Fe2O3 Nanoparticles (fe2o3 + nanoparticle)

Distribution by Scientific Domains

Selected Abstracts

A new method for the aqueous functionalization of superparamagnetic Fe2O3 nanoparticles

Fernando Herranz
Abstract A new methodology for the synthesis of hydrophilic iron oxide nanoparticles has been developed. This new method is based on the direct chemical modification of the nanoparticles' surfactant molecules. Using this methodology both USPIO (ultrasmall super paramagnetic iron oxide) (hydrodynamic size smaller than 50,nm) and SPIO (super paramagnetic iron oxide) (hydrodynamic size bigger than 50,nm) were obtained. In addition, we also show that it is possible to further functionalize the hydrophilic nanoparticles via covalent chemistry in water. The magnetic properties of these nanoparticles were also studied, showing their potential as MRI contrast agents. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Magnetically Controllable Silver Nanocomposite with Multifunctional Phosphotriazine Matrix and High Antimicrobial Activity

Panagiotis Dallas
Abstract A recently developed multi-functional phosphotriazine-based polymer is used as a matrix for embedding ,-Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4-phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum-inhibition concentrations are below 100,mg,L,1, which is comparable to their equivalent minimum-inhibition concentrations in colloidal silver systems. [source]

Cover Picture: Composite Silica Spheres with Magnetic and Luminescent Functionalities (Adv. Funct.

Abstract Photographs of a colloidal dispersion of composite nanoparticles with magnetic and luminescent functionalities are shown (left, in column), which are schematically illustrated in the main image. As reported by Salgueirińo-Maceira and co-workers on p.,509, such functionalities are imparted by magnetic and semiconductor nanoparticles within a silica matrix. In the absence of a magnetic field the particles are uniformly dispersed, although they accumulate and can be dragged under the influence of a magnetic field. Their movement can be monitored by their photoluminescence. A new class of highly fluorescent, photostable, and magnetic core/shell nanoparticles in the submicrometer size range has been synthesized from a modified Stöber method combined with the layer-by-layer (LbL) assembly technique. Luminescent magnetic nanoparticles are prepared via two main steps. The first step involves controlled addition of tetraethoxysilane to a dispersion of Fe3O4/,-Fe2O3 nanoparticles, which are thereby homogeneously incorporated as cores into monodisperse silica spheres. The second step involves the LbL assembly of polyelectrolytes and luminescent CdTe quantum dots onto the surfaces of the silica-coated magnetite/maghemite particles, which are finally covered with an outer shell of silica. These spherical particles have a typical diameter of 220,±,10,nm and a saturation magnetization of 1.34,emu,g,1 at room temperature, and exhibit strong excitonic photoluminescence. Nanoparticles with such a core/shell architecture have the added benefit of providing a robust platform (the outer silica shell) for incorporating diverse functionalities into a single nanoparticle. [source]

Repairing Polymers Using Oscillating Magnetic Field

Cathrin C. Corten
Repair of physically separated thermoplastic polymers containing , -Fe2O3 nanoparticles without sacrificing their mechanical properties is achieved by applying an oscillating magnetic field. As , -Fe2O3 nanoparticles oscillate at the frequency of the magnetic field, localized amorphous flow occur, and a permanent repair of physically separated polymeric films is achieved. [source]

A Highly Efficient Chemical Sensor Material for H2S: ,-Fe2O3 Nanotubes Fabricated Using Carbon Nanotube Templates,

Z. Sun
,-Fe2O3 nanotubes that can be used as chemical sensors (see Figure) are fabricated by a novel carbon nanotube (CNT) templated synthesis. CNTs are coated with a continuous layer of Fe2O3 nanoparticles by the decomposition of Fe(NO3)3 in a supercritical CO2/ethanol solution. Subsequent removal of the CNTs gives ,-Fe2O3 nanotubes that are highly sensitive to H2S, which makes them attractive materials for chemiluminescent H2S sensors. [source]

Facile Fabrication of Pure ,-Fe2O3 Nanoparticles via Forced Hydrolysis Using Microwave-Assisted Esterification and their Sensing Property

Yafeng Li
In this paper we firstly demonstrate a facile approach for the rapid fabrication of ,-Fe2O3 using microwave-assisted esterification. In situ -generated water leads to the forced hydrolysis of Fe3+. Microwave irradiation greatly promotes the growth of ,-Fe2O3 nanoparticles compared with conventional solvothermal approach, and agitation can assure the obtainment of pure hematite phase. The akaganeite phase is preserved without stirring. The BET specific surface area reaches 83 m2/g although high concentration of FeCl3 is adopted. Our approach can assure the very rapid acquisition of hematite nanoparticles. Electrochemical studies indicate that our product can function as a candidate for high-performance sensor. [source]