Biodistribution of ultra small superparamagnetic iron oxide nanoparticles in BALB mice

Recently ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (NPs) have been widely used for medical applications. One of their important applications is using these particles as MRI contrast agent. While various research works have been done about MRI application of USPIOs, there is limited research about their uptakes in various organs. The aim of this study was to evaluate the biodistribution of dextran coated iron oxide NPs labelled with ^99mTc in various organs via intravenous injection in Balb/c mice. The magnetite NPs were dispersed in phosphate buffered saline and SnCl₂ which was used as a reduction reagent. Subsequently, the radioisotope ^99mTc was mixed directly into the reaction solution. The labeling efficiency of USPIOs labeled with ^99mTc, was above 99 %. Sixty mice were sacrificed at 12 different time points (From 1 min to 48 h post injections; five mice at each time). The percentage of injected dose per gram of each organ was measured by direct counting for 19 harvested organs of the mice. The biodistribution of ^99mTc-USPIO in Balb/c mice showed dramatic uptake in reticuloendothelial system. Accordingly, about 75 percent of injected dose was found in spleen and liver at 15 min post injection. More than 24 % of the NPs remain in liver after 48 h post-injection and their clearance is so fast in other organs. The results suggest that USPIOs as characterized in our study can be potentially used as contrast agent in MR Imaging, distributing reticuloendothelial system specially spleen and liver.     

Effects of compositional defects on small polaron hopping in micas

Hartree-Fock calculations and electron transfer (ET) theory were used to model the effects of compositional defects on ET in the brucite-like octahedral sheet of mica. ET was modeled as an Fe(IIIII) valence interchange reaction across shared octahedral edges of the M2-M2 iron sublattice. The model entails the hopping of localized electrons and small polaron behavior. Hartree-Fock calculations indicate that substitution of F for structural OH bridges increases the reorganization energy lambda, decreases the electronic coupling matrix element V(AB), and thereby substantially decreases the hopping rate. The lambda increase arises from modification of the metal-ligand bond force constants, and the V(AB) decrease arises from reduction of superexchange interaction through anion bridges. Deprotonation of an OH bridge, consistent with a possible mechanism of maintaining charge neutrality during net oxidation, yields a net increase in the ET rate. Although substitution of Al or Mg for Fe in M1 sites distorts the structure of adjacent Fe-occupied M2 sites, the distortion has little net impact on ET rates through these M2 sites. Hence the main effect of Al or Mg substitution for Fe, should it occur in the M2 sublattice, is to block ET pathways. Collectively, these findings pave the way for larger-scale oxidation/reduction models to be constructed for realistic, compositionally diverse micas.     

Entropy generation in peristalsis with iron oxide

Journal of Thermal Analysis and Calorimetry - High-density polyethylene (HDPE) nanocomposites were prepared by a melting-compounding process with a polymethylsilsesquioxane (PMSQ) as nanofiller. In...     

Polymer nanocomposites with iron oxide nanoparticles

Novel polymer nanocomposites with iron oxide nanoparticles in a poly(1-vinyl-1,2,4-triazole) matrix are promising for the development of new biomedical materials of long-term effect.     

Spatially resolved energy electron loss spectroscopy studies of iron oxide nanoparticles.

The oxidation state of iron oxide nanoparticles co-generated with soot during a combustion process was studied using electron energy-loss spectroscopy (EELS). Spatially resolved EELS spectra in the scanning transmission electron microscopy mode were collected to detect changes in the oxidation state between the cores and surfaces of the particles. Quantification of the intensity ratio of the white lines of the iron L-ionization edge was used to measure the iron oxidation state. Quantitative results obtained from Pearson's method, which can be directly compared with the literature data, indicated that the L3 /L2-intensity ratio for these particles changes from 5.5 +/- 0.3 in the particles' cores to 4.4 +/- 0.3 at their surfaces. This change can be directly related to the reduction of the iron oxidation state at the surface of the particles. Experimental results indicate that the cores of the particles are composed of gamma-Fe2O3, which seems to be reduced to FeO at their surfaces. These results were also supported by the fine structure of the oxygen K-edge and by the significant chemical shift of the iron L-edge.     

Bis-phosphonates-ultra small superparamagnetic iron oxide nanoparticles: a platform towards diagnosis and therapy

A new type of multifunctional magnetic nano-platform for diagnosis and therapy applications was designed using bisphosphonate/carboxylic ligands.     

Nano iron oxide with the neural-network morphology

To improve network-functioning, an arc discharge method was developed for the synthesis of nano iron oxide with “neuralnetwork” morphology. Iron wires with diameters of 0.01–0.05 cm were subjected to currents of 50–200 A, until explosions occured in the open air. The XRD and RAMAN spectra of the as-prepared-products indicate formation of nano-Fe₂O₃ (tetragonal and monoclinic) crystals. Their SEM images show fabrication of nano iron oxide with three different morphologies: spheres, chains, and a “neural-network” biological form. While the latter is unprecedented, our fabrications of nano iron oxide with both sphere and chain morphologies are reproductions of previously reported results. The sphere shaped nanoparticles show a uniform distribution with sizes in the range of 50–250 nm. The specifications of the chain nano products appear consistent with those reported.     

Superparamagnetic iron oxide nanoparticles with photoswitchable fluorescence

The incorporation of superparamagnetic iron oxide nanoparticles with sulfur-oxidized diarylethene molecules resulted in a novel multifunctional nanosystem, in which the fluorescent performance and flocculation and dispersion are reversibly switched by light irradiation and external magnetic field, respectively.     

Decoration of carbon nanotubes with iron oxide

A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with iron oxide nanoparticles was synthesized successfully by a simple and effective chemistry precipitation method. The composite was characterized by X-ray diffraction analysis (XRD), Mössbauer spectrum (MS), transmission electron microscopy (TEM), and Fourier transform spectroscopy (FTIR) techniques. The patterns of XRD and MS indicated that MWNTs, γ-Fe₂O₃, and Fe₃O₄ coexisted in the composite. The TEM observation indicated that the nanoparticles of iron oxide were attached on the surface of the MWNTs, and the sizes of the particles ranged from 25 to 80 nm. FTIR spectra showed that SO₄⁻ functional groups existed on the surface of MWNTs after modification by sodium dodecylbenzene sulfonic acid (SDBS), which could immobilize Fe³⁺ ions onto the MWNTs. The hysteresis loops of the MWNTs and decorated MWNTs were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 20.07 emu/g, and the coercive of 163.44 Oe.     

Sterols associated with small unilamellar vesicles (SUVs): intrinsic mobility role for 1H NMR detection

Small unilamellar vesicles (SUVs) of phospholipids are often used as a membrane model system for studying the interaction of molecules. When using NMR under the standard liquid‐state conditions, SUV phospholipid proton spectra can be recorded, exhibiting sharp signals. This is not only because of the fast vesicular tumbling but also because of the combination of this tumbling with the individual motion of the lipids inside the bilayer. This appears evident because addition of cholesterol is responsible of broader resonances because of the slowing down of the lipid motion. On the other hand, no ¹H signal is detected for cholesterol in the bilayer. This lack of detection of the inserted molecules explains why generally SUVs are not considered as a good model for NMR studies under the standard liquid‐state conditions. Here, we use two other sterols in order to demonstrate that an increase of the molecular mobility inside the bilayer could allow the detection of their proton resonances. For desmosterol and lanosterol, which show higher mobility inside the bilayer, with increasing lateral diffusion rates, ¹H sterol signals are detected in contrast to cholesterol. For the fast diffusing lanosterol, no significant improvement in detection is observed using deuterated lipids, demonstrating that homonuclear dipolar coupling is fully averaged out. Furthermore, in the case of low mobility such as for cholesterol, the use of a fast magic angle spinning probe is shown to be efficient to recover the full proton spectrum. Copyright © 2014 John Wiley & Sons, Ltd.     

Graphene-based multifunctional iron oxide nanosheets with tunable properties

We report the synthesis of graphenes with tunable properties due to the growth of needlelike iron oxide (IO) nanoparticles on their surfaces. The electrical conductivity, flexibility, and magnetic properties of graphene nanosheets (GNSs) could be tuned on demand by fine controlling both the surface coverage and the length of the IO nanoneedles. The degree of coverage of the IO nanoparticles on the surface of the GNSs made it possible to control the resulting properties of the IO/GNSs on demand. As examples of their utility, paperlike materials were generated by simple filtration, and the resulting IO/GNS nanocomposites showed extraordinary removal capacity and fast adsorption rates for As(V) and Cr(VI) ions in water. Another possible application is the preparation of multifunctional films equipped with conductivity, flexibility, and magnetic properties. The fabrication process is easy to scale up at a low cost. In addition, both the colloidal solution and film forms of the resulting IO/GNSs were effective for removal of heavy metal ions, meaning this material could be utilized for actual industrial applications.     

纳米氧化铁的研究进展

介绍纳米氧化铁在颜料、气敏材料、催化剂及生物医学等方面的应用,纳米氧化铁的氧化沉淀法、固相合成法、胶溶-相转移法、溶胶-凝胶法、强迫水解法、水热法、柠檬酸铁热分解法等制备方法,并对今后的研究方向进行了展望。     

Sorption of small amounts of cobalt(II) on iron(III) oxide

Summary The sorption of small amounts of cobalt(II) on iron (III) oxide has been studied as a function of pH. The mechanism of sorption is discussed. Iron (III) oxide carrier can be used for the preconcentration of small or trace amounts of cobalt(II). The influence of EDTA, glycine,L(+)-arginine andL(+)-cysteine on the sorption yields of cobalt(II) has also been studied.

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Zusammenfassung Die Abhängigkeit der Adsorption geringer Mengen Co (II) an Eisen (III)-hydroxid vom pH wurde untersucht und der Mechanismus der Adsorption erörtert. Eisen (III) oxidträger kann für die Anreicherung kleiner Mengen oder Spuren Co(II) verwendet werden. Der Einfluß von ÄDTA, Glycin, L(+)-Arginin und L(+)-Cystein auf die sorbierte Menge Co(II) wurde gleichfalls geprüft.

     

Determination of metallic iron, iron(II) oxide, and iron(III) oxide in a mixture

A procedure is described for the estimation of metallic iron, ferrous oxide, and ferric oxide when present together. The sample is treated with bromine dissolved in ethanol, and filtered. Iron in the filtrate is titrated iodometrically, and corresponds to the metallic iron present in the mixture. The oxide residue is dissolved in hydrochloric acid under a carbon dioxide atmosphere. The iron(II) formed, equivalent to FeO present, is titrated with a standard vanadate solution, and the total iron(III) (FeO + Fe₂O₃) in the titrated solution is then estimated iodometrically.     

A cast-mold approach to iron oxide and Pt/iron oxide nanocontainers and nanoparticles with a reactive concave surface

We report the synthesis of various iron oxide nanocontainers and Pt-iron oxide nanoparticles based on a cast-mold approach, starting from nanoparticles having a metal core (either Au or AuPt) and an iron oxide shell. Upon annealing, the particles evolve to asymmetric core-shells and then to heterodimers. If iodine is used to leach Au out of these structures, asymmetric core-shells evolve into "nanocontainers", that is, iron oxide nanoparticles enclosing a cavity accessible through nanometer-sized pores, while heterodimers evolve into particles with a concave region. When starting from a metal domain made of AuPt, selective leaching of the Au atoms yields the same iron oxide nanoparticle morphologies but now encasing Pt domains (in their concave region or in their cavity). We found that the concave nanoparticles are capable of destabilizing Au nanocrystals of sizes matching that of the concave region. In addition, for the nanocontainers, we propose two different applications: (i) we demonstrate loading of the cavity region of the nanocontainers with the antitumoral drug cis-platin; and (ii) we show that nanocontainers encasing Pt domains can act as recoverable photocatalysts for the reduction of a model dye.     

Nanoengineering of iron oxide and iron oxide/silica hollow spheres by sequential layering combined with a sol-gel process

Fe2O3 and Fe2O3/SiO2 hollow spheres with tailored dimensions and compositions were created by consecutively coating polystyrene (PS) latices either with Fe3+ alternately adsorbed with Nafion or combining a sol-gel process based on the hydrolysis of tetraethoxysilane (TEOS), and subsequently removing the cores upon pyrolysis.     

Free solution mobility of small single-stranded oligonucleotides with variable charge densities

The free solution mobilities of six single-stranded 16-nucleotide DNA oligomers with the same sequence, containing up to 11 neutral phosphoramidate internucleoside linkages, have been measured by capillary electrophoresis. The mobilities of the partially charged oligomers increase linearly with the logarithm of increasing charge density, as predicted by the Manning theory of electrophoresis (G. S. Manning, J. Phys. Chem. 1981, 85, 1506-1515). For comparison, the mobilities of eight fully charged single-stranded oligomers containing similar numbers of charged phosphate residues have also been measured. The mobilities of the variable length, fully charged oligomers increase more rapidly with the increasing number of charged phosphate residues than the mobilities of the constant size, partially charged phosphoramidate derivatives, because of the larger diffusion coefficients of the modified oligomers.     

Reorganization energy of electron transfer in viscous solvents above the glass transition

We present a molecular-dynamics study of the solvent reorganization energy of electron transfer in supercooled water. We observe a sharp decrease of the reorganization energy at a temperature identified as the temperature of structural arrest due to cage effect as discussed by the mode coupling theory. Both the heat capacity and dielectric susceptibility of the pure water show sharp drops at about the same temperature. This temperature also marks the onset of the enhancement of translational diffusion relative to rotational relaxation signaling the breakdown of the Stokes-Einstein relation. The change in the reorganization energy at the transition temperature reflects the dynamical arrest of the slow, collective relaxation of the solvent related to Debye relaxation of the solvent dipolar polarization.     

Small polaron hopping in Li(x)FePO4 solid solutions: coupled lithium-ion and electron mobility

Transition metal phosphates such as LiFePO(4) have been recognized as very promising electrodes for lithium-ion batteries because of their energy storage capacity combined with electrochemical and thermal stability. A key issue in these materials is to unravel the factors governing electron and ion transport within the lattice. Lithium extraction from LiFePO(4) results in a two-phase mixture with FePO(4) that limits the power characteristics owing to the low mobility of the phase boundary. This boundary is a consequence of low solubility of the parent phases, and its mobility is impeded by slow migration of the charge carriers. In principle, these limitations could be diminished in a solid solution, Li(x)FePO(4). Here, we show that electron delocalization in the solid solution phases formed at elevated temperature is due to rapid small polaron hopping and is unrelated to consideration of the band gap. We give the first experimental evidence for a strong correlation between electron and lithium delocalization events that suggests they are coupled. Furthermore, the exquisite frequency sensitivity of M?ssbauer measurements provides direct insight into the electron hopping rate.