Search results for "Magnetite"
showing 10 items of 98 documents
Smart copolymer coated SPIONs for colon cancer chemotherapy
2019
Human colon cancer is one of the higher aggressive solid tumors, whose high mortality, much like many other solid tumors, results from metastasis formation. To reduce this high mortality, more effective chemotherapy, allowing a specific tumor accumulation and an efficient early-stage medical imaging as well, are still needed. At this regard, stimuli-responsive nanocarriers for anticancer drug delivery are promising strategy in cancer therapy. For this purpose, a dual targeted redox-responsive drug delivery system, prepared by coating superparamagnetic nanoparticles (SPIONs) with the amphiphilic copolymer INU-LA-PEG-FA and loading doxorubicin (DOXO-SPIONs) was investigated as tool for solid …
Effects of MRI Contrast Agents on the Stem Cell Phenotype
2010
The ultimate therapy for ischemic stroke is restoration of blood supply in the ischemic region and regeneration of lost neural cells. This might be achieved by transplanting cells that differentiate into vascular or neuronal cell types, or secrete trophic factors that enhance self-renewal, recruitment, long-term survival and functional integration of endogenous stem/progenitor cells. Experimental stroke models have been developed to determine potential beneficial effect of stem/progenitor cell based therapies. To follow the fate of grafted cells in vivo, a number of non-invasive imaging approaches have been developed. Magnetic Resonance Imaging (MRI) is a high resolution, clinically relevan…
Liver methylene fraction by dual- and triple-echo gradient-echo imaging at 3.0T: Correlation with proton MR spectroscopy and estimation of robustness…
2011
Purpose To assess the systematic errors in liver methylene fraction (LMF) resulting from fat–fat interference effects with dual- and triple-echo gradient-recalled-echo Dual/Triple GRE) sequences and to test the robustness of these sequences after iron overloading. Materials and Methods Forty type-2 diabetic patients underwent LMF measurement by 3.0T 1H magnetic resonance spectroscopy (corrected for T1 and T2 decays) as the reference standard and liver fat fraction (%Fat) measurement by four Dual/Triple GRE sequences with 20° and 60° flip angle (α), corrected for T1 recovery. The same four sequences were repeated in eight patients after ferumoxide injection. Corrections for systematic errors…
Polymeric Nanocarriers for Magnetic Targeted Drug Delivery: Preparation, Characterization, and in Vitro and in Vivo Evaluation
2013
In this paper the preparation of magnetic nano- carriers (MNCs), containing superparamagnetic domains, is reported, useful as potential magnetically targeted drug delivery systems. The preparation of MNCs was performed by using the PHEA-IB-p(BMA) graft copolymer as coating material through the homogenization−solvent evaporation method. Magnetic and nonmagnetic nanocarriers containing flutamide (FLU-MNCs) were prepared. The prepared nanocarriers have been exhaustively characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and magnetic measurements. Biological evaluation was performed by in vitro cytotoxicity and cell uptake tests and in vivo biodistribution …
Search for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity
2008
[1] The Rock Abrasion Tool (RAT) on board the Mars Exploration Rovers (MER) is a grinding tool designed to remove dust coatings and/or weathering rinds from rocks and expose fresh rock material. Four magnets of different strengths that are built into the structure of the RAT have been attracting substantial amounts of magnetic material during RAT activities from rocks throughout both rover missions. The RAT magnet experiment as performed on Spirit demonstrates the presence of a strongly ferrimagnetic phase in Gusev crater rocks, which based on Mossbauer and visible/near-infrared reflectance spectra is interpreted as magnetite. The amount of abraded rock material adhering to the magnets vari…
Quantification of pedogenic particles masked by geogenic magnetic fraction
2021
AbstractPedogenic magnetic fraction in soils is attributed to fine-grained particles, i.e. superparamagnetic grains. In the case of a strongly magnetic geogenic fraction, pedogenic magnetic contribution is hard to detect. To the best of our knowledge, detailed research into the masking of pedogenic superparamagnetic grains and quantification of this effect has not yet been carried out. The principal aim of our research is to quantify the influence of coarse-grained ferrimagnetic fraction on the detection of the superparamagnetic grains. In order to describe the masking phenomenon, volume and frequency-dependent magnetic susceptibility were determined on a set of laboratory prepared samples …
Model colloids to study surface – ligand interactions in nanosized Fe3O4
2019
Using electrodispersion of metallic iron in an aqueous environment without additional reagents we create a chemically clean model system based on nanosized synthetic magnetite where the details of magnetic metal oxide – surfactant chemisorption can be studied by high fidelity magnetometry with nanometric precision. A comparative analysis of model colloidal solutions based on oleic acid and iron Fe2+ oleate indicates a significant influence of the mode of surfactant adsorption on the magnetic diameter of the particles.
Evidence for the verwey transition in highly nonstoichiometric nanometric fe-based ferrites
2001
The nanometric scale allows an investigation of the Verwey transition: the impact of varying degree of oxidation of Fe cations on this transition was studied by means of zero-field-cooled superconducting quantum interference device measurements in nanometric highly nonstoichiometric particles of pure and Ti-substituted magnetite synthesized using soft chemistry route. It is clearly shown that (i) there is a shift of the transition towards higher temperatures for nanometer scaled compounds and (ii) the amplitude, the temperature, and the order of the transition are only depending on the number of ${\mathrm{Fe}}^{2+}{/\mathrm{F}\mathrm{e}}^{3+}$ pairs in octahedral coordination.
Temperature dependence of magnetization reversal in Co and Fe3O4 nanowire arrays
2005
Abstract In this paper, we investigate the magnetization reversal of cobalt and magnetite nanowires, 4 nm in diameter, synthesized within the pores of mesoporous silica thin films. A SQUID magnetometer was used to study the magnetic properties of the nanowire arrays over a broad temperature interval, T= 1.8–300 K. The magnetization reversal process was found to be strongly temperature dependent. While a coherent rotation may occur at room temperature, a process involving the formation of domain structures takes place as the temperature decreases down to 1.8 K.
Bulk spin polarization of magnetite from spin-resolved hard x-ray photoelectron spectroscopy
2021
Physical review / B 104(4), 045129 (1-10) (2021). doi:10.1103/PhysRevB.104.045129