Magnetic control of bioelectrocatalytic processes based on assembled iron oxide particles

A facile magnetic control system was designed in bioelectrocatalytic process based on functionalized iron oxide particles. The iron oxide particles were modified with glucose oxidase, and ferrocene dicarboxylic acid was used as electron transfer mediator. Functionalized iron oxide particles can assemble along the direction of applied magnetic field, and the directional dependence of the assembled iron oxide particles can be utilized for device purposes. We report here how such functionalized magnetic particles are used to modulate the bioelectrocatalytic signal by changing the orientation of the applied magnetic field. (C) 2008 Elsevier B.V. All rights reserved.

Fabrication of Iron Oxide Core/Gold Shell Submicrometer Spheres with Nanoscale Surface Roughness for Efficient Surface-Enhanced Raman Scattering

A method to synthesize Fe3O4 core/Au shell submicrometer structures with very rough surfaces on the nanoscale is reported. The Fe3O4 particles were first modified with uniform polymers through the layer-by-layer technique and then adsorbed a lot of gold nanoseeds for further Au shell formation. The shell was composed of a large number of irregular nanoscale An particles arranged randomly, and there were well-defined boundaries between these Au nanoparticles. The Fe3O4 core/Au shell particles showed strong plasmon resonance absorption in the near-infrared range, and can be separated quickly from solution by an external magnet.

On the chemical synthesis and drug delivery response of folate receptor-activated, polyethylene glycol-functionalized magnetite nanoparticles

We describe here the chemical synthesis and in vitro drug delivery response of polyethylene glycol (PEG)-functionalized magnetite (Fe3O4) nanoparticles, which were activated with a stable ligand, folic acid, and conjugated with an anticancer drug, doxorubicin. The functionalization and conjugation steps in the chemical synthesis were confirmed using Fourier transform infrared spectroscopy. The drug-release behavior of PEG-functionalized and folic acid-doxorubicin-conjugated magnetic nanoparticles was characterized by two stages involving an initial rapid release, followed by a controlled release. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

One-pot green synthesis of biocompatible arginine-stabilized magnetic nanoparticles

A green one-step approach has been developed for the synthesis of amino-functionalized magnetite nanoparticles. The synthesis was accomplished by simply mixing FeCl2 with arginine under ambient conditions. It was found that the Fe2+/arginine molar ratio, reaction duration and temperature greatly influence the size, morphology and composition of magnetic nanoparticles. The arginine-stabilized magnetic nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy techniques.

Monodisperse mesoporous superparamagnetic single-crystal magnetite nanoparticles for drug delivery

In this contribution, we report a facile, gram-scale, low-cost route to prepare monodisperse superparamagnetic single-crystal magnetite NPs with mesoporous structure (MSSMN) via a very simple solvothermal method. The formation mechanism of MSSMN is also discussed and we think that Ostwald ripening probably plays an important role in this synthesis process. It is also interestingly found that the size and morphology of mesoporous Fe3O4 NPs can be easily controlled by changing the amount of NaOH and 1,2-ethylenediamine (ETH). Most importantly, the MSSMN can be used as an effective drug delivery carrier. A typical anticancer drug, doxorubicin (Dox), is used for drug loading, and the release behaviors of Dox in two different pH solutions are studied. The results indicate that the MSSMN has a high drug loading capacity and favorable release property for Dox; thus, it is very promising for the application in drug delivery.

An organic-inorganic hybrid ultrathin film: preparation and characterization of copper phthalocyanine derivative-ferric oxide nanoparticles

A nanoparticulate ferric oxide-copper tris(2,4-di-tert-amylphenoxy)-8-quinolinolylphthalocyanine hybrid ultrathin film was constructed from alternate layers by the Langmuir-Blodgett technique. The composition, morphology and structure of the film were studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, atomic force microscopy, small-angle X-ray diffraction, visible spectroscopy and polarized UV-Vis spectroscopy. All the above analyses suggest that the thin film is a kind of one-dimensional superlattice, composed of organic and inorganic components. The XPS data reveal that the nanoparticulate ferric oxide exists as an alpha-Fe2O3 phase in the films. Gas-sensing measurements show that the hybrid LB film has very fast response-recovery characteristics towards 2 ppm C2H5OH vapor.

Alternating LB film of ferric oxide nanoparticles-copper phthalocyanine derivative and its gas sensitivity

Nanoparticulate ferric oxide - tris - (2,4-di-t-amylphenoxy) - (8-quinolinolyl) copper phthalocyanine Langmuir-Blodgett Z-type multilayers were obtained by using monodisperse nanoparticle ferric oxide hydrosol as the subphase. XPS data reveal that the nanoparticle ferric oxide exist as alpha -Fe2O3 phase in the films. Transition electron microscopic (TEM) image of the alternating monolayer shows that the film was highly covered by the copper phthalocyanine derivative and the nanoparticles were arranged rather closely. IR and visible spectra all give the results that the nanoparticles were deposited onto the substrate with the copper phthalocyanine derivative. The gas-sensing measurements show that the alternating LB film had very fast response-recovery characteristic to 2 ppm C2H5OH gas, and also sensitive to larger than 200 ppm NH3.