous tissues.

  15. The compositional, structural, and magnetic properties of a Fe3O4/Ga2O3/GaN spin injecting hetero-structure grown by metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Xu, Zhonghua; Huang, Shimin; Tang, Kun; Gu, Shulin; Zhu, Shunming; Ye, Jiandong; Xu, Mingxiang; Wang, Wei; Zheng, Youdou

    2016-12-01

    In this article, the authors have designed and fabricated a Fe3O4/Ga2O3/GaN spin injecting hetero-structure by metal-organic chemical vapor deposition. The compositional, structural, and magnetic properties of the hetero-structure have been characterized and discussed. From the characterizations, the hetero-structure has been successfully grown generally. However, due to the unintentional diffusion of Ga ions from Ga2O3/GaN layers, the most part of the nominal Fe3O4 layer is actually in the form of GaxFe3-xO4 with gradually decreased x values from the Fe3O4/Ga2O3 interface to the Fe3O4 surface. Post-annealing process can further aggravate the diffusion. Due to the similar ionic radius of Ga and Fe, the structural configuration of the GaxFe3-xO4 does not differ from that of pure Fe3O4. However, the ferromagnetism has been reduced with the incorporation of Ga into Fe3O4, which has been explained by the increased Yafet-Kittel angles in presence of considerable amount of Ga incorporation. A different behavior of the magnetoresistance has been found on the as-grown and annealed samples, which could be modelled and explained by the competition between the spin-dependent and spin-independent conduction channels. This work has provided detailed information on the interfacial properties of the Fe3O4/Ga2O3/GaN spin injecting hetero-structure, which is the solid basis for further improvement and application of the structure.

  16. Superparamagnetic Fe3 O4 @SiO2 core-shell composite nanoparticles for the mixed hemimicelle solid-phase extraction of benzodiazepines from hair and wastewater samples before high-performance liquid chromatography analysis.

    PubMed

    Esmaeili-Shahri, Effat; Es'haghi, Zarrin

    2015-12-01

    Magnetic Fe3 O4 /SiO2 composite core-shell nanoparticles were synthesized, characterized, and applied for the surfactant-assisted solid-phase extraction of five benzodiazepines diazepam, oxazepam, clonazepam, alprazolam, and midazolam, from human hair and wastewater samples before high-performance liquid chromatography with diode array detection. The nanocomposite was synthesized in two steps. First, Fe3 O4 nanoparticles were prepared by the chemical co-precipitation method of Fe(III) and Fe(II) as reaction substrates and NH3 /H2 O as precipitant. Second, the surface of Fe3 O4 nanoparticles was modified with shell silica by Stober method using tetraethylorthosilicate. The Fe3 O4 /SiO2 composite were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. To enhance their adsorptive tendency toward benzodiazepines, cetyltrimethylammonium bromide was added, which was adsorbed on the surface of the Fe3 O4 /SiO2 nanoparticles and formed mixed hemimicelles. The main parameters affecting the efficiency of the method were thoroughly investigated. Under optimum conditions, the calibration curves were linear in the range of 0.10-15 μgmL(-1) . The relative standard deviations ranged from 2.73 to 7.07%. The correlation coefficients varied from 0.9930 to 0.9996.

  17. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    PubMed

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-04

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.

  18. PEGylated FePt-Fe3O4 composite nanoassemblies (CNAs): in vitro hyperthermia, drug delivery and generation of reactive oxygen species (ROS).

    PubMed

    Sahu, Niroj Kumar; Gupta, Jagriti; Bahadur, Dhirendra

    2015-05-21

    Chemothermal therapy is widely used in clinical applications for the treatment of tumors. However, the major challenge is the use of a multifunctional nano platform for significant regression of the tumor. In this study, a simple synthesis of highly aqueous stable, carboxyl enriched, PEGylated mesoporous iron platinum-iron(ii,iii) oxide (FePt-Fe3O4) composite nanoassemblies (CNAs) by a simple hydrothermal approach is reported. CNAs exhibit a high loading capacity ∼90 wt% of the anticancer therapeutic drug, doxorubicin (DOX) because of its porous nature and the availability of abundant negatively charged carboxylic groups on its surface. DOX loaded CNAs (CNAs + DOX) showed a pH responsive drug release in a cell-mimicking environment. Furthermore, the release was enhanced by the application of a alternating current magnetic field. CNAs show no appreciable cytotoxicity in mouse fibroblast (L929) cells but show toxic effects in cervical cancer (HeLa) cells at a concentration of ∼1 mg mL(-1). A suitable composition of CNAs with a concentration of 2 mg mL(-1) can generate a hyperthermic temperature of ∼43 °C. Also, CNAs, because of their Fe and Pt contents, have an ability to generate reactive oxygen species (ROS) in the presence of hydrogen peroxide inside the cancer cells which helps to enhance its therapeutic effects. The synergistic combination of chemotherapy and ROS is very efficient for killing cancer cells.

  19. Fe2O3/Reduced Graphene Oxide/Fe3O4 Composite in Situ Grown on Fe Foil for High-Performance Supercapacitors.

    PubMed

    Zhao, Chongjun; Shao, Xiaoxiao; Zhang, Yuxiao; Qian, Xiuzhen

    2016-11-09

    A Fe2O3/reduced graphene oxide (RGO)/Fe3O4 nanocomposite in situ grown on Fe foil was synthesized via a simple one-step hydrothermal growth process, where the iron foil served as support, reductant of graphene oxide, Fe source of Fe3O4, and also the current collector of the electrode. When it directly acted as the electrode of a supercapacitor, as-synthesized Fe2O3/RGO/Fe3O4@Fe exhibited excellent electrochemical performance with a high capability of 337.5 mF/cm(2) at 20 mA/cm(2) and a superior cyclability with 2.3% capacity loss from the 600th to the 2000th cycle.

  20. 3-D graphene-supported mesoporous SiO2 @Fe3 O4 composites for the analysis of pesticides in aqueous samples by magnetic solid-phase extraction with high-performance liquid chromatography.

    PubMed

    Wang, Xuemei; Wang, Huan; Lu, Muxin; Ma, Xiaomin; Huang, Pengfei; Lu, Xiaoquan; Du, Xinzhen

    2016-05-01

    Three-dimensional graphene-supported mesoporous silica@Fe3 O4 composites (mSiO2 @Fe3 O4 -G) were prepared by modifying mesoporous SiO2 -coated Fe3 O4 onto hydrophobic graphene nanosheets through a simple adsorption co-condensation method. The obtained composites possess unique properties of large surface area (332.9 m(2) /g), pore volume (0.68 cm(3) /g), highly open pore structure with uniform pore size (31.1 nm), as well as good magnetic separation properties. The adsorbent (mSiO2 @Fe3 O4 -G) was used for the magnetic solid-phase extraction of seven pesticides with benzene rings in different aqueous samples before high-performance liquid chromatography. The main parameters affecting the extraction such as adsorbent amount, volume of elution solvent, time of extraction and desorption, salt effect, oscillation rate were investigated. Under the optimal conditions, this method provided low limits of detection (S/N = 3, 0.525-3.30 μg/L) and good linearity (5.0-1000 μg/L, R(2) > 0.9954). Method validation proved the feasibility of the developed adsorbent, which has a high extraction efficiency and excellent enhancement performance for pesticides in this study. The proposed method was successfully applied to real aqueous samples, and satisfactory recoveries ranging from 77.5 to 113.6% with relative standard deviations within 9.7% were obtained.

  1. Magnetic and structural characteristics of multiferroic Fe3O4/(Bi3.25Nd0.65Eu0.10)Ti3O12 composite thin films deposited by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kobune, Masafumi; Furotani, Ryosuke; Fujita, Satoshi; Kikuchi, Kazuki; Kikuchi, Takeyuki; Fujisawa, Hironori; Shimizu, Masaru; Fukumuro, Naoki

    2016-10-01

    Ferromagnetic magnetite (Fe3O4) thin films for magnetoelectric multiferroic applications were deposited on (200) (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT)/(101) Nb:TiO2 substrates by metalorganic chemical vapor deposition (MOCVD) using an iron(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionato) precursor as the iron source. The BNEuT film utilized as a ferroelectric template material was in the form of freestanding nanoplates with narrow spaces between them. The effects of deposition conditions such as the deposition time and substrate temperature on the magnetic and structural characteristics of the Fe3O4/BNEuT composite films were investigated. All the films consisted of mostly single-phase Fe3O4 with a cubic inverse-spinel structure. When deposition was carried out at temperatures of 400-420 °C, the filling rates of particles introduced into the narrow spaces between the BNEuT nanoplates exhibited high values of 76-89% including the amorphous phase. This suggested that the deposition in this temperature range made progress according to the growth mechanism of MOCVD in the surface reaction rate determining state. Room-temperature magnetic moment-magnetic field curves for Fe3O4 thin films deposited at 400-500 °C for 60 min exhibited narrow rectangular hysteresis loops, indicating typical soft magnetic characteristics.

  2. Synthesis, Characterization, and Study of In Vitro Cytotoxicity of ZnO-Fe3O4 Magnetic Composite Nanoparticles in Human Breast Cancer Cell Line (MDA-MB-231) and Mouse Fibroblast (NIH 3T3).

    PubMed

    Bisht, Gunjan; Rayamajhi, Sagar; Kc, Biplab; Paudel, Siddhi Nath; Karna, Deepak; Shrestha, Bhupal G

    2016-12-01

    Novel magnetic composite nanoparticles (MCPs) were successfully synthesized by ex situ conjugation of synthesized ZnO nanoparticles (ZnO NPs) and Fe3O4 NPs using trisodium citrate as linker with an aim to retain key properties of both NPs viz. inherent selectivity towards cancerous cell and superparamagnetic nature, respectively, on a single system. Successful characterization of synthesized nanoparticles was done by XRD, TEM, FTIR, and VSM analyses. VSM analysis showed similar magnetic profile of thus obtained MCPs as that of naked Fe3O4 NPs with reduction in saturation magnetization to 16.63 emu/g. Also, cell viability inferred from MTT assay showed that MCPs have no significant toxicity towards noncancerous NIH 3T3 cells but impart significant toxicity at similar concentration to breast cancer cell MDA-MB-231. The EC50 value of MCPs on MDA-MB-231 is less than that of naked ZnO NPs on MDA-MB-231, but its toxicity on NIH 3T3 was significantly reduced compared to ZnO NPs. Our hypothesis for this prominent difference in cytotoxicity imparted by MCPs is the synergy of selective cytotoxicity of ZnO nanoparticles via reactive oxygen species (ROS) and exhausting scavenging activity of cancerous cells, which further enhance the cytotoxicity of Fe3O4 NPs on cancer cells. This dramatic difference in cytotoxicity shown by the conjugation of magnetic Fe3O4 NPs with ZnO NPs should be further studied that might hold great promise for the development of selective and site-specific nanoparticles. Schematic representation of the conjugation, characterization and cytotoxicity analysis of Fe3O4-ZnO magnetic composite particles (MCPs).

  3. Investigation of the structure, elemental and phase compositions of Fe3O4-SiO2 composite layers by scanning electron microscopy, X-ray spectroscopy, and thermal nitrogen desorption methods

    NASA Astrophysics Data System (ADS)

    Al'myashev, V. I.; Gareev, K. G.; Ionin, S. A.; Levitskii, V. S.; Moshnikov, V. A.; Terukov, E. I.

    2014-11-01

    The composite layers formed by drying a Fe3O4-SiO2-based colloidal solution were studied. The colloidal solution was obtained by the precipitation of Fe3O4 in the presence of highly dispersed silicon dioxide synthesized by the sol-gel method from a tetraethoxysilane alcohol solution. The microstructure and composition of the layers were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, thermal nitrogen desorption, and Raman spectroscopy. The emphasis was placed on the study of phase transitions in iron oxides under laser radiation. It was found that the tetraethoxysilane content has a substantial influence on the ratio of iron oxide and silicon dioxide in the layer, the specific surface area of SiO2 powders, the threshold laser radiation power necessary to induce the Fe3O4 α -Fe2O3 phase transformation, and on the position of the maximum of the absorption band corresponding to the A 1 g vibrations in α-Fe2O3.

  4. Synthesis, Characterization, and Study of In Vitro Cytotoxicity of ZnO-Fe3O4 Magnetic Composite Nanoparticles in Human Breast Cancer Cell Line (MDA-MB-231) and Mouse Fibroblast (NIH 3T3)

    NASA Astrophysics Data System (ADS)

    Bisht, Gunjan; Rayamajhi, Sagar; KC, Biplab; Paudel, Siddhi Nath; Karna, Deepak; Shrestha, Bhupal G.

    2016-12-01

    Novel magnetic composite nanoparticles (MCPs) were successfully synthesized by ex situ conjugation of synthesized ZnO nanoparticles (ZnO NPs) and Fe3O4 NPs using trisodium citrate as linker with an aim to retain key properties of both NPs viz. inherent selectivity towards cancerous cell and superparamagnetic nature, respectively, on a single system. Successful characterization of synthesized nanoparticles was done by XRD, TEM, FTIR, and VSM analyses. VSM analysis showed similar magnetic profile of thus obtained MCPs as that of naked Fe3O4 NPs with reduction in saturation magnetization to 16.63 emu/g. Also, cell viability inferred from MTT assay showed that MCPs have no significant toxicity towards noncancerous NIH 3T3 cells but impart significant toxicity at similar concentration to breast cancer cell MDA-MB-231. The EC50 value of MCPs on MDA-MB-231 is less than that of naked ZnO NPs on MDA-MB-231, but its toxicity on NIH 3T3 was significantly reduced compared to ZnO NPs. Our hypothesis for this prominent difference in cytotoxicity imparted by MCPs is the synergy of selective cytotoxicity of ZnO nanoparticles via reactive oxygen species (ROS) and exhausting scavenging activity of cancerous cells, which further enhance the cytotoxicity of Fe3O4 NPs on cancer cells. This dramatic difference in cytotoxicity shown by the conjugation of magnetic Fe3O4 NPs with ZnO NPs should be further studied that might hold great promise for the development of selective and site-specific nanoparticles.

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

    PubMed

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

    2014-03-01

    Fe3O4 nanoparticles were modified with Hydroxypropyl-β-cyclodextrin (HP-β-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-β-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.

  6. Combined tween 20-stabilized gold nanoparticles and reduced graphite oxide-Fe3O4 nanoparticle composites for rapid and efficient removal of mercury species from a complex matrix.

    PubMed

    Shih, Ya-Chen; Ke, Chen-Yi; Yu, Cheng-Ju; Lu, Chi-Yu; Tseng, Wei-Lung

    2014-10-22

    This study describes a simple method for removing mercuric ions (Hg(2+)) from a high-salt matrix based on the use of Tween-20-stabilized gold nanoparticles (Tween 20-Au NPs) as Hg(2+) adsorbents and composites of reduced graphite oxide and Fe3O4 NPs as NP collectors. Citrate ions adsorbed on the surface of the Tween 20-Au NPs reduced Hg(2+) to Hg(0), resulting in the deposition of Hg(0) on the surface of the NPs. To circumvent time-consuming centrifugation and transfer steps, the Hg(0)-containing gold NPs were collected using reduced graphite oxide-Fe3O4 NP composites. Compared with the reported NP-based methods for removing Hg(2+), Tween 20-Au NPs offered the rapid (within 30 min), efficient (>99% elimination efficiency), durable (>10 cycles), and selective removal of Hg(2+), CH3Hg(+), and C2H5Hg(+) in a high-salt matrix without the interference of other metal ions. This was attributed to the fact that the dispersed Tween 20-Au NPs exhibited large surface-area-to-volume ratio to bind Hg(2+) through Hg(2+)-Au(+) metallophilic interactions in a high-salt matrix. The formation of graphite oxide sheets and reduced graphite oxide-Fe3O4 NP composites was demonstrated using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectrometry, and transmission electron microscopy. The mechanism of interaction between Tween 20-Au NPs and Hg(2+) was studied using visible spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.

  7. A novel magnetic nanoscaled Fe3O4/CeO2 composite prepared by oxidation-precipitation process and its application for degradation of orange G in aqueous solution as Fenton-like heterogeneous catalyst.

    PubMed

    Gan, Guoqiang; Liu, Juan; Zhu, Zhixi; Yang, Ziran; Zhang, Conglu; Hou, Xiaohong

    2017-02-01

    In this work, magnetic nanoparticles (MNPs) Fe3O4/CeO2 were firstly synthesized using three different preparation methods, including coprecipitation, impregnation oxidation-precipitation and impregnation reduction-precipitation, respectively. The catalytic activities of Fe3O4/CeO2 MNPs, prepared by above three methods, were compared systematically in terms of the degradation of orange G (OG). The impregnation oxidation-precipitation process was economical and maneuverable due to the usage of air, no need of nitrogen protection and higher utilization efficiency of iron. Response surface methodology based on central composite design were used to investigate the individual and interactive effects of three process parameters on the OG degradation, i.e. the initial pH of the solution, the dosage of H2O2 and the initial concentration of OG. Under the optimal conditions of pH 2.5, H2O2 30 mM, OG 50 mg L(-1), catalyst 2.0 g L(-1) and 35 °C, the degradation percentage of OG was 98.2% within 120 min, which agreed well with the modeling prediction (R(2) = 0.9984, and Adj-R(2) = 0.9969). And the degradation reaction well followed the first-order kinetic with R(2) = 0.9969. The Fe3O4/CeO2-OX MNPs showed high catalytic activity, stability and reusability in the degradation of OG.

  8. A Fe3O4/FeAl2O4 composite coating via plasma electrolytic oxidation on Q235 carbon steel for Fenton-like degradation of phenol.

    PubMed

    Wang, Jiankang; Yao, Zhongping; Yang, Min; Wang, Yajing; Xia, Qixing; Jiang, Zhaohua

    2016-08-01

    The Fe3O4/FeAl2O4 composite coatings were successfully fabricated on Q235 carbon steel by plasma electrolytic oxidation technique and used to degrade phenol by Fenton-like system. XRD, SEM, and XPS indicated that Fe3O4 and FeAl2O4 composite coating had a hierarchical porous structure. The effects of various parameters such as pH, phenol concentration, and H2O2 dosage on catalytic activity were investigated. The results indicated that with increasing of pH and phenol content, the phenol degradation efficiency was reduced significantly. However, the degradation rate was improved with the addition of H2O2, but dropped with further increasing of H2O2. Moreover, 100 % removal efficiency with 35 mg/L phenol was obtained within 60 min at 303 K and pH 4.0 with 6.0 mmol/L H2O2 on 6-cm(2) iron oxide coating. The degradation process consisted of induction period and rapid degradation period; both of them followed pseudo-first-order reaction. Hydroxyl radicals were the mainly oxidizing species during phenol degradation by using n-butanol as hydroxyl radical scavenger. Based on Fe leaching and the reaction kinetics, a possible phenol degradation mechanism was proposed. The catalyst exhibited excellent stability.

  9. Fluorescence analysis of 6-mercaptopurine with the use of a nano-composite consisting of BSA-capped Au nano-clusters and core-shell Fe3O4-SiO2 nanoparticles.

    PubMed

    Li, Zhuo; Wang, Yong; Ni, Yongnian; Kokot, Serge

    2015-08-15

    A magnetic and fluorescent nano-composite was prepared. It comprised of a core of Fe3O4 nanoparticles (NPs), a silica shell and satellitic Au nano-clusters (AuNCs) capped with bovine serum albumin (BSA). This nano-composite has many desirable properties, e.g. magnetism, red emission, high water solubility, and high resistance to photo-bleaching. On addition of the analyte, 6-mercaptopurine (6-MP) or indeed other similar thiols, AuNCs formed aggregates because the existing cross-links within the Fe3O4 NPs@SiO2 and AuNC structure were broken in favor of the gold-thiol bonds. On suitable irradiation of such aggregates, red fluorescence was emitted at 613 nm. It decreased significantly as a function of the added 6-MP concentration, and the quenching ratio (F0 - F) / F0 was related linearly to the concentration of 6-MP in the range of 0.01 to 0.5 μmol L(-1). The detection limit was 0.004 μmol L(-1) (S/N=3). The method was strongly selective for 6-MP in the presence of oxidants, phenols, heavy-metal ions, and especially bio-thiols.

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

    PubMed

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

    2015-05-13

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

  11. Magnetic biodegradable Fe3O4/CS/PVA nanofibrous membranes for bone regeneration.

    PubMed

    Wei, Yan; Zhang, Xuehui; Song, Yu; Han, Bing; Hu, Xiaoyang; Wang, Xinzhi; Lin, Yuanhua; Deng, Xuliang

    2011-10-01

    In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. The aim of this study is to develop magnetic biodegradable fibrous materials with potential use in bone regeneration. Magnetic biodegradable Fe(3)O(4)/chitosan (CS)/poly vinyl alcohol (PVA) nanofibrous membranes were achieved by electrospinning with average fiber diameters ranging from 230 to 380 nm and porosity of 83.9-85.1%. The influences of polymer concentration, applied voltage and Fe(3)O(4) nanoparticles loading on the fabrication of nanofibers were investigated. The polymer concentration of 4.5 wt%, applied voltage of 20 kV and Fe(3)O(4) nanoparticles loading of lower than 5 wt% could produce homogeneous, smooth and continuous Fe(3)O(4)/CS/PVA nanofibrous membranes. X-ray diffraction (XRD) data confirmed that the crystalline structure of the Fe(3)O(4), CS and PVA were maintained during electrospinning process. Fourier transform infrared spectroscopy (FT-IR) demonstrated that the Fe(3)O(4) loading up to 5 wt% did not change the functional groups of CS/PVA greatly. Transmission electron microscopy (TEM) showed islets of Fe(3)O(4) nanoparticles evenly distributed in the fibers. Weak ferrimagnetic behaviors of membranes were revealed by vibrating sample magnetometer (VSM) test. Tensile test exhibited Young's modulus of membranes that were gradually enhanced with the increase of Fe(3)O(4) nanoparticles loading, while ultimate tensile stress and ultimate strain were slightly reduced by Fe(3)O(4) nanoparticles loading of 5%. Additionally, MG63 human osteoblast-like cells were seeded on the magnetic nanofibrous membranes to evaluate their bone biocompatibility. Cell growth dynamics according to MTT assay and scanning electron microscopy (SEM) observation exhibited good cell adhesion and proliferation, suggesting that this magnetic biodegradable Fe(3)O(4)/CS/PVA nanofibrous membranes can be one of promising biomaterials for facilitation of osteogenesis.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  13. Size dependent structural and magnetic properties of FeO-Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lak, Aidin; Kraken, Mathias; Ludwig, Frank; Kornowski, Andreas; Eberbeck, Dietmar; Sievers, Sibylle; Litterst, F. J.; Weller, Horst; Schilling, Meinhard

    2013-11-01

    The magnetic properties of monodisperse FeO-Fe3O4 nanoparticles with different mean sizes and volume fractions of FeO synthesized via decomposition of iron oleate were correlated to their crystallographic and phase compositional features by exploiting high resolution transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy and field and zero field cooled magnetization measurements. A model describing the phase transformation from a pure Fe3O4 phase to a mixture of Fe3O4, FeO and interfacial FeO-Fe3O4 phases as the particle size increases was established. The reduced magnetic moment in FeO-Fe3O4 nanoparticles was attributed to the presence of differently oriented Fe3O4 crystalline domains in the outer layers and paramagnetic FeO phase. The exchange bias energy, dominating magnetization reversal mechanism and superparamagnetic blocking temperature in FeO-Fe3O4 nanoparticles depend strongly on the relative volume fractions of FeO and the interfacial phase.The magnetic properties of monodisperse FeO-Fe3O4 nanoparticles with different mean sizes and volume fractions of FeO synthesized via decomposition of iron oleate were correlated to their crystallographic and phase compositional features by exploiting high resolution transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy and field and zero field cooled magnetization measurements. A model describing the phase transformation from a pure Fe3O4 phase to a mixture of Fe3O4, FeO and interfacial FeO-Fe3O4 phases as the particle size increases was established. The reduced magnetic moment in FeO-Fe3O4 nanoparticles was attributed to the presence of differently oriented Fe3O4 crystalline domains in the outer layers and paramagnetic FeO phase. The exchange bias energy, dominating magnetization reversal mechanism and superparamagnetic blocking temperature in FeO-Fe3O4 nanoparticles depend strongly on the relative volume fractions of FeO and the interfacial phase. Electronic supplementary

  14. Synthesis, characterization and properties of ethylenediamine-functionalized Fe3O4 magnetic polymers for removal of Cr(VI) in wastewater.

    PubMed

    Zhao, Yong-Gang; Shen, Hao-Yu; Pan, Sheng-Dong; Hu, Mei-Qin

    2010-10-15

    A series of ethylenediamine (EDA)-functionalized magnetic polymers (EDA-MPs) have been prepared via suspension polymerization with the usage amount of the functional monomer glycidylmethacrylate (GMA) varied during the suspension polymerization procedure. The EDA-MPs were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray diffractometer (XRD), thermogravimetry and differential thermogravimetry analysis (TG-DTA), Fourier-transformed infrared spectroscopy (FTIR) and elementary analyzer (EA). The adsorption properties of the EDA-MPs for the removal of Cr(VI) in wastewater were deeply studied. The results showed the adsorption efficiency was highly pH dependent and decreased with the increasing of initial concentration of Cr(VI). The adsorption data taken at the optimized condition, i.e., 35 degrees C and pH of 2.5 were well fitted with the Langmuir isotherm. The maximum adsorption capacities (q(m)) of EDA-MPs to Cr(VI) were highly related to the contents of EDA-MPs, i.e., the q(m) of EDA-MPs to Cr(VI) calculated from the Langmuir isotherm increased from 32.15 to 61.35 mg g(-1) with the increasing of the usage amount of GMA. The adsorption kinetic data were modeled by the pseudo-second-order rate equation, and the adsorption of Cr(VI) by all the present EDA-MPs reached equilibrium in 60 min.

  15. Use of tetraethylenepentamine-functional Fe3O4 magnetic polymers for matrix solid phase dispersion extraction and preconcentration of Cr(VI) in water samples at ultratrace levels.

    PubMed

    Yao, Xun-Ping; Fu, Zhen-Jun; Zhao, Yong-Gang; Wang, Li; Fang, Lan-Yun; Shen, Hao-Yu

    2012-08-15

    A new method that utilizes tetraethylenepentamine-functional Fe(3)O(4) magnetic polymers (TEPA-NMPs) as a solid-phase extractant for matrix solid phase dispersion extraction (MSPD) has been developed for preconcentration of Cr(VI) at ultratrace levels prior to the measurement by flame atomic absorption spectroscopy (FAAS). The separation/preconcentration conditions of Cr(VI) was investigated, including the pH value, shaking time, adsorption temperature, sample volume, desorption conditions and interfering ions. The results showed the adsorption properties of the TEPA-NMPs were highly pH dependent. The data of adsorption kinetics obeyed pseudo-second-order rate mechanism well. Adsorption thermodynamic studies suggested that the adsorption processes of Cr(VI) onto the TEPA-NMPs was endothermic and entropy favored in nature. Under the best experimental conditions, the enhancement factor was 125 times, the detection limit of the method was 0.16 μg L(-1) and the relative standard deviation was 1.9% (n=7). Furthermore, the developed method was validated by comparing with Graphite Furnace atomic absorption spectrometry (GF-AAS) method, and has been applied for the determination of ultratrace Cr(VI) ions in the river and tap water samples with satisfactory results, which revealed the sensitivity of the proposed TEPA-NMPs MSPD-FAAS method was comparable with that of GF-AAS method.

  16. Nanostructured Fe3O4@C as anode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zeng, Zhipeng; Zhao, Hailei; Wang, Jie; Lv, Pengpeng; Zhang, Tianhou; Xia, Qing

    2014-02-01

    The active particle cracking and electrode pulverization of iron oxide anode material as a result of volume expansion during charge/discharge process cause poor reversibility and significant capacity fading in rechargeable lithium-ion batteries. Here, we demonstrate a facile solvothermal route to immobilize the Fe3O4 particles on the porous active carbon. The present method enables us to obtain nano-porous and mosaic structured Fe3O4@C spheres with an average size of ca. 100 nm. The porous active carbon plays an important role in the improvement of electrochemical properties of Fe3O4. It not only acts as a host for the deposition of Fe3O4 particles, but also provides void spaces for active Fe3O4 to buffer the volume expansion. The good contact between Fe3O4 and active carbon ensures the fast electron/Li-ion transport. As a result, the porous Fe3O4@C shows a high reversible specific capacity of ∼1000 mAh g-1, good cycle stability and excellent rate capability. Therefore, we believe that this composite is a potential candidate for anode material of high-energy lithium-ion battery.

  17. Synergistic Removal of Pb(II), Cd(II) and Humic Acid by Fe3O4@Mesoporous Silica-Graphene Oxide Composites

    PubMed Central

    Wang, Yilong; Liang, Song; Chen, Bingdi; Guo, Fangfang; Yu, Shuili; Tang, Yulin

    2013-01-01

    The synergistic adsorption of heavy metal ions and humic acid can be very challenging. This is largely because of their competitive adsorption onto most adsorbent materials. Hierarchically structured composites containing polyethylenimine-modified magnetic mesoporous silica and graphene oxide (MMSP-GO) were here prepared to address this. Magnetic mesoporous silica microspheres were synthesized and functionalized with PEI molecules, providing many amine groups for chemical conjugation with the carboxyl groups on GO sheets and enhanced the affinity between the pollutants and the mesoporous silica. The features of the composites were characterized using TEM, SEM, TGA, DLS, and VSM measurements. Series adsorption results proved that this system was suitable for simultaneous and efficient removal of heavy metal ions and humic acid using MMSP-GO composites as adsorbents. The maximum adsorption capacities of MMSP-GO for Pb(II) and Cd (II) were 333 and 167 mg g−1 caculated by Langmuir model, respectively. HA enhances adsorption of heavy metals by MMSP-GO composites due to their interactions in aqueous solutions. The underlying mechanism of synergistic adsorption of heavy metal ions and humic acid were discussed. MMSP-GO composites have shown promise for use as adsorbents in the simultaneous removal of heavy metals and humic acid in wastewater treatment processes. PMID:23776514

  18. Synergistic removal of Pb(II), Cd(II) and humic acid by Fe3O4@mesoporous silica-graphene oxide composites.

    PubMed

    Wang, Yilong; Liang, Song; Chen, Bingdi; Guo, Fangfang; Yu, Shuili; Tang, Yulin

    2013-01-01

    The synergistic adsorption of heavy metal ions and humic acid can be very challenging. This is largely because of their competitive adsorption onto most adsorbent materials. Hierarchically structured composites containing polyethylenimine-modified magnetic mesoporous silica and graphene oxide (MMSP-GO) were here prepared to address this. Magnetic mesoporous silica microspheres were synthesized and functionalized with PEI molecules, providing many amine groups for chemical conjugation with the carboxyl groups on GO sheets and enhanced the affinity between the pollutants and the mesoporous silica. The features of the composites were characterized using TEM, SEM, TGA, DLS, and VSM measurements. Series adsorption results proved that this system was suitable for simultaneous and efficient removal of heavy metal ions and humic acid using MMSP-GO composites as adsorbents. The maximum adsorption capacities of MMSP-GO for Pb(II) and Cd (II) were 333 and 167 mg g(-1) caculated by Langmuir model, respectively. HA enhances adsorption of heavy metals by MMSP-GO composites due to their interactions in aqueous solutions. The underlying mechanism of synergistic adsorption of heavy metal ions and humic acid were discussed. MMSP-GO composites have shown promise for use as adsorbents in the simultaneous removal of heavy metals and humic acid in wastewater treatment processes.

  19. Preparation and electrochemical property of Fe3O4/MWCNT nanocomposite

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  20. Fe3O4 nanoparticles: superparamagnetic behavior

    NASA Astrophysics Data System (ADS)

    Trevino, Matea; Chesnel, Karine; Olsen, Betsy; Boerio-Goates, Julie

    2010-10-01

    Magnetite ( Fe3O4 ) nanoparticles exhibit a superparamagnetic behavior when small, 1-50 nm in diameter. When cooling the sample, we reach a point called the blocking temperature (Tb), below which the magnetic moments are frozen. Each particle carries a super macrospin and aligns with other macrospins in the presence of a magnetic field. We will show results obtained on the nanoparticles of two batches: 5-15nm and 40-50nm in diameter. We studied these particles with Vibrating Sample Magnetometry (VSM). We will show magnetization curves taken at different temperatures and Field Cooling versus Zero Field Cooling measurements, to determine Tb. We will show Atomic Force Microscopy (AFM) images of nanoparticles deposited on a substrate. The AFM images provide information about the structure and morphology of the nanoparticles assembly. We will include Magnetic Force Microscopy (MFM) images to show the local magnetic profile of individual particles. By comparing VSM data and AFM/MFM images, our goal is to understand the superparamagnetic behavior of nanoparticles.

  1. Heterogeneous dimer peptide-conjugated polylysine dendrimer-Fe3O4 composite as a novel nanoscale molecular probe for early diagnosis and therapy in hepatocellular carcinoma.

    PubMed

    Shen, Jian-Min; Li, Xin-Xin; Fan, Lin-Lan; Zhou, Xing; Han, Ji-Min; Jia, Ming-Kang; Wu, Liang-Fan; Zhang, Xiao-Xue; Chen, Jing

    2017-01-01

    A novel nanoscale molecular probe is formulated in order to reduce toxicity and side effects of antitumor drug doxorubicin (DOX) in normal tissues and to enhance the detection sensitivity during early imaging diagnosis. The mechanism involves a specific targeting of Arg-Gly-Asp peptide (RGD)-GX1 heterogeneous dimer peptide-conjugated dendrigraft poly-l-lysine (DGL)-magnetic nanoparticle (MNP) composite by αvβ3-integrin/vasculature endothelium receptor-mediated synergetic effect. The physicochemical properties of the nanoprobe were characterized by using transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering (DLS), and vibrating sample magnetometer. The average diameter of the resulting MNP-DGL-RGD-GX1-DOX nanoparticles (NPs) was ~150-160 nm by DLS under simulate physiological medium. In the present experimental system, the loading amount of DOX on NPs accounted for 414.4 mg/g for MNP-DGL-RGD-GX1-DOX. The results of cytotoxicity, flow cytometry, and cellular uptake consistently indicated that the MNP-DGL-RGD-GX1-DOX NPs were inclined to target HepG2 cells in selected three kinds of cells. In vitro exploration of molecular mechanism revealed that cell apoptosis was associated with the overexpression of Fas protein and the significant activation of caspase-3. In vivo magnetic resonance imaging and biodistribution study showed that the MNP-DGL-RGD-GX1-DOX formulation had high affinity to the tumor tissue, leading to more aggregation of NPs in the tumor. In vivo antitumor efficacy research verified that MNP-DGL-RGD-GX1-DOX NPs possessed significant antitumor activity and the tumor inhibitory rate reached 78.5%. These results suggested that NPs could be promising in application to early diagnosis and therapy in hepatocellular carcinoma as a specific nanoprobe.

  2. Heterogeneous dimer peptide-conjugated polylysine dendrimer-Fe3O4 composite as a novel nanoscale molecular probe for early diagnosis and therapy in hepatocellular carcinoma

    PubMed Central

    Shen, Jian-Min; Li, Xin-Xin; Fan, Lin-Lan; Zhou, Xing; Han, Ji-Min; Jia, Ming-Kang; Wu, Liang-Fan; Zhang, Xiao-Xue; Chen, Jing

    2017-01-01

    A novel nanoscale molecular probe is formulated in order to reduce toxicity and side effects of antitumor drug doxorubicin (DOX) in normal tissues and to enhance the detection sensitivity during early imaging diagnosis. The mechanism involves a specific targeting of Arg-Gly-Asp peptide (RGD)-GX1 heterogeneous dimer peptide-conjugated dendrigraft poly-l-lysine (DGL)–magnetic nanoparticle (MNP) composite by αvβ3-integrin/vasculature endothelium receptor-mediated synergetic effect. The physicochemical properties of the nanoprobe were characterized by using transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering (DLS), and vibrating sample magnetometer. The average diameter of the resulting MNP–DGL–RGD-GX1–DOX nanoparticles (NPs) was ~150−160 nm by DLS under simulate physiological medium. In the present experimental system, the loading amount of DOX on NPs accounted for 414.4 mg/g for MNP–DGL–RGD-GX1–DOX. The results of cytotoxicity, flow cytometry, and cellular uptake consistently indicated that the MNP–DGL–RGD-GX1–DOX NPs were inclined to target HepG2 cells in selected three kinds of cells. In vitro exploration of molecular mechanism revealed that cell apoptosis was associated with the overexpression of Fas protein and the significant activation of caspase-3. In vivo magnetic resonance imaging and biodistribution study showed that the MNP–DGL–RGD-GX1–DOX formulation had high affinity to the tumor tissue, leading to more aggregation of NPs in the tumor. In vivo antitumor efficacy research verified that MNP–DGL–RGD-GX1–DOX NPs possessed significant antitumor activity and the tumor inhibitory rate reached 78.5%. These results suggested that NPs could be promising in application to early diagnosis and therapy in hepatocellular carcinoma as a specific nanoprobe. PMID:28243083

  3. Exchange bias effect in Au-Fe3O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Chandra, Sayan; Frey Huls, N. A.; Phan, M. H.; Srinath, S.; Garcia, M. A.; Lee, Youngmin; Wang, Chao; Sun, Shouheng; Iglesias, Òscar; Srikanth, H.

    2014-02-01

    We report exchange bias (EB) effect in the Au-Fe3O4 composite nanoparticle system, where one or more Fe3O4 nanoparticles are attached to an Au seed particle forming ‘dimer’ and ‘cluster’ morphologies, with the clusters showing much stronger EB in comparison with the dimers. The EB effect develops due to the presence of stress at the Au-Fe3O4 interface which leads to the generation of highly disordered, anisotropic surface spins in the Fe3O4 particle. The EB effect is lost with the removal of the interfacial stress. Our atomistic Monte Carlo studies are in excellent agreement with the experimental results. These results show a new path towards tuning EB in nanostructures, namely controllably creating interfacial stress, and opens up the possibility of tuning the anisotropic properties of biocompatible nanoparticles via a controllable exchange coupling mechanism.

  4. Determination of trace/ultratrace rare earth elements in environmental samples by ICP-MS after magnetic solid phase extraction with Fe3O4@SiO2@polyaniline-graphene oxide composite.

    PubMed

    Su, Shaowei; Chen, Beibei; He, Man; Hu, Bin; Xiao, Zuowei

    2014-02-01

    A novel Fe3O4@SiO2@polyaniline-graphene oxide composite (MPANI-GO) was prepared through a simple noncovalent method and applied to magnetic solid phase extraction (MSPE) of trace rare earth elements (REEs) in tea leaves and environmental water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The prepared MPANI-GO was characterized by transmission electron microscopy and vibrating sample magnetometer. Various parameters affecting MPANI-GO MSPE of REEs have been investigated. Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.04-1.49 ng L(-1) and the relative standard deviations (RSDs, c=20 ng L(-1), n=7) were 1.7-6.5%. The accuracy of the proposed method was validated by analyzing a Certified Reference Material of GBW 07605 tea leaves. The method was also successfully applied for the determination of trace REEs in tea leaves and environmental water samples. The developed MPANI-GO MSPE-ICP-MS method has the advantages of simplicity, rapidity, high sensitivity, high enrichment factor and is suitable for the analysis of trace REEs in samples with complex matrix.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    PubMed Central

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

    2012-01-01

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

  7. Facile self-assembly of Fe3O4 nanoparticles@WS2 nanosheets: A promising candidate for supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Dai, Yu; Wu, Xiao; Sha, Dawei; Chen, Ming; Zou, Han; Ren, Jie; Wang, Jingjing; Yan, Xuehua

    2016-10-01

    Graphene-like dichalcogenides with huge surface area and nanostructured transition metal oxides with extraordinarily high theoretical capacities could be composited as promising electrode candidates for supercapacitors. In this work, monolayer and few-layers WS2 nanosheets were exfoliated by combination of ball-milling and sonication. A facile strategy for the hierarchical self-assembly of Fe3O4 nanoparticles (Fe3O4NPs) on WS2 nanosheets was developed to synthesize Fe3O4NPs@WS2 nanocomposites via hydrothermal method. Fe3O4NPs are uniformly dispersed on the WS2 nanosheets without aggregation. The particle size of Fe3O4NPs is about 3 nm. The nanocomposite shows strong enhancements of electrochemical behaviors. This self-assembly synthesis strategy may have great prospects for other 0D/2D nanocomposites in supercapacitors and other energy devices. [Figure not available: see fulltext.

  8. The sandwich-type electrochemiluminescence immunosensor for α-fetoprotein based on enrichment by Fe3O4-Au magnetic nano probes and signal amplification by CdS-Au composite nanoparticles labeled anti-AFP.

    PubMed

    Zhou, Hankun; Gan, Ning; Li, Tianhua; Cao, Yuting; Zeng, Saolin; Zheng, Lei; Guo, Zhiyong

    2012-10-09

    A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe(3)O(4)-Au nanoparticles, which was first employed to capture AFP antigens to form Fe(3)O(4)-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe(3)O(4)-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe(3)O(4)-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL(-1) with a detection limit of 0.2 pg mL(-1). The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2016-03-01

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

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

    PubMed

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

    2015-11-01

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

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

    PubMed

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

    2014-09-01

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

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

    PubMed

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

    2016-05-01

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

  14. Controlled assembly of Fe3O4 magnetic nanoparticles on graphene oxide

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

  15. Fabrication and caffeine release from Fe3O4/P(MAA-co-NVP) magnetic microspheres with controllable core-shell architecture.

    PubMed

    Di, Hong-Wei; Luo, Yan-Ling; Xu, Feng; Chen, Yao-Shao; Nan, Yun-Fei

    2011-01-01

    A novel route was proposed to design and construct a magnetic composite microsphere consisting of Fe(3)O(4) nanoparticles chemically-covalently encapsulated with pH-smart poly(methacrylic acid-co-N-vinyl pyrrolidone) (P(MAA-co-NVP)) cross-linked co-polymers by a surface-initiated radical dispersion polymerization route. The multistep surface treatment was employed to improve the dispersity and surface-chemical reactivity of Fe(3)O(4) nanoparticles, involving introduction of active -NH(2) groups, coupling of 1,1-methylene bis-(4-isocyanato-cyclohexane) and immobilization of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide]. The structure and morphological characterization was carried out by FT-IR, TEM, SEM and XRD. The chemically covalent interactions were investigated by FT-IR, TEM, TGA and DSC. The neat Fe(3)O(4) nanoparticles took on an aggregated spherical shape with an average diameter of about 12 nm, while Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres assumed controllable and monodispersed spheres with a mean dimension of ca. 0.8 μm. The microspheres exhibited superparamagnetic properties. The in vitro caffeine release behavior under varying pH environment was investigated to evaluate the potential of Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres as a magnetic drug targeting carrier. The results indicated that the microspheres have a faster drug-release rate at pH 7.4 than at pH 1.4, corresponding to their pH swelling. The kinetic modeling demonstrated that the drug release is controlled by a balance between co-polymer chain relaxation and Fickian diffusion process, and the proposed carrier is suitable for a magnetic targeting drug-delivery system.

  16. Synthesis and microwave absorption enhancement of graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures.

    PubMed

    Wang, Lei; Huang, Ying; Sun, Xu; Huang, Haijian; Liu, Panbo; Zong, Meng; Wang, Yan

    2014-03-21

    Hierarchical structures of graphene@Fe3O4@SiO2@NiO nanosheets were prepared by combining the versatile sol-gel process with a hydrothermal reaction. Graphene@Fe3O4 composites were first synthesized by the reduction reaction between FeCl3 and diethylene glycol (DEG) in the presence of GO. Then, graphene@Fe3O4 was coated with SiO2 to obtain graphene@Fe3O4@SiO2. Finally, NiO nanosheets were grown perpendicularly on the surface of graphene@Fe3O4@SiO2 and graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures were formed. Moreover, the microwave absorption properties of both graphene@Fe3O4 and graphene@Fe3O4@SiO2@NiO nanosheets were investigated between 2 and 18 GHz microwave frequency bands. The electromagnetic data demonstrate that graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures exhibit significantly enhanced microwave absorption properties compared with graphene@Fe3O4, which probably originate from the unique hierarchical structure with a large surface area and high porosity.

  17. Supraparamagnetic, conductive, and processable multifunctional graphene nanosheets coated with high-density Fe3O4 nanoparticles.

    PubMed

    He, Hongkun; Gao, Chao

    2010-11-01

    The amazing properties of graphene are triggering extensive interests of both scientists and engineers, whereas how to fully utilize the unique attributes of graphene to construct novel graphene-based composites with tailor-made, integrated functions remains to be a challenge. Here, we report a facile approach to multifunctional iron oxide nanoparticle-attached graphene nanosheets (graphene@Fe(3)O(4)) which show the integrated properties of strong supraparamagnetism, electrical conductivity, highly chemical reactivity, good solubility, and excellent processability. The synthesis method is efficient, scalable, green, and controllable and has the feature of reduction of graphene oxide and formation of Fe(3)O(4) nanoparticles in one step. When the feed ratios are adjusted, the average diameter of Fe(3)O(4) nanoparticles (1.2-6.3 nm), the coverage density of Fe(3)O(4) nanoparticles on graphene nanosheets (5.3-57.9%), and the saturated magnetization of graphene@Fe(3)O(4) (0.5-44.1 emu/g) can be controlled readily. Because of the good solubility of the as-prepared graphene@Fe(3)O(4), highly flexible and multifunctional films composed of polyurethane and a high content of graphene@Fe(3)O(4) (up to 60 wt %) were fabricated by the solution-processing technique. The graphene@Fe(3)O(4) hybrid sheets showed electrical conductivity of 0.7 S/m and can be aligned into a layered-stacking pattern in an external magnetic field. The versatile graphene@Fe(3)O(4) nanosheets hold great promise in a wide range of fields, including magnetic resonance imaging, electromagnetic interference shielding, microwave absorbing, and so forth.

  18. Modeling Verwey transition temperature of Fe3O4 nanocrystals

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao bao; Xiao, Bei bei; Yang, Hong yu; Gu, Xiao yan; Sheng, Hong chao; Zhang, Xing hua

    2016-11-01

    The Verwey transition in nanoscale is an important physical property for Fe3O4 nanocrystals and has attracted extensive attention in recent years. In this work, an analytic thermodynamic model without any adjusting parameters is developed to estimate the size and shape effects on modulating the Verwey transition temperature of Fe3O4 nanocrystals. The results show that the Verwey transition temperature reduces with increasing shape parameter λ or decreasing size D. A good agreement between the prediction and the experimental data verified our physical insight that the Verwey transition of Fe3O4 can be directly related to the atomic thermal vibration. The results presented in this work will be of benefit to the understanding of the microscopic mechanism of the Verwey transition and the design of future generation switching and memory devices.

  19. Bio and nanomaterials based on Fe3O4.

    PubMed

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

    2014-12-22

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

  20. Fabrication of graphene oxide decorated with Fe3O4@SiO2 for immobilization of cellulase

    NASA Astrophysics Data System (ADS)

    Li, Yue; Wang, Xiang-Yu; Jiang, Xiao-Ping; Ye, Jing-Jing; Zhang, Ye-Wang; Zhang, Xiao-Yun

    2015-01-01

    Fe3O4@SiO2-graphene oxide (GO) composites were successfully fabricated by chemical binding of functional Fe3O4@SiO2 and GO and applied to immobilization of cellulase via covalent attachment. The prepared composites were further characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. Fe3O4 nanoparticles (NPs) were monodisperse spheres with a mean diameter of 17 ± 0.2 nm. The thickness of SiO2 layer was calculated as being 6.5 ± 0.2 nm. The size of Fe3O4@SiO2 NPs was 24 ± 0.3 nm, similar to that of Fe3O4@SiO2-NH2. Fe3O4@SiO2-GO composites were synthesized by linking of Fe3O4@SiO2-NH2 NPs to GO with the catalysis of EDC and NHS. The prepared composites were used for immobilization of cellulase. A high immobilization yield and efficiency of above 90 % were obtained after the optimization. The half-life of immobilized cellulase (722 min) was 3.34-fold higher than that of free enzyme (216 min) at 50 °C. Compared with the free cellulase, the optimal temperature of the immobilized enzyme was not changed; but the optimal pH was shifted from 5.0 to 4.0, and the thermal stability was enhanced. The immobilized cellulase could be easily separated and reused under magnetic field. These results strongly indicate that the cellulase immobilized onto the Fe3O4@SiO2-GO composite has potential applications in the production of bioethanol.

  1. Enhanced rate performance and cyclic stability of Fe3O4-graphene nanocomposites for Li ion battery anodes.

    PubMed

    Behera, Shantanu K

    2011-10-07

    Monodispersed Fe(3)O(4) nanoparticles of size ∼10 nm were processed by a simple ultrasonic assisted co-precipitation method, mechanically mixed with graphene oxide, and thermally reduced to form a magnetite-graphene composite. Electrochemical characterization of the Fe(3)O(4)-graphene nanocomposites showed excellent capacity in excess of 1200 mA h g(-1), and exceptional stability during high current cycling for at least 1000 cycles.

  2. Heteroepitaxy of Fe3O4/Muscovite: A New Perspective for Flexible Spintronics.

    PubMed

    Wu, Ping-Chun; Chen, Ping-Fan; Do, Thi Hien; Hsieh, Ying-Hui; Ma, Chun-Hao; Ha, Thai Duy; Wu, Kun-Hong; Wang, Yu-Jia; Li, Hao-Bo; Chen, Yi-Chun; Juang, Jenh-Yih; Yu, Pu; Eng, Lukas M; Chang, Chun-Fu; Chiu, Po-Wen; Tjeng, Liu Hao; Chu, Ying-Hao

    2016-12-14

    Spintronics has captured a lot of attention since it was proposed. It has been triggering numerous research groups to make their efforts on pursuing spin-related electronic devices. Recently, flexible and wearable devices are in a high demand due to their outstanding potential in practical applications. In order to introduce spintronics into the realm of flexible devices, we demonstrate that it is feasible to grow epitaxial Fe3O4 film, a promising candidate for realizing spintronic devices based on tunneling magnetoresistance, on flexible muscovite. In this study, the heteroepitaxy of Fe3O4/muscovite is characterized by X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectroscopy. The chemical composition and magnetic feature are investigated by a combination of X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. The electrical and magnetic properties are examined to show the preservation of the primitive properties of Fe3O4. Furthermore, various bending tests are performed to show the tunability of functionalities and to confirm that the heterostructures retain the physical properties under repeated cycles. These results illustrate that the Fe3O4/muscovite heterostructure can be a potential candidate for the applications in flexible spintronics.

  3. Synthesis and characterization of magnetic opal/Fe3O4 colloidal crystal

    NASA Astrophysics Data System (ADS)

    Carmona-Carmona, A. J.; Palomino-Ovando, M. A.; Hernández-Cristobal, Orlando; Sánchez-Mora, E.; Toledo-Solano, M.

    2017-03-01

    We report an experimental study of colloidal crystals based on SiO2 artificial opals, infiltrated with 1.34(M1), 2.03(M2) and 24.4(M3) wt% Fe3O4 nanoparticles, using the co-assembly method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Vibration sample magnetometer (VSM) were used to study the structural, magnetic and optical properties of the samples. At 300 K all the samples exhibit superparamagnetic behavior due to the magnetic coupling of Fe3O4 nanoparticles infiltrated into opal. However, for higher concentration of nanoparticles this strong coupling distorts the opal network. The UV-vis diffuse reflectance spectroscopy and Kubelka-Munk theory were applied to determine that the energy band gap of the opal-magnetite composites can be adjusted by varying the concentration of Fe3O4 nanoparticles. This values are between the energy band gap of SiO2 and Fe3O4.

  4. Fe3O4 nanoparticles on graphene oxide sheets for isolation and ultrasensitive amperometric detection of cancer biomarker proteins.

    PubMed

    Sharafeldin, Mohamed; Bishop, Gregory W; Bhakta, Snehasis; El-Sawy, Abdelhamid; Suib, Steven L; Rusling, James F

    2017-05-15

    Ultrasensitive mediator-free electrochemical detection for biomarker proteins was achieved at low cost using a novel composite of Fe3O4 nanoparticles loaded onto graphene oxide (GO) nano-sheets (Fe3O4@GO). This paramagnetic Fe3O4@GO composite (1µm size range) was decorated with antibodies against prostate specific antigen (PSA) and prostate specific membrane antigen (PSMA), and then used to first capture these biomarkers and then deliver them to an 8-sensor detection chamber of a microfluidic immunoarray. Screen-printed carbon sensors coated with electrochemically reduced graphene oxide (ERGO) and a second set of antibodies selectively capture the biomarker-laden Fe3O4@GO particles, which subsequently catalyze hydrogen peroxide reduction to detect PSA and PSMA. Accuracy was confirmed by good correlation between patient serum assays and enzyme-linked immuno-sorbent assays (ELISA). Excellent detection limits (LOD) of 15 fg/mL for PSA and 4.8 fg/mL for PSMA were achieved in serum. The LOD for PSA was 1000-fold better than the only previous report of PSA detection using Fe3O4. Dynamic ranges were easily tunable for concentration ranges encountered in serum samples by adjusting the Fe3O4@GO Concentration. Reagent cost was only $0.85 for a single 2-protein assay.

  5. Magnetite activities across the MgAl2O4-Fe3O4 spinel join, with application to thermobarometric estimates of upper mantle oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Mattioli, Glen S.; Wood, Bernard J.

    1988-02-01

    The activity of Fe3O4 component in MgAl2O4-Fe3O4 spinels has been measured at 900° and 1000° C and 1 atm total pressure using a zirconia oxygen electrolyte. As previously reported for the dilute Fe3O4 concentration region (Mattioli and Wood 1986a), magnetite activity at 1000° C is greater than at 900° C at constant Fe3O4 mole fraction, for compositions across the MgAl2O4-Fe3O4 join between 20 and 80 mol% Fe3O4 component. The 1-atm solvus crest lies between 900° and 1000° C and, at 900° C the limbs are at Fe3O4 mole fractions of 0.2 and 0.6 approximately. Application of the O'Neill and Navrotsky (1983, 1984) cation distribution model indicates that the unusual activity — composition behavior of Fe3O4 is caused by changes in the equilibrium state of disorder of mixed MgAl2O4-Fe3O4 spinels relative to the disordered Fe3O4 standard state. In addition, both stoichiometric volumes (Mattioli et al. 1987) and activities across the MgAl2O4-Fe3O4 join suggest that short range order is significant for this binary. Excess free energy terms must be added to “ideal” Fe3O4 activities formulated from equilibrium cation distributions in complex MgAl2O4-Fe3O4 spinels in order to increase Fe3O4 activities to values consistent with observation and to generate the apparent region of immiscibility at 900° C. We have applied our activity data to the estimation of upper mantle spinel-lherzolite oxygen fugacities. We calculated that minimum f_{O_2 }'s are about 2 log units below the synthetic QFM buffer at 15 kbar total pressure for Fe3O4 concentration of 2 mol%, in a Cr-free spinel phase. If a preliminary calibration of an additional 25 mol% Fe2+-substitution as FeCr2O4 or FeAl2O4 component is incorporated into Fe3O4 activity, then olivine-orthopyroxene-spinel assemblages of depleted-Type 1-spinel-lherzolite xenoliths indicate f_{O_2 }'s close to QFM at 15 kbar. This is in good agreement with previous thermobarometric f_{O_2 } estimates and in sharp contrast to 1 atm

  6. Development of novel magnetic solid phase extraction materials based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide)-Pluronic L64 composite microspheres and their application to the enrichment of natamycin.

    PubMed

    Tian, Miaomiao; Zou, Yongcun; Zhou, Shaoyan; Wang, Tianpeng; Lv, Xueju; Jia, Qiong

    2015-12-15

    Novel magnetic adsorbents based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide) magnetic microspheres modified with non-ionic triblock copolymer surfactant were successfully prepared as a magnetic solid phase extraction adsorbent for the determination of trace natamycin in jam samples. The adsorbent was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transformed infrared spectroscopy, vibrating sample magnetometer, and X-ray diffractometer analysis, confirming that Pluronic L64 was effectively functionalized on the magnetic materials. Various experimental parameters affecting the extraction capacity were investigated including adsorbent amount, extraction time, desorption time, sample pH, and ionic strength. For recovery evaluations, the jam samples were spiked at two concentration levels of 100 and 200μgkg(-1) of natamycin and the recovery values were in the range of 78.8-93.4%. The relative standard deviations (RSD) for the recoveries were less than 3.5%. The novel magnetic solid phase extraction method provided several advantages, such as simplicity, low environmental impact, convenient extraction procedure, and short analysis time when used for natamycin analysis.

  7. Local probing of magnetoelectric properties of PVDF/Fe3O4 electrospun nanofibers by piezoresponse force microscopy.

    PubMed

    Zheng, Tian; Yue, Zhilian; Wallace, Gordon G; Du, Yi; Martins, Pedro; Lanceros-Mendez, Senentxu; Higgins, Michael J

    2017-02-10

    The coupling of magnetic and electric properties in polymer-based magnetoelectric composites offers new opportunities to develop contactless electrodes, effectively without electrical connections, for less-invasive integration into devices such as energy harvesters, sensors, wearable and implantable electrodes. Understanding the macroscale-to-nanoscale conversion of the properties is important, as nanostructured and nanoscale magnetoelectric structures are increasingly fabricated. However, whilst the magnetoelectric effect at the macroscale is well established both theoretically and experimentally, it remains unclear how this effect translates to the nanoscale, or vice versa. Here, PVDF/Fe3O4 polymer-based composite nanofibers are fabricated using electrospinning to investigate their piezoelectric and magnetoelectric properties at the single nanofiber level.

  8. Local probing of magnetoelectric properties of PVDF/Fe3O4 electrospun nanofibers by piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Zheng, Tian; Yue, Zhilian; Wallace, Gordon G.; Du, Yi; Martins, Pedro; Lanceros-Mendez, Senentxu; Higgins, Michael J.

    2017-02-01

    The coupling of magnetic and electric properties in polymer-based magnetoelectric composites offers new opportunities to develop contactless electrodes, effectively without electrical connections, for less-invasive integration into devices such as energy harvesters, sensors, wearable and implantable electrodes. Understanding the macroscale-to-nanoscale conversion of the properties is important, as nanostructured and nanoscale magnetoelectric structures are increasingly fabricated. However, whilst the magnetoelectric effect at the macroscale is well established both theoretically and experimentally, it remains unclear how this effect translates to the nanoscale, or vice versa. Here, PVDF/Fe3O4 polymer-based composite nanofibers are fabricated using electrospinning to investigate their piezoelectric and magnetoelectric properties at the single nanofiber level.

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

    NASA Astrophysics Data System (ADS)

    Arora, Manju; Zargar, R. A.

    2015-08-01

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

  10. Reversal modes and magnetostatic interactions in Fe3O4/ZrO2/Fe3O4 multilayer nanotubes.

    PubMed

    Pitzschel, Kristina; Bachmann, Julien; Montero-Moreno, Josep M; Escrig, Juan; Görlitz, Detlef; Nielsch, Kornelius

    2012-12-14

    Reversal modes and magnetostatic interactions of multilayered Fe(3)O(4)/ZrO(2)/Fe(3)O(4) nanotubes consisting of a ferromagnetic internal tube, an intermediate non-magnetic spacer and an external magnetic shell are investigated as a function of their geometric parameters and compared with those produced inside the pores of anodic alumina membranes by atomic layer deposition. Based on a continuum approach we obtained analytical expressions that underline the first experimental results and support their interpretation that the system of multilayer tubes behaves as the reversal of two isolated systems. It is observed that the magnetostatic interaction between both phases depends on the magnetic configurations in each phase and also on the geometrical parameters considered. These structures have potential applications in novel spintronics devices, ultra-small magnetic media and other nano-devices.

  11. Formation and characterization of β-cyclodextrin (β-CD) - polyethyleneglycol (PEG) - polyethyleneimine (PEI) coated Fe3O4 nanoparticles for loading and releasing 5-Fluorouracil drug.

    PubMed

    Prabha, G; Raj, V

    2016-05-01

    In this work, β-cyclodextrin (β-CD) - polyethyleneglycol (PEG) - polyethyleneimine (PEI) coated iron oxide nanoparticles (Fe3O4-β-CD-PEG-PEI) were developed as drug carriers for drug delivery applications. The 5- Fluorouracil (5-FU) was chosen as model drug molecule. The developed nanoparticles (Fe3O4-β-CD-PEG-PEI) were characterized by various techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The average particles size range of 5-FU loaded Fe3O4-β-CD, Fe3O4-β-CD-PEG and Fe3O4-β-CD-PEG-PEI nanoparticles were from 151 to 300nm and zeta potential value of nanoparticles were from -43mV to -20mV as measured using Malvern Zetasizer. Finally, encapsulation efficiency (EE), loading capacity (LC) and in-vitro drug release performance of 5-FU drug loaded Fe3O4-β-CD, Fe3O4-β-CD-PEG and Fe3O4-β-CD-PEG-PEI nanoparticles was evaluated by UV-vis spectroscopy. In-vitro cytotoxicity tests investigated by MTT assay indicate that 5-FU loaded Fe3O4-β-CD-PEG-PEI nanoparticles were toxic to cancer cells and non-toxic to normal cells. The in-vitro release behavior of 5-FU from drug (5-FU) loaded Fe3O4-β-CD-PEG-PEI composite at different pH values and temperature was studied. It was found that 5-FU was released faster in pH 6.8 than in the acidic mediums (pH 1.2), and the released quantity was higher. Therefore, the newly prepared Fe3O4-β-CD-PEG-PEI carrier exhibits a promising potential capability for anticancer drug delivery in tumor therapy.

  12. Synthesis of hierarchical Mg-doped Fe3O4 micro/nano materials for the decomposition of hexachlorobenzene.

    PubMed

    Su, Guijin; Liu, Yexuan; Huang, Linyan; Lu, Huijie; Liu, Sha; Li, Liewu; Zheng, Minghui

    2014-03-01

    An ethylene-glycol (EG) mediated self-assembly process was firstly developed to synthesize micrometer-sized nanostructured Mg-doped Fe3O4 composite oxides to decompose hexachlorobenzene (HCB) at 300°C. The synthesized samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and inductively coupled plasma optical emission spectrometer. The morphology and composition of the composite oxide precursor were regulated by the molar ratio of the magnesium acetate and ferric nitrate as the reactants. Calcination of the precursor particles, prepared with different molar ratio of the metal salts, under a reducing nitrogen atmosphere, generated three kinds of Mg doped Fe3O4 composite oxide micro/nano materials. Their reactivity toward HCB decomposition was likely influenced by the material morphology and content of Mg dopants. Ball-like MgFe2O4-Fe3O4 composite oxide micro/nano material showed superior HCB dechlorination efficiencies when compared with pure Fe3O4 micro/nano material, prepared under similar experimental conditions, thus highlighting the benefits of doping Mg into Fe3O4 matrices.

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

    PubMed Central

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

    2016-01-01

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

  14. [Adsorption of methylene blue from aqueous solution onto magnetic Fe3O4/ graphene oxide nanoparticles].

    PubMed

    Chang, Qing; Jiang, Guo-Dong; Hu, Meng-Xuan; Huang, Jia; Tang, He-Qing

    2014-05-01

    A simple ultrasound-assisted co-precipitation method was developed to prepare magnetic Fe3O4/graphene oxide (Fe3O4/ GO) nanoparticles. The characterization with transmission electron microscope (TEM) indicated that the products possessed small particle size. The hysteresis loop of the dried Fe3O4/GO nanoparticles demonstrated that the sample had typical features of superparamagnetic material. Batch adsorption studies were carried out to investigate the effects of the initial pH of the solution, the dosage of adsorbent, the contact time and temperature on the adsorption of methylene blue. The results indicated that the composites prepared could be used over a broad pH range (pH 6-9). The adsorption process was very fast within the first 25 min and the equilibrium was reached at 180 min. The adsorption equilibrium and kinetics data fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model. The adsorption process was a spontaneous and endothermic process in nature. The composite exhibited fairly high adsorption capacity (196.5 mg.g-1) of methylene blue at 313 K. In addition, the magnetic composite could be effectively and simply separated by using an external magnetic field, and then regenerated by hydrogen peroxide and recycled for further use. The results indicated that the adsorbent had a potential in the application of the dye wastewater treatment.

  15. One-step thermolysis synthesis of two-dimensional ultrafine Fe3O4 particles/carbon nanonetworks for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Wanqun; Li, Xiaona; Liang, Jianwen; Tang, Kaibin; Zhu, Yongchun; Qian, Yitai

    2016-02-01

    To tackle the issue of inferior cycle stability and rate capability for Fe3O4 anode materials in lithium ion batteries, ultrafine Fe3O4 nanocrystals uniformly encapsulated in two-dimensional (2D) carbon nanonetworks have been fabricated through thermolysis of a simple, low-cost iron(iii) acetylacetonate without any extra processes. Moreover, compared to the reported Fe3O4/carbon composites, the particle size of Fe3O4 is controllable and held down to ~3 nm. Benefitting from the synergistic effects of the excellent electroconductive carbon nanonetworks and uniform distribution of ultrafine Fe3O4 particles, the prepared 2D Fe3O4/carbon nanonetwork anode exhibits high reversible capacity, excellent rate capability and superior cyclability. A high capacity of 1534 mA h g-1 is achieved at a 1 C rate and is maintained without decay up to 500 cycles (1 C = 1 A g-1). Even at the high current density of 5 C and 10 C, the 2D Fe3O4/carbon nanonetworks maintain a reversible capacity of 845 and 647 mA h g-1 after 500 discharge/charge cycles, respectively. In comparison with other reported Fe3O4-based anodes, the 2D Fe3O4/carbon nanonetwork electrode is one of the most attractive of those in energy storage applications.To tackle the issue of inferior cycle stability and rate capability for Fe3O4 anode materials in lithium ion batteries, ultrafine Fe3O4 nanocrystals uniformly encapsulated in two-dimensional (2D) carbon nanonetworks have been fabricated through thermolysis of a simple, low-cost iron(iii) acetylacetonate without any extra processes. Moreover, compared to the reported Fe3O4/carbon composites, the particle size of Fe3O4 is controllable and held down to ~3 nm. Benefitting from the synergistic effects of the excellent electroconductive carbon nanonetworks and uniform distribution of ultrafine Fe3O4 particles, the prepared 2D Fe3O4/carbon nanonetwork anode exhibits high reversible capacity, excellent rate capability and superior cyclability. A high capacity of 1534 mA h

  16. A facile one-pot solvothermal method to produce superparamagnetic graphene-Fe3O4 nanocomposite and its application in the removal of dye from aqueous solution.

    PubMed

    Wu, Qiuhua; Feng, Cheng; Wang, Chun; Wang, Zhi

    2013-01-01

    A superparamagnetic graphene-Fe(3)O(4) nanocomposite (G/Fe(3)O(4)) was synthesized by a facile one-pot solvothermal method. The nanocomposite G/Fe(3)O(4) prepared by the new method was firstly used as an adsorbent to remove dye for water pollution remediation. In comparison with G/Fe(3)O(4) prepared by the in situ chemical coprecipitation, the newly prepared G/Fe(3)O(4) had a higher adsorption efficiency for the dye. The adsorption characteristics of the nanocomposite adsorbent were examined using the organic dye pararosaniline as the adsorbate. The adsorption kinetics, adsorption capacity of the adsorbent, and the effect of the adsorbent dosage and solution pH on the removal efficiency of pararosaniline were investigated. The adsorption capacity of G/Fe(3)O(4) for pararosaniline was evaluated using the Freundlich and Langmuir adsorption isotherm models. The G/Fe(3)O(4) hybrid composite can be easily manipulated in magnetic field for desired separation, leading to an easy removal of the dye from polluted water. The G/Fe(3)O(4) hybrid composite would have a great potential in removing organic dyes from polluted water.

  17. Tailoring mechanical and antibacterial properties of chitosan/gelatin nanofiber membranes with Fe3O4 nanoparticles for potential wound dressing application

    NASA Astrophysics Data System (ADS)

    Cai, Ning; Li, Chao; Han, Chao; Luo, Xiaogang; Shen, Liang; Xue, Yanan; Yu, Faquan

    2016-04-01

    In this work, magnetic Fe3O4 nanoparticles (NPs) were utilized to improve the mechanical and antibacterial properties of chitosan (CS)/gelatin (GE) composite nanofiber membranes. Homogeneous Fe3O4/CS/GE nanofibers were electrospun successfully. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the presence of well-dispersed Fe3O4 NPs in the composite nanofibers. Fourier transform infrared spectroscopy (FTIR) spectra revealed the effective interactions of Fe3O4 NPs to the composite matrix through hydrogen bonding. The improvement on the thermal stability of the Fe3O4/CS/GE was observed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA), which is tightly correlated to strong filler-matrix adhesion. The incorporation of Fe3O4 NPs resulted in a substantial enhancement of mechanical properties. The optimum mechanical performance was demonstrated on 1 wt% Fe3O4/CS/GE nanofiber membranes, achieving 155% augment of Young's modulus, 128% increase of tensile strength, and 100% boost of toughness from CS/GE. The excellent mechanical enhancement can be explained by the effective dispersion of fillers and the filler-matrix interactions, which ensures the efficient load transfer from CS/GE matrix to Fe3O4 nanofillers. Moreover, zones of inhibition for Escherichia coli and Staphylococcus aureus expanded markedly with the supplement of Fe3O4 NPs. In all, nanofiber membranes made of Fe3O4/CS/GE composite with tailored mechanical and antibacterial properties appear a promising wound dressing material.

  18. Uniform Fe3O4 microflowers hierarchical structures assembled with porous nanoplates as superior anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoliang; Liu, Yanguo; Arandiyan, Hamidreza; Yang, Hongping; Bai, Lu; Mujtaba, Jawayria; Wang, Qingguo; Liu, Shanghe; Sun, Hongyu

    2016-12-01

    Uniform Fe3O4 microflowers assembled with porous nanoplates were successfully synthesized by a solvothermal method and subsequent annealing process. The structural and compositional analysis of the Fe3O4 microflowers were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The Bruauer-Emmett-Teller (BET) specific surface area was calculated by the nitrogen isotherm curve and pore size distribution of Fe3O4 microflowers was determined by the Barret-Joyner-Halenda (BJH) method. When evaluated as anode material for lithium-ion batteries, the as-prepared Fe3O4 microflowers electrodes delivered superior capacity, better cycling stability and rate capability than that of Fe3O4 microspheres electrodes. The improved electrochemical performance was attributed to the microscale flowerlike architecture and the porous sheet structural nature.

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

    PubMed

    Yu, Shoushan; Wan, Jiaqi; Chen, Kezheng

    2016-01-01

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

  20. Origin of Surface Canting within Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  1. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    PubMed

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  2. Amino-Fe3O4 Microspheres Directed Synthesis of a Series of Polyaniline Hierarchical Nanostructures with Different Wettability

    NASA Astrophysics Data System (ADS)

    Ma, Yong; Chen, Yanhui; Hou, Chunping; Zhang, Hao; Qiao, Mingtao; Zhang, Hepeng; Zhang, Qiuyu

    2016-09-01

    We demonstrated polyaniline (PANI) dimensional transformation by adding trace amino-Fe3O4 microspheres to aniline polymerization. Different PANI nanostructures (i.e., flowers, tentacles, and nanofibers) could be produced by controlling the nucleation position and number on the surface of Fe3O4 microspheres, where hydrogen bonding were spontaneously formed between amino groups of Fe3O4 microspheres and aniline molecules. By additionally introducing an external magnetic field, PANI towers were obtained. These PANI nanostructures displayed distinctly different surface wettability in the range from hydrophobicity to hydrophilicity, which was ascribed to the synergistic effect of their dimension, hierarchy, and size. Therefore, the dimension and property of PANI nanostructures can be largely rationalized and predicted by adjusting the PANI nucleation and growth. Using PANI as a model system, the strategies presented here provide insight into the general scheme of dimension and structure control for other conducting polymers.

  3. Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

    2016-12-01

    Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

  4. Fabrication of Bi-Fe3O4@RGO hybrids and their catalytic performance for the reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Wang, Xuefang; Xia, Fengling; Li, Xichuan; Xu, Xiaoyang; Wang, Huan; Yang, Nian; Gao, Jianping

    2015-11-01

    Nanocatalysts are frequently connected to magnetic nanoparticles. These composites are easy to be retrieved from the reaction system under a magnetic field because of their magnetic properties. Magnetic separation is particularly promising in industry since it can solve many issues present in filtration, centrifugation, or gravitation separation. Herein, a facile method to prepare bismuth and Fe3O4 nanoparticles loaded on reduced graphene oxide magnetic hybrids (Bi-Fe3O4@RGO) using soluble starch as a dispersant is demonstrated. The magnetic Fe3O4 nanoparticles were synthesized by the co-precipitation of Fe2+ and Fe3+ ions, and Bi nanoparticles were fabricated by the redox reactions between sodium borohydride and ammonium bismuth citrate in the presence of soluble starch. Transmission electron microscopy images demonstrate that the average diameter of the Fe3O4 nanoparticles is about 5 nm and the diameters of Bi nanoparticles range from 10 to 20 nm. The magnetic Bi-Fe3O4@RGO hybrids exhibit high catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 with a first-order rate constant (K) of 0.00808 s-1 and is magnetically recyclable for at least five cycles. This strategy provides an efficient and recyclable catalyst for the use in environmental protection applications.

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

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

    PubMed Central

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

    2015-01-01

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

  7. Production of nearly monodisperse Fe3O4 and Fe@Fe3O4 nanoparticles in aqueous medium and their surface modification for biomedical applications

    NASA Astrophysics Data System (ADS)

    Tegafaw, Tirusew; Xu, Wenlong; Lee, Sang Hyup; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2017-02-01

    Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe3O4) and Fe@Fe3O4 (core: Fe, shell: Fe3O4) nanoparticles in aqueous medium under argon flow and then, coated them with various biocompatible ligands and silica. In this study, eight types of surface-modified nanoparticles were investigated, namely, Fe3O4@PAA (PAA = polyacrylic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PAA-FA (FA = folic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PEI-fluorescein (PEI = polyethylenimine; Mw of PEI = 1300 amu), Fe@Fe3O4@PEI (Mw of PEI = 10,000 amu), Fe3O4@SiO2 and Fe@Fe3O4@SiO2 nanoparticles. We characterized the prepared surface-modified nanoparticles using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy, a superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and confocal microscopy. Finally, we measured the cytotoxicity of the samples. The results indicate that the surface-modified nanoparticles are biocompatible and are potential candidates for various biomedical applications.

  8. Uniform Fe3O4 coating on flower-like ZnO nanostructures by atomic layer deposition for electromagnetic wave absorption.

    PubMed

    Wan, Gengping; Wang, Guizhen; Huang, Xianqin; Zhao, Haonan; Li, Xinyue; Wang, Kan; Yu, Lei; Peng, Xiange; Qin, Yong

    2015-11-21

    An elegant atomic layer deposition (ALD) method has been employed for controllable preparation of a uniform Fe3O4-coated ZnO (ZnO@Fe3O4) core-shell flower-like nanostructure. The Fe3O4 coating thickness of the ZnO@Fe3O4 nanostructure can be tuned by varying the cycle number of ALD Fe2O3. When serving as additives for microwave absorption, the ZnO@Fe3O4-paraffin composites exhibit a higher absorption capacity than the ZnO-paraffin composites. For ZnO@500-Fe3O4, the effective absorption bandwidth below -10 dB can reach 5.2 GHz and the RL values below -20 dB also cover a wide frequency range of 11.6-14.2 GHz when the coating thickness is 2.3 mm, suggesting its potential application in the treatment of the electromagnetic pollution problem. On the basis of experimental observations, a mechanism has been proposed to understand the enhanced microwave absorption properties of the ZnO@Fe3O4 composites.

  9. Fe3O4 nanowire arrays synthesized in AAO templates

    NASA Astrophysics Data System (ADS)

    Xue, D. S.; Zhang, L. Y.; Gui, A. B.; Xu, X. F.

    2005-02-01

    Fe3O4 nanowire arrays with an average diameter of about 120 nm and lengths up to 8 μm were synthesized in anodic aluminum oxide templates through electrodepositing and heat treating a precursor β-FeOOH. The nanowires have a polycrystalline spinel structure with a=8.31 Å and each nanowire is composed of fine particles. Influences of the sintering and the reducing temperatures on the products have been demonstrated by Mössbauer spectra and X-ray diffraction. It was found that high-coercivity nanowires can be obtained when the precursor was sintered at 500 °C in air and then reduced at 325 °C in H2. Hysteresis loops measured at room temperature show a clear perpendicular magnetic anisotropy.

  10. One-pot green synthesis of reduced graphene oxide (RGO)/Fe3O4 nanocomposites and its catalytic activity toward methylene blue dye degradation.

    PubMed

    Vinothkannan, M; Karthikeyan, C; Gnana kumar, G; Kim, Ae Rhan; Yoo, Dong Jin

    2015-02-05

    The reduced graphene oxide (RGO)/Fe3O4 nanocomposites were synthesized through a facile one-pot green synthesis by using solanum trilobatum extract as a reducing agent. Spherical shaped Fe3O4 nanoparticles with the diameter of 18 nm were uniformly anchored over the RGO matrix and the existence of fcc structured Fe3O4 nanoparticles over the RGO matrix was ensured from X-ray diffraction patterns. The amide functional groups exist in the solanum trilobatum extract is directly responsible for the reduction of Fe(3+) ions and GO. The thermal stability of GO was increased by the removal of hydrophilic functional groups via solanum trilobatum extract and was further promoted by the ceramic Fe3O4 nanoparticles. The ID/IG ratio of RGO/Fe3O4 was increased over GO, indicating the extended number of structural defects and disorders in the RGO/Fe3O4 composite. The catalytic efficiency of prepared nanostructures toward methylene blue (MB) dye degradation mediated through the electron transfer process of BH4(-) ions was studied in detail. The π-π stacking, hydrogen bonding and electrostatic interaction exerted between the RGO/Fe3O4 composite and methylene blue, increased the adsorption efficiency of dye molecules and the large surface area and extended number of active sites completely degraded the MB dye within 12 min.

  11. Enhanced Microwave Absorption Performance of Coated Carbon Nanotubes by Optimizing the Fe3O4 Nanocoating Structure.

    PubMed

    Li, Na; Huang, Gui-Wen; Li, Yuan-Qing; Xiao, Hong-Mei; Feng, Qing-Ping; Hu, Ning; Fu, Shao-Yun

    2017-01-25

    It is well accepted that the microwave absorption performance (MAP) of carbon nanotubes (CNTs) can be enhanced via coating magnetic nanoparticles on their surfaces. However, it is still unclear if the magnetic coating structure has a significant influence on the microwave absorption behavior. In this work, nano-Fe3O4 compact-coated CNTs (FCCs) and Fe3O4 loose-coated CNTs (FLCs) are prepared using a simple solvothermal method. The MAP of the Fe3O4-coated CNTs is shown to be adjustable via controlling the Fe3O4 nanocoating structure. The results reveal that the overall MAP of coated CNTs strongly depends on the magnetic coating structure. In addition, the FCCs show a much better MAP than the FLCs. It is shown that the microwave absorption difference between the FLCs and FCCs is due to the disparate complementarities between the dielectric loss and the magnetic loss, which are related to the coverage density of Fe3O4 nanoparticles on the surfaces of CNTs. For FCCs, the mass ratio of CNTs to Fe(3+) is then optimized to maximize the effective complementarities between the dielectric loss and the magnetic loss. Finally, a comparison is made with the literature on Fe3O4-carbon-based composites. The FCCs at the optimized CNT to Fe(3+) ratio in the present work show the most effective specific RLmin (28.7 dB·mm(-1)) and the widest effective bandwidth (RL < -10 dB) (8.3 GHz). The excellent MAP of the as-prepared FCC sample is demonstrated to result from the consequent dielectric relaxation process and the improved magnetic loss. Consequently, the structure-property relationship revealed is significant for the design and preparation of CNT-based materials with effective microwave absorption.

  12. Enhanced dechlorination of 2,4-dichlorophenol by recoverable Ni/Fe-Fe3O4 nanocomposites.

    PubMed

    Xu, Cancan; Liu, Rui; Chen, Lvjun; Tang, Jialu

    2016-10-01

    Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol (2,4-DCP). The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorination efficiency were investigated, in addition to the reusability of the nanocomposites. The results showed that increasing content of Ni in Ni/Fe-Fe3O4 nanocomposites, from 1 to 5wt.%, greatly increased the dechlorination efficiency; the Ni/Fe-Fe3O4 nanocomposites had much higher dechlorination efficiency than bare Ni/Fe nanoparticles. Ni content of 5wt.% and initial pH below 6.0 was found to be the optimal conditions for the catalytic dechlorination of 2,4-DCP. Both 2,4-DCP and the intermediate product 2-chlorophenol (2-CP) were completely removed, and the concentration of the final product phenol was close to the theoretical phenol production from complete dechlorination of 20mg/L of 2,4-DCP, after 3hr reaction at initial pH value of 6.0, 3g/L Ni/Fe-Fe3O4, 5wt.% Ni content in the composite, and temperature of 22°C. 2,4-DCP dechlorination was enhanced by Cl(-) and inhibited by NO3(-) and SO4(2-). The nanocomposites were easily separated from the solution by an applied magnetic field. When the catalyst was reused, the removal efficiency of 2,4-DCP was almost 100% for the first seven uses, and gradually decreased to 75% in cycles 8-10. Therefore, the Ni/Fe-Fe3O4 nanocomposites can be considered as a potentially effective tool for remediation of pollution by 2,4-DCP.

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

    PubMed Central

    2013-01-01

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

  14. Rapid ultrasound-assisted magnetic microextraction of gallic acid from urine, plasma and water samples by HKUST-1-MOF-Fe3O4-GA-MIP-NPs: UV-vis detection and optimization study.

    PubMed

    Asfaram, Arash; Ghaedi, Mehrorang; Dashtian, Kheibar

    2017-01-01

    Magnetite (Fe3O4 nanoparticles (NPs)) HKUST-1 metal organic framework (MOF) composite as a support was used for surface imprinting of gallic acid imprinted polymer (HKUST-1-MOF-Fe3O4-GA-MIP) using vinyltrimethoxysilane (VTMOS) as the cross-linker. Subsequently, HKUST-1-MOF-Fe3O4-NPs-GA-MIP characterized by FT-IR, XRD and FE-SEM analysis and applied for fast and selective and sensitive ultrasound assisted dispersive magnetic solid phase microextraction of gallic acid (GA) by UV-Vis (UA-DMSPME-UV-Vis) detection method. Plackett-Burman design (PBD) and central composite design (CCD) according to desirability function (DF) indicate the significant variables among the extraction factors vortex (mixing) time (min), sonication time (min), temperature (°C), eluent volume (L), pH and HKUST-1-MOF-Fe3O4-NPs-GA-MIP mass (mg) and their contribution on the response. Optimum conditions and values correspond to pH, HKUST-1-MOF-Fe3O4-NPs-GA-MIP mass, sonication time and the eluent volume were set as follow 3.0, 1.6mg, 4.0min and 180μL, respectively. The average recovery (ER%) of GA was 98.13% with desirability of 0.997, while the present method has best operational performance like wide linear range 8-6000ngmL(-1) with a Limit of detection (LOD) of 1.377ngmL(-1), limit of quantification (LOQ) 4.591ngmL(-1) and precision (<3.50% RSD). The recovery of GA in urine, human plasma and water samples within the range of 92.3-100.6% that strongly support high applicability of present method for real samples analysis, which candidate this method as promise for further application.

  15. Rapid degradation of methylene blue in a novel heterogeneous Fe3O4 @rGO@TiO2-catalyzed photo-Fenton system

    PubMed Central

    Yang, Xiaoling; Chen, Wei; Huang, Jianfei; Zhou, Ying; Zhu, Yihua; Li, Chunzhong

    2015-01-01

    Herein, a ternary nanocomposite with TiO2 nanoparticles anchored on reduced graphene oxide (rGO)-encapsulated Fe3O4 spheres (Fe3O4@rGO@TiO2) is presented as a high efficient heterogeneous catalyst for photo-Fenton degradation of recalcitrant pollutants under neutral pH. Fe3O4@rGO@TiO2 was synthesized by depositing TiO2 nanoparticles on the surface of the Fe3O4 spheres wrapped by graphene oxide (GO) which was obtained by an electrostatic layer-by-layer method. This as-prepared catalyst reflected good ferromagnetism and superior stability which makes it convenient to be separated and recycled. Due to the synergic effects between the different components composed the catalyst, swift reduction of Fe3+ can be achieved to regenerate Fe2+. Fe3O4@rGO@TiO2 exhibited enhancing catalytic activity for the degradation of azo-dyes compared with Fe3O4, Fe3O4@SiO2@TiO2 or SiO2@rGO@TiO2, further conforming the rapid redox reaction between Fe2+ and Fe3+. All these merits indicate that the composite catalyst possesses great potential for visible-light driven destruction of organic compounds. PMID:26000975

  16. Rapid degradation of methylene blue in a novel heterogeneous Fe3O4 @rGO@TiO2-catalyzed photo-Fenton system.

    PubMed

    Yang, Xiaoling; Chen, Wei; Huang, Jianfei; Zhou, Ying; Zhu, Yihua; Li, Chunzhong

    2015-05-22

    Herein, a ternary nanocomposite with TiO2 nanoparticles anchored on reduced graphene oxide (rGO)-encapsulated Fe3O4 spheres (Fe3O4@rGO@TiO2) is presented as a high efficient heterogeneous catalyst for photo-Fenton degradation of recalcitrant pollutants under neutral pH. Fe3O4@rGO@TiO2 was synthesized by depositing TiO2 nanoparticles on the surface of the Fe3O4 spheres wrapped by graphene oxide (GO) which was obtained by an electrostatic layer-by-layer method. This as-prepared catalyst reflected good ferromagnetism and superior stability which makes it convenient to be separated and recycled. Due to the synergic effects between the different components composed the catalyst, swift reduction of Fe(3+) can be achieved to regenerate Fe(2+). Fe3O4@rGO@TiO2 exhibited enhancing catalytic activity for the degradation of azo-dyes compared with Fe3O4, Fe3O4@SiO2@TiO2 or SiO2@rGO@TiO2, further conforming the rapid redox reaction between Fe(2+) and Fe(3+). All these merits indicate that the composite catalyst possesses great potential for visible-light driven destruction of organic compounds.

  17. One-step synthesis of novel PANI-Fe3O4@ZnO core-shell microspheres: An efficient photocatalyst under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyuan; Wu, Jianning; Meng, Guihua; Guo, Xuhong; Liu, Chang; Liu, Zhiyong

    2016-03-01

    For the first time, novel multifunctional superparamagnetic PANI-Fe3O4@ZnO core-shell composite photocatalysts with different PANI: ZnO ratios were synthesized by Pickering emulsion route in one step in the presence of ZnO nanoparticles. PANI-Fe3O4@ZnO core-shell microspheres consist of PANI core which embedded with Fe3O4-OA (oleic acid modified Fe3O4) nanoparticles and tunable ZnO shell thickness. The resulting samples were thoroughly studied by using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The catalytic activity of the as-prepared PANI-Fe3O4@ZnO core-shell microspheres is investigated by the degradation of MB under visible light irradiation. As expected, the as prepared PANI-Fe3O4@ZnO photocatalysts exhibit highly enhanced photocatalytic activities in the degradation of MB under visible light irradiation owing to fast separation of photo-generated electron-hole pairs. Significantly, the PANI-Fe3O4@ZnO catalysts can be separated from the reaction media by applying an external magnet, and can be reused for seven cycles without change in stability and degradation efficiency.

  18. Functionalized Fe3O4@Au superparamagnetic nanoparticles: in vitro bioactivity

    NASA Astrophysics Data System (ADS)

    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

    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.

  19. Encapsulation of Fe3O4 Nanoparticles into N, S co-Doped Graphene Sheets with Greatly Enhanced Electrochemical Performance

    PubMed Central

    Yang, Zunxian; Qian, Kun; Lv, Jun; Yan, Wenhuan; Liu, Jiahui; Ai, Jingwei; Zhang, Yuxiang; Guo, Tailiang; Zhou, Xiongtu; Xu, Sheng; Guo, Zaiping

    2016-01-01

    Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg−1, a high reversible specific capacity of 1055.20 mAhg−1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg−1 when cycled at the current density of 1000 mAg−1, indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries. PMID:27296103

  20. Encapsulation of Fe3O4 Nanoparticles into N, S co-Doped Graphene Sheets with Greatly Enhanced Electrochemical Performance

    NASA Astrophysics Data System (ADS)

    Yang, Zunxian; Qian, Kun; Lv, Jun; Yan, Wenhuan; Liu, Jiahui; Ai, Jingwei; Zhang, Yuxiang; Guo, Tailiang; Zhou, Xiongtu; Xu, Sheng; Guo, Zaiping

    2016-06-01

    Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg‑1, a high reversible specific capacity of 1055.20 mAhg‑1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg‑1 when cycled at the current density of 1000 mAg‑1, indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries.

  1. Encapsulation of Fe3O4 Nanoparticles into N, S co-Doped Graphene Sheets with Greatly Enhanced Electrochemical Performance.

    PubMed

    Yang, Zunxian; Qian, Kun; Lv, Jun; Yan, Wenhuan; Liu, Jiahui; Ai, Jingwei; Zhang, Yuxiang; Guo, Tailiang; Zhou, Xiongtu; Xu, Sheng; Guo, Zaiping

    2016-06-14

    Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg(-1), a high reversible specific capacity of 1055.20 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries.

  2. Preparation of Fe 3O 4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride) by emulsifier-free emulsion polymerization and its interaction with DNA

    NASA Astrophysics Data System (ADS)

    Li, Xiaolong; Liu, Guoqiang; Yan, Wei; Chu, Paul K.; Yeung, Kelvin W. K.; Wu, Shuilin; Yi, Changfeng; Xu, Zushun

    2012-04-01

    Cationic magnetic polymer particles Fe3O4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride), a type of potential gene carrier, were prepared by emulsifier-free emulsion polymerization with oleic acid modified magnetite Fe3O4, styrene, butyl acrylate and [2-(methacryloxy)ethyl]trimethylammonium chloride) (METAC). The morphology of the particles was characterized by transmission electron microscopy and the composites of particles were characterized by FT-IR spectroscopy, X-ray diffraction. These results showed that magnetic particles were well dispersed in polymers with the content of about 15%(wt/wt). The composites exhibited superparamagnetism and possessed a certain level of magnetic response. The interactions between the particles with calf-thymus DNA (ct DNA) were confirmed by zeta potential measurement, UV-vis spectroscopy and fluorescence spectroscopy. The DNA-binding capacity determined by the agarose gel electrophoresis showed good binding capacity of the emulsion to DNA. These results suggested the potential of the cationic magnetic polymer emulsion as gene target delivery carrier.

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

    PubMed Central

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

    2015-01-01

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

  4. Optimization of Fe3 O4 Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

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

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

  5. Fluorescent magnetic Fe3 O4 /rare Earth colloidal nanoparticles for dual-modality imaging.

    PubMed

    Zhu, Haie; Shang, Yalei; Wang, Wenhao; Zhou, Yingjie; Li, Penghui; Yan, Kai; Wu, Shuilin; Yeung, Kelvin W K; Xu, Zushun; Xu, Haibo; Chu, Paul K

    2013-09-09

    Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two-step, seed emulsifier-free emulsion polymerization in the presence of oleic acid and sodium undecylenate-modified Fe3 O4 nanoparticles (NPs). The Fe3 O4 /poly(St-co-GMA) nanoparticles are first synthesized as the seed and Eu(AA)3 Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core-shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T2 relaxivity of the FMCNPs is 353.86 mM(-1) S(-1) suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T2 -weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.

  6. Supercritical carbon dioxide assisted deposition of Fe(3)O(4) nanoparticles on hierarchical porous carbon and their lithium-storage performance.

    PubMed

    Wang, Lingyan; Zhuo, Linhai; Zhang, Chao; Zhao, Fengyu

    2014-04-07

    A composite of highly dispersed Fe3 O4 nanoparticles (NPs) anchored in three-dimensional hierarchical porous carbon networks (Fe3 O4 /3DHPC) as an anode material for lithium-ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO2 )-expanded ethanol solution. The as-synthesized Fe3 O4 /3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7 nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe3 O4 NPs was closely coated. As an anode material for LIBs, the Fe3 O4 /3DHPC composite with 79 wt % Fe3 O4 (Fe3 O4 /3DHPC-79) delivered a high reversible capacity of 1462 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1) , and maintained good high-rate performance (728, 507, and 239 mA h g(-1) at 1, 2, and 5 C, respectively). Moreover, it showed excellent long-term cycling performance at high current densities, 1 and 2 A g(-1) . The enhanced lithium-storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe3 O4 NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon-based transition-metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.

  7. Magnetically Separable Fe3O4/AgBr Hybrid Materials: Highly Efficient Photocatalytic Activity and Good Stability

    NASA Astrophysics Data System (ADS)

    Cao, Yuhui; Li, Chen; Li, Junli; Li, Qiuye; Yang, Jianjun

    2015-06-01

    Magnetically separable Fe3O4/AgBr hybrid materials with highly efficient photocatalytic activity were prepared by the precipitation method. All of them exhibited much higher photocatalytic activity than the pure AgBr in photodegradation of methyl orange (MO) under visible light irradiation. When the loading amount of Fe3O4 was 0.5 %, the hybrid materials displayed the highest photocatalytic activity, and the degradation yield of MO reached 85 % within 12 min. Silver halide often suffers serious photo-corrosion, while the stability of the Fe3O4/AgBr hybrid materials improved apparently than the pure AgBr. Furthermore, depositing Fe3O4 onto the surface of AgBr could facilitate the electron transfer and thereby leading to the elevated photocatalytic activity. The morphology, phase structure, and optical properties of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-vis DRS), and photoluminescence (PL) techniques.

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

    USGS Publications Warehouse

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

    1990-01-01

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

  9. A moderate method for preparation DMSA coated Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Song, L. N.; Gu, N.; Zhang, Y.

    2017-01-01

    A moderate way to prepare water soluble magnetic Fe3O4 nanoparticles has been developed. Firstly, oleic acid coated Fe3O4 is prepared by coprecipitation. Second, oleic acid were replaced by 2,3-dimercaptosuccinnic acid (DMSA) to prepare DMSA/Fe3O4 in the mixed solution of n-hexane and acetone. After dialysis and filtration the DMSA/Fe3O4 can be transferred into distilled water to form stable Fe3O4 nanoparticle solutions. The TEM images indicated that the particles had spherical shape and the nanoparticles were found to be 12 nm with a relatively narrow size distribution with the hydrodynamic size of 30 nm. And the result of VSM shows that DMSA/Fe3O4 nanoparticles have a saturation magnetization of 31 emu/g. The IR spectra indicated that the iron oxide was located by carboxyl matrix.

  10. Synthesis and characterization of "mulberry"-like Fe3O4/multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Song, Hao-Jie; Li, Na; Jing, Xiaojing; Yang, Xiaofei; Tang, Hua

    2011-10-01

    Nanocomposites composed of multi-wall carbon nanotubes (MWNTs) and Fe3O4 nanoparticles were fabricated using solvothermal method. Transmission and scanning electron microscopy, energy dispersive spectroscopy, and X-ray powder diffraction measurements confirmed that these mulberry-like Fe3O4 microparticles which were combined with the MWNTs in a random pattern are constructed with tiny nanocrystallites (12 nm in average diameter). The magnetic properties of the Fe3O4/MWNTs nanocomposites were measured using a vibrating sample magnetometer. Results showed that the Fe3O4/MWNTs nanocomposites exhibited superparamagnetism at room temperature and possessed a lower saturation magnetization (around 27.6 emu/g) than that of the pure Fe3O4 nanoparticles (around 33.7 emu/g). The Fe3O4/MWNTs nanocomposites have potential applications in engineering and medicine.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  12. Influence of nanographene platelets (NGP) incorporation on Fe3O4 nanoparticles as materials additives for enhancement thermal properties stearic acid

    NASA Astrophysics Data System (ADS)

    Nuryadin, M. K.; Andiarto, R.; Taufik, A.; Saleh, R.

    2016-11-01

    In this work, Fe3O4 nanoparticles, and Fe3O4/NGP composite were used as material additive for enhancement thermal properties of stearic acid (SA). The both material additive were synthesized using sol-gel method. Phase change material (PCM) composites SA-Fe3O4 and Sa-Fe3O4/NGP mixtures were made through the dispersion technique with three different weight % ratio of material additives into stearic acid: 1 wt.%, 3 wt.%, and 5 wt.%. X-Ray Diffractometer (XRD) and Fourier Transform Infrared (FTIR) spectroscopy were used to investigate the structural properties. Magnetic properties also measured by vibrating sample magnetometer (VSM) to see influence of NGP in PCM composites. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) were used in order to analyse the thermal properties of the samples. The results show an enhancement of the latent heat, thermal stability as well as specific heat by the presence of material additives in SA. Compare to SA- Fe3O4, SA-Fe3O4/NGP show better improvement in enhancement of thermal performance of SA. The improvement by about 41.2% in specific heat and 21.2% in latent heat.

  13. Thermodynamic Properties of α-Fe2O3 and Fe3O4 Nanoparticles

    DOE PAGES

    Spencer, Elinor C.; Ross, Nancy L.; Olsen, Rebecca E.; ...

    2015-04-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  15. Synthesis and Characterization of Magnetized Photocatalyst Fe3O4/SiO2/TiO2 by Heteroagglomeration Method

    NASA Astrophysics Data System (ADS)

    Hasnah Dewi, Sari; Sutanto; Fisli, A.; Wardiyati, S.

    2016-08-01

    Magnetic photocatalysts Fe3O4/SiO2/TiO2 have been prepared using heteroagglomeration method. Synthesis of magnetic photocatalyst Fe3O4/SiO2/TiO2 was carried out through four stages : (1) synthesis of photocatalyst TiO2 nanoparticles by TiCl4 coprecipitation in ammonia solution, (2) synthesis of Fe3O4 nanoparticles through precipitation method using a mixture of Fe (III) / Fe (II) (2: 1 mole ratio) in ammonia solution, (3) coating with SiO2 through hydrolysis of silicate ion, (4) in the final stage, Fe3O4/SiO2 was mixed with TiO2 in hetero-agglomeration manner. Structure and morphology of resultan composites have been investigated by X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR) and Transmission electron microscopy (TEM) were confirmed that composite Fe3O4/SiO2/TiO2 succefully synthesized. The functionality photocatalyst of the particles was tested by eliminating of methylene blue (MB) under UV light. The result showed the magnetite photocatalyst Fe3O4/SiO2/TiO2 has phototacalytic and absorbtion properties so that it has good performance at dyes removal in water higher than pure TiO2, and capable to perform repeatition process at least 4 times.

  16. Sono-assisted preparation of highly-efficient peroxidase-like Fe(3)O(4) magnetic nanoparticles for catalytic removal of organic pollutants with H(2)O(2).

    PubMed

    Wang, Nan; Zhu, Lihua; Wang, Dali; Wang, Mingqiong; Lin, Zhifen; Tang, Heqing

    2010-03-01

    Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4) MNPs) with much improved peroxidase-like activity were successfully prepared through an advanced reverse co-precipitation method under the assistance of ultrasound irradiation. The characterizations with XRD, BET and SEM indicated that the ultrasound irradiation in the preparation induced the production of Fe(3)O(4) MNPs possessing smaller particle sizes (16.5nm), greater BET surface area (82.5m(2)g(-1)) and much higher dispersibility in water. The particle sizes, BET surface area, chemical composition and then catalytic property of the Fe(3)O(4) MNPs could be tailored by adjusting the initial concentration of ammonia water and the molar ratio of Fe(2+)/Fe(3+) during the preparation process. The H(2)O(2)-activating ability of Fe(3)O(4) MNPs was evaluated by using Rhodamine B (RhB) as a model compound of organic pollutants to be degraded. At pH 5.4 and temperature 40 degrees C, the sonochemically synthesized Fe(3)O(4) MNPs were observed to be able to activate H(2)O(2) and remove ca. 90% of RhB (0.02mmolL(-1)) in 60min with a apparent rate constant of 0.034min(-1) for the RhB degradation, being 12.6 folds of that (0.0027min(-1)) over the Fe(3)O(4) MNPs prepared via a conventional reverse co-precipitation method. The mechanisms of the peroxidase-like catalysis with Fe(3)O(4) MNPs were discussed to develop more efficient novel catalysts.

  17. Synthesis, characterisation of polyaniline-Fe3O4 magnetic nanocomposite and its application for removal of an acid violet 19 dye

    NASA Astrophysics Data System (ADS)

    Patil, Manohar R.; Khairnar, Subhash D.; Shrivastava, V. S.

    2016-04-01

    The present work deals with the development of a new method for the removal of dyes from an aqueous solution using polyaniline (PANI)-Fe3O4 magnetic nanocomposite. It is synthesised in situ through self-polymerisation of monomer aniline. Photocatalytic degradation studies were carried out for cationic acid violet 19 (acid fuchsine) dye using PANI-Fe3O4 nanocomposite in aqueous solution. Different parameters like catalyst dose, contact time and pH have been studied to optimise reaction condition. The optimum conditions for the removal of the dye are initial concentration 20 mg/l, adsorbent dose 6 gm/l, pH 7. The EDS technique gives elemental composition of synthesised PANI-Fe3O4. The SEM and XRD studies were carried for morphological feature characteristics of PANI-Fe3O4 nanocomposite. The VSM (vibrating sample magnetometer) gives magnetic property of PANI-Fe3O4 nanocomposite; also FT-IR analysis gives characteristics frequency of synthesised PANI-Fe3O4. Besides the above studies kinetic study has also been carried out.

  18. Electrospun Fe3O4/TiO2 hybrid nanofibers and their in vitro biocompatibility: prospective matrix for satellite cell adhesion and cultivation.

    PubMed

    Amna, Touseef; Hassan, M Shamshi; Van Ba, Hoa; Khil, Myung-Seob; Lee, Hak-Kyo; Hwang, I H

    2013-03-01

    We report the fabrication of novel Fe3O4/TiO2 hybrid nanofibers with the improved cellular response for potential tissue engineering applications. In this study, Fe3O4/TiO2 hybrid nanofibers were prepared by facile sol-gel electrospinning using titanium isopropoxide and iron(III) nitrate nonahydrate as precursors. The obtained electrospun nanofibers were vacuum dried at 80 °C and then calcined at 500 °C. The physicochemical characterization of the synthesized composite nanofibers was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction pattern. To examine the in vitro cytotoxicity, satellite cells were treated with as-prepared Fe3O4/TiO2 and the viability of cells was analyzed by Cell Counting Kit-8 assay at regular time intervals. The morphological features of unexposed satellite cells and exposed to Fe3O4/TiO2 composite were examined with a phase contrast microscope whereas the quantification of cell viability was carried out via confocal laser scanning microscopy. The morphology of the cells attached to hybrid matrix was observed by Bio-SEM. Cytotoxicity experiments indicated that the satellite cells could attach to the Fe3O4/TiO2 composite nanofibers after being cultured. We observed that Fe3O4-TiO2 composite nanofibers could support cell adhesion and growth. Results from this study therefore suggest that Fe3O4/TiO2 composite scaffold with small diameters (approximately 200 nm) can mimic the natural extracellular matrix well and provide possibilities for diverse applications in the field of tissue engineering and regenerative medicine.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  20. Preparation and cell response of bio-mineralized Fe3O4 nanoparticles.

    PubMed

    Yin, Guangfu; Huang, Zhongbing; Deng, Min; Zeng, Jingwen; Gu, Jianwen

    2011-11-01

    Silk fibroin (SF)-coated Fe(3)O(4) nanoparticles (NPs) with good superparamagnetism were successfully prepared via a bio-mineralization process at room temperature. Two cell tests revealed that mineralized SF-coated Fe(3)O(4) NPs presented good cytocompatibility for L929 and osteoblast cells and higher cell density after 5 d with high concentrations of SF-coated Fe(3)O(4) NPs (up to 0.5 mg/mL). These resulted from SF surface coating on NPs, nano-surface morphology and iron ion release of Fe(3)O(4) NPs. The mineralized SF-coated Fe(3)O(4) NPs could be envisioned for various bone orthopedic and therapeutic applications, in which SF-coated NPs location is controlled through an external magnetic field to promoted bone growth.

  1. Sea-urchin-like Fe3O4@C@Ag particles: an efficient SERS substrate for detection of organic pollutants

    NASA Astrophysics Data System (ADS)

    Ye, Yingjie; Chen, Jin; Ding, Qianqian; Lin, Dongyue; Dong, Ronglu; Yang, Liangbao; Liu, Jinhuai

    2013-06-01

    Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization.Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization. Electronic supplementary information (ESI) available: Additional XRD patterns and SEM images of Fe3O4@C particles, SERS spectra of 4-ATP and 4-MPY using Fe3O4@C@Ag particles as the active substrates, magnetic behaviour of Fe3O4@C and Fe3O4@C@Ag particles. See DOI: 10.1039/c3nr01273e

  2. One-pot sequential synthesis of magnetically separable Fe3O4/AgCl photocatalysts with enhanced activity and stability

    NASA Astrophysics Data System (ADS)

    Liu, Zening; Liu, Yongcheng; Cai, Mujin; Xu, Piaopiao; Ma, Zonghua; Yuan, Hong

    2017-03-01

    Magnetically separable Fe3O4/AgCl photocatalysts were prepared by a one-pot sequential method. A series of techniques proved the hybrid structure of Fe3O4/AgCl composites. Fe3O4/AgCl composites had a much higher photocatalytic activity toward Rhodamine B (RhB) degradation than pure AgCl under the simulated solar light irradiation. The existence of metal Ag resulted in high photocatalytic activity of Fe3O4/AgCl, which was related with the amount of metallic Ag. The scavenging experiments showed that the degradation reaction most probably was initiated by the photoinduced single-electron transfer, and the generation of superoxide anion (O 2 -· ) played a significant role. The composite photocatalysts could be recycled by applying an external magnetic field, and the reused composites maintained their original photocatalytic activity. Fe3O4/AgCl composites were highly efficient, magnetically separable, and recoverable. This proves their potential applications in the photodegradation of organic pollutants.

  3. Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe3O4-TiO2

    NASA Astrophysics Data System (ADS)

    Jia, Xiaohua; Dai, Rongrong; Lian, Dandan; Han, Song; Wu, Xiangyang; Song, Haojie

    2017-01-01

    Fe3O4-TiO2 heterostructures were synthesized through co-precipitation method based on TiO2 nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO2 nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe3O4 nanoparticles were adhere to TiO2 nanobelts which have one-dimensional structure with 100-200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe3O4-TiO2 nanocomposites studies confirm that Ag is in Ag0 state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV-vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO2 due to the higher degree of recombination reactions after combined with Fe3O4 nanoparticles. After coated the composite of 15% Fe3O4-TiO2 with Ag, the new nanocomposite of Ag@Fe3O4-TiO2 can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of Ag nanoparticle decorated Fe3O4-TiO2 nanocomposites with surface heterostructures are discussed.

  4. Combined use of lightweight magnetic Fe3O4-coated hollow glass spheres and electrically conductive reduced graphene oxide in an epoxy matrix for microwave absorption

    NASA Astrophysics Data System (ADS)

    Wang, Junpeng; Wang, Jun; Zhang, Bin; Sun, Yu; Chen, Wei; Wang, Tao

    2016-03-01

    Epoxy resin based lightweight composites comprising Fe3O4-coated hollow glass spheres (HGS@Fe3O4) and reduced graphene oxide (RGO) were prepared. Impedance matching condition and electromagnetic wave attenuation characteristic are used for analysis of the reflection loss (RL) performance of the composites. Compared with pure HGS@Fe3O4 and RGO composite, the -10 dB absorption bandwidth and the minimum RL of the hybrid composites are enhanced. RL values less than -10 dB are obtained in a wide frequency range and the corresponding bandwidth can reach up to 3.6 GHz when an appropriate absorber thickness is chosen. The density of the hybrid composite is in the range of 0.57-0.72 g/cm3, which is attractive candidate for a new type of lightweight microwave absorber.

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

    PubMed

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

    2014-06-01

    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.

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

    PubMed

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

    2014-07-07

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

  7. Superior Antibacterial Activity of Fe3O4-TiO2 Nanosheets under Solar Light.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-10-07

    Fe3O4-TiO2 nanosheets (Fe3O4-TNS) were synthesized by means of lamellar reverse micelles and solvothermal method, which were characterized by TEM, XRD, XPS, BET, and magnetic property analysis. It can be found that Fe3O4-TNS nanosheets exhibited better photocatalytic antibacterial activity toward Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus than pure Fe3O4 and TNS, and the antibacterial efficiency could reach 87.2% and 93.7% toward E. coli and S. aureus with 100 μg/mL Fe3O4-TNS after 2 h of simulated solar light illumination, respectively. The photocatalytic destruction of bacteria was further confirmed by fluorescent-based cell live/dead test and SEM images. It was uncovered that Fe3O4-TNS inactivated G- E. coli and G+ S. aureus by different mechanisms: the destruction of outer membranes and ruptured cell bodies were responsible for the bactericidal effect against E. coli, while the antibacterial effect toward S. aureus were due to the fact that the cells were adsorbed in form of clusters by massive Fe3O4-TNS, which could restrict their activities and cause malfunction of the selective permeable barriers. Furthermore, the antibacterial mechanism was studied by employing scavengers to understand exact roles of different reactive species, indicating the key roles of h(+) and H2O2. The recovery and reusability experiments indicated that Fe3O4-TNS still retained more than 90% bacteria removal efficiency even after five cycles. Considering the easy magnetic separation, bulk availability, and high antibacterial activity of Fe3O4-TNS, it is a promising candidate for cleaning the microbial contaminated water environment.

  8. Investigation of Coal Fueled Chemical Looping Combustion Using Fe3O4 as Oxygen Carrier

    NASA Astrophysics Data System (ADS)

    Xlang, Wenguo; Sun, Xiaoyan; Wangt, Sha; Tian, Wendong; Xu, Xiang; Xu, Yanji; Xiao, Yunhan

    Chemical-looping combustion (CLC) is a novel combustion technique with CO2 separation. Magnetite (Fe3O4) was selected as the oxygen carrier and Shenhua coal (Inner Mongolia, China) as the fuel for this study. The influences of operation temperatures, and coal to Fe3O4 mass ratios on the reduction characteristics of the oxygen carrier were investigated using an atmosphere TGA. The sample, comprised of 2.25mg coal and 12.75mg Fe3O4, was heated to 1000°C. Experimental results show that the reaction between the coal volatile and Fe3O4 began at 700°C while the reaction between the coal char and Fe3O4 occurred at 800°C and reached a peak at 900°C. Fe3O4 was fully reduced into FeO, while some FeO was further reduced to Fe. As the operation temperature rises, the reduction conversion rate increases. At the temperatures of 850°C, 900°C, and 950°C, the reduction conversion rates were 37.1%, 46.5%, and 54.1% respectively. When the mass ratios of coal to Fe3O4 were 5/95, 10/90, 15/85, and 20/80, the reduction conversion rates were 29.5%,40.8%,46.5%, and 46.6% respectively. With the increase of coal to Fe3O4 mass ratio, the conversion rate increases first and then changes no more. There exists an optimal coal to Fe3O4 mass ratio.

  9. Click chemistry: a new facile and efficient strategy for the preparation of Fe3O4 nanoparticles covalently functionalized with IDA-Cu and their application in the depletion of abundant protein in blood samples.

    PubMed

    Jian, Guiqin; Liu, Yuxing; He, Xiwen; Chen, Langxing; Zhang, Yukui

    2012-10-21

    In this study, we report a novel method to synthesize core-shell structured Fe(3)O(4) nanoparticles (NPs) covalently functionalized with iminodiacetic acid (IDA) via click chemistry between the azide and alkyne groups and charged with Cu(2+). Firstly, the Fe(3)O(4)@SiO(2) NPs were obtained using tetraethoxysilane (TEOS) to form a silica shell on the surface of the Fe(3)O(4) core. The azide group-modified Fe(3)O(4)@SiO(2) NPs were obtained by a sol-gel process using 3-azidopropyltriethoxysilane (AzPTES) as the silane agent. Fe(3)O(4)@SiO(2)-N(3) was directly reacted with N-propargyl iminodiacetic via click chemistry, in the presence of a Cu(I) catalyst, to acquire the IDA-modified Fe(3)O(4) NPs. Finally, through the addition of Cu(2+), the Fe(3)O(4)@SiO(2)-IDA-Cu NP product was obtained. The morphology, structure and composition of the NPs were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The resulting NPs showed a strong magnetic response to an externally applied magnetic field, a high adsorption capacity and excellent specificity towards hemoglobin (Hb). In addition, the Fe(3)O(4)@SiO(2)-IDA-Cu NPs can be used for the selective removal of abundant Hb protein in bovine and human blood samples.

  10. A Facile Solvothermal Synthesis of Octahedral Fe3O4 Nanoparticles

    SciTech Connect

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

    2015-06-01

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

  11. The post-spinel transition in Fe3O4-Fe2SiO4 and Fe3O4- FeCr2O4 solid solutions

    NASA Astrophysics Data System (ADS)

    Woodland, Alan; Schollenbruch, Klaus; Frost, Daniel; Langenhorst, Falko

    2010-05-01

    Minerals with spinel structure are important phases in the Earth's mantle. Both magnetite (mt, Fe3O4) and chromite (chr, FeCr2O4) are known to transform to denser orthorhombic post-spinel phases at pressures≥10 GPa and ≥12.5 GPa, respectively (Schollenbruch et al. 2009a; Chen et al. 2003). On the other hand, Fe2SiO4 decomposes to its constituent oxides, FeO and SiO2 at high P and no post-spinel polymorph appears to be stable (e.g. Ito & Takahashi 1989). An important question is how spinel solid solutions behave at high pressures and temperatures since such compositions are arguably more petrologically relevant. In addition, since h-Fe3O4 is apparently not quenchable, it is difficult to investigate its structure. In contrast, two high-P polymorphs of FeCr2O4-rich compositions have been found in a meteorite (Chen et al. 2003), suggesting that the addition of Cr might allow us to recover the post-spinel phase of Fe3O4-bearing compositions from experiments. Building on recent results for the Fe3O4 end member (Schollenbruch et al. 2009a, 2009b), we have begun a study of the high-pressure behaviour of solid solutions along the Fe3O4 -Fe2SiO4 and Fe3O4- FeCr2O4 joins. Multianvil experiments were performed at 10 and 13 GPa and 1200-1300°C on pre-synthesised spinels with compositions 85mt-15 Fe2SiO4, 50mt-50chr and 80mt-20chr. For the Si-bearing experiments, stishovite was present in the run products. This occurrence, along with observed twinning in the Fe-oxide phase (Schollenbruch et al. 2009a) allows us to conclude that the original spinel had transformed to a high-P polymorph at a pressure and that Si is essentially excluded from this new structure. However, the powder XRD data from the run products could not be indexed either to magnetite (spinel structure) or to any other expected phase, including the known post-spinel structures. Interestingly, these are the same reflections reported by Koch et al. (2004) for an unidentified phase in their high-P (> 9 GPa

  12. Controllable synthesis of magnetic Fe3O4 particles with different morphology by one-step hydrothermal route

    NASA Astrophysics Data System (ADS)

    Chen, Zhongtao; Du, Yi; Li, Zhongfu; Yang, Kai; Lv, Xingjie

    2017-03-01

    Well-defined Fe3O4 particles were successfully fabricated by a facile triethanolamine (TEA)-assisted method under mild hydrothermal conditions. Hydrated ferric salt was employed as the single iron precursor. TEA was used as the complexing agent and/or alkaline source. The crystalline phases of the as-obtained samples were characterized by X-ray diffraction (XRD). Furthermore, the morphology as well as the compositions of the samples were investigated by scanning electron microscopy (SEM) equipped with an energy dispersion spectroscopy (EDS). The results indicated that the products were Fe3O4 crystal phase, and the morphology and powder size of the particles were varied with adding different amount of NaOAc and keeping the content of TEA unchanged. On the basis of these results, the possible formation mechanism of Fe3O4 was discussed. It was observed that TEA and NaOAc affected the growth rate of crystal planes and nucleation. Besides, the magnetic property tested by a vibrating sample magnetometer (VSM) showed that the products exhibited a ferromagnetic behavior and possessed the excellent saturation magnetization (Ms) at room temperature.

  13. Synthesis of Fe3O4 nanoparticles and its antibacterial application

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  14. Dumbbell-like Au-Fe3O4 nanoparticles: a new nanostructure for supercapacitors.

    PubMed

    Liu, Sheng; Guo, Shaojun; Sun, Shouheng; You, Xiao-Zeng

    2015-03-21

    Monodispersed dumbbell-like Au-Fe3O4 nanoparticles (NPs) were synthesized and studied for use in supercapacitors. These dumbbell NPs show Au/Fe3O4-size dependent capacitive behaviors and the 7-14 nm Au-Fe3O4 NPs have the best specific capacitance of 464 F g(-1) at 1 A g(-1) and capacity retention of 86.4% after 1000 cycles, much larger than pure Fe3O4 NPs (160 F g(-1) and 72.8% retention). This capacitive enhancement is believed to arise from the Au-induced increase in electron transfer across the dumbbell-like NPs. Thise report demonstrates a new strategy to enhance oxide NP capacitance for applications in high performance supercapacitors.

  15. Time behavior and capacitance analysis of nano-Fe3O4 added microbial fuel cells.

    PubMed

    Peng, Xinhong; Yu, Hongbing; Ai, Lina; Li, Nan; Wang, Xin

    2013-09-01

    The addition of nano Fe3O4 is beneficial to boost the transient charge storage of the anode accompanying with the enhancement of power performance in microbial fuel cells (MFCs) in our previous study. Here we found that both the anodic open circuit potential and the current increased when comparing the AcFeM (Fe3O4 added activated carbon anode) with the AcM (activated carbon anode), indicating that the Fe3O4 dynamically accelerated the anodic electron transfer although it thermodynamically limited the anode potential. The net storage capacity initially increased followed by a decrease with the maximum capacitance of 574.6 C m(-2) (AcFeM) and 459 C m(-2) (AcM) under 20 min of open circuit interval. The Fe3O4/Fe(II) possibly stored charges temporarily as a solid-state electron shuttle.

  16. Spin motive force induced in Fe3O4 thin films with negative spin polarization

    NASA Astrophysics Data System (ADS)

    Nagata, Masaki; Moriyama, Takahiro; Tanabe, Kenji; Tanaka, Kensho; Chiba, Daichi; Ohe, Jun-ichiro; Hisamatsu, Yuki; Niizeki, Tomohiko; Yanagihara, Hideto; Kita, Eiji; Ono, Teruo

    2015-12-01

    Spin motive force (SMF) is induced by a time and spatial derivative of magnetizations and is dependent on spin polarization. We compare the SMF in FeNi with positive spin polarization with that in a magnetite (Fe3O4) with negative spin polarization. We observe the SMF induced by a nonuniform ferromagnetic resonance in Fe3O4 and find that the SMF in Fe3O4 is opposite to that in FeNi. This result originates from the negative spin polarization of Fe3O4. Our clear observation of the SMF depending on the sign of the spin polarization agrees well with the framework of the SMF theory.

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    EPA Science Inventory

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

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

    PubMed

    Shen, Mao; Yu, Yujing; Fan, Guodong; Chen, Guang; Jin, Ying Min; Tang, Wenyuan; Jia, Wenping

    2014-01-01

    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.

  1. Multifunctional Fe3O4 @ Au core/shell nanostars: a unique platform for multimode imaging and photothermal therapy of tumors

    NASA Astrophysics Data System (ADS)

    Hu, Yong; Wang, Ruizhi; Wang, Shige; Ding, Ling; Li, Jingchao; Luo, Yu; Wang, Xiaolin; Shen, Mingwu; Shi, Xiangyang

    2016-06-01

    We herein report the development of multifunctional folic acid (FA)-targeted Fe3O4 @ Au nanostars (NSs) for targeted multi-mode magnetic resonance (MR)/computed tomography (CT)/photoacoustic (PA) imaging and photothermal therapy (PTT) of tumors. In this present work, citric acid-stabilized Fe3O4/Ag composite nanoparticles prepared by a mild reduction route were utilized as seeds and exposed to the Au growth solution to induce the formation of Fe3O4 @ Au core/shell NSs. Followed by successive decoration of thiolated polyethyleneimine (PEI-SH), FA via a polyethylene glycol spacer, and acetylation of the residual PEI amines, multifunctional Fe3O4 @ Au NSs were formed. The designed multifunctional NSs possess excellent colloidal stability, good cytocompatibility in a given concentration range, and specific recognition to cancer cells overexpressing FA receptors. Due to co-existence of Fe3O4 core and star-shaped Au shell, the NSs can be used for MR and CT imaging of tumors, respectively. Likewise, the near infrared plasmonic absorption feature also enables the NSs to be used for PA imaging and PTT of tumors. Our study clearly demonstrates a unique theranostic nanoplatform that can be used for high performance multi-mode imaging-guided PTT of tumors, which may be extendable for theranostics of different diseases in translational medicine.

  2. Multifunctional Fe3O4 @ Au core/shell nanostars: a unique platform for multimode imaging and photothermal therapy of tumors

    PubMed Central

    Hu, Yong; Wang, Ruizhi; Wang, Shige; Ding, Ling; Li, Jingchao; Luo, Yu; Wang, Xiaolin; Shen, Mingwu; Shi, Xiangyang

    2016-01-01

    We herein report the development of multifunctional folic acid (FA)-targeted Fe3O4 @ Au nanostars (NSs) for targeted multi-mode magnetic resonance (MR)/computed tomography (CT)/photoacoustic (PA) imaging and photothermal therapy (PTT) of tumors. In this present work, citric acid-stabilized Fe3O4/Ag composite nanoparticles prepared by a mild reduction route were utilized as seeds and exposed to the Au growth solution to induce the formation of Fe3O4 @ Au core/shell NSs. Followed by successive decoration of thiolated polyethyleneimine (PEI-SH), FA via a polyethylene glycol spacer, and acetylation of the residual PEI amines, multifunctional Fe3O4 @ Au NSs were formed. The designed multifunctional NSs possess excellent colloidal stability, good cytocompatibility in a given concentration range, and specific recognition to cancer cells overexpressing FA receptors. Due to co-existence of Fe3O4 core and star-shaped Au shell, the NSs can be used for MR and CT imaging of tumors, respectively. Likewise, the near infrared plasmonic absorption feature also enables the NSs to be used for PA imaging and PTT of tumors. Our study clearly demonstrates a unique theranostic nanoplatform that can be used for high performance multi-mode imaging-guided PTT of tumors, which may be extendable for theranostics of different diseases in translational medicine. PMID:27325015

  3. Graphene/Fe3 O4 Nanocomposites as Efficient Anodes to Boost the Lifetime and Current Output of Microbial Fuel Cells.

    PubMed

    Song, Rong-Bin; Zhao, Cui-E; Gai, Pan-Pan; Guo, Dan; Jiang, Li-Ping; Zhang, Qichun; Zhang, Jian-Rong; Zhu, Jun-Jie

    2017-02-01

    The enhancement of microbial activity and electrocatalysis through the design of new anode materials is essential to develop microbial fuel cells (MFCs) with longer lifetimes and higher output. In this research, a novel anode material, graphene/Fe3 O4 (G/Fe3 O4 ) composite, has been designed for Shewanella-inoculated MFCs. Because the Shewanella species could bind to Fe3 O4 with high affinity and their growth could be supported by Fe3 O4 , the bacterial cells attached quickly onto the anode surface and their long-term activity improved. As a result, MFCs with reduced startup time and improved stability were obtained. Additionally, the introduction of graphene not only provided a large surface area for bacterial attachment, but also offered high electrical conductivity to facilitate extracellular electron transfer (EET). The results showed that the current and power densities of a G/Fe3 O4 anode were much higher than those of each individual component as an anode.

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

    PubMed

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  6. Synthesis and microwave absorption property of graphene oxide/carbon nanotubes modified with cauliflower-like Fe3O4 nanospheres

    NASA Astrophysics Data System (ADS)

    Yan, Shaojiu; Wang, Lina; Wang, Tihong; Zhang, Liqiang; Li, Yongfeng; Dai, Shenglong

    2016-03-01

    We report a simple procedure to fabricate graphene oxide/carbon nanotube hybrids coated with cauliflower-like Fe3O4 sphere. Characterizations have been carried out to investigate the morphology, crystalline structure of the composites by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Fe3O4 particles have the morphologies of multi-lacuna; moreover, some spheres are hollow. As a kind of potential microwave absorption material, the composites are lightweight and exhibit excellent microwave absorbing ability in the range of 2-16 GHz.

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

    PubMed

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

    2016-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  9. Growth mechanism and magnetism in carbothermal synthesized Fe3O4 nanoparticles from solution combustion precursors

    NASA Astrophysics Data System (ADS)

    Wang, Xuanli; Qin, Mingli; Cao, Zhiqin; Jia, Baorui; Gu, Yueru; Qu, Xuanhui; Volinsky, Alex A.

    2016-12-01

    Magnetic Fe3O4 nanoparticles were prepared by carbothermal reduction using solution combustion synthesis precursors derived from ferric nitrate (oxidizer), glycine (fuel) and glucose (carbon source) mixed solution. In this paper, the growth mechanism and magnetism in Fe3O4 nanoparticles were investigated by adjusting the glucose content in precursor and the heat temperature in carbothermal process. The products were analyzed by X-ray diffraction, Field emission scanning electron microscopy, Infrared adsorption method and Vibrating sample magnetometry. The results revealed that the more amount of glucose, the earlier Fe3O4 phase generated as temperature increasing. Depending on glucose content and thermal temperature, the average grain size of Fe3O4 nanoparticles varied from 19.9 nm to 48 nm and saturation magnetization changed from 21.2 emu/g to 71.77 emu/g, which indicated that the saturation magnetization of Fe3O4 nanoparticles fell off as the average grain size decreasing. These results were crucial not only from the application stand-point, but more importantly leaded to a new platform for further studies of high quality magnetic Fe3O4 particles at nanoscale.

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

    PubMed Central

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

    2015-01-01

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

  11. External magnetic field-induced mesoscopic organization of Fe3O4 pyramids and carbon sheets.

    PubMed

    Pol, S V; Pol, V G; Gedanken, A; Felner, I; Sung, M-G; Asai, S

    2007-06-11

    The current investigation is centered on the thermal decomposition of iron(II) acetyl acetonate, Fe(C5H7O2)2, in a closed cell at 700 degrees C, which is conducted under a magnetic field (MF) of 10 T. The product is compared with a similar reaction that was carried out without a MF. This article shows how the reaction without a MF produces spherical Fe3O4 particles coated with carbon. The same reaction in the presence of a 10 T MF causes the rejection of the carbon from the surface of pyramid-shaped Fe3O4 particles, increases the Fe3O4 particle diameter, forms separate carbon particles, and leads to the formation of an anisotropic (long cigarlike) orientation of Fe3O4 pyramids and C sheets. The macroscopic orientation of Fe3O4 pyramids+C sheets is stable even after the removal of an external MF. The suggested process can be used to fabricate large arrays of uniform wires comprised of some magnetic nanoparticles, and to improve the magnetic properties of nanoscale magnetic materials. The probable mechanism is developed for the growth and assembly behavior of magnetic Fe3O4 pyramids+C sheets under an external MF. The effect of an applied MF to synthesize morphologically different, but structurally the same, products with mesoscopic organization is the key theme of the present paper.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  13. Facile fabrication of core-shell structured magnetic Fe3O4/cross-linked polyphosphazene nanocomposite particles with high stability

    NASA Astrophysics Data System (ADS)

    Wang, Xuzhe; Wang, Minghuan; Fu, Jianwei; Zhang, Chao; Xu, Qun

    2013-08-01

    We herein report a facile approach to the fabrication of core-shell structured magnetic Fe3O4/poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanocomposite particles via precipitation polymerization of comonomers hexachlorocyclotriphosphazene and 4,4'-sulfonyldiphenol in the presence of Fe3O4 nanopaticles. The morphology, composition, thermal property, and magnetic property of the magnetic nanocomposite particles were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer, respectively. Results indicated that the submicron-sized magnetic nanocomposite particles own core/shell structures, 410 °C of initial decomposition temperature under an air atmosphere, and 6.2 emu/g of saturation magnetization, which should make them have potential applications in biotechnology and catalyst supports. Furthermore, we also proposed a possible formation mechanism of these magnetic Fe3O4/PZS nanocomposite particles.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  15. Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

    NASA Astrophysics Data System (ADS)

    Li, Yana; Wu, Tong; Jin, Keying; Qian, Yao; Qian, Naxin; Jiang, Kedan; Wu, Wenhua; Tong, Guoxiu

    2016-11-01

    We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+] = 0.05 M. The maximum reflection loss (RL) reaches -58.4 dB at 13.68 GHz, which corresponds to a 2.1 mm matching thickness. The absorbing bandwidth (RL ≤ -20 dB) reaches 14.4 GHz with the sample thickness at 1.6-2.4 and 2.8-10.0 mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

  16. Osteogenic differentiation of MC3T3-E1 cells on poly(L-lactide)/Fe3O4 nanofibers with static magnetic field exposure.

    PubMed

    Cai, Qing; Shi, Yuzhou; Shan, Dingying; Jia, Wenkai; Duan, Shun; Deng, Xuliang; Yang, Xiaoping

    2015-10-01

    Proliferation and differentiation of bone-related cells are modulated by many factors such as scaffold design, growth factor, dynamic culture system, and physical simulation. Nanofibrous structure and moderate-intensity (1 mT-1 T) static magnetic field (SMF) have been identified as capable of stimulating proliferation and differentiation of osteoblasts. Herein, magnetic nanofibers were prepared by electrospinning mixture solutions of poly(L-lactide) (PLLA) and ferromagnetic Fe3O4 nanoparticles (NPs). The PLLA/Fe3O4 composite nanofibers demonstrated homogeneous dispersion of Fe3O4 NPs, and their magnetism depended on the contents of Fe3O4 NPs. SMF of 100 mT was applied in the culture of MC3T3-E1 osteoblasts on pure PLLA and PLLA/Fe3O4 composite nanofibers for the purpose of studying the effect of SMF on osteogenic differentiation of osteoblastic cells on magnetic nanofibrous scaffolds. On non-magnetic PLLA nanofibers, the application of external SMF could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells. In comparison with pure PLLA nanofibers, the incorporation of Fe3O4 NPs could also promote the proliferation and osteogenic differentiation of MC3T3-E1 cells in the absence or presence of external SMF. The marriage of magnetic nanofibers and external SMF was found most effective in accelerating every aspect of biological behaviors of MC3T3-E1 osteoblasts. The findings demonstrated that the magnetic feature of substrate and microenvironment were applicable ways in regulating osteogenesis in bone tissue engineering.

  17. Magneto-optical and catalytic properties of Fe3O4@HA@Ag magnetic nanocomposite

    NASA Astrophysics Data System (ADS)

    Amir, Md.; Güner, S.; Yıldız, A.; Baykal, A.

    2017-01-01

    Fe3O4@HA@Ag magnetic nanocomposites (MNCs) were successfully synthesized by the simple reflux method for the removal of azo dyes from the industrial aqueous media. Fe3O4@HA@AgMNCs exhibited high catalytic activity to reduce MB within 20 min from the waste water. The obtained materials were characterized by the means of different techniques. Powder X-ray diffraction (XRD) analysis confirmed the single-phase of Fe3O4 spinel structure. SEM and TEM analysis indicated that Fe3O4@HA@AgMNCs were nanoparticles like structure with small agglomeration. TG result showed that the products contained 9% of HA. The characteristic peaks of HA at 1601 cm-1 and 1703 cm-1 was observed by the means of FT-IR spectra of Fe3O4@HA@AgMNCs. The hysteresis (σ-H) curves revealed Fe3O4@HA@Ag MNCs exhibit a typical superparamagnetic characteristic with a saturation magnetization of 59.11 emu/g and measured magnetic moment is 2.45 μB. The average magnetic particle dimension (Dmag) is 13.25 nm. In accordance, the average crystallite and particle dimensions were obtained as 11.50 nm and 13.10 nm from XRD and TEM measurements, respectively. Magnetocrystalline anisotropy was offered as uniaxial and calculated effective anisotropy constant (Keff) is 2.96×105 Erg/g. The blocking temperature was estimated as 522 K. The size-dependent saturation magnetization suggests the existence of a magnetically dead layer as 0.793 nm for Fe3O4@HA@Ag MNCs. The UV-vis diffuse reflectance spectroscopy (DRS) and Kubelka-Munk theory were applied to determine the optical properties of powder samples. The direct optical energy band gap (Eg) values were estimated from Tauc plots between 1.62 eV and 2.12 eV.

  18. Biaxial strain effect induced electronic structure alternation and trimeron recombination in Fe3O4

    PubMed Central

    Liu, Xiang; Yin, Li; Mi, Wenbo

    2017-01-01

    The Verwey transition in Fe3O4 is the first metal-insulator transition caused by charge ordering. However, the physical mechanism and influence factors of Verwey transition are still debated. Herewith, the strain effects on the electronic structure of low-temperature phase (LTP) Fe3O4 with P2/c and Cc symmetries are investigated by first-principles calculations. LTP Fe3O4 with each space group has a critical strain. With P2/c, Fe3O4 is sensitive to the compressive strain, but it is sensitive to tensile strain for Cc. In the critical region, the band gap of LTP Fe3O4 with both two symmetries linearly increases with strain. When strain exceeds the critical value, DOS of spin-down t2g electron at Fe(B4) with P2/c and Fe(B42) with Cc changes between dx2-y2 and dxz + dyz. The trimerons appear in Cc can be affected by strain. With a compressive strain, the correlation of trimeron along x and y axes is strengthened, but broken along the face diagonal of FeB4O4, which is opposite at the tensile strains. The results suggest that the electronic structure of Fe3O4 is tunable by strain. The narrower or wider band gap implies a lower or higher transition temperature than its bulk without strains, which also gives a glimpse of the origin of charge-orbital ordering in Fe3O4. PMID:28230194

  19. One-pot synthesis of in-situ carbon-coated Fe3O4 as a long-life lithium-ion battery anode.

    PubMed

    Liu, Min; Jin, Hongyun; Uchaker, Evan; Xie, Zhiqiang; Wang, Ying; Cao, Guozhong; Hou, Shuen; Li, Jiangyu

    2017-04-18

    Fe3O4 has been regarded as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, low cost, and environmental friendliness. In this work, we present a one-pot reducing-composite-hydroxide-mediated (R-CHM) method to synthesize in situ carbon-coated Fe3O4 (Fe3O4@C) at 280 °C using Fe(NO3)3 · 9H2O and PEG800 as raw materials and NaOH/KOH as the medium. The as-prepared Fe3O4 octahedron has an average size of 100 nm in diameter, covered by a carbon layer with a thickness of 3 nm, as revealed by FESEM and HRTEM images. When used as anode materials in LIBs, Fe3O4@C exhibited an outstanding rate capability (1006, 918, 825, 737, 622, 455 and 317 mAh g(-1) at 0.1, 0.2, 0.5, 0.8, 1.0, 1.5 and 2.0 A g(-1)). Moreover, it presented an excellent cycling stability, with a retained capacity of 261 mAh g(-1) after 800 cycles under an extremely high specific current density of 2.0 A g(-1). Such results indicate that Fe3O4@C can provide a new route into the development of long-life electrodes for future rechargeable LIBs. Importantly, the R-CHM developed in our work can be extended for the synthesis of other carbon-coated electrodes for LIBs and functional nanostructures for broader applications.

  20. One-pot synthesis of in-situ carbon-coated Fe3O4 as a long-life lithium-ion battery anode

    NASA Astrophysics Data System (ADS)

    Liu, Min; Jin, Hongyun; Uchaker, Evan; Xie, Zhiqiang; Wang, Ying; Cao, Guozhong; Hou, Shuen; Li, Jiangyu

    2017-04-01

    Fe3O4 has been regarded as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, low cost, and environmental friendliness. In this work, we present a one-pot reducing-composite-hydroxide-mediated (R-CHM) method to synthesize in situ carbon-coated Fe3O4 (Fe3O4@C) at 280 °C using Fe(NO3)3 · 9H2O and PEG800 as raw materials and NaOH/KOH as the medium. The as-prepared Fe3O4 octahedron has an average size of 100 nm in diameter, covered by a carbon layer with a thickness of 3 nm, as revealed by FESEM and HRTEM images. When used as anode materials in LIBs, Fe3O4@C exhibited an outstanding rate capability (1006, 918, 825, 737, 622, 455 and 317 mAh g‑1 at 0.1, 0.2, 0.5, 0.8, 1.0, 1.5 and 2.0 A g‑1). Moreover, it presented an excellent cycling stability, with a retained capacity of 261 mAh g‑1 after 800 cycles under an extremely high specific current density of 2.0 A g‑1. Such results indicate that Fe3O4@C can provide a new route into the development of long-life electrodes for future rechargeable LIBs. Importantly, the R-CHM developed in our work can be extended for the synthesis of other carbon-coated electrodes for LIBs and functional nanostructures for broader applications.

  1. Stability and magnetically induced heating behavior of lipid-coated Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Allam, Ayat A.; Sadat, Md Ehsan; Potter, Sarah J.; Mast, David B.; Mohamed, Dina F.; Habib, Fawzia S.; Pauletti, Giovanni M.

    2013-10-01

    Magnetic nanoparticles that are currently explored for various biomedical applications exhibit a high propensity to minimize total surface energy through aggregation. This study introduces a unique, thermoresponsive nanocomposite design demonstrating substantial colloidal stability of superparamagnetic Fe3O4 nanoparticles (SPIONs) due to a surface-immobilized lipid layer. Lipid coating was accomplished in different buffer systems, pH 7.4, using an equimolar mixture of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and l-α-dipalmitoylphosphatidyl glycerol (DPPG). Particle size and zeta potential were measured by dynamic laser light scattering. Heating behavior within an alternating magnetic field was compared between the commercial MFG-1000 magnetic field generator at 7 mT (1 MHz) and an experimental, laboratory-made magnetic hyperthermia system at 16.6 mT (13.7 MHz). The results revealed that product quality of lipid-coated SPIONs was significantly dependent on the colloidal stability of uncoated SPIONs during the coating process. Greatest stability was achieved at 0.02 mg/mL in citrate buffer (mean diameter = 80.0 ± 1.7 nm; zeta potential = -47.1 ± 2.6 mV). Surface immobilization of an equimolar DPPC/DPPG layer effectively reduced the impact of buffer components on particle aggregation. Most stable suspensions of lipid-coated nanoparticles were obtained at 0.02 mg/mL in citrate buffer (mean diameter = 179.3 ± 13.9 nm; zeta potential = -19.1 ± 2.3 mV). The configuration of the magnetic field generator significantly affected the heating properties of fabricated SPIONs. Heating rates of uncoated nanoparticles were substantially dependent on buffer composition but less influenced by particle concentration. In contrast, thermal behavior of lipid-coated nanoparticles within an alternating magnetic field was less influenced by suspension vehicle but dramatically more sensitive to particle concentration. These results underline the advantages of lipid

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

    PubMed

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

    2013-01-01

    The aim of this research was to synthesize and develop a new method for the preparation of iron oxide (Fe(3)O(4)) nanoparticles on talc layers using an environmentally friendly process. The Fe(3)O(4) 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 Fe(3)O(4) 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, Fe(3)O(4) 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/Fe(3)O(4) nanocomposites may have potential applications in the chemical and biological industries.

  3. Catalytic wet air oxidation of phenol over Co-doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Song, Xu Chun; Zheng, Yi Fan; Yin, Hao Yong

    2013-08-01

    The Fe3O4 nanoparticles doped with cobalt ions have been successfully synthesized by the co-precipitation process. The X-ray diffraction, inductively coupled plasma, scanning electron microscopy, and transmission electron microscopy were used to characterize the as-prepared nanoparticles. The results show that the phase structure of the nanoparticles is spinel structure of pure Fe3O4 with the particle size ranging from 40 to 50 nm. The Co-doping concentration can be controlled by changing the atomic ratio of the stock materials. The catalytic activity of the Co-doped Fe3O4 was further investigated by decomposing the phenol in liquid phase. The results show that cobalt ions doping can improve the catalytic efficiency of Fe3O4 nanoparticles in phenol degradation with catalytic reaction fitting the first-order kinetics. According to the estimated reaction rate of Co-doped Fe3O4 nanoparticles at different temperatures, the activation energy was calculated to be 45.63 kJ/mol.

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

    PubMed

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

    2014-04-01

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

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

    PubMed

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

    2010-11-01

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

  6. Signal amplification for DNA detection based on the HRP-functionalized Fe3O4 nanoparticles.

    PubMed

    Dong, Xiao-Ya; Mi, Xiao-Na; Wang, Bo; Xu, Jing-Juan; Chen, Hong-Yuan

    2011-04-15

    An electrochemical approach for the sensitive detection of sequence-specific DNA has been developed. Horseradish peroxidase (HRP) assembled on the Fe(3)O(4) nanoparticles (NPs) were utilized as signal amplification sources. High-content HRP was adsorbed on the Fe(3)O(4) NPs via layer-by-layer (LbL) technique to prepare HRP-functionalized Fe(3)O(4) NPs. Signal probe and diluting probe were then immobilized on the HRP-functionalized Fe(3)O(4) NPs through the bridge of Au NPs. Thereafter, the resulting DNA-Au-HRP-Fe(3)O(4) (DAHF) bioconjugates were successfully anchored to the gold nanofilm (GNF) modified electrode surface for the construction of sandwich-type electrochemical DNA biosensor. The electrochemical behaviors of the prepared biosensor had been investigated by the cyclic voltammetry (CV), chronoamperometry (i-t), and electrochemical impedance spectroscopy (EIS). Under optimal conditions, the proposed strategy could detect the target DNA down to the level of 0.7 fmol with a dynamic range spanning 4 orders of magnitude and exhibited excellent discrimination to two-base mismatched DNA and non-complementary DNA sequences.

  7. Structural and magnetic properties of core-shell Au/Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    León Félix, L.; Coaquira, J. A. H.; Martínez, M. A. R.; Goya, G. F.; Mantilla, J.; Sousa, M. H.; Valladares, L. De Los Santos; Barnes, C. H. W.; Morais, P. C.

    2017-02-01

    We present a systematic study of core-shell Au/Fe3O4 nanoparticles produced by thermal decomposition under mild conditions. The morphology and crystal structure of the nanoparticles revealed the presence of Au core of d = (6.9 ± 1.0) nm surrounded by Fe3O4 shell with a thickness of ~3.5 nm, epitaxially grown onto the Au core surface. The Au/Fe3O4 core-shell structure was demonstrated by high angle annular dark field scanning transmission electron microscopy analysis. The magnetite shell grown on top of the Au nanoparticle displayed a thermal blocking state at temperatures below TB = 59 K and a relaxed state well above TB. Remarkably, an exchange bias effect was observed when cooling down the samples below room temperature under an external magnetic field. Moreover, the exchange bias field (HEX) started to appear at T~40 K and its value increased by decreasing the temperature. This effect has been assigned to the interaction of spins located in the magnetically disordered regions (in the inner and outer surface of the Fe3O4 shell) and spins located in the ordered region of the Fe3O4 shell.

  8. Structural and magnetic properties of core-shell Au/Fe3O4 nanoparticles

    PubMed Central

    León Félix, L.; Coaquira, J. A. H.; Martínez, M. A. R.; Goya, G. F.; Mantilla, J.; Sousa, M. H.; Valladares, L. de los Santos; Barnes, C. H. W.; Morais, P. C.

    2017-01-01

    We present a systematic study of core-shell Au/Fe3O4 nanoparticles produced by thermal decomposition under mild conditions. The morphology and crystal structure of the nanoparticles revealed the presence of Au core of d = (6.9 ± 1.0) nm surrounded by Fe3O4 shell with a thickness of ~3.5 nm, epitaxially grown onto the Au core surface. The Au/Fe3O4 core-shell structure was demonstrated by high angle annular dark field scanning transmission electron microscopy analysis. The magnetite shell grown on top of the Au nanoparticle displayed a thermal blocking state at temperatures below TB = 59 K and a relaxed state well above TB. Remarkably, an exchange bias effect was observed when cooling down the samples below room temperature under an external magnetic field. Moreover, the exchange bias field (HEX) started to appear at T~40 K and its value increased by decreasing the temperature. This effect has been assigned to the interaction of spins located in the magnetically disordered regions (in the inner and outer surface of the Fe3O4 shell) and spins located in the ordered region of the Fe3O4 shell. PMID:28165012

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

    PubMed

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

    2016-06-01

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

  10. Weaving a two-dimensional fishing net from titanoniobate nanosheets embedded with Fe3O4 nanocrystals for highly efficient capture and isotope labeling of phosphopeptides

    NASA Astrophysics Data System (ADS)

    Chen, Xueqin; Li, Siyuan; Zhang, Xiaoxia; Min, Qianhao; Zhu, Jun-Jie

    2015-03-01

    Qualitative and quantitative characterization of phosphopeptides by means of mass spectrometry (MS) is the main goal of MS-based phosphoproteomics, but suffers from their low abundance in the large haystack of various biological molecules. Herein, we introduce two-dimensional (2D) metal oxides to tackle this biological separation issue. A nanocomposite composed of titanoniobate nanosheets embedded with Fe3O4 nanocrystals (Fe3O4-TiNbNS) is constructed via a facile cation-exchange approach, and adopted for the capture and isotope labeling of phosphopeptides. In this nanoarchitecture, the 2D titanoniobate nanosheets offer enlarged surface area and a spacious microenvironment for capturing phosphopeptides, while the Fe3O4 nanocrystals not only incorporate a magnetic response into the composite but, more importantly, also disrupt the restacking process between the titanoniobate nanosheets and thus preserve a greater specific surface for binding phosphopeptides. Owing to the extended active surface, abundant Lewis acid sites and excellent magnetic controllability, Fe3O4-TiNbNS demonstrates superior sensitivity, selectivity and capacity over homogeneous bulk metal oxides, layered oxides, and even restacked nanosheets in phosphopeptide enrichment, and further allows in situ isotope labeling to quantify aberrantly-regulated phosphopeptides from sera of leukemia patients. This composite nanosheet greatly contributes to the MS analysis of phosphopeptides and gives inspiration in the pursuit of 2D structured materials for separation of other biological molecules of interests.Qualitative and quantitative characterization of phosphopeptides by means of mass spectrometry (MS) is the main goal of MS-based phosphoproteomics, but suffers from their low abundance in the large haystack of various biological molecules. Herein, we introduce two-dimensional (2D) metal oxides to tackle this biological separation issue. A nanocomposite composed of titanoniobate nanosheets embedded with Fe3

  11. Magnetic Fe3O4@C nanoparticles as adsorbents for removal of amoxicillin from aqueous solution.

    PubMed

    Kakavandi, Babak; Esrafili, Ali; Mohseni-Bandpi, Anoushiravan; Jonidi Jafari, Ahmad; Rezaei Kalantary, Roshanak

    2014-01-01

    In the present study, powder activated carbon (PAC) combined with Fe(3)O(4) magnetite nanoparticles (MNPs) were used for the preparation of magnetic composites (MNPs-PAC), which was used as an adsorbent for amoxicillin (AMX) removal. The properties of magnetic activated carbon were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunaeur, Emmett and Teller and vibrating sample magnetometer. The operational factors affecting adsorption such as pH, contact time, adsorbent dosage, initial AMX concentration and temperature were studied in detail. The high surface area and saturation magnetization for the synthesized adsorbent were found to be 671.2 m(2)/g and 6.94 emu/g, respectively. The equilibrium time of the adsorption process was 90 min. Studies of adsorption equilibrium and kinetic models revealed that the adsorption of AMX onto MNPs-PAC followed Freundlich and Langmuir isotherms and pseudo-second-order kinetic models. The calculated values of the thermodynamic parameters, such as ΔG°, ΔH° and ΔS° demonstrated that the AMX adsorption was endothermic and spontaneous in nature. It could be concluded that MNPs-PAC have a great potential for antibiotic removal from aquatic media.

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

    NASA Astrophysics Data System (ADS)

    Shen, Xiaofang; Ge, Zhaoqiang; Pang, Yuehong

    2015-02-01

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

  13. Structure determination of (Fe3O4)n+(n = 1 - 3) clusters via DFT

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    PubMed

    Ghaseminezhad, Seyedeh Masumeh; Shojaosadati, Seyed Abbas

    2016-06-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  18. Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles.

    PubMed

    Wang, Liying; Sun, Ying; Wang, Jing; Wang, Jian; Yu, Aimin; Zhang, Hanqi; Song, Daqian

    2011-06-01

    In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.

  19. Green synthesis and characterization of superparamagnetic Fe 3O 4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lu, Wensheng; Shen, Yuhua; Xie, Anjian; Zhang, Weiqiang

    2010-07-01

    In this paper, we have first demonstrated a facile and green synthetic approach for preparing superparamagnetic Fe 3O 4 nanoparticles using α- D-glucose as the reducing agent and gluconic acid (the oxidative product of glucose) as stabilizer and dispersant. The X-ray powder diffraction (XRD), X-ray photoelectron spectrometry (XPS), and selected area electron diffraction (SAED) results showed that the inverse spinel structure pure phase polycrystalline Fe 3O 4 was obtained. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results exhibited that Fe 3O 4 nanoparticles were roughly spherical shape and its average size was about 12.5 nm. The high-resolution TEM (HRTEM) result proved that the nanoparticles were structurally uniform with a lattice fringe spacing about 0.25 nm, which corresponded well with the values of 0.253 nm of the (3 1 1) lattice plane of the inverse spinel Fe 3O 4 obtained from the JCPDS database. The superconducting quantum interference device (SQUID) results revealed that the blocking temperature ( Tb) was 190 K, and that the magnetic hysteresis loop at 300 K showed a saturation magnetization of 60.5 emu/g, and the absence of coercivity and remanence indicated that the as-synthesized Fe 3O 4 nanoparticles had superparamagnetic properties. Fourier transform infrared spectroscopy (FT-IR) spectrum displayed that the characteristic band of Fe-O at 569 cm -1 was indicative of Fe 3O 4. This method might provide a new, mild, green, and economical concept for the synthesis of other nanomaterials.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. Magnetically separable Fe3O4@DOPA??Pd: a heterogeneous catalyst for aqueous Heck reaction

    EPA Pesticide Factsheets

    Magnetically separable Fe3O4@DOPA??Pd catalyst has been synthesized via anchoring of palladium over dopamine-coated magnetite via co-ordinate interactionand the catalyst is utilized for expeditious Heck coupling in aqueous media.This dataset is associated with the following publication:Baig, N., J. Leazer , and R. Varma. Magnetically Separable Fe3O4@DOPA-Pd: A Heterogeneous Catalyst for Aqueous Heck Reaction. CLEAN TECHNOLOGIES AND ENVIRONMENTAL POLICY. Springer-Verlag, New York, NY, USA, 17(7): 2073-2077, (2015).

  2. Radiolytic Formation of Fe3O4 Nanoparticles: Influence of Radiation Dose on Structure and Magnetic Properties

    PubMed Central

    Abedini, Alam; Daud, Abdul Razak; Abdul Hamid, Muhammad Azmi; Kamil Othman, Norinsan

    2014-01-01

    Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solution containing iron chloride in presence of polyvinyl alcohol and isopropanol as colloidal stabilizer and hydroxyl radical scavenger, respectively. Gamma irradiation was carried out in a 60Co gamma source chamber at different absorbed doses. Increasing the radiation dose above a certain critical dose (100 kGy) leads to particle agglomeration enhancement, and this can influence the structure and crystallinity, and consequently the magnetic properties of the resultant particles. The optimal condition for formation of Fe3O4 nanoparticles with a uniform and narrow size distribution occurred at a dose of 100 kGy, as confirmed by X-ray diffractometry and transmission electron microscopy. A vibrating sample magnetometry study showed that, when radiation dose increased, the saturation and remanence magnetization decreased, whereas the coercivity and the remanence ratio increased. This magnetic behavior results from variations in crystallinity, surface effects, and particle size effects, which are all dependent on the radiation dose. In addition, Fourier transform infrared spectroscopy was performed to investigate the nature of the bonds formed between the polymer chains and the metal surface at different radiation doses. PMID:24608715

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  4. Synergetic signal amplification of multi-walled carbon nanotubes-Fe3O4 hybrid and trimethyloctadecylammonium bromide as a highly sensitive detection platform for tetrabromobisphenol A

    NASA Astrophysics Data System (ADS)

    Zhou, Feng; Wang, Yue; Wu, Wei; Jing, Tao; Mei, Surong; Zhou, Yikai

    2016-11-01

    In this work, we fabricated an electrochemical sensor based on trimethyloctadecylammonium bromide and multi-walled carbon nanotubes-Fe3O4 hybrid (TOAB/MWCNTs-Fe3O4) for sensitive detection of tetrabromobisphenol A (TBBPA). The nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) techniques. The electrochemical behaviors of TBBPA on TOAB/MWCNTs-Fe3O4 composite film modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) method. The experimental results indicated that the incorporation of MWCNTs-Fe3O4 with TOAB greatly enhanced the electrochemical response of TBBPA. This fabricated sensor displayed excellent analytical performance for TBBPA detection over a range from 3.0 nM to 1000.0 nM with a detection limit of 0.73 nM (S/N = 3). Moreover, the proposed electrochemical sensor exhibited good reproducibility and stability, and could be successfully applied to detect TBBPA in water samples with satisfactory results.

  5. Remote controlled drug release from multi-functional Fe3O4/GO/Chitosan microspheres fabricated by an electrospray method.

    PubMed

    Li, Sheng; Xiao, Ling; Deng, Hongbing; Shi, Xiaowen; Cao, Qihua

    2017-03-01

    The construction of multifunctional microspheres for remote controlled drug release requires the exquisite selection of composite materials and preparation approaches. In this study, chitosan, an amino polysaccharide, was blended with inorganic nanocomponents, Fe3O4 and graphene oxide (GO) and electrosprayed to fabricate uniform microspheres with the diameters ranging from 100μm to 1100μm. An anti-cancer drug, doxorubicin (DOX), was loaded to the microspheres by an adsorption or embedding method. The microsphere is responsive to magnetic fields due to the presence of Fe3O4, and the incorporation of GO enhanced the drug loading capacity. The fast stimuli-responsive release of DOX can be facilely controlled by using NIR irradiation due to the strong photo-thermal conversion of Fe3O4 and GO. In addition, ultrasound was used as another external stimulus for DOX release. The results suggest the Fe3O4/GO/Chitosan microspheres fabricated by the electrospray method provide an efficient platform for remote controlled drug release, which may have potential applications in drug eluting microspheres.

  6. Synergetic signal amplification of multi-walled carbon nanotubes-Fe3O4 hybrid and trimethyloctadecylammonium bromide as a highly sensitive detection platform for tetrabromobisphenol A

    PubMed Central

    Zhou, Feng; Wang, Yue; Wu, Wei; Jing, Tao; Mei, Surong; Zhou, Yikai

    2016-01-01

    In this work, we fabricated an electrochemical sensor based on trimethyloctadecylammonium bromide and multi-walled carbon nanotubes-Fe3O4 hybrid (TOAB/MWCNTs-Fe3O4) for sensitive detection of tetrabromobisphenol A (TBBPA). The nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) techniques. The electrochemical behaviors of TBBPA on TOAB/MWCNTs-Fe3O4 composite film modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) method. The experimental results indicated that the incorporation of MWCNTs-Fe3O4 with TOAB greatly enhanced the electrochemical response of TBBPA. This fabricated sensor displayed excellent analytical performance for TBBPA detection over a range from 3.0 nM to 1000.0 nM with a detection limit of 0.73 nM (S/N = 3). Moreover, the proposed electrochemical sensor exhibited good reproducibility and stability, and could be successfully applied to detect TBBPA in water samples with satisfactory results. PMID:27897238

  7. Bacteria-Affinity 3D Macroporous Graphene/MWCNTs/Fe3O4 Foams for High-Performance Microbial Fuel Cells.

    PubMed

    Song, Rong-Bin; Zhao, Cui-E; Jiang, Li-Ping; Abdel-Halim, Essam Sayed; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-06-29

    Promoting the performance of microbial fuel cells (MFCs) relies heavily on the structure design and composition tailoring of electrode materials. In this work, three-dimensional (3D) macroporous graphene foams incorporated with intercalated spacer of multiwalled carbon nanotubes (MWCNTs) and bacterial anchor of Fe3O4 nanospheres (named as G/MWCNTs/Fe3O4 foams) were first synthesized and used as anodes for Shewanella-inoculated microbial fuel cells (MFCs). Thanks to the macroporous structure of 3D graphene foams, the expanded electrode surface by MWCNTs spacing, as well as the high affinity of Fe3O4 nanospheres toward Shewanella oneidensis MR-1, the anode exhibited high bacterial loading capability. In addition to spacing graphene nanosheets for accommodating bacterial cells, MWCNTs paved a smoother way for electron transport in the electrode substrate of MFCs. Meanwhile, the embedded bioaffinity Fe3O4 nanospheres capable of preserving the bacterial metabolic activity provided guarantee for the long-term durability of the MFCs. With these merits, the constructed MFC possessed significantly higher power output and stronger stability than that with conventional graphite rod anode.

  8. Characterizing the phase purity of nanocrystalline Fe3O4 thin films using Verwey transition

    NASA Astrophysics Data System (ADS)

    Bohra, Murtaza; Prasad, K. Eswar; Bollina, Ravi; Sahoo, S. C.; Kumar, Naresh

    2016-11-01

    We have employed Verwey transition as a probe to check phase purity of nanocrystalline Fe3O4 films grown at different substrate temperatures (Ts) by means of magnetization study. The drop in magnetization at temperatures other than Verwey transition temperature Tv (120 K), in the low and high Ts films indicates the presence of antiferromagnetic (α-Fe2O3/FeO) impurity phases. After wet H2 reduction treatment on these films, a vibrant appearance of Verwey transition is observed which confirms Fe3O4 phase at all Ts. However, high Ts films exhibit low Tv value with distribution, Tv±ΔTv=112+25 K emanating from residual magnetic phases, which were not traced by XRD studies. Interestingly, these nanocrystalline Fe3O4 films exhibit anisotropic magnetic behaviors above Tv, similar to the single crystal Fe3O4. Below the saturation field, the easy (111) and relatively hard (110) axis of magnetizations align along their texture planes.

  9. Synthesis and studies of trisubstituted biphthalonitrile/Fe3O4 magnetic hybrid microspheres

    NASA Astrophysics Data System (ADS)

    Kamzin, A. S.; Liu, X. B.

    2016-10-01

    New trisubstituted biphthalonitrile/magnetite (TSB/Fe3O4) magnetic hybrid microspheres were synthesized from TSB and FeCl3 · 6H2O using the method of one-stage thermal temperature crystallization of solvents. The morphology and structure of magnetic hybrid microspheres were inspected using a scanning electron microscope, IR Fourier spectroscopy, and X-ray diffraction. It was found that the grown TSB/Fe3O4 magnetic hybrid microspheres represent spherical particles with an average size of 137 nm and a small size spread. The size and size distribution of magnetic hybrid microspheres can be controlled by a small change in the ratio of TSB and Fe3+ ion contents in the microsphere. TSB/Fe3O4 hybrid microspheres exhibit a rather high saturation magnetization (58.16 emu g-1) and new microwave electromagnetic properties, i.e., lower (in comparison with published) dielectric losses at low frequencies; magnetic losses are increased obviously due to an increase in the TSB content. Furthermore, it is detected that magnetic hybrid microspheres absorb microwaves, and strong reflection losses in a wide frequency range are established. The effective reflection loss of-31 dB is obtained in the microwave range from 2 to 16 GHz due to TSB content variations. Wide absorption properties of microwaves along with regular spherical shape and excellent magnetic properties offer wide opportunities for various applications of TSB/Fe3O4 magnetic hybrid microspheres as functional materials.

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  11. A facile solvothermal synthesis of octahedral Fe3O4 nanoparticles

    DOE PAGES

    DuChene, Joseph S.; Qiu, Jingjing; Graham, Jeremy O.; ...

    2015-01-26

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  13. Controlled synthesis of Fe3O4/ZIF-8 nanoparticles for magnetically separable nanocatalysts.

    PubMed

    Pang, Fei; He, Mingyuan; Ge, Jianping

    2015-04-27

    Fe3O4/ZIF-8 nanoparticles were synthesized through a room-temperature reaction between 2-methylimidazolate and zinc nitrate in the presence of Fe3O4 nanocrystals. The particle size, surface charge, and magnetic loading can be conveniently controlled by the dosage of Zn(NO3)2 and Fe3O4 nanocrystals. The as-prepared particles show both good thermal stability (stable to 550 °C) and large surface area (1174 m(2) g(-1)). The nanoparticles also have a superparamagnetic response, so that they can strongly respond to an external field during magnetic separation and disperse back into the solution after withdrawal of the magnetic field. For the Knoevenagel reaction, which is catalyzed by alkaline active sites on external surface of catalyst, small Fe3O4/ZIF-8 nanoparticles show a higher catalytic activity. At the same time, the nanocatalysts can be continuously used in multiple catalytic reactions through magnetic separation, activation, and redispersion with little loss of activity.

  14. Photo-catalytic properties of doped or substituted polyaniline-coated Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Song, Weijie; Zhao, Zongshan; Cheng, Yang

    2014-10-01

    In this work, doped and substituted polyaniline (PANI)-coated Fe3O4 nanoparticles were synthesized. The diameter of Fe3O4 core was 430 nm, and the thickness of PANI shell was 20 nm. Their photo-catalytic properties for methyl orange were investigated under natural light illumination. The photo-catalytic activity sequence of three doped PANI/Fe3O4 nanoparticles is as follows: iodine doping > without doping > graphite powder doping. This should be due to the difference of structure, conductivity, and band gap resulting from the dopants. The photo-catalytic activity of five substituted PANI/Fe3O4 nanoparticles followed the order of poly(1,2-diaminobenzene) > poly( o-toluidine) > poly(1,3-diaminobenzene) > PANI > polydiphenylamine. The effects of steric hindrance, activated ability, and conjugation of the substituents on the photo-catalytic properties were discussed. The ESR results suggested that O2 and H2O2 dissolved in the solutions were important factors on the photo-degradation, and the ·OH generated via h+-mediated pathway was the key oxidizing substance.

  15. Preparation and characterization of spindle-like Fe3O4 mesoporous nanoparticles

    PubMed Central

    2011-01-01

    Magnetic spindle-like Fe3O4 mesoporous nanoparticles with a length of 200 nm and diameter of 60 nm were successfully synthesized by reducing the spindle-like α-Fe2O3 NPs which were prepared by forced hydrolysis method. The obtained samples were characterized by transmission electron microscopy, powder X-ray diffraction, attenuated total reflection fourier transform infrared spectroscopy, field emission scanning electron microscopy, vibrating sample magnetometer, and nitrogen adsorption-desorption analysis techniques. The results show that α-Fe2O3 phase transformed into Fe3O4 phase after annealing in hydrogen atmosphere at 350°C. The as-prepared spindle-like Fe3O4 mesoporous NPs possess high Brunauer-Emmett-Teller (BET) surface area up to ca. 7.9 m2 g-1. In addition, the Fe3O4 NPs present higher saturation magnetization (85.2 emu g-1) and excellent magnetic response behaviors, which have great potential applications in magnetic separation technology. PMID:21711591

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  17. Preparation of magnetic Fe3O4@SiO2 nanoparticles for immobilization of lipase.

    PubMed

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

    2014-04-01

    Magnetic Fe3O4 nanoparticles were prepared with coprecipitatation method and covered with SiO2 to form the core-shell Fe3O4@SiO2 nanoparticles. Then the nanoparticles were modified with glutaradehyde for functionalization of the surface to aldehyde groups. The transmission electron microscopy confirmed the core-shell structure and revealed that the size of the nanoparticles was around 10 nm. It was observed that the lipase was immobilized on the nanoparticles successfully from the Fourier transform infrared spectra. The immobilized lipase on Fe3O4@SiO2 nanoparticles was characterized and compared to free enzyme. There are no significant differences observed in the optimal pH, temperature and Km before and after immobilization. However, the immobilized lipase displayed higher relative activity in the range of pH from 7.0 to 9.5. Compare with the free enzyme, the immobilized one showed higher thermal stability at temperature range from 30 to 70 degrees C, especially at high temperature. The relative activity of immobilized enzyme was 5.8 fold of the free lipase at 70 degrees C after 10 h incubation. Thus, the prepared lipase was proved to have the advantages like higher relative activity, better stability, broader pH range and easy to recovery. These results suggest that immobilization of lipase on Fe3O4@SiO2 nanoparticles has the potential industrial applications.

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

    NASA Astrophysics Data System (ADS)

    Kamzin, A. S.

    2016-03-01

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

  19. Synthesis, characterization and wound healing imitation of Fe3O4 magnetic nanoparticle grafted by natural products

    NASA Astrophysics Data System (ADS)

    Pala, Sravan Kumar

    This research focused on the study of the core-shelled magnetic nanomaterials derived from a colloidal chemistry. The goals are four-fold: (1) synthesis of Fe3O4MNMs using colloidal chemistry. The Fe 3O4 MNMs were then grafted with extracts derived from natural products, namely Olecraceavar italica (broccoli), Boletus edulis (mushroom)and Solanum lycopersicum (tomato);(2)characterization of natural products by chromatography and mass spectrometry;(3) characterization of MNMs to determine their crystallinity, morphological and elemental composition by the state-of-the-art instruments; and (4) biological evaluation using Gram-negative and Gram-positive bacteria. The approach provides advantages to precisely control the composition and homogeneity. The second advantage of the colloidal chemistry is its user friendliness and feasibility. Due to the nature of the natural products, the compatibility of MNM is anticipated to be enhanced.In this chapter, the nanomaterials will be discussed from four perspectives,§1.1 Nanotechnology (§1.1), §1.2 Synthesis of nanomaterials; §1.3 The natural product extract,; §1.4 Characterization of nanomaterials; and §1.5Biological application of nanomaterials.Fig. 1 summarized the overarching goals of this study.

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  2. Thiol-functionalized Fe3O4/SiO2 microspheres with superparamagnetism and their adsorption properties for Au(III) ion separation

    NASA Astrophysics Data System (ADS)

    Peng, Xiangqian; Zhang, Wei; Gai, Ligang; Jiang, Haihui; Tian, Yan

    2016-08-01

    Thiol-functionalized Fe3O4/SiO2 microspheres (Fe3O4/SiO2-SH) with high saturation magnetization (69.3 emu g-1), superparamagnetism, and good dispersibility have been prepared by an ethylene glycol reduction method in combination with a modified Stöber method. The as-prepared composite magnetic spheres are characterized with fourier transform infrared spectroscopy (FT-IR), zeta potential, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference magnetometer, and tested in separation of Au(III) ions from aqueous solutions. The data for Au(III) adsorption on Fe3O4/SiO2-SH are analyzed with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models, and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. The adsorption behaviors of Au(III) on Fe3O4/SiO2-SH follow the Langmuir isotherm model, and the adsorption process conforms to the pseudo-second-order kinetic model. The maximum adsorption capacity of Au(III) on Fe3O4/SiO2-SH is 43.7 mg g-1. Acetate anions play an important role yet Cu(II) ions have little interference in the adsorption of Au(III) on the adsorbent. A satisfactory recovery percentage of 89.5% is acquired by using an eluent with 1 M thiourea and 5% HCl, although thiols have a high affinity to Au(III) ions based on the hard-soft acid-base (HSAB) theory by Pearson.

  3. Seeded preparation of ultrathin FeS2 nanosheets from Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  4. Fe3O4 nanoparticles for magnetic hyperthermia and drug delivery; synthesis, characterization and cellular studies

    NASA Astrophysics Data System (ADS)

    Palihawadana Arachchige, Maheshika

    In recent years, magnetic nanoparticles (MNPs), especially superparamagnetic Fe3O4nanoparticles, have attracted a great deal of attention because of their potential applications in biomedicine. Among the other applications, Magnetic hyperthermia (MHT), where localized heating is generated by means of relaxation processes in MNPs when subjected to a radio frequency magnetic field, has a great potential as a non-invasive cancer therapy treatment. Specific absorption rate (SAR), which measures the efficiency of heat generation, depends on magnetic properties of the particles such as saturation magnetization (M s), magnetic anisotropy (K), particle size distribution, magnetic dipolar interactions, and the rheological properties of the target medium.We have investigated MHT in two Fe3O4 ferrofluids prepared by co-precipitation (CP) and hydrothermal (HT) synthesis methods showing similar physical particle size distribution and Ms, but very different SAR 110 W/g and 40 W/g at room temperature. This observed reduction in SAR has been explained by taking the dipolar interactions into account using the so called T* model. Our analysis reveals that HT ferrofluid shows an order of magnitude higher effective dipolar interaction and a wider distribution of magnetic core size of MNPs compared to that of CP ferrofluid. We have studied dextran coated Gd-doped Fe3O4 nanoparticles as a potential candidate in theronostics for multimodal contrast imaging and cancer treatment by hyperthermia. The effect of surfactant on the MHT efficiency and cytotoxicity on human pancreatic cancer cells was explored as well. Though further in vivo study is necessary in the future, these results imply that the dextran coated Fe3O4 dispersion could maintain their high heating capacity in physiological environments while citric acid coating require further surface modification to reduce the non-specific protein adsorption. We have also investigated the traffic, distribution, and cytotoxicity, associated

  5. Magnetic C-C@Fe3O4 double-shelled hollow microspheres via aerosol-based Fe3O4@C-SiO2 core-shell particles.

    PubMed

    Zhu, Yangzhi; Li, Xiangcun; He, Gaohong; Qi, Xinhong

    2015-02-18

    Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.

  6. Hydrothermal synthesis of Ag@TiO2-Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Bokare, Anuja; Singh, Hema; Pai, Mrinal; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A.

    2014-12-01

    Fe3O4-TiO2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe3O4, nanospheres of TiO2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO2. The composite (15% Fe3O4-TiO2) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values.

  7. Reversed ageing of Fe3O4 nanoparticles by hydrogen plasma

    PubMed Central

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

    2016-01-01

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

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

    SciTech Connect

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

    2015-01-15

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

  9. A sensitive choline biosensor using Fe3O4 magnetic nanoparticles as peroxidase mimics.

    PubMed

    Zhang, Zhanxia; Wang, Xiaolei; Yang, Xiurong

    2011-12-07

    A sensitive choline biosensor using Fe(3)O(4) magnetic nanoparticles and a choline oxidase modified gold electrode was developed. Fe(3)O(4) magnetic nanoparticles as peroxidase mimics used in the choline biosensor can not only improve the sensitivity of the response signal, but also possess the favorable properties of stability, magnetic separation and easy preparation, etc. When using the reduction currents of square wave voltammetry as the detection signals, the interferences of ascorbic acid and uric acid to the choline biosensor can be reduced effectively. The reduction currents of the square wave voltammetry were increased with the logarithm values of the choline chloride concentration (from 10(-9) to 10(-2) M), the detection limit was estimated to be 0.1 nM (S/N = 3). This choline biosensor also exhibited favorable selectivity and stability in the determination of choline chloride.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  11. Dynamic Atomic Reconstruction: How Fe3O4 Thin Films Evade Polar Catastrophe for Epitaxy

    NASA Astrophysics Data System (ADS)

    Chang, C. F.; Hu, Z.; Klein, S.; Liu, X. H.; Sutarto, R.; Tanaka, A.; Cezar, J. C.; Brookes, N. B.; Lin, H.-J.; Hsieh, H. H.; Chen, C. T.; Rata, A. D.; Tjeng, L. H.

    2016-10-01

    Polar catastrophe at the interface of oxide materials with strongly correlated electrons has triggered a flurry of new research activities. The expectations are that the design of such advanced interfaces will become a powerful route to engineer devices with novel functionalities. Here, we investigate the initial stages of growth and the electronic structure of the spintronic Fe3O4/MgO (001 ) interface. Using soft x-ray absorption spectroscopy, we have discovered that the so-called A-sites are completely missing in the first Fe3O4 monolayer. This discovery allows us to develop an unexpected but elegant growth principle in which, during deposition, the Fe atoms are constantly on the move to solve the divergent electrostatic potential problem, thereby ensuring epitaxy and stoichiometry at the same time. This growth principle provides a new perspective for the design of interfaces.

  12. Temperature-dependent anisotropic magnetoresistance inversion behaviors in Fe3O4 films

    NASA Astrophysics Data System (ADS)

    Yoon, Kap Soo; Hong, Jin Pyo

    2017-02-01

    We address the abnormal anisotropic magnetoresistance (AMR) reversal feature of half-metallic polycrystalline Fe3O4 films occurring at a specific temperature. Experimental results revealed a positive to negative MR transition in the Fe3O4 films at 264 K, which reflect the influence of additional domain wall scattering. These features was described by a correlation between domain wall resistance and inversion behavior of AMR with additional domain wall scattering factors. We further describe a possible model based on systematic structural and electrical measurements that employs a temperature-dependent domain wall width and spin diffusion length of the conducting electrons. This model allows for spin-flipping scattering of spin polarized electrons inside a proper domain width.

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

    PubMed

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

    2016-01-28

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

  14. Fe3O4 nanoparticles engineered for plasmid DNA delivery to Escherichia coli

    NASA Astrophysics Data System (ADS)

    Saei, Amir Ata; Barzegari, Abolfazl; Majd, Mostafa Heidari; Asgari, Davoud; Omidi, Yadollah

    2014-08-01

    Heat shock treatment is the most popular method for transformation of Escherichia coli. We have used 19-nm Fe3O4 nanoparticles for improving heat shock protocol. PGEM- T (3,000 bp) and pCAMBIA (8,428 bp) were used as test plasmids for transformation of competent E. coli cells (strains DH5α and Jm107) obtained from heat shock- and CaCl2-treated bacteria. A combination of heat shock and Fe3O4 nanoparticles led to a significant increase (6-10 fold) in number of transformed colonies in comparison with heat shock alone. The percent increase in transformation efficiency was higher for larger pCAMBIA plasmids compared to PGEM- T. The transformation efficiency decreased in the absence of CaCl2 and increased by addition of glycerol to the bacterial culture.

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

    USGS Publications Warehouse

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

    1976-01-01

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

  16. Facile synthesis of size tunable Fe3O4 nanoparticles in bisolvent system

    NASA Astrophysics Data System (ADS)

    Huang, Zhuanzhuan; Wu, Kelu; Yu, Qiao-He; Wang, Yi-Yan; Xing, Jiayi; Xia, Tian-Long

    2016-11-01

    Magnetic nanoparticle clusters with magnetization of about 80 emu/g and tunable size between 55 and 500 nm were synthesized through a bisolvent solvothermal process in the presence of ethylene glycol (EG) and diethylene glycol (DEG), triethylene glycol (TEG) or 1,2-propanediol (PG) with polyethylene glycol (PEG) or hexadecyltrimethyl ammonium bromide (CTAB) as surfactant. It was found that the volume ratio of EG to the other polyol played an important role in controlling the size and morphology of Fe3O4. Effect of the concentration of Ferric chloride hexahydrate (FeCl3·6H2O) and original reactants on controlling the size of Fe3O4 particles was also discussed.

  17. Synthesis of Fe 3O 4 magnetic fluid used for magnetic resonance imaging and hyperthermia

    NASA Astrophysics Data System (ADS)

    Wang, Y. M.; Cao, X.; Liu, G. H.; Hong, R. Y.; Chen, Y. M.; Chen, X. F.; Li, H. Z.; Xu, B.; Wei, D. G.

    2011-12-01

    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.

  18. Self-assembled 3D flowerlike hierarchical Fe3O4@Bi2O3 core-shell architectures and their enhanced photocatalytic activity under visible light.

    PubMed

    Wang, Yang; Li, Shikuo; Xing, Xianran; Huang, Fangzhi; Shen, Yuhua; Xie, Anjian; Wang, Xiufang; Zhang, Jian

    2011-04-18

    Three-dimensional (3D) flowerlike hierarchical Fe(3)O(4)@Bi(2)O(3) core-shell architectures were synthesized by a simple and direct solvothermal route without any linker shell. The results indicated that the size of the 3D flowerlike hierarchical microspheres was about 420 nm and the shell was composed of several nanosheets with a thickness of 4-10 nm and a width of 100-140 nm. The saturation magnetization of the superparamagnetic composite microspheres was about 41 emu g(-1) at room temperature. Moreover, the Fe(3)O(4)@Bi(2)O(3) composite microspheres showed much higher (7-10 times) photocatalytic activity than commercial Bi(2)O(3) particles under visible-light irradiation. The possible formation mechanism was proposed for Ostwald ripening and the self-assembled process. This novel composite material may have potential applications in water treatment, degradation of dye pollutants, and environmental cleaning, for example.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  2. An Fe3O4-nanoparticles-based amperometric biosensor for creatine determination.

    PubMed

    Kaçar, Ceren; Erden, Pinar Esra; Pekyardimci, Sule; Kiliç, Esma

    2013-02-01

    An amperometric biosensor for the detection of creatine was designed, based on carbon paste electrode modified with Fe(3)O(4) nanoparticles. Electron transfer properties of unmodified and Fe(3)O(4)-nanoparticles-modified carbon paste electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. Fe(3)O(4) nanoparticles increased the surface area and electric conductivity of the electrode, thus enhancing the sensitivity of the electrode. Optimum pH, buffer concentration, working potential and enzyme loading were selected as 7.0; 0.05 mol L(-1); +0.30 V and 2.0 Unit creatinase (CI), 1.0 Unit sarcosine oxidase (SO), respectively. The purposed biosensor exhibited linear response from 2.0 × 10(-7) mol L(-1) to 3.8 × 10(-6) mol L(-1) and from 9.0 × 10(-6) mol L(-1) to 1.2 × 10(-4) mol L(-1) with a detection limit of 2.0 × 10(-7) mol L(-1). Biosensor was used for determination of creatine in commercial creatine powder samples and showed a good sensing performance.

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

    PubMed

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

    2016-08-08

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

  4. Ultrathin magnetite in Fe3O4/MgO superlattices: Investigating the enhanced thin film magnetic moment

    NASA Astrophysics Data System (ADS)

    Mauit, Ozhet; Fleischer, Karsten; O'Coileáin, Cormac; Bulfin, Brendan; Fox, Daniel S.; Smith, Christopher M.; Mullarkey, Daragh; Sugurbekova, Gulnar; Zhang, Hongzhou; Shvets, Igor V.

    2017-03-01

    The electrical, crystallographic, and magnetic properties of ultrathin magnetite (Fe3O4 ) have been studied in detail, by employing superlattice structures of Fe3O4 /MgFe2O4 and Fe3O4 /MgO on a variety of substrates. By careful analysis of their properties, the influence of substrate stoichiometry, Fe3O4 thin film thickness, antiphase boundaries on the magnetic properties can be separated. In particular, the controversial enhanced magnetic moment in ultrathin films (<5 nm) was confirmed to be related to the substrate stoichiometry, specifically the migration of oxygen vacancies into the Fe3O4 thin films. The multilayer concept can be employed with many other such systems and offers methods of tuning the properties of thin magnetic oxides.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    PubMed

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

    2016-03-07

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

  10. Novel fungus-Fe3O4 bio-nanocomposites as high performance adsorbents for the removal of radionuclides.

    PubMed

    Ding, Congcong; Cheng, Wencai; Sun, Yubing; Wang, Xiangke

    2015-09-15

    The bio-nanocomposites of fungus-Fe3O4 were successfully synthesized using a low-cost self-assembly technique. SEM images showed uniform decoration of nano-Fe3O4 particles on fungus surface. The FTIR analysis indicated that nano-Fe3O4 was combined to the fungus surface by chemical bonds. The sorption ability of fungus-Fe3O4 toward Sr(II), Th(IV) and U(VI) was evaluated by batch techniques. Radionuclide sorption on fungus-Fe3O4 was independent of ionic strength, indicating that inner-sphere surface complexion dominated their sorption. XPS analysis indicated that the inner-sphere radionuclide complexes were formed by mainly bonding with oxygen-containing functional groups (i.e., alcohol, acetal and carboxyl) of fungus-Fe3O4. The maximum sorption capacities of fungus-Fe3O4 calculated from Langmuir isotherm model were 100.9, 223.9 and 280.8 mg/g for Sr(II) and U(VI) at pH 5.0, and Th(IV) at pH 3.0, respectively, at 303 K. Fungus-Fe3O4 also exhibited excellent regeneration performance for the preconcentration of radionuclides. The calculated thermodynamic parameters showed that the sorption of radionuclides on fungus-Fe3O4 was a spontaneous and endothermic process. The findings herein highlight the novel synthesis method of fungus-Fe3O4 and its high sorption ability for radionuclides.

  11. Fe3O4 magnetic nanoparticles/reduced graphene oxide nanosheets as a novel electrochemical and bioeletrochemical sensing platform.

    PubMed

    Teymourian, Hazhir; Salimi, Abdollah; Khezrian, Somayeh

    2013-11-15

    We have developed Fe3O4 magnetic nanoparticles/reduced graphene oxide nanosheets modified glassy carbon (Fe3O4/r-GO/GC) electrode as a novel system for the preparation of electrochemical sensing platform. Decorating Fe3O4 nanoparticles on graphene sheets was performed via a facile one-step chemical reaction strategy, where the reduction of GO and the in-situ generation of Fe3O4 nanoparticles occurred simultaneously. Characterization of as-made nanocomposite using X-ray diffraction (XRD), transmission electron microscopy (TEM) and alternative gradient force magnetometry (AGFM) clearly demonstrate the successful attachment of monodisperse Fe3O4 nanoparticles to graphene sheets. Electrochemical studies revealed that the Fe3O4/r-GO/GC electrode possess excellent electrocatalytic activities toward the low potential oxidation of NADH (0.05 V vs. Ag/AgCl) as well as the catalytic reduction of O2 and H2O2 at reduced overpotentials. Via immobilization of lactate dehydrogenase (LDH) as a model dehydrogenase enzyme onto the Fe3O4/r-GO/GC electrode surface, the ability of modified electrode for biosensing lactate was demonstrated. In addition, using differential pulse voltammetry (DPV) to investigate the electrochemical oxidation behavior of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at Fe3O4/r-GO/GC electrode, the high electrocatalytic activity of the modified electrode toward simultaneous detection of these compounds was indicated. Finally, based on the strong electrocatalytic action of Fe3O4/r-GO/GC electrode toward both oxidation and reduction of nitrite, a sensitive amperometric sensor for nitrite determination was proposed. The Fe3O4/r-GO hybrid presented here showing favorable electrochemical features may hold great promise to the development of electrochemical sensors, molecular bioelectronic devices, biosensors and biofuel cells.

  12. Synthesis of novel nanocomposite Fe3O4/ZrO2/chitosan and its application for removal of nitrate and phosphate

    NASA Astrophysics Data System (ADS)

    Jiang, Hualin; Chen, Pinghua; Luo, Shenglian; Tu, Xinman; Cao, Qun; Shu, Meng

    2013-11-01

    A novel nanocomposite with a BET surface area of 212.9 m2/g was synthesized from chitosan and Fe3O4/ZrO2 using an inexpensive protocol at mild condition. The Fe3O4/ZrO2/chitosan composite has the ability to adsorb both nitrate and phosphate. The maximum adsorption amount of nitrate and phosphate is 89.3 mg/g and 26.5 mg P/g, respectively. The adsorption process fits well to the pseudo-first-order kinetic rate model, and the mechanism involves simultaneous adsorption and intra-particle diffusion. The experimental results suggest that the composite is a promising adsorbent for treating water that is contaminated with nutrients.

  13. Magnetic activated carbon-Fe3O4 nanocomposites--synthesis and applications in the removal of acid yellow dye 17 from water.

    PubMed

    Ranjithkumar, V; Hazeen, A Nizarul; Thamilselvan, M; Vairam, S

    2014-07-01

    In this work, synthesis of activated carbon-Fe3O4 composites using activated carbon and iron benzoate/oxalate precursors by simple pyrolytic method and its utility for the removal of acid yellow dye from water are presented. Iron carboxylates held up into the pores of carbon dissociate at their decomposition temperatures form dispersed Fe3O4 nanoparticles in carbon matrix. The composites were characterized by FTIR, PXRD, SEM, TEM, EDX and magnetization measurements. The size of the nano iron oxides are in the range of 21-33 nm formed from iron benzoate precursor and 6-11 nm from iron oxalate precursor. The oxides are magnetic and their saturation magnetization in the range of 0.08-0.16 emu/g and Coercivity (H(c)) 474-600, being lower and higher than that of bare bulk Fe3O4 are due to the nano size of oxides. Composites find application in the removal of acid yellow dye 17 from the synthetic aqueous solution at pH 5. The adsorption data are found to fit well for Langmuir adsorption isotherm. Kinetics data of adsorption of dyes indicate that the adsorption follows pseudo-second order kinetic model.

  14. Effect of Fe(3)O(4) on the sedimentation and structure-property relationship of starch under different pHs.

    PubMed

    Palanikumar, S; Siva, P; Meenarathi, B; Kannammal, L; Anbarasan, R

    2014-06-01

    The nanosized ferrite (Fe3O4) was synthesized and characterized by analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy and transmission electron microscopy (TEM). The structure-property relationship of starch was studied under three different pHs namely 3.8, 7.1 and 12.5. The starch treated under acidic condition was degraded. In a similar manner, the structure-property relationship of starch in the presence of ferrite nanoparticles at three different pHs, as mentioned above was studied. The starch/ferrite nanocomposite prepared under acidic condition showed a degraded structure. Further, the polymer/nanocomposite systems were characterized by analytical techniques such as FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vibrating sample measurement (VSM), TEM and scanning electron microscopy (SEM). Finally, the settling velocity of starch under three different pHs both in the presence and absence of Fe3O4 was carried out to ensure the role of pH and effect of Fe3O4 on the settling velocity of starch.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  16. Novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles for clinical detection of creatinine.

    PubMed

    Wen, Tingting; Zhu, Wanying; Xue, Cheng; Wu, Jinhua; Han, Qing; Wang, Xi; Zhou, Xuemin; Jiang, Huijun

    2014-06-15

    A novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles (Fe3O4@PANI NPs) has been for the first time fabricated for the sensitive detection of creatinine in biological fluids. The template molecule, creatinine, was self-assembled on the surface of Fe3O4@PANI NPs together with the functional monomer aniline by the formation of N-H hydrogen bonds. After pre-assembled, through the magnetic-induction of the magnetic glassy carbon electrode (MGCE), the ordered structure of molecularly imprinted polymers (MIPs) were established by the electropolymerization and assembled on the surface of MGCE with the help of magnetic fields by a simple one-step approach. The structural controllability of the MIPs film established by magnetic field-induced self-assembly was further studied. The stable and hydrophilic Fe3O4@PANI can not only provide available functionalized sites with which the template molecule creatinine can form hydrogen bond by the abundant amino groups in PANI matrix, but also afford a promoting pathway for electron transfer. The as-prepared molecularly imprinted electrochemical sensor (MIES) shows good stability and reproducibility for the determination of creatinine with the detection limit reached 0.35 nmol L(-1) (S/N=3). In addition, the highly sensitive and selective MIES has been successfully used for the clinical determination of creatinine in human plasma and urine samples. The average recoveries were 90.8-104.9% with RSD lower than 2.7%.

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

    PubMed Central

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

    2016-01-01

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

  18. Monodispersed Silica Nanospheres Encapsulating Fe3O4 and LaF3:Eu3+ Nanoparticles for MRI Contrast Agent and Luminescent Imaging

    NASA Astrophysics Data System (ADS)

    Tian, Yang; Yu, Binbin; Yang, Hong-Yu; Liao, Ji

    2013-03-01

    Bifunctional nanospheres of silica encapsulating Fe3O4 and LaF3:Eu nanoparticles were synthesized in a reverse microemulsion solution. The nanospheres were perfectly monodispersed with a small diameter of 20 nm. The composition of the bifunctional nanospheres was confirmed by powder X-ray diffraction. Their magnetic and luminescent properties were measured at room temperature. The relaxation efficiency and T2-weighted images showed the high-performance for the product as a resonance imaging contrast agent. In addition, a qualitative cell uptake in human cervical cancer HeLa cells demonstrated that the SFLE nanospheres were efficiently up-taken into cytosol. Taken together, these findings suggest that the SiO2/Fe3O4-LaF3:Eu3+ nanospheres are good luminescence probes for bio-imaging.

  19. Ultrasound-assisted removal of Acid Red 17 using nanosized Fe3O4-loaded coffee waste hydrochar.

    PubMed

    Khataee, Alireza; Kayan, Berkant; Kalderis, Dimitrios; Karimi, Atefeh; Akay, Sema; Konsolakis, Michalis

    2017-03-01

    The Fe3O4-loaded coffee waste hydrochar (Fe3O4-CHC) was synthesized using a simple precipitation method. The as-prepared adsorbent was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR). The EDX analysis indicated the presence of Fe in the structure of Fe3O4-CHC. The specific surface area of hydrochar increased from 17.2 to 34.7m(2)/g after loading of Fe3O4 nanoparticles onto it. The prepared Fe3O4-CHC was used for removal of Acid Red 17 (AR17) through ultrasound-assisted process. The decolorization efficiency decreased from 100 to 74% with the increase in initial dye concentration and from 100 to 91 and 85% in the presence of NaCl and Na2SO4, respectively. The synthesized Fe3O4-CHC exhibited good stability in the repeated adsorption-desorption cycles. The high correlation coefficient (R(2)=0.997) obtained from Langmuir model indicated that physical and monolayer adsorption of dye molecules occurred on the Fe3O4-CHC surface. Furthermore, the by-products generated through the degradation of AR17 was identified by gas chromatography-mass spectrometry analysis.

  20. Physiological effects of magnetite (Fe3O4) nanoparticles on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) plants.

    PubMed

    Wang, Huanhua; Kou, Xiaoming; Pei, Zhiguo; Xiao, John Q; Shan, Xiaoquan; Xing, Baoshan

    2011-03-01

    To date, knowledge gaps and associated uncertainties remain unaddressed on the effects of nanoparticles (NPs) on plants. This study was focused on revealing some of the physiological effects of magnetite (Fe(3)O(4)) NPs on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta cv. white cushaw) plants under hydroponic conditions. This study for the first time reports that Fe(3)O(4) NPs often induced more oxidative stress than Fe(3)O(4) bulk particles in the ryegrass and pumpkin roots and shoots as indicated by significantly increased: (i) superoxide dismutase and catalase enzyme activities, and (ii) lipid peroxidation. However, tested Fe(3)O(4) NPs appear unable to be translocated in the ryegrass and pumpkin plants. This was supported by the following data: (i) No magnetization was detected in the shoots of either plant treated with 30, 100 and 500 mg l(-1) Fe(3)O(4) NPs; (ii) Fe K-edge X-ray absorption spectroscopic study confirmed that the coordination environment of Fe in these plant shoots was similar to that of Fe-citrate complexes, but not to that of Fe(3)O(4) NPs; and (iii) total Fe content in the ryegrass and pumpkin shoots treated with Fe(3)O(4) NPs was not significantly increased compared to that in the control shoots.

  1. Magnetically separable Cu2O/chitosan-Fe3O4 nanocomposites: Preparation, characterization and visible-light photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Cao, Chunhua; Xiao, Ling; Chen, Chunhua; Cao, Qihua

    2015-04-01

    A novel magnetically-separable visible-light-induced photocatalyst, Cu2O/chitosan-Fe3O4 nanocomposite (Cu2O/CS-Fe3O4 NC), was prepared via a facile one-step precipitation-reduction process by using magnetic chitosan chelating copper ions as precursor. The structure and properties of Cu2O/CS-Fe3O4 NCs were characterized by XRD, FT-IR, SEM, HRTEM, SAED, EDS, BET, VSM, XPS and UV-vis/DRS. The photocatalytic activity of Cu2O/CS-Fe3O4 NCs was evaluated by decolorization of reactive brilliant red X-3B (X-3B) under visible light irradiation. The characterization results indicated that Cu2O/CS-Fe3O4 NCs exhibited relatively large specific surface areas and special dimodal pore structure because Cu2O was wrapped in chitosan matrix embedded with Fe3O4 nanoparticles. The tight combination of magnetic Fe3O4 and semiconductor Cu2O through chitosan made the nanocomposites show good superparamagnetism and photocatalytic activity. It was found that X-3B could be decolorized more efficiently in acidic media than in neutral or alkaline media. The decolorization of X-3B was ascribed to the synergistic effect of photocatalysis and adsorption. Cu2O/CS-Fe3O4 NCs could be easily separated from the solution by an external magnet, and the decolorization rates of X-3B were still above 87% after five reaction cycles, indicating that Cu2O/CS-Fe3O4 NCs had excellent reusability and stability.

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

    PubMed

    Mohammadi, Abbas; Daemi, Hamed; Barikani, Mehdi

    2014-08-01

    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.

  3. Synthesis of water-dispersible poly-l-lysine-functionalized magnetic Fe3O4-(GO-MWCNTs) nanocomposite hybrid with a large surface area for high-efficiency removal of tartrazine and Pb(II).

    PubMed

    Hu, Dan; Wan, Xiaodong; Li, Xiaohui; Liu, Jianguo; Zhou, Chunhua

    2017-03-07

    In this study, a novel, effective and environment-friendly methods was used to prepare poly-l-lysine (PLL)-functionalized magnetic Fe3O4-(GO-MWCNTs) hybrid composite with large surface area and abundant hydroxyl and amino groups. The as-prepared PLL-Fe3O4-(GO-MWCNTs) nanocomposite was systematically characterized by FT-IR, XRD, TGA, SEM, TEM, VSM and EDX. The PLL-Fe3O4-(GO-MWCNTs) hybrid composite exhibited excellent adsorption performance for the removal of a dye (tartrazine) and a heave metal (Pb(II)). The result showed that adsorption of Pb(II) reached equilibrium in 30min and adsorption of tartrazine reached equilibrium in approximately 60min. Most importantly, PLL-Fe3O4-(GO-MWCNTs) hybrid possesses high adsorption capacity, rapid separation, and less time-consuming. The equilibrium adsorption capacity was 1038.42mgg(-1) for Pb(II) and 775.19mgg(-1) for tartrazine under the optimal conditions. These two pollutants removal were found to obey Langmuir adsorption model, while the kinetics of adsorption followed pseudo-second-order kinetic model. A possible adsorption mechanism has been proposed where the chelation between PLL and Pb(II) or electrostatic interaction between GO and tartrazine. These results demonstrated the potential applications of PLL-Fe3O4-(GO-MWCNTs) hybrid composite in deep-purification of polluted water.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  5. Use of aerosol route to fabricate positively charged Au/Fe3O4 Janus nanoparticles as multifunctional nanoplatforms

    NASA Astrophysics Data System (ADS)

    Byeon, Jeong Hoon; Park, Jae Hong

    2016-10-01

    Gold (Au)-decorated iron oxide (Fe3O4), Au/Fe3O4, Janus nanoparticles were fabricated via the continuous route for aerosol Au incorporation with Fe3O4 domains synthesized in an aqueous medium as multifunctional nanoplatforms. The fabricated nanoparticles were subsequently exposed to 185-nm UV light to generate positive charges on Au surfaces, and their activities were tested in computed tomography (CT) and magnetic resonance (MR) imaging, gene-delivery and photothermal therapy. No additional polymeric coatings of the Janus particles also had a unique ability to suppress inflammatory responses in macrophages challenged with lipopolysaccharide, which may be due to the absence of amine groups.

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

    NASA Astrophysics Data System (ADS)

    Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R. Matthew; Krishnan, Kannan M.

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  8. Folate-conjugated luminescent Fe3O4 nanoparticles for magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  9. A novel electrochemical DNA biosensor based on a modified magnetic bar carbon paste electrode with Fe3O4NPs-reduced graphene oxide/PANHS nanocomposite.

    PubMed

    Jahanbani, Shahriar; Benvidi, Ali

    2016-11-01

    In this study, we have designed a label free DNA biosensor based on a magnetic bar carbon paste electrode (MBCPE) modified with nanomaterial of Fe3O4/reduced graphene oxide (Fe3O4NP-RGO) as a composite and 1- pyrenebutyric acid-N- hydroxysuccinimide ester (PANHS) as a linker for detection of DNA sequences. Probe (BRCA1 5382 insC mutation detection) strands were immobilized on the MBCPE/Fe3O4-RGO/PANHS electrode for the exact incubation time. The characterization of the modified electrode was studied using different techniques such as scanning electron microscopy (SEM), infrared spectroscopy (IR), vibrating sample magnetometer (VSM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry methods. Some experimental parameters such as immobilization time of probe DNA, time and temperature of hybridization process were investigated. Under the optimum conditions, the immobilization of the probe and its hybridization with the target DNA (Complementary DNA) were tested. This DNA biosensor revealed a good linear relationship between ∆Rct and logarithm of the complementary target DNA concentration ranging from 1.0×10(-18)molL(-1) to 1.0×10(-8)molL(-1) with a correlation coefficient of 0.9935 and a detection limit of 2.8×10(-19)molL(-1). In addition, the mentioned biosensor was satisfactorily applied for discriminating of complementary sequences from non-complementary sequences. The constructed biosensor (MBCPE/Fe3O4-RGO/PANHS/ssDNA) with high sensitivity, selectivity, stability, reproducibility and low cost can be used for detection of BRCA1 5382 insC mutation.

  10. Study on enhanced photocatalytic activity of magnetically recoverable Fe3O4@C@TiO2 nanocomposites with core-shell nanostructure

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Meng, Guihua; Wu, Jianning; Li, Deqiang; Liu, Zhiyong

    2015-08-01

    A novel and simple approach for the fabrication of Fe3O4@C@TiO2 nanocomposites with a good core-shell structure has been successfully constructed. The as-synthesized core-shell structure is composed of a magnetic core, an interlayer of carbon, and an outer TiO2 shell. In this method, the carbon middle layer could provide negatively charged for the TiO2 coating without the surfactants. The as-obtained core-shell structure composites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray photoelectron spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), N2 adsorption-desorption isotherm analyses and the magnetization measurement (SQUID). The TEM images showed that the thickness of TiO2 shell could be controlled by varying tertrabutyl titanate (TBOT) content in the ethanol/acetonitrile mixed solvents. Photocatalytic property of Fe3O4@C@TiO2 nanocomposites were evaluated by photodegradation methylene blue (MB). The results showed that the well-designed nanocomposites exhibited a higher photoactivity than Fe3O4@TiO2 nanocomposites. Moreover, this photocatalyst can be easily recovered by an external magnetic field and remain stable photocatalytic activity after five cycles. The presence of carbon interlayer can avoid the occurrence of photodissolution. Therefore, the photocatalytic activity of titania would not deteriorate seriously, which played key role for the enhanced photocatalytic activity.

  11. A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals

    PubMed Central

    Labiadh, Houcine; Ben Chaabane, Tahar; Sibille, Romain; Balan, Lavinia

    2015-01-01

    Summary Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL) spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs) showed marked visible emission around 584 nm related to the 4T1 → 6A1 Mn2+ transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications. PMID:26425426

  12. Carbon-Coated Fe3O4/VOx Hollow Microboxes Derived from Metal-Organic Frameworks as a High-Performance Anode Material for Lithium-Ion Batteries.

    PubMed

    Zhao, Zhi-Wei; Wen, Tao; Liang, Kuang; Jiang, Yi-Fan; Zhou, Xiao; Shen, Cong-Cong; Xu, An-Wu

    2017-02-01

    As the ever-growing demand for high-performance power sources, lithium-ion batteries with high storage capacities and outstanding rate performance have been widely considered as a promising storage device. In this work, starting with metal-organic frameworks, we have developed a facile approach to the synthesis of hybrid Fe3O4/VOx hollow microboxes via the process of hydrolysis and ion exchange and subsequent calcination. In the constructed architecture, the hollow structure provides an efficient lithium ion diffusion pathway and extra space to accommodate the volume expansion during the insertion and extraction of Li(+). With the assistance of carbon coating, the obtained Fe3O4/VOx@C microboxes exhibit excellent cyclability and enhanced rate performance when employed as an anode material for lithium-ion batteries. As a result, the obtained Fe3O4/VOx@C delivers a high Coulombic efficiency (near 100%) and outstanding reversible specific capacity of 742 mAh g(-1) after 400 cycles at a current density of 0.5 A g(-1). Moreover, a remarkable reversible capacity of 556 mAh g(-1) could be retained even at a current density of 2 A g(-1). This study provides a fundamental understanding for the rational design of other composite oxides as high-performance electrode materials for lithium-ion batteries.

  13. Facile synthesis of Fe3O4-graphene@mesoporous SiO2 nanocomposites for efficient removal of Methylene Blue

    NASA Astrophysics Data System (ADS)

    Wu, Xi-Lin; Shi, Yanpeng; Zhong, Shuxian; Lin, Hongjun; Chen, Jian-Rong

    2016-08-01

    Herein, we have developed a facile and low-cost method for the synthesis of novel graphene based nanosorbents. Firstly, well-defined Fe3O4 nanoparticles were decorated onto graphene sheets, and then a layer of mesoporous SiO2 were deposited on the surface of the Fe3O4-graphene composites. The obtained Fe3O4-graphene@mesoporous SiO2 nanocomposites (denoted as MG@m-SiO2) were characterized by scanning electron microscopic (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The adsorptive property was investigated by using MG@m-SiO2 as sorbents and Methylene Blue (MB), a common dye, as model of the organic pollutants. Adsorption kinetics, isotherms, thermodynamics as well as effects of pH and adsorbent dose on the adsorption were studied. The adsorption isotherms and kinetics are better described by Langmuir isotherm model and pseudo-second-order kinetic model, respectively. Thermodynamic studies suggest that the adsorption of MB onto the MG@m-SiO2 is endothermic and spontaneous process. The results imply that the MG@m-SiO2 can be served as a cost-effective adsorbent for the removal of organic pollutants from aqueous solutions.

  14. Degradation of sulfamethazine using Fe3O4-Mn3O4/reduced graphene oxide hybrid as Fenton-like catalyst.

    PubMed

    Wan, Zhong; Wang, Jianlong

    2017-02-15

    In this paper, Fe3O4-Mn3O4/reduced graphene oxide (RGO) hybrid was synthesized through polyol process and impregnation method and used as heterogeneous Fenton-like catalyst for degradation of sulfamethazine (SMT) in aqueous solution. The hybrid catalyst had higher catalytic efficiency compared with Fe3O4-Mn3O4 and Mn3O4 as catalyst for degradation of SMT. The effects of pH value, H2O2 concentration, catalyst dosage, initial SMT concentration and temperature on SMT degradation were investigated. The removal efficiency of SMT was about 98% at following optimal conditions: pH=3, T=35°C, Fe3O4/Mn3O4-RGO composites=0.5g/L, H2O2=6mM. The inhibitor experiments indicated that the main active species was hydroxyl radicals (·OH) on catalyst surface. At last, the possible catalytic mechanism was proposed.

  15. Multifunctional nanocomposites Fe3O4@SiO2-EDTA for Pb(II) and Cu(II) removal from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Fu, Ruiqi; Sun, Yue; Zhou, Xiaoxin; Baig, Shams Ali; Xu, Xinhua

    2016-04-01

    In this study, EDTA-functionalized Fe3O4 (Fe3O4@SiO2-EDTA) was prepared by silanization reaction between N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (EDTA-silane) and hydroxyl groups for Pb(II) and Cu(II) removal from aqueous solutions. Fe3O4@SiO2-EDTA composites were characterized using SEM, TEM, EDX, FTIR, XPS, TGA and saturated magnetization techniques. Maximum Pb(II) adsorption capacity was found to be 114.94 mg g-1 with SiO2/EDTA molar ratio of 2.5:1. The adsorption rate was significantly fast and the equilibrium was reached within 10 min. The optimum pH was recorded to be 5.0. The maximum adsorption capacity of the studied heavy metal ions calculated by Langmuir model followed the order: Cu(II) (0.58 mmol g-1) > Pb(II) (0.55 mmol g-1) ≈ Ni(II) (0.55 mmol g-1) > Cd(II) (0.45 mmol g-1). Moreover, Pb(II) and Cu(II) adsorption capacities were not significantly affected by co-existing cations and NOM. These results suggested that this adsorbent can be considered as a promising adsorbent to remove Pb(II) and Cu(II) from wastewaters.

  16. Solid-state synthesis of the ZnO-Fe3O4 nanocomposite: Structural and magnetic properties

    NASA Astrophysics Data System (ADS)

    Bykova, L. E.; Myagkov, V. G.; Tambasov, I. A.; Bayukov, O. A.; Zhigalov, V. S.; Polyakova, K. P.; Bondarenko, G. N.; Nemtsev, I. V.; Polyakov, V. V.; Patrin, G. S.; Velikanov, D. A.

    2015-02-01

    The structural and magnetic properties of ZnO-Fe3O4 nanocomposites produced by the solid-state reaction Zn + 3Fe2O3 → ZnO + 2Fe3O4 upon annealing of Zn/α-Fe2O3 films under vacuum at a temperature of 450°C have been studied. Ferrimagnetic Fe3O4 clusters with an average grain size of 40 nm and a magnetization of ˜430 emu/cm3 at room temperature, which are surrounded by a ZnO layer with a large contact surface, have been synthesized. The magnetic characteristics of the ZnO-Fe3O4 nanocomposite in the temperature range of 10-300 K have been presented.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  18. Bias voltage-dependent low field spin transport properties of Fe3O4-PEG with different particle sizes

    NASA Astrophysics Data System (ADS)

    Xu, Chunlong; Wang, Zhen; Wang, Lei; Shi, Gang; Hou, Zhaoyang; Xi, Li

    2016-08-01

    Spin-dependent transport properties of Fe3O4 spheres with diameters from 200 nm to 900 nm have been investigated and polyethylene glycol (PEG) exists on the surface of Fe3O4 particles. The nonlinear I-V curve became obvious with the increase of Fe3O4 diameter, which indicated the tunneling barrier height decreases with the increasing diameter. The magnetoresistance (MR) can reach -13% with an applied low field of 0.2 T at room temperature. With the diameter increase, the MR decreases and the required applied field increases. Moreover, the decrease of MR with the bias voltage increase can be attributed to the spin-dependent tunneling effect through the insulating surface layer of Fe3O4 and PEG.

  19. Reversible control of magnetization of Fe3O4 by a solid-state film lithium battery

    NASA Astrophysics Data System (ADS)

    Wei, Guodong; Wei, Lin; Wang, Dong; Chen, Yanxue; Tian, Yufeng; Yan, Shishen; Mei, Liangmo; Jiao, Jun

    2017-02-01

    The LiCoO2/LISICON/Fe3O4 structured solid-state film lithium battery is designed to realize a reversible control of the magnetization in Fe3O4 film. LISICON (Li1.5Al0.5Ge1.5P3O12) is selected to serve as the solid-state electrolyte owing to its excellent Li ion transport property at room temperature. A reversible and non-volatile control of the saturation magnetization of Fe3O4 film between the charged and discharged states was obtained, and the modulation ratio can reach as high as 10%. The redox of Fe ions, caused by the intercalation/deintercalation of lithium ion in Fe3O4 film, is responsible for the observed magnetic variation. The battery consisting entirely of solid films provides a promising strategy to control the magnetic properties electrically, which will be a very hopeful candidate for many practical applications.

  20. Facile graft of poly(2-methacryloyloxyethyl phosphorylcholine) onto Fe(3) O(4) nanoparticles by ATRP: synthesis, properties, and biocompatibility.

    PubMed

    Sun, Xiao-Yan; Yu, Shou-Shan; Wan, Jia-Qi; Chen, Ke-Zheng

    2013-02-01

    Magnetite (Fe(3) O(4) ) nanoparticles with the surface hydroxyl groups were achieved by a polyol process. Using 2-(4-chlorosulfonylphenyl) ethyltrichlorosilane (CTCS) as initiator, 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) as monomer, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC)-grafted Fe(3) O(4) nanoparticles (MNP) were successfully prepared via the atom transfer radical polymerization (ATRP) method. The successful grafting of PMPC on the Fe(3) O(4) nanoparticles surface was ascertained from the FTIR analysis. The modified nanoparticles (MNP-CTCS-PMPC) showed a good biocompatibility in the cytotoxicity test in vitro. Performance testing of MNP-CTCS-PMPC was performed through magnetic resonance analysis (MR), and its r(2) /r(1) value was 24.1. These results indicated that the modified Fe(3) O(4) nanoparticles would be a potential MRI contrast reagent.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  2. Highly regenerable carbon-Fe3O4 core-satellite nanospheres as oxygen reduction electrocatalyst and magnetic adsorbent

    NASA Astrophysics Data System (ADS)

    Zhou, Wenqiang; Liu, Minmin; Cai, Chao; Zhou, Haijun; Liu, Rui

    2017-02-01

    We present the synthesis and multifunctional utilization of core-satellite carbon-Fe3O4 nanoparticles to serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. Starting from polydopamine (PDA) nanoparticles and Fe(NO3)3, carbon-Fe3O4 core-satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The synergistic combination of Fe3O4 and N-doped carbon endows the nanocomposite with high electrochemical activity in ORR and mainly four electrons transferred in reaction process. Furthermore, carbon-Fe3O4 nanoparticles used as magnetic adsorbent exhibit the efficient removal of Rhodamine B from an aqueous solution. The recovery and reuse of the adsorbent is demonstrated 5 times without any detectible loss in activity.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed Central

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

    2012-01-01

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

  5. Fe3O4/salicylic acid nanoparticles versatility in magnetic mediated vascular nanoblockage

    NASA Astrophysics Data System (ADS)

    Mîndrilă, I.; Buteică, S. A.; Mihaiescu, D. E.; Badea, G.; Fudulu, A.; Mărgăritescu, D. N.

    2016-01-01

    An aqueous dispersion of Fe3O4/salicylic acid magnetic nanoparticles (SaMNPs) was synthesized by a modified Massart method, characterized by Inductively Coupled Plasma-Optic Emission Spectrometry (ICP-OES), High-Resolution Transmission Electron Microscopy (HRTEM) and Dynamic Light Scattering (DLS) methods, and tested on the chick chorioallantoic membrane (CAM) model to evaluate biocompatibility, biodistribution, intravascular time persistence, and ability to be magnetically target driven in order to block the blood supply into a tumor xenograft. ICP-OES, DLS, and HRTEM SaMNPs sample analyses showed a 0.356 mg/mL Fe concentration, a good stability in water (average Zeta potential of 39.3 mV), a hydrodynamic diameter around 52 nm and a core diameter in the 7-15 nm range for the Fe3O4 nanoparticles. In vivo CAM assay showed that SaMNPs were biocompatible with the chick embryo, were fixed almost completely by the liver, had no embolic potential, and a threshold-dose-dependent intravascular magnetic targeting time. Study on the CAM tumor model showed that SaMNPs could be used for long-term magnetically mediated nanoblocking of the capillary networks and 70-µm smaller arterioles.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  9. Fe3O4-based PLGA nanoparticles as MR contrast agents for the detection of thrombosis

    PubMed Central

    Liu, Jia; Xu, Jie; Zhou, Jun; Zhang, Yu; Guo, Dajing; Wang, Zhigang

    2017-01-01

    Thrombotic disease is a great threat to human health, and early detection is particularly important. Magnetic resonance (MR) molecular imaging provides noninvasive imaging with the potential for early disease diagnosis. In this study, we developed Fe3O4-based poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) surface-modified with a cyclic Arg-Gly-Asp (cRGD) peptide as an MR contrast agent for the detection of thrombosis. The physical and chemical characteristics, biological toxicity, ability to target thrombi, and biodistribution of the NPs were studied. The Fe3O4-PLGA-cRGD NPs were constructed successfully, and hematologic and pathologic assays indicated no in vivo toxicity of the NPs. In a rat model of FeCl3-induced abdominal aorta thrombosis, the NPs readily and selectively accumulated on the surface of the thrombosis and under vascular endothelial cells ex vivo and in vivo. In the in vivo experiment, the biodistribution of the NPs suggested that the NPs might be internalized by the macrophages of the reticuloendothelial system in the liver and the spleen. The T2 signal decreased at the mural thrombus 10 min after injection and then gradually increased until 50 min. These results suggest that the NPs are suitable for in vivo molecular imaging of thrombosis under high shear stress conditions and represent a very promising MR contrast agent for sensitive and specific detection of thrombosis. PMID:28223802

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

    PubMed

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

    2014-06-01

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

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

    PubMed

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

    2016-03-15

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

  12. High surface area monodispersed Fe3O4 nanoparticles alone and on physical exfoliated graphite for improved supercapacitors

    NASA Astrophysics Data System (ADS)

    Sarno, Maria; Ponticorvo, Eleonora; Cirillo, Claudia

    2016-12-01

    Highly conductive, unsophisticated and easy to be obtained physical exfoliated graphite (PHG) supporting well dispersed magnetite, Fe3O4/PHG nanocomposite, has been prepared by a one-step chemical strategy and physico-chemical characterized. The nanocomposite, favoured by the a-polar nanoparticles (NPs) capping, results in a self-assembled monolayer of monodispersed Fe3O4, covering perfectly the hydrophobic surfaces of PHG. The nanocomposite as an electrode material was fabricated into a supercapacitor and characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. It shows, after a suitable annealing, significant electrochemical properties (capacitance value of 787 F/g at 0.5 A g-1 and a Fe3O4/PHG weight ratio of 0.31) and good cycling stability (retention 91% after 30,000 cycles). Highly monodispersed very fine Fe3O4 NPs, covered by organic chains, have been also synthesized. The high surface area Fe3O4 NPs, after washing to leave a low content of organic chains able to avoid aggregation without excessively affecting the electrical properties of the material, exhibit remarkable pseudocapacitive activities, including the highest specific capacitance over reported for Fe3O4 (300 F/g at 0.5 A g-1).

  13. Polydopamine-Encapsulated Fe3O4 with an Adsorbed HSP70 Inhibitor for Improved Photothermal Inactivation of Bacteria.

    PubMed

    Liu, Dongdong; Ma, Liyi; Liu, Lidong; Wang, Lu; Liu, Yuxin; Jia, Qi; Guo, Quanwei; Zhang, Ge; Zhou, Jing

    2016-09-21

    Photothermal treatment, a new approach for inactivation of bacteria and pathogens that does not depend on traditional therapeutic approaches, has recently received much attention. In this study, a new type of nanoplatform (PDA@Fe3O4 + PES) was fabricated by using polydopamine (PDA, a photothermal conversion agent) to encapsulate Fe3O4 (a magnetic nanoparticle) and support 2-phenylethynesulfonamide (PES, an inhibitor of heat shock protein 70 (HSP70)). Upon near-infrared light irradiation, the increased temperature weakens π-π and hydrogen bonding interactions, and PES is released from the PDA@Fe3O4 + PES. The released PES inhibits the function of HSP70, reducing bacterial tolerance to photothermal therapy and improving the therapeutic effect against infectious bacterial pathogens. After treatment, PDA@Fe3O4 + PES can be recovered using the magnetic property of the Fe3O4 cores. Consequently, PDA@Fe3O4 + PES possesses the potential to be a recyclable photothermal agent for enhanced photothermal bacterial inactivation without causing secondary pollution.

  14. Fe(3)O(4)@Au/polyaniline multifunctional nanocomposites: their preparation and optical, electrical and magnetic properties.

    PubMed

    Yu, Qiaozhen; Shi, Minmin; Cheng, Yunan; Wang, Mang; Chen, Hong-Zheng

    2008-07-02

    Fe(3)O(4)@Au/polyaniline (PANI) nanocomposites were fabricated by in situ polymerization in the presence of mercaptocarboxylic acid. The mercaptocarboxylic acid was used to introduce hydrogen bonding and/or electrostatic interaction; it acts as a template in the formation of Fe(3)O(4)@Au/PANI nanorods. The morphology and structure of the resulting nanocomposites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, x-ray diffraction and x-ray energy dispersion spectroscopy (EDS). It was found that the nanocomposites were rod-like with an average diameter of 153 nm, and they exhibited a core-shell structure. A UV-visible spectrometer, semiconductor parameter analyzer and vibrating sample magnetometer (VSM) were used to characterize the optical, electrical and magnetic properties of the Fe(3)O(4)@Au/PANI nanocomposites. It was interesting to find that these properties are dependent on the molar ratio of Au to Fe(3)O(4) when the molar ratio of Fe(3)O(4)@Au to PANI is fixed. The magnetic property of the Fe(3)O(4)@Au/PANI nanocomposite is very close to superparamagnetic behavior.

  15. Efficient purification of lysozyme from egg white by 2-mercapto-5-benzimidazolesulfonic acid modified Fe3O4/Au nanoparticles.

    PubMed

    Zhu, Xinjun; Zhang, Lianying; Fu, Aiyun; Yuan, Hao

    2016-02-01

    2-Mercapto-5-benzimidazolesulfonic acid (MBISA) modified Fe3O4/Au nanoparticles were synthesized in aqueous solution and characterized by photo correlation spectroscopy (PCS) and vibrating sample magnetometer (VSM). The so-obtained Fe3O4/Au-MBISA nanoparticles were capable of specific adsorbing lysozyme. The maximum amount of lysozyme adsorbed on 1.0mg Fe3O4/Au-MBISA nanoparticles was 346μg. The lysozyme desorption behavior was studied and the lysozyme recovery from Fe3O4/Au-MBISA nanoparticles approached 100% under optimal conditions, and the reusability studies showed that the nanoparticles could maintain about 91% of the initial lysozyme adsorption capacity after 7 repeated adsorption-elution cycles. The Fe3O4/Au-MBISA nanoparticles were used in the purification of lysozyme from chicken egg white, which was verified by a single SDS-PAGE band. Therefore, the obtained Fe3O4/Au-MBISA nanoparticles exhibited excellent performance in the direct purification of lysozyme from egg white.

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

    PubMed Central

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

    2015-01-01

    A coagulation (FeCl3)-ultrafiltration process was used to treat two different raw waters with/without the presence of Fe3O4 nanoparticle contaminants. The existence of Fe3O4 nanoparticles in the raw water was found to increase both irreversible and reversible membrane fouling. The trans-membrane pressure (TMP) increase was similar in the early stages of the membrane runs for both raw waters, while it increased rapidly after about 15 days in the raw water with Fe3O4 nanoparticles, suggesting the involvement of biological effects. Enhanced microbial activity with the presence of Fe3O4 nanoparticles was evident from the measured concentrations of extracellular polymeric substances (EPS) and deoxyribonucleic acid (DNA), and fluorescence intensities. It is speculated that Fe3O4 nanoparticles accumulated in the cake layer and increased bacterial growth. Associated with the bacterial growth is the production of EPS which enhances the bonding with, and between, the coagulant flocs; EPS together with smaller sizes of the nano-scale primary particles of the Fe3O4-CUF cake layer, led to the formation of a lower porosity, more resilient cake layer and membrane pore blockage. PMID:26268589

  17. Synthesis, Mössbauer Spectra and Magnetic Properties of Quasi-One-Dimensional Fe3O4 Nanowires

    NASA Astrophysics Data System (ADS)

    Xue, De-Sheng; Zhang, Li-Ying; Gao, Cun-Xu; Xu, Xue-Fei; Gui, An-Biao

    2004-04-01

    Quasi-one-dimensional Fe3O4 nanowires in diameter of about 200 nm were assembled into anodic aluminium oxide templates via electrodepositing and heat-treating processes. The nanowires have a polycrystalline spinel structure with a = 8.317 Å, and each nanowire is composed of fine Fe3O4 crystallites with size of about 30 nm. The magnetic moments of Fe3O4 crystallites in nanowires have a preferred orientation leaning to the wire axis but not parallel to the wire axis. Mössbauer spectra (MS) were used to verify the presence of Fe3O4 further and the existence of superparamagnetic particles in nanowires. A perpendicular magnetic anisotropy was observed obviously. Temperature dependence of the magnetic moments (M-T) shows that the Verwey transition for the Fe3O4 nanowires occurs at 50 K, and the behaviour of the M-T curve is different from that of other magnetite materials. These characteristic magnetic properties of Fe3O4 nanowires are mainly due to the reduced dimension and the configuration of preferred orientation in the nanowires caused by the shape anisotropy.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    PubMed

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

    2016-01-01

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

  20. Comparative study on ultrasonic assisted adsorption of dyes from single system onto Fe3O4 magnetite nanoparticles loaded on activated carbon: Experimental design methodology.

    PubMed

    Bagheri, Ahmad Reza; Ghaedi, Mehrorang; Asfaram, Arash; Bazrafshan, Ali Akbar; Jannesar, Ramin

    2017-01-01

    The present study the ultrasound assisted adsorption of dyes in single system onto Fe3O4 magnetite nanoparticles loaded on activated carbon (Fe3O4-MNPs-AC) was described following characterization and identification of this adsorbent by conventional techniques likes field emission scanning electron microscopy, transmission electron microscopy, particle-size distribution, X-ray diffraction and Fourier transform infrared spectroscopy. A central composite design in conjunction with a response surface methodology according to f-test and t-test for recognition and judgment about significant term led to construction of quadratic model which represent relation among responses and effective terms. This model has unique ability to predict adsorption data behavior over a large space around central and optimum point. Accordingly Optimum conditions for well and quantitative removal of present dyes was obtained best operation and conditions: initial SY, MB and EB dyes concentration of 15, 15 and 25mgL(-1), 4.0, 6.0 and 5.0 of pH, 360, 360 and 240s sonication time and 0.04, 0.03 and 0.032g of Fe3O4-MNPs-AC. Replication of similar experiment (N=5) guide that average removal percentage of SY, MB and EB were found to be 96.63±2.86%, 98.12±1.67% and 99.65±1.21% respectively. Good agreement and closeness of Predicted and experimental result and high adsorption capacity of dyes in short time strongly confirm high suitability of present method for waste water treatment, while easy separation of present nanoparticle and its good regeneration all support good applicability of Fe3O4-MNPs-AC for waste water treatment. The kinetic study can be represented by combination of pseudo second-order and intraparticle diffusion. The obtained maximum adsorption capacities correspond to Langmuir as best model for representation of experimental data correspond to dyes adsorption onto Fe3O4-MNPs-AC were 76.37, 78.76 and 102.00mgg(-1) for SY, MB and EB, respectively. In addition, the performance

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

    PubMed Central

    2012-01-01

    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%

  2. Fast and Selective Preconcentration of Europium from Wastewater and Coal Soil by Graphene Oxide/Silane@Fe3O4 Dendritic Nanostructure.

    PubMed

    Patra, Santanu; Roy, Ekta; Madhuri, Rashmi; Sharma, Prashant K

    2015-05-19

    In this study, nanocomposite of graphene oxide and silane modified magnetic nanoparticles (silane@Fe3O4) were synthesized in a form of dendritic structure. For this, silane@Fe3O4 nanoparticle gets sandwiched between two layers of graphene oxide by chemical synthesis route. The synthesized dendritic structure was used as a monomer for synthesis of europium ion imprinted polymer. The synthesis of imprinted polymer was contemplated onto the surface of the vinyl group modified silica fiber by activated generated free radical atom-transfer radical polymerization, that is, AGET-ATRP technique. The synthesized dendritic monomer was characterized by XRD, FT-IR, VSM, FE-SEM, and TEM analyses. The imprinted polymer modified silica fiber was first validated in the aqueous and blood samples for successful extraction and detection of europium ion with limit of detection = 0.050 pg mL(-1) (signal/noise = 3). The imprinted polymer modified silica fiber was also used for preconcentration and separation of europium metal ion from various soil samples of coal mine areas. However, the same silica fiber was also used for wastewater treatment and shows 100% performance for europium removal. The findings herein suggested that dendritic nanocomposite could be potentially used as a highly effective material for the enrichment and preconcentration of europium or other trivalent lanthanides/actinides in nuclear waste management.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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 m2 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.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 m2 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

  4. Large low-field magnetoresistance of Fe3O4 nanocrystal at room temperature

    NASA Astrophysics Data System (ADS)

    Mi, Shu; Liu, Rui; Li, Yuanyuan; Xie, Yong; Chen, Ziyu

    2017-04-01

    Superparamagnetic magnetite (Fe3O4) nanoparticles with an average size of 6.5 nm and good monodispersion were synthesized and investigated by X-ray diffraction, Raman spectrometer, transmission electron microscopy and vibrating sample magnetometer. Corresponding low-field magnetoresistance (LFMR) was tested by physical property measurement system. A quite high LFMR has been observed at room temperature. For examples, at a field of 3000 Oe, the LFMR is -3.5%, and when the field increases to 6000 Oe, the LFMR is up to -5.1%. The electron spin polarization was estimated at 25%. This result is superior to the previous reports showing the LFMR of no more than 2% at room temperature. The conduction mechanism is proposed to be the tunneling of conduction electrons between adjacent grains considering that the monodisperse nanocrystals may supply more grain boundaries increasing the tunneling probability, and consequently enhancing the overall magnetoresistance.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

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

    PubMed Central

    Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R. Matthew

    2014-01-01

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy. PMID:25422526

  7. Asymmetric anisotropic magnetoresistance in epitaxial Fe3O4 thin films

    NASA Astrophysics Data System (ADS)

    Chen, B. L.; Ding, Z.; Ma, D. H.; Li, J. X.; Xiao, X.; Wu, Y. Z.

    2015-09-01

    We aimed to study the effect of current orientation on the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a single-crystalline Fe3O4 (001) thin film at room temperature. AMR exhibits an unusual asymmetric behavior with respect to the current direction when the current does not flow along the high symmetry crystal axes, such as the <100> or <110> directions. AMR and PHE strongly depend upon the current direction angle, θJ, with an in-plane fourfold symmetry. The amplitude and phase shift of AMR and PHE can be understood quantitatively by a phenomenological description of the anisotropic resistivity tensor in a single-crystalline system. These results prove that the current direction can be used to modify the AMR effect.

  8. Crystal-Site-Selective Spectrum of Fe3O4 Obtained by Mössbauer Diffraction

    NASA Astrophysics Data System (ADS)

    Nakamura, Shin; Mitsui, Takaya; Fujiwara, Kosuke; Ikeda, Naoshi; Kurokuzu, Masayuki; Shimomura, Susumu

    2017-02-01

    We have succeeded for the first time in obtaining a crystal-site-selective Mössbauer spectrum of Fe3O4 using the Mössbauer diffractometer at SPring-8 BL11XU. In order to extract the nuclear resonant scattering, which provides the crystal-site-selective emission spectrum, reflections having a Bragg angle near 45° were used. The 666 and 10 10 0 reflection spectra reveal only B- and A-site spectra, respectively. Mössbauer diffraction spectroscopy enables us to measure the crystal-site-selective spectrum and to determine the precise hyperfine structure. This technique provides new possibilities for studying the local crystallographic and magnetic structure on iron sublattices in various multisite materials.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  10. Characterization of superparamagnetic Fe3O4 nanoparticles by fluxgate magnetorelaxometry for use in biomedical applications

    NASA Astrophysics Data System (ADS)

    Ludwig, F.; Heim, E.; Schilling, M.; Enpuku, K.

    2008-04-01

    We have investigated the magnetorelaxometry (MRX) of various Fe3O4 nanoparticle suspensions utilizing a differential fluxgate setup. To estimate the distribution of the hydrodynamic size of the magnetic nanoparticles (MNPs) with organic shell, the cluster moment superposition model is applied. On a sample series of MNPs from the same batch diluted in water-glycerine mixtures of varying viscosity, it is demonstrated that the model is suited for the estimation of the distribution of the hydrodynamic size of MNPs and clusters. Since a MRX measurement lasts only a few seconds, it is also highly suited to study the aggregation kinetics. This is demonstrated on MNPs with silica shell suspended in 5% phosphate-buffered saline solution.

  11. Fe3O4 thin films: controlling and manipulating an elusive quantum material

    NASA Astrophysics Data System (ADS)

    Liu, Xionghua; Chang, Chun-Fu; Rata, Aurora Diana; Komarek, Alexander Christoph; Tjeng, Liu Hao

    2016-12-01

    Fe3O4 (magnetite) is one of the most elusive quantum materials and at the same time one of the most studied transition metal oxide materials for thin-film applications. The theoretically expected half-metallic behaviour generates high expectations that it can be used in spintronic devices. Yet, despite the tremendous amount of work devoted to preparing thin films, the enigmatic first-order metal-insulator transition, and the hallmark of magnetite known as the Verwey transition, is in thin films extremely broad and occurs at substantially lower temperatures as compared with that in high-quality bulk single crystals. Here we have succeeded in finding and making a particular class of substrates that allows the growth of magnetite thin films with the Verwey transition as sharp as in the bulk. Moreover, we are now able to tune the transition temperature and, using tensile strain, increase it to substantially higher values than in the bulk.

  12. A novel synthesis method for TiO2 particles with magnetic Fe3O4 cores.

    PubMed

    Dong, Qi; Zhang, Keqiang; An, Yi

    2014-01-01

    TiO2@(AC/Fe3O4) (AC is activated carbon) was prepared by using AC and Fe3O4 as joint support. The morphological features, crystal structure, and magnetism of the final product were characterized. The results indicate that TiO2 particles formed on the surface of AC and Fe3O4; the sizes of TiO2 and Fe3O4 were 0.5 and 0.7 μm respectively, and that of AC fell within a wide range. The highly crystalline cubic structures of the TiO2 particles was in accord with the standard X-ray diffractometry spectrum of magnetite and anatase. The maximum saturation magnetization of TiO2@(AC/Fe3O4) was 75 emu g(-1), which was enough to support magnetic recovery. The rate of methylene blue (MB) removal photocatalyzed by TiO2@(AC/Fe3O4) was higher by 50% than that achieved with AC/Fe3O4 photocatalysis, and similar to that achieved with TiO2@AC. The removal rate (kobs) decreased drastically from 1.77 × 10(-2) to 9.36 × 10(-3)min(-1) when the initial concentration of MB solution increased from 2.0 to 5.0 mg L(-1). The kobs value increased from 9.41 × 10(-3) to 1.34 × 10(-2)min(-1) with increasing photocatalyst dosage from 0.2 to 1.0 g, then slightly decreased to 1.33 × 10(-2)min(-1) at 2.0 g dosage.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Murine RAW 264.7 cells were exposed to spheroidal core-shell Fe3O4@Au nanoparticles (SCS-NPs, ca. 34 nm) or nanostars (NSTs, ca. 100 nm) in the presence of bovine serum albumin, with variable effects observed after macrophagocytosis. Uptake of SCS-NPs caused macrophages to adopt a rounded, amoeboid form, accompanied by an increase in surface detachment. In contrast, the uptake of multibranched NSTs did not induce gross changes in macrophage shape or adhesion, but correlated instead with cell enlargement and signatures of macrophage activation such as TNF-α 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-α 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

  14. Remotely Controlled Micromanipulation by Buckling Instabilities in Fe3O4 Nanoparticle Embedded Poly(N-isopropylacrylamide) Surface Arrays.

    PubMed

    Carias, Vinicio; Nemati Porshokouh, Zohreh; Stojak Repa, Kristen; Alonso, Javier; Srikanth, Hariharan; Rühe, Jürgen; Toomey, Ryan; Wang, Jing

    2016-10-05

    The micromanipulation of biological samples is important for microbiology, pharmaceutical science, and related bioengineering fields. In this work, we report the fabrication and characterization of surface-attached microbeam arrays of 20 μm width and 25 μm height made of poly(N-isopropylacrylamide), a thermoresponsive polymer, with embedded spherical or octopod Fe3O4 nanoparticles. Below 32 °C, the microbeams imbibe water and buckle with an amplitude of approximately 20 μm. Turning on an AC-magnetic field induces the microbeam array to expel water due to the heating effect of the nanoparticles (magnetic hyperthermia), leading to a reversible transition from a buckled to nonbuckled state. It is observed that the octopod nanoparticles have a heating rate 30% greater (specific absorption rate, SAR) than that of the spherical nanoparticles, which shortens the time scale of the transition from the buckled and nonbuckled state. The return of the microbeams to the buckled state is accomplished by turning off the AC magnetic field, the rate of which is dictated by dissipation of heat and is independent of the type of nanoparticle. It is further demonstrated that this transition can be used to propel 50 μm spherical objects along a surface. While the motion is random, this study shows the promise of harnessing shape-shifting patterns in microfluidics for object manipulation.

  15. Facile synthesis of Fe3O4@C hollow nanospheres and their application in polluted water treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanguang; Xu, Shihao; Xia, Hongyu; Zheng, Fangcai

    2016-11-01

    Nanostructured carbon-based materials, such as carbon nanotube arrays have shown respectable removal ability for heavy metal ions and organic dyes in aqueous solution. Although the carbon-based materials exhibited excellent removal ability, the separation of them from the aqueous solution is difficult and time-consuming. Here we demonstrated a novel and facile route for the large-scale fabrication of Fe3O4@C hollow nanospheres, with using ferrocene as a single reagent and SiO2 as a template. The as-prepared Fe3O4@C hollow nanospheres exhibited adsorption ability for heavy metal ions and organic dyes from aqueous solution, and can be easily separated by an external magnet. When the as-prepared Fe3O4@C hollow nanospheres were mixed with the aqueous solution of Hg2+ within 15 min, the removal efficiency was 90.3%. The as-prepared Fe3O4@C hollow nanospheres were also exhibited a high adsorption capacity (100%) as the adsorbent for methylene blue (MB). In addition, the as-prepared Fe3O4@C hollow nanospheres can be used as the recyclable sorbent for water treatment via a simple magnetic separation.

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

    SciTech Connect

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

    2015-08-10

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

  17. Engineering the mesopores of Fe3O4@mesosilica core-shell nanospheres through a solvothermal post-treatment method.

    PubMed

    Yang, Yan; Liu, Jia; Bai, Shiyang; Li, Xiaobo; Yang, Qihua

    2013-03-01

    A solvothermal post-treatment method was developed to synthesize Fe(3)O(4)@mesosilica core-shell nanospheres (CSNs) with a well-preserved morphology, mesoporous structure, and tunable large pore diameters (2.5-17.6 nm) for the first time. N,N-Dimethylhexadecylamine (DMHA), which was generated in situ during the heat-treatment process, was mainly responsible for this pore-size enlargement, as characterized by NMR spectroscopy. This pore-size expansion can be strengthened with the aid of hexamethyldisilazane (HMDS), whilst the nature of the surface of the Fe(3)O(4)@mesosilica CSNs can be easily modified with trimethylsilyl groups during the pore-size-expansion process. The hydrophobicity of the Fe(3)O(4)@mesosilica CSNs increased for the enlarged mesopores and the adsorption capacity of these CSNs for benzene (up to 1.5 g g(-1)) is the highest ever reported for Fe(3)O(4)@mesosilica CSNs. The resultant Fe(3)O(4)@mesosilica CSNs (pore size: 10 nm) showed a 3.6-times higher adsorption capacity of lysozyme than those without the pore expansion (pore size: 2.5 nm), thus making them a good candidate for loading large molecules.

  18. Multifunctional Fe3O4-TiO2 nanocomposites for magnetic resonance imaging and potential photodynamic therapy.

    PubMed

    Zeng, Leyong; Ren, Wenzhi; Xiang, Lingchao; Zheng, Jianjun; Chen, Bin; Wu, Aiguo

    2013-03-07

    Multifunctional Fe(3)O(4)-TiO(2) nanocomposites with Janus structure for magnetic resonance imaging (MRI) and potential photodynamic therapy (PDT) were synthesized, in which Fe(3)O(4) was used as a MRI contrast agent and TiO(2) as an inorganic photosensitizer for PDT. Their morphology, structure, and MRI and PDT performance were characterized, respectively. Moreover, the location of Fe(3)O(4)-TiO(2) nanocomposites in MCF-7 cells was also investigated by the staining of Prussian blue and alizarin red, respectively. The results showed that the as-prepared Fe(3)O(4)-TiO(2) nanocomposites had good T(2)-weighted MRI performance, and the MCF-7 cells incubated with nanocomposites could be killed under the irradiation of UV light. Compared with traditional organic photosensitizers, TiO(2) inorganic photosensitizers could have more stable PDT performance due to their nanoscale size and anti-photodegradable stability. Therefore, the as-prepared Fe(3)O(4)-TiO(2) nanocomposites could have potential applications as a new kind of multifunctional agent for both MRI and PDT.

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

    PubMed

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

    2011-06-01

    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.

  20. Adsorption-desorption behavior of magnetic amine/Fe3O4 functionalized biopolymer resin towards anionic dyes from wastewater.

    PubMed

    Song, Wen; Gao, Baoyu; Xu, Xing; Xing, Lulu; Han, Shuang; Duan, Pijun; Song, Wuchang; Jia, Ruibao

    2016-06-01

    In this work, a new kind of magnetic amine/Fe3O4 functionalized biopolymer resin (amine/Fe3O4-resin) was prepared and applied to remove various anionic dyes from water. Methyl Orange (MO), Reactive Brilliant Red K-2BP (RBR) and Acid Red 18 (AR) were selected as the typical anionic dye for this research. Meanwhile, amine/Fe3O4-resin was characterized by VSM, XRD, FT-IR, SEM, TEM and XPS. Three anionic dyes removed by amine/Fe3O4-resin were investigated using batch adsorption technique, and the parameters including adsorbent dosage, pH, contact time and temperature were considered. Due to a large number of amine groups and high surface areas, amine/Fe3O4-resin exhibited a remarkably high adsorption capacity for all three dyes, reaching 101.0mg/g, 222.2mg/g and 99.4mg/g for RBR, MO and AR at 25°C, respectively. The pseudo second order model and Langmuir model agreed well with the experimental data, and regeneration experiments indicated its merit of separability and reusability.

  1. Facile Hydrothermal Synthesis of Fe3O4/C Core-Shell Nanorings for Efficient Low-Frequency Microwave Absorption.

    PubMed

    Wu, Tong; Liu, Yun; Zeng, Xiang; Cui, Tingting; Zhao, Yanting; Li, Yana; Tong, Guoxiu

    2016-03-23

    Using elliptical iron glycolate nanosheets as precursors, elliptical Fe3O4/C core-shell nanorings (NRs) [25 ± 10 nm in wall thickness, 150 ± 40 nm in length, and 1.6 ± 0.3 in long/short axis ratio] are synthesized via a one-pot hydrothermal route. The surface-poly(vinylpyrrolidone) (PVP)-protected-glucose reduction/carbonization/Ostwald ripening mechanism is responsible for Fe3O4/C NR formation. Increasing the glucose/precursor molar ratio can enhance carbon contents, causing a linear decrease in saturation magnetization (Ms) and coercivity (Hc). The Fe3O4/C NRs reveal enhanced low-frequency microwave absorption because of improvements to their permittivity and impedance matching. A maximum RL value of -55.68 dB at 3.44 GHz is achieved by Fe3O4/C NRs with 11.95 wt % C content at a volume fraction of 17 vol %. Reflection loss (RL) values (≤-20 dB) are observed at 2.11-10.99 and 16.5-17.26 GHz. Our research provides insights into the microwave absorption mechanism of elliptical Fe3O4/C core-shell NRs. Findings indicate that ring-like and core-shell nanostructures are promising structures for devising new and effective microwave absorbers.

  2. Shape-Controllable Synthesis of Peroxidase-Like Fe3O4 Nanoparticles for Catalytic Removal of Organic Pollutants

    NASA Astrophysics Data System (ADS)

    Wan, Dong; Li, Wenbing; Wang, Guanghua; Wei, Xiaobi

    2016-10-01

    The shape of Fe3O4 nanoparticles is controlled using a simple oxidation-precipitation method without any surfactant. The morphology and structure of the obtained Fe3O4 nanoparticles were characterized by using x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, N2 physisorption and vibrating sample magnetometer. As-prepared Fe3O4 samples showed octahedron, cube, hexagonal plate and sphere morphologies. Peroxidase-like activity of the four nanostructures was evaluated for catalytic removal of organic pollutants in the presence of H2O2, using rhodamine B as a model compound. The results showed that the H2O2-activating ability of the Fe3O4 nanocrystals was structure dependent and followed the order sphere > cube > octahedron > hexagonal plate, which was closely related to their surface FeII/FeIII ratios or crystal planes. The reusability of Fe3O4 spheres was also investigated after five successive runs, which demonstrated the promising application of the catalyst in the degradation of organic pollutants. This investigation is of great significance for the heterogeneous catalysts with enhanced activity and practical application.

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

    DOE PAGES

    Feygenson, Mikhail; Bauer, John C; Gai, Zheng; ...

    2015-08-10

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

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

    PubMed Central

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

    2014-01-01

    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. PMID:24699690

  5. Synthesis and characterization of rice straw/Fe3O4 nanocomposites by a quick precipitation method.

    PubMed

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

    2013-06-05

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

  6. Mesocrystalline Zn-Doped Fe3O4 Hollow Submicrospheres: Formation Mechanism and Enhanced Photo-Fenton Catalytic Performance.

    PubMed

    Nguyen, Xuan Sang; Zhang, Gaoke; Yang, Xianfeng

    2017-03-15

    Uniform and magnetic recyclable mesocrystalline Zn-doped Fe3O4 hollow submicrospheres (HSMSs) were successfully synthesized via a simple one-pot solvothermal route and were used for efficient heterogeneous photo-Fenton catalyst. XRD, XPS, Raman spectroscopy, Mössbauer spectroscopy, SEM, HRTEM, and EDX analyses revealed that the shell of HSMSs is highly porous and assembled by oriented attachment of magnetite nanocrystal building blocks with Zn-rich surfaces. Furthermore, a possible formation mechanism of mesocrystalline hollow materials was proposed. First, Fe3O4 mesocrystals were assembled by oriented nanocrystals, and a Zn-rich amorphous shell grew on the surfaces. Then, Zn gradually diffused into Fe3O4 crystals to form Zn-doped Fe3O4 due to the Kirkendall effect with increasing the reaction time. Meanwhile, the inner nanocrystals would be dissolved, and outer particles would grow larger owing to the Ostwald ripening process, leading to the formation of a hollow structure with porous shell. The Zn-doped Fe3O4 HSMSs exhibited high and stable photo-Fenton activity for degradation of rhodamine B (RhB) and cephalexin under visible-light irradiation in the presence of H2O2, which results from their hollow mesocrystal structure and Zn doping. It could be easily separated and reused by an external magnetic field. The results suggested that the as-obtained magnetite hollow mesocrystals could be a promising catalyst in the photo-Fenton process.

  7. Density functional theory study on the interaction of CO2 with Fe3O4(111) surface

    NASA Astrophysics Data System (ADS)

    Su, Tongming; Qin, Zuzeng; Huang, Guan; Ji, Hongbing; Jiang, Yuexiu; Chen, Jianhua

    2016-08-01

    CO2 adsorption on the Fetet1- and Feoct2-tet1-terminated Fe3O4(111) surface was investigated in order to understand the adsorption mechanism of CO2 by using density functional theory (DFT). Both weak and strong adsorptions exist between the CO2 and the Fe3O4(111) surface. The preferred adsorption site was found to be the Od site on the Feoct2-tet1-termination, after adsorption, the CO2 molecule was bent and the Csbnd O bond was elongated, indicating the activation of CO2. And it is found that Feoct2-tet1-terminated Fe3O4(111) surface is more active than Fetet1-terminated surface, CO2 serves as a charge acceptor to withdraw electrons from the Feoct2-tet1-terminated Fe3O4(111) surface. In addition, partial density of states, electron localization function and difference electron density reveal that covalent bond was formed between the C atom of CO2 and the surface O atom. These results provide fundamental insight into the CO2 adsorption mechanism on Fe3O4(111) surface and potential application on the activation of CO2.

  8. Preparation and photocatalytic properties of magnetically reusable Fe3O4@ZnO core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Yang, Jinghai; Li, Xiuyan; Wang, Dandan; Wei, Bing; Song, Hang; Li, Xuefei; Fu, Siwei

    2016-01-01

    Fe3O4@ZnO binary nanoparticles were synthesized by a simple two-step chemical method and characterized using various analytical instruments. TEM result proved the binary nanoparticles have core/shell structures and average particle size is 60 nm. Photocatalytic investigation of Fe3O4@ZnO core/shell nanoparticles was carried out using rhodamine B (RhB) solution under UV light. Fe3O4@ZnO core/shell nanoparticles showed enhanced photocatalytic performance in comparison with the as prepared ZnO nanoparticles. The enhanced photocatalytic activity for Fe3O4@ZnO might be resulting from the higher concentration of surface oxygen vacancies and the suppressing effect of the Fe3+ ions on the recombination of photoinduced electron-hole pairs. Magnetization saturation value (5.96 emu/g) of Fe3O4@ZnO core/shell nanoparticles is high enough to be magnetically removed by applying a magnetic field. The core/shell photocatalyst can be easily separated by using a commercial magnet and almost no decrease in photocatalytic efficiency was observed even after recycling six times.

  9. Bio-Inspired Composite Interfaces: Controlling Hydrogel Mechanics via Polymer-Nanoparticle Coordination Bond Dynamics

    NASA Astrophysics Data System (ADS)

    Holten-Andersen, Niels

    2015-03-01

    In soft nanocomposite materials, the effective interaction between polymer molecules and inorganic nanoparticle surfaces plays a critical role in bulk mechanical properties. However, controlling these interfacial interactions remains a challenge. Inspired by the adhesive chemistry in mussel threads, we present a novel approach to control composite mechanics via polymer-particle interfacial dynamics; by incorporating iron oxide nanoparticles (Fe3O4 NPs) into a catechol-modified polymer network the resulting hydrogels are crosslinked via reversible coordination bonds at Fe3O4 NP surfaces thereby providing a dynamic gel network with robust self-healing properties. By studying the thermally activated composite network relaxation processes we have found that the polymer-NP binding energy can be controlled by engineering both the organic and inorganic side of the interface.

  10. Thermal conversion of an Fe3O4@metal-organic framework: a new method for an efficient Fe-Co/nanoporous carbon microwave absorbing material

    NASA Astrophysics Data System (ADS)

    Zhang, Xingmiao; Ji, Guangbin; Liu, Wei; Quan, Bin; Liang, Xiaohui; Shang, Chaomei; Cheng, Yan; Du, Youwei

    2015-07-01

    A novel FeCo nanoparticle embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL < -10 dB which covers from 12.2 to 18 GHz can be obtained, and its minimum reflection loss and bandwidth (RL values exceeding -10 dB) are far greater than those of commercial carbonyl iron powder under a very low thickness (1-1.5 mm). This study not only provides a good reference for future preparation of carbon-based lightweight microwave absorbing materials but also broadens the application of such kinds of metal-organic frameworks.A novel FeCo nanoparticle embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL < -10 dB which covers from 12.2 to 18 GHz can be obtained, and its minimum reflection loss and bandwidth (RL values exceeding -10 dB) are far greater than those of commercial carbonyl iron powder under a very low thickness (1-1.5 mm). This study not only provides a good reference for future preparation of carbon-based lightweight microwave absorbing materials but also broadens the application of such kinds of metal-organic frameworks. Electronic

  11. Hydrothermal synthesis of 3D hollow porous Fe3O4 microspheres towards catalytic removal of organic pollutants

    PubMed Central

    2014-01-01

    Three-dimensional hollow porous superparamagnetic Fe3O4 microspheres were synthesized via a facile hydrothermal process. A series of characterizations done with X-ray diffraction, Brunauer-Emmett-Teller method, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy indicated that the production of Fe3O4 microspheres possessed good monodispersity, uniform size distribution, hollow and porous structural characters, and strong superparamagnetic behavior. The obtained Fe3O4 microspheres have a diameter of ca. 300 nm, which is composed of many interconnected nanoparticles with a size of ca. 20 nm. The saturation magnetization is 80.6 emu·g-1. The as-prepared products had promising applications as novel catalysts to remove organic pollutants (methylene blue) from wastewater in the presence of H2O2 and ultrasound irradiation. PMID:25520596

  12. Functionalized Fe3O4@silica core-shell nanoparticles as microalgae harvester and catalyst for biodiesel production.

    PubMed

    Chiang, Ya-Dong; Dutta, Saikat; Chen, Ching-Tien; Huang, Yu-Tzu; Lin, Kuen-Song; Wu, Jeffrey C S; Suzuki, Norihiro; Yamauchi, Yusuke; Wu, Kevin C-W

    2015-03-01

    Core-shell Fe3O4@silica magnetic nanoparticles functionalized with a strong base, triazabicyclodecene (TBD), were successfully synthesized for harvesting microalgae and for one-pot microalgae-to-fatty acid methyl ester (FAME, or so-called biodiesel) conversion. Three types of algae oil sources (i.e., dried algae, algae oil, and algae concentrate) were used and the reaction conditions were optimized to achieve the maximum biodiesel yield. The results obtained in this study show that our TBD-functionalized Fe3O4@silica nanoparticles could effectively convert algae oil to biodiesel with a maximum yield of 97.1 %. Additionally, TBD-Fe3O4@silica nanoparticles act as an efficient algae harvester because of their adsorption and magnetic properties. The method presented in this study demonstrates the wide scope for the use of covalently functionalized core-shell nanoparticles for the production of liquid transportation fuels from algal biomass.

  13. Synthesis and characterization of core∕shell Fe3O4∕ZnSe fluorescent magnetic nanoparticles

    PubMed Central

    Vargas, José M.; McBride, Amber A.; Plumley, John B.; Fichou, Yann; Memon, Tosifa A.; Shah, Vichiksha; Cook, Nathaniel C.; Akins, Brian A.; Rivera, Antonio C.; Smolyakov, Gennady A.; O’Brien, James R.; Adolphi, Natalie L.; Smyth, Hugh D. C.; Osiński, Marek

    2011-01-01

    We report on the successful preparation and characterization of fluorescent magnetic core∕shell Fe3O4∕ZnSe nanoparticles (NPs) with a spherical shape by organometallic synthesis. The 7 nm core∕3 nm shell NPs show good magnetic and photoluminescence (PL) responses. The observed PL emission∕excitation spectra are shifted to shorter wavelengths, compared to a reference ZnSe NP sample. A dramatic reduction of PL quantum yield is also observed. The temperature dependence of the magnetization for the core∕shell NPs shows the characteristic features of two coexisting and interacting magnetic (Fe3O4) and nonmagnetic (ZnSe) phases. Compared to a reference Fe3O4 NP sample, the room-temperature Néel relaxation time in core∕shell NPs is three times longer. PMID:21559088

  14. Use of aerosol route to fabricate positively charged Au/Fe3O4 Janus nanoparticles as multifunctional nanoplatforms

    PubMed Central

    Byeon, Jeong Hoon; Park, Jae Hong

    2016-01-01

    Gold (Au)-decorated iron oxide (Fe3O4), Au/Fe3O4, Janus nanoparticles were fabricated via the continuous route for aerosol Au incorporation with Fe3O4 domains synthesized in an aqueous medium as multifunctional nanoplatforms. The fabricated nanoparticles were subsequently exposed to 185-nm UV light to generate positive charges on Au surfaces, and their activities were tested in computed tomography (CT) and magnetic resonance (MR) imaging, gene-delivery and photothermal therapy. No additional polymeric coatings of the Janus particles also had a unique ability to suppress inflammatory responses in macrophages challenged with lipopolysaccharide, which may be due to the absence of amine groups. PMID:27713519

  15. Investigation of temperature dependent magnetic hyperthermia in Fe3O4 ferrofluids

    NASA Astrophysics Data System (ADS)

    Nemala, Humeshkar Bhaskar

    Magnetic nanoparticles (MNPs) of Fe3O4 and gamma-Fe2O3 have been exploited in the biomedical fields for imaging, targeted drug delivery and magnetic hyperthermia. Magnetic hyperthermia (MHT), the production of heat using ferrofluids, colloidal suspensions of MNPs, in an external AC magnetic field (amplitude, 100-500 Oe and frequency 50 kHz -1MHz), has been explored by many researchers, both in vitro and in vivo, as an alternative viable option to treat cancer. The heat energy generated by Neel and Brownian relaxation processes of the internal magnetic spins could be used to elevate local tissue temperature to about 46 ˚C to arrest cancerous growth. MHT, due to its local nature of heating, when combined with other forms of treatment such as chemotherapy and/or radiation therapy, it could become an effective therapy for cancer treatment. The efficiency of heat production in MHT is quantified by specific absorption rate (SAR), defined as the power output per gram of the MNPs used. In this thesis, ferrofluids consisting of Fe3O4 MNPs of three different sizes (˜ 10 - 13 nm) coated with two different biocompatible surfactants, dextran and polyethylene glycol (PEG), have been investigated. The structural and magnetic characterization of the MNPs were done using XRD, TEM, and DC magnetization measurements. While XRD revealed the crystallite size, TEM provided the information about morphology and physical size distribution of the MNPs. Magnetic measurements of M-vs-H curves for ferrofluids provided information about the saturation magnetization (Ms) and magnetic core size distribution of MNPs. Using MHT measurements, the SAR has been studied as a function of temperature, taking into account the heat loss due to non-adiabatic nature of the experimental set-up. The observed SAR values have been interpreted using the theoretical framework of linear response theory (LRT). We found the SAR values depend on particle size distribution of MNPs, Ms (65-80 emu/g) and the magnetic

  16. Core/shell Fe3O4/BiOI nanoparticles with high photocatalytic activity and stability

    NASA Astrophysics Data System (ADS)

    Zheng, Liyun; Wang, Shuling; Zhao, Lixin; Zhao, Shuguo

    2016-11-01

    Core/shell Fe3O4/BiOI nanoparticles with BiOI sheath have been synthesized by a solvothermal reaction method and were characterized by transmission electron microscopy (TEM) with an energy dispersive spectrum (EDS), high-resolution TEM and X-ray diffraction (XRD). Their photocatalytic activities were evaluated by methylene blue (MB) under the simulated solar light. The results indicate that the spherical Fe3O4 particles were coated with BiOI sheath when the sample were synthesized at 160 °C with ethylene glycol and deionized water, forming a core/shell structure. The degradation rate of MB assisted with the core/shell Fe3O4/BiOI catalysts reached 98 % after 40-min irradiation. The catalytic performance enhancement of the core/shell Fe3O4/BiOI catalysts mainly attributes to the band structure that can improve the generation efficiency, separation and transfer process of the photo-induced electron-hole pairs and decrease their recombination. The magnetic Fe3O4 core not only contributes to the efficient separation of electron and holes, but also helps catalysts be collected conveniently using a magnet for reuse. After five repeated trials, the degradation rate of MB still maintains over 90 % and the saturated magnetization of the catalysts remains 51.5 emu/g, which indicate that the core/shell Fe3O4/BiOI nanoparticles have excellent photocatalytic stability and are recyclable for decomposing organic pollutants under visible light irradiation.

  17. Fabrication of cube-like Fe3O4@SiO2@Ag nanocomposites with high SERS activity and their application in pesticide detection

    NASA Astrophysics Data System (ADS)

    Li, Lei; Zhao, Aiwu; Wang, Dapeng; Guo, Hongyan; Sun, Henghui; He, Qinye

    2016-07-01

    The cube-like Fe3O4@SiO2@Ag (FSA) nanocomposites with great SERS activity have been successfully synthesized by a layer-by-layer procedure in this paper. The cube-like Fe3O4@SiO2 core-shell structures were prepared via a new route and Ag nanoparticles were introduced onto their surface through a one-pot hydrothermal reaction. By controlling the reaction time, the coverage rate of Ag on the FSA surface could be tuned, and then a series of FSA composites were obtained. The SERS properties of these FSA composites were investigated using p-aminothiophenol ( p-ATP) as the probe molecule. It was found that the FSA composites synthesized with a reaction time of 6 h showed the best SERS performance, and the detection limit for p-ATP could reach 1 × 10-7 M. For practical application, the FSA composites were also used to detect thiram, one of the dithiocarbamate fungicides that has been widely used as a pesticide in agriculture. The detection limit is as low as 1 × 10-6 M (0.24 ppm), lower than the maximal residue limit of 7 ppm in fruit prescribed by the US Environmental Protection Agency. The resulting substrate with high SERS activity, stability and strong magnetic responsivity makes the FSA composite a perfect choice for practical SERS detection applications.

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

    NASA Astrophysics Data System (ADS)

    Ke, Fei; Wang, Luhuan; Zhu, Junfa

    2014-12-01

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

  19. Unusual Fe-H bonding associated with oxygen vacancies at the (001) surface of Fe3O4

    NASA Astrophysics Data System (ADS)

    Liu, Fangyang; Chen, Chen; Guo, Hangwen; Saghayezhian, Mohammad; Wang, Gaomin; Chen, Lina; Chen, Wei; Zhang, Jiandi; Plummer, E. W.

    2017-01-01

    An unusual Fe-H bonding rather than conventional OH bonding is identified at Fe3O4 (001) surface. This abnormal behavior is associated with the oxygen vacancies which exist on the surface region but also penetrate deep into the bulk Fe3O4. In contrast, OH bonding becomes preferential as generally expected on an ozone processed surface, which has appreciably less oxygen vacancies. Such bonding site selective behavior, depending on oxygen vacancy concentrations, is further confirmed with DFT calculations. The results demonstrate an opportunity for tuning the chemical properties of oxide surfaces or oxide clusters.

  20. Reclamation of acid pickling waste: A facile route for preparation of single-phase Fe3O4 nanoparticle

    NASA Astrophysics Data System (ADS)

    Zhang, Wenxue; Lu, Bin; Tang, Huihui; Zhao, Jingxiang; Cai, Qinghai

    2015-05-01

    Using an alternative method of dropwise addition of iron salt in NaOH aqueous solution, nanocrystalline Fe3O4 materials were prepared from acid pickling waste as a starting material with ultrasonic enhancement and polyethylene glycol as a dispersant, as proved by XRD, TEM, TG-DSC and ICP-MS. The results showed that the Fe3O4 material was a well-crystallized magnetite with an average size of about 25 nm and purity 99.15%. Magnetic measurement revealed the nanocrystals were stronger superparamagnetic with a saturation magnetization of 82.1 emu/g.

  1. Magnetically recoverable Fe3O4/graphene nanocomposite towards efficient removal of triazine pesticides from aqueous solution: Investigation of the adsorption phenomenon and specific ion effect.

    PubMed

    Boruah, Purna K; Sharma, Bhagyasmeeta; Hussain, Najrul; Das, Manash R

    2017-02-01

    Spillage of effluents containing high concentration levels of pesticides into water has been considered as one of the serious environmental problems. In this study Fe3O4/reduced graphene oxide (rGO) nanocomposite has been efficiently utilized for the adsorption of five harmful pesticides namely ametryn, prometryn, simazine, simeton and atrazine in an aqueous medium. Electrostatic interaction between the pesticides and Fe3O4/rGO nanocomposite was analyzed by the zeta potential analysis, which is strongly related to the adsorption capacity of the adsorbent. The kinetics parameters of adsorption followed the pseudo second-order linear model. The adsorption isotherm studies show that, the maximum adsorption capacity of 54.8 mg g(-1) is achieved at pH 5 and it was enhanced in the presence of different ions (Mg(2+), Ca(2+), Na(+) and SO4(2)) and maximum (63.7 mg g(-1)) for ametryn adsorption was found in seawater medium. Thermodynamic parameter shows that, the adsorption process is physisorption and spontaneity in nature. The mechanism of the adsorption process was established by the DRIFT spectroscopy analysis. Efficient adsorption (93.61%) of pesticides was observed due to electrostatic, hydrophobic and π-π interactions of composite towards the heterocyclic conjugation of pesticide molecules. Further, Fe3O4/rGO nanocomposite was easily and rapidly separated from an aqueous medium using the external magnet for reuse and 88.66% adsorption efficiency was observed up to seven cycles.

  2. Fe3O4 nanoflakes in an N-doped carbon matrix as high-performance anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Guo, Cong; Wang, Lili; Zhu, Yongchun; Wang, Danfeng; Yang, Qianqian; Qian, Yitai

    2015-05-01

    Fe3O4 nanoflakes in an N-doped carbon matrix (Fe3O4 NF@NC) were prepared by solvothermal synthesis of Fe3O4 nanoflakes and in situ polymerization of pyrrole on the surface of Fe3O4 followed by heat treatment. The Fe3O4 NF@NC is composed of Fe3O4 nanoflakes with a width of 50-60 nm and a thickness of 10 nm dispersed in the N-doped carbon matrix. The carbon content varies from 18% to 50% on controlling the amount of pyrrole added, therefore the Fe3O4 NF@NC with 44% carbon content performs the best. Due to the cooperation of the two-dimensional (2D) structure of Fe3O4 nanoflakes and the N-doped carbon matrix, the obtained Fe3O4 NF@NC (44% carbon content) exhibits electrochemical performance with a reversible capacity of 1046 mA h g-1 at 0.2 C (1 C = 924 mA g-1) over 200 cycles, 662 mA h g-1 at 1 C after 500 cycles and 600 mA h g-1 at 5 C over 200 cycles.Fe3O4 nanoflakes in an N-doped carbon matrix (Fe3O4 NF@NC) were prepared by solvothermal synthesis of Fe3O4 nanoflakes and in situ polymerization of pyrrole on the surface of Fe3O4 followed by heat treatment. The Fe3O4 NF@NC is composed of Fe3O4 nanoflakes with a width of 50-60 nm and a thickness of 10 nm dispersed in the N-doped carbon matrix. The carbon content varies from 18% to 50% on controlling the amount of pyrrole added, therefore the Fe3O4 NF@NC with 44% carbon content performs the best. Due to the cooperation of the two-dimensional (2D) structure of Fe3O4 nanoflakes and the N-doped carbon matrix, the obtained Fe3O4 NF@NC (44% carbon content) exhibits electrochemical performance with a reversible capacity of 1046 mA h g-1 at 0.2 C (1 C = 924 mA g-1) over 200 cycles, 662 mA h g-1 at 1 C after 500 cycles and 600 mA h g-1 at 5 C over 200 cycles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01953b

  3. Highly dispersed Fe3O4 nanosheets on one-dimensional carbon nanofibers: Synthesis, formation mechanism, and electrochemical performance as supercapacitor electrode materials

    NASA Astrophysics Data System (ADS)

    Mu, Jingbo; Chen, Bin; Guo, Zengcai; Zhang, Mingyi; Zhang, Zhenyi; Zhang, Peng; Shao, Changlu; Liu, Yichun

    2011-12-01

    Highly dispersed Fe3O4 nanosheets on one-dimensional (1D) carbon nanofibers (CNFs) were firstly fabricated by combining the versatility of the electrospinning technique and solvent-thermal process. The electrochemical performances of the Fe3O4/CNFs nanocomposites as the electrode materials for supercapacitors were evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M Na2SO3 electrolyte. At different scan rates, the sample showed excellent capacitance behavior. The high capacitive behavior could be ascribed to the high electrical conductivity and the one-dimensional properties of the CNFs in Fe3O4/CNFs nanocomposites, which could decrease the charge transfer resistance of the Fe3O4. At the same time, the high specific surface area and high level exposure of the Fe3O4 nanosheets on the surface of the CNFs increased the electrochemical utilization of Fe3O4. Moreover, in comparison to the pure Fe3O4 (83 F g-1), the as-prepared Fe3O4/CNFs nanocomposites electrode exhibited a higher specific capacitance (135 F g-1). Meanwhile, the supercapacitor devices of the Fe3O4/CNFs nanocomposites exhibited excellent long cycle life along with 91% specific capacitance retained after 1000 cycle tests. Finally, a possible mechanism for the formation of the Fe3O4 nanosheets on the surface of CNFs was suggested.

  4. A novel reusable nanocomposite adsorbent, xanthated Fe3O4-chitosan grafted onto graphene oxide, for removing Cu(II) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Liu, Jinshui; Liu, Wenxiu; Wang, Yiru; Xu, Meijiao; Wang, Bin

    2016-03-01

    Novel nanocomposites of xanthated Fe3O4-chitosan grafted onto graphene oxide (xanthated Fe3O4-CS-GO) were successfully synthesized for the first time using an amidation reaction. The xanthated Fe3O4-CS-GO was used to remove Cu(II) from aqueous solutions. The xanthated Fe3O4-CS-GO was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and energy dispersive X-ray spectroscopy. The Cu(II) adsorption isotherms for the xanthated Fe3O4-CS-GO fitted the Langmuir isotherm model. The maximum Cu(II) adsorption capacity of the xanthated Fe3O4-CS-GO was 426.8 mg g-1, which is much higher than the maximum adsorption capacities of other adsorbents that have been described in the literature. This was attributed to xanthated Fe3O4-CS-GO having abundant functional groups. The xanthated Fe3O4-CS-GO could be regenerated using ethylene diamine tetraacetic acid, and could easily be removed from a liquid using an external magnetic field. These features would allow secondary pollution of the environment to be avoided more easily than is the case for other adsorbents. Cu(II) was adsorbed from aqueous solutions quickly and efficiently by the xanthated Fe3O4-CS-GO complex, suggesting that xanthated Fe3O4-CS-GO may be an ideal candidate for removing Cu(II) from wastewater.

  5. Covalent Immobilization of Penicillin G Acylase onto Fe3O