Fe3O4@organic@Au: core-shell nanocomposites with high saturation magnetisation as magnetoplasmonic MRI contrast agents

The synthesis and characterization of core-shell Fe(3)O(4)@organic@Au nanoparticles displaying plasmonic behavior, high magnetism, and high relaxivity is presented. The incorporation of a thin organic layer between the two metals is crucial in maintaining the saturation magnetisation of the superparamagnetic core.     

Magnetically retrievable Bi2WO6/Fe3O4/Na-MMT composite: fabrication and photocatalytic activity

Research on Chemical Intermediates - Magnetically retrievable bismuth tungstate/iron oxide/sodium montmorillonite composite (Bi2WO6/Fe3O4/Na-MMT) was synthesized via a simple solvothermal process....     

High rate capability of Fe/FeO/Fe3O4 composite as anode material for lithium-ion batteries

Fe/FeO/Fe₃O₄ composite was synthesized by a simple solid method using ferric citrate and phenolic resin as raw materials. The reaction processes of raw materials mixture were characterized by thermogravimetric analysis (TGA) under nitrogen. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structure and morphology of the products. The results showed that the obtained material was octahedral Fe/FeO/Fe₃O₄ composite with a size of 2-4 μm. The electrochemical performances of Fe/FeO/Fe₃O₄ composite as anode material were also evaluated, which exhibited a stable specific capacity of 260.3 mAh g^-1 and an ideal initial coulombic efficiency of 90.8% in the range of 0.05~3 V at the 5C rate. A good rate capacity of Fe/FeO/Fe₃O₄ composite electrode was also shown by the charge-discharge testing even at the rate of 60C. The better rate capability of Fe/FeO/Fe₃O₄ electrode could be measured in higher temperature.     

Synthesis of Gd-DTPA-cholesterol: a new lipophilic gadolinium complex as a potential MRI contrast agent

A straightforward and efficient synthesis of Gd-DTPA-cholesterol is reported. This new lipophilic gadolinium complex can be easily incorporated into mixed micelles in order to achieve MRI contrast agents with increased relaxivity. These supramolecular systems can find potential application in magnetic resonance angiography (MRA).     

Preparation and characterization of Fe_3O_4/Au composite particles

Colloid gold with different sizes has been widely used in immunoassay and nucleic acid detection mainly because of their properties for immobilization of biomolecules, such as antibodies and oligonucleo-tides, through chemical reactions via active group SH on the biomolecules. Magnetic particles modified with various chemical groups on their surface can not only exhibit good magnetic responsiveness to an external magnetic field but also immobilize biomolecules through these chemical groups. As…     

Fe_3O_4/Au composite nano-particles and their optical properties

The colloid gold and magnetic particle modified with various chemical groups have been widely used in the areas of biomedical and molecular biology[1―6]. Therefore, a great deal of attention has been given to the preparation and application of colloid go…     

Application of a Sawdust/Fe3O4 and Sawdust/Fe3O4/PEI as a Selective Adsorbent for Pb(II) Removal

Based on the advantages of Fe₃O₄ nanoparticles (MNPs), sawdust (SD), and polyethlenimine (PEI) respectively, the SD/MNPs/PEI composites with layered structure were synthesized. The features of the nanocomposites were characterized and experimental conditions were used to evaluate the potential of SD/ MNPs and SD/MNPs/PEI nanocomposites in removing lead ions Pb2+ in a batch system. By cross-linking PEI on the SD/ MNPs, chelating group on the surface of adsorbent is made, which increases the ability of the nanocomposite to attract Pb(II) from aqueous solutions. Results show an increase in the adsorption by about 31% on SD/MNPs, by about 98% in SD/MNPs/PEI.

     

A Gd3Al tetranuclear complex as a potential bimodal MRI/optical imaging agent

A new self-assembled gadolinium(III)-aluminum(III) complex (Gd(3)Al) was synthesized and characterized. The efficacy of this Gd(3)Al complex as a potential bimodal magnetic resonance imaging (MRI)/optical imaging agent has been evaluated. Relaxivity studies showed that the Gd(3)Al complex has higher relaxation efficiency (7.18 mM(-1) s(-1)) compared with the clinically used complex gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA, 3.9 mM(-1) s(-1)) at 400 MHz and 25 °C. In vitro T(1)-MR images on a 0.5 T magnetic field exhibited a remarkable enhancement of signal contrast for Gd(3)Al compared to Gd-DTPA. Furthermore, the Gd(3)Al complex exhibits bright-green luminescence with the emission spectrum centred at 510 nm. Live-cell fluorescence imaging reveals that the Gd(3)Al complex is permeable to cells and localizes to the cytoplasm. In view of the relaxometric and luminescent properties, this Gd(3)Al complex could serve as a potential bimodal MRI/optical imaging agent.     

Synthesis of a novel amphiphilic GdPCTA-[12] derivative as a potential micellar MRI contrast agent

A novel amphiphilic contrast agent, a GdPCTA-[12] derivative containing a dodecyl chain as lipophilic moiety, has been prepared. A convergent synthetic route from commercially available diethylene triamine and 3-hydroxypyridine is described. The target amphiphilic gadolinium complex was obtained in nine steps in 22% overall yield. Physicochemical properties and relaxivity measurements of this new contrast agent are described.     

Synthesis of Fe3O4, Fe2O3, Ag/Fe3O4 and Ag/Fe2O3 nanoparticles and their electrocatalytic properties

Two important iron oxides:Fe3O4 and Fe2O3,as well as Fe3O4 and Fe2O3 nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure.The samples were confirmed and characterized by X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The morphology of the samples was observed by transmission electron microscopy(TEM).The results indicated Fe3O4,Fe2O3,Ag/Fe3O4 and Ag/Fe2O3 samples all were nanoparticles with smaller sizes.The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated.The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode.Furthermore,p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/Fe3O4 or Ag/Fe2O3 composite nanoparticles.     

Tuning of the size of Dy2O3 nanoparticles for optimal performance as an MRI contrast agent

The transverse 1H relaxivities of aqueous colloidal solutions of dextran coated Dy2O3 nanoparticles of different sizes were investigated at magnetic field strengths (B) between 7 and 17.6 T. The particle size with the maximum relaxivity (r2) appears to vary between 70 nm at 7 T (r2 approximately = 190 s(-1) mM(-1)) and 60 nm at 17.6 T (r2 approximately = 675 s(-1) mM(-1)). A small difference between r2 and r2* was observed, which was ascribed to the effect of the dextran coating. The value of r2 is proportional to B2 up to 12 T after which it saturates. Independent magnetization measurements on these particles at room temperature at magnetic field strengths up to 30 T, however, show a typical paramagnetic behavior with a magnetization of the particle that is proportional to the field strength. The saturation in the curve of r2 as a function of B2 was tentatively explained by the presence of an extremely fast relaxing component of the signal at high field strengths, which is not observable on the NMR time scale. The results of this study can be exploited for the rational design of MRI contrast agents, based on lanthanide oxide particles, with high efficiencies at magnetic field strengths of more than 1.5 T.     

Preparation and electrochemical properties of Fe/Fe3O4@r-GO composite nanocage with 3D hollow structure

Journal of Solid State Electrochemistry - Fe/Fe3O4@r-GO composite nanocages with a hollow porous heterostructure, which look like “flower cluster,” are prepared by a mild, simple, and...     

Synthesis of a tricyclic tetraazatriacetic ligand for gadolinium(III) as potential contrast agent for MRI

A tricyclic tetraazatriacetic compound, which is a rigidified derivative of PCTA12 ligand with a cyclohexylene bridge replacing an ethylene one, was prepared. Two synthetic routes have been investigated, both of them implying a common functionalized triamine intermediate. Whatever the route, four synthetic steps were necessary to obtain the target tricyclic ligand. The more effective one (Route B) led to the desired compound in 19% overall yield from the triamine intermediate. The corresponding gadolinium complex of 1/1 stoichiometry was then prepared in order to evaluate it as potential contrast agent for MRI.     

A new strategy for fabrication Fe2O3/SiO2 composite coatings on the Ti substrate

We report here on the synthesis of homogenous, well-adherent composite film of Fe₂O₃/SiO₂, up to 7 μm thick, on the titanium substrate by anodic treatment optimized for an aqueous suspension of K₂O·SiO₂ and Fe₂O₃ powder under galvanostatic conditions. The end products were characterized by scanning electron microscopy, energy-dispersive X-ray, X-ray powder diffractometry, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy, concluding that the formation of composite coating at the SiO₂ to Fe₂O₃ ratio of approximately 1:1 proceeds just after formation of a thin TiO₂ layer with Fe₂O₃ particle inclusions without transformations via an electrophoresis deposition of negatively charged Fe₂O₃ species enveloped by silica ions.     

An investigation on polycaprolactone/chitosan/Fe3O4 nanofibrous composite used for hyperthermia

Hyperthermia is considered as an effective supplementary cancer treatment. However, the uneven temperature distribution is the major challenge in hyperthermia. Nanotechnology could solve this problem by applying magnetic nanoparticles directly or in nanofibers as implants. Low solubility, poor cancer targeting, and leakage are limitations of free magnetic nanoparticles. In this work, Fe₃O₄ nanoparticles were loaded into polycaprolactone/chitosan blended nanofibers in various contents. Magnetic, chemical, physical, and morphology of the derived nanofibrous composites were then studied. The results showed the magnetic properties of the nanocomposite had low coercivity, which was close to superparamagnetic particles. Chemical analysis showed that components had no interaction with each other. Nevertheless, Fe₃O₄ was slightly transformed to other iron oxides. However, the magnetic analysis showed this transformation had no significant effect on final magnetic content of the nanofibers. The results of X‐ray diffraction (XRD) (19.5 nm), transmittance electron microscopy (TEM) (21.6 nm), and vibration sample magnetometer (VSM) (17 nm) suggested that the magnetic nanoparticles were single domain. Thermal analysis results showed that 7% Fe₃O₄ nanofibers had more heat increase as oppose to other nanofibrous composites in the alternative magnetic field (AMF). Nonetheless, the heat performance of 3% Fe₃O₄ nanofibers was more than others according to its specific power absorption (SPA). Therefore, due to the importance of using nanoparticles in the least possible content, this method can be used as a postsurgical treatment by applying these nanofibrous composites as implants on the tumor site. Moreover, these nanofiber composites could carry anticancer drugs, which are applied as a multi‐mode treatment system.     

Recyclable Fe3O4/ZnO/PPy composite photocatalyst: Fabrication and photocatalytic activity

In this work, a magnetically separable polypyrrole (PPy) modified Fe₃O₄/ZnO composite photo-catalyst was synthesized and its photocatalytic activity was tested. The as-prepared Fe₃O₄/ZnO/PPy nanocomposite was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra. Furthermore, three different photocatalysts including the Fe₃O₄/ZnO/PPy composite were tested using methyl orange (MO) degradation reaction under UV light irradiation. The relative results demonstrated that the Fe₃O₄/ZnO/PPy composite has the highest photochemical activity after 4 h photocatalytic experiment. It can be easily separated using an external magnetic field. This kind of composite photocatalysts with easiness of separation can have potential applications in the treatment of water contaminated by organic pollutants.     

新型Fe_3O_4-Fe复合阳极的研制

制备超细Fe3O4颗粒,然后与还原铁粉混合烧结制成Fe3O4-Fe复合阳极,分别进行析氯电位、循环伏安和强化电解寿命等实验测试,优化该复合阳极的最佳烧结温度和最佳Fe含量,为实用型Fe3O4-Fe复合阳极的制作提供了可行性依据.     

Superdispersible PVP-coated Fe3O4 nanocrystals prepared by a "one-pot" reaction

Poly( N-vinyl-2-pyrrolidone) (PVP)-coated Fe3O4 nanocrystals were prepared by a "one-pot" synthesis through the pyrolysis of ferric triacetylacetonate (Fe(acac)3) in N-vinyl-2-pyrrolidone (NVP). The polymerization of NVP was followed by measuring the shear viscosity of the reaction mixture. The PVP molecules formed in the reaction mixture was investigated by gel permeation chromatography. As the resultant Fe3O4 nanocrystals presented superdispersibility in 10 different types of organic solvents and aqueous solutions with different pH, including 0.01 M phosphate-buffered saline buffer, their hydrodynamic properties in both organic and aqueous systems were investigated by dynamic light-scattering. The results indicated that the PVP-coated Fe3O4 nanocrystals can completely be dispersed forming stable colloidal solutions in both organic solvents and water. Fourier transform infrared spectroscopy results suggested that PVP interacted with Fe3O4 via its carbonyl groups. Further surface analysis by X-ray photoelectron spectroscopy revealed that there were both coordinating and noncoordinating segments of PVP on the particle surface; the molar ratio between them was of 1:2.6.     

Magnetically modified bentonite as a possible contrast agent in MRI of gastrointestinal tract

A composite of iron oxide nanoparticles and mineral matrix has been studied by XRD, Mössbauer spectroscopy, and TEM. Magnetite and superparamagnetic magnetite have been identified by Mössbauer spectroscopy in the nanocomposite. A relationship between the hyperfine parameters and iron oxide particle size has been confirmed by TEM. The optimal concentration of “magnetite—bentonite” composite, when the MRI signal is fully reduced, was found for using this composite as a negative contrast agent.