Search results for "magnetite"
showing 10 items of 98 documents
Inulin-Ethylenediamine Coated SPIONs Magnetoplexes: A Promising Tool for Improving siRNA Delivery.
2015
An inulin based polycation (Inu-EDA) has been synthesized by the grafting of ethylenediamine molecules onto inulin backbone. The obtained inulin copolymer has been though to coat SPIONs (IC-SPIONs) and obtain stable magnetoplexes by complexation of IC-SPIONs with a model duplexed siRNA, for improving oligonucleotide transfection efficiency.The physical-chemical characteristics of IC-SPIONs and IC-SPIONs/siRNA magnetoplexes have been investigated by scanning and transmission electron microscopies, dynamic light scattering, FT-IR and qualitative surface elementary analysis. Cell compatibility and internalization in vitro of IC-SPIONs have been evaluated by MTS and fluorescence microscopy resp…
Functionalized Fe3O4 nanoparticles: influence of ligand addition sequence and pH during their continuous hydrothermal synthesis
2015
In this study we report various new efficient ways to synthesize and modify in situ magnetite (Fe3O4) iron oxide nanoparticles (NPs). Thanks to an apparatus especially developed for this new method of grafting, the NPs have been synthesized and functionalized by 3,4-dihydroxyhydrocinnamic acid (DHCA) or 3,4-dihydroxy-L-phenylalanine (LDOPA) in one step and under hydrothermal conditions using varying concentration ratios ([organic molecules]/[ferrous and ferric ions]). The organic molecules were added before or after the NP synthesis. The addition of these organic molecules modifies the structure, the morphology, the oxidation degree and the growth of the crystallites. Adding the organic mol…
Revealing Magnetite Nanoparticles Aggregation Dynamics – A SLS and DLS Study
2010
\(\mathrm{Fe}_{3}\mathrm{O}_{4}\) nanoparticles in aqueous suspensions are not stable but aggregate, tremendously changing the rheological properties of the nanofluid. Modified version of both the Static Light Scattering (SLS) setup and of Dynamic Light Scattering (DLS) setup experiment were used to monitor \(\mathrm{Fe}_{3}\mathrm{O}_{4}\) nanoparticle aggregation in aqueous diluted suspension. The experiments are described in detail and the variation of the average aggregate diameter in time is presented in this work.
Development of stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles and its analytical application to the determination of…
2014
A novel microextraction technique combining the principles of stir bar sorptive extraction (SBSE) and dispersive micro-solid phase extraction (DμSPE) is presented. The main feature of the method is the use of a neodymium-core stirring bar physically coated with a hydrophobic magnetic nanosorbent. Depending on stirring speed, the magnetic sorbent either acts as a coating material to the stir bar, thus affording extraction alike SBSE, or as a dispersed nanosorbent medium for the collection and extraction of the target analytes, in close analogy to DμSPE. Once the stirring process is finished, the strong magnetic field of the stir bar prevails again and rapidly retrieves the dispersed MNPs. Al…
A concept for a magnetic particle imaging scanner with Halbach arrays
2020
Magnetic particle imaging (MPI) is a new medical imaging technique visualizing the concentration distribution of superparamagnetic nanoparticles used as tracer material. MPI is not yet in clinical routine, since one of the challenges is the upscaling of scanners. Typically, the magnetic fields of MPI scanners are generated electromagnetically, resulting in an immense power consumption but providing high flexibility in terms of adjusting the field strengths and very fast image acquisition rates. Permanent magnets provide high flux densities and do not need any power supply. However, the flux density is not adjustable, and a mechanical movement is slow compared to electromagnetically varying …
Technogenic Magnetic Particles in Alkaline Dusts from Power and Cement Plants
2012
During this study, we investigated the mineralogical characterization of technogenic magnetic particles (TMPs) contained in alkaline industrial dust and fly ash emitted by coal burning power plants and cement plants. The reaction of tested dust samples varied between values of pH 8 and pH 12. Their magnetic properties were characterized by measurement of magnetic susceptibility (χ), frequency dependence of magnetic susceptibility (χ(fd)), and temperature dependence of magnetic susceptibility. Mineralogical and geochemical analyses included scanning electron microscopy with energy dispersive spectroscopy, microprobe analysis and X-ray diffraction. The TMPs in fly ash from hard coal combustio…
Water-soluble magnetic nanoparticles with biologically active stabilizers
2009
We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11 nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed obse…
CHARACTERIZATION OF IRON COMPOUNDS FROM URBAN AND RURAL AEROSOL SOURCES
2000
Abstract Iron plays an important role in the chemistry and physics (by varying the hygroscopicity) of the atmosphere. Bulk samples were taken from an air-conditioning device, from the electrofilter of a gas–oil power station of the Technical University of and from rural sites near Darmstadt, situated between medium-altitude mountains and with a climate dominated by air masses from the west. Samples were collected in urban and rural (meadow) air, from different waste incineration power stations, from the exhausts of a gasoline and from a diesel motor car, and from a private gas fired heating system. The samples were characterized for elemental composition by total reflection X-ray fluorescen…
Mineralogy at Gusev Crater from the Mössbauer spectrometer on the Spirit Rover.
2004
Mössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crat…
Magnetic Properties Experiments on the Mars Exploration Rover Spirit at Gusev Crater
2004
The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars—and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of ∼2% by weight. The most magnetic fraction of the dust appears darker than the average dust. Magnetite was detected in the first two rocks ground by Spirit.