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[en] Nitrilimine cycloadditions to ethylenes, acetylenes, and activated nitriles have been exploited in the presence of catalytic amounts of oleic-acid-coated iron oxide nanoparticles (diameter = 11.9 ± 1.0 nm). The reactions were fully regioselective with monosubstituted ethylenes and ethyl cyanoformiate, while mixtures of cycloadducts were obtained in the presence of methyl propiolate. The intervention of iron oxide nanoparticles allowed carrying out the cycloadditions at milder conditions compared to the metal-free thermal processes. A labile intermediate has been proposed to explain this behavior. .
[en] Recent developments in nanotechnology and application of magnetic nanoparticles, in particular in magnetic iron oxide nanosystems, offer exciting possibilities for cancer theranostics. This work focuses on the development of way of Fe3O4 nanoparticles surface functionalization with silicon based coatings for successful attachment of therapeutic agent—carborane. Comprehensive study of both pristine magnetic nanoparticles and covered/functionalized one was carried out as well as influence of modification on the structural and magnetic characteristics was analyzed. The prospects of (3-Aminopropyl)trimethoxysilane modified Fe3O4 nanoparticles applications as carrier for target delivery of carboranes are thoroughly appraised. (paper)
[en] Studies on the removal of frequently used herbicide for controlling broad-leafed weeds, Paraquat Dichloride (PQ) has been carried out intensively. Waste from steelmaking industries (Electric Arc Furnace (EAF) slag) and natural zeolite (clinoptilolite) were used as the starting materials. Preparation of an adsorbent involved two steps, namely extraction iron oxide (IO) from slag and precipitation of IO onto clinoptilolite. Characterization of NZIC were done using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), single-point Brunauer Emmett Teller (BET) surface area analysis, Vibrating Sample Magnetometer (VSM) and pH at zero point charge (pHzpc). The NZIC showed a lower magnetic saturation at 8.13 emu/ g compared to maghemite at 29.5 emu/ g. The BET surface area of NZIC was 146.29 m2/ g, larger compared to the individual surface area of clinoptilolite and maghemite which are 37.84 and 17.84 m2/ g respectively. Adsorption of PQ onto clinoptilolite and NZIC were investigated using a batch experiment. Surface characteristic of NZIC was investigated by pHzpc experiment showing that at pH 8.2 its electric surface charge is zero. Optimum parameters for adsorption of PQ in water were found at pH 12 with 0.01 g/ 10 mL of NZIC and equilibrium time of 20 minutes. Desorption experiment revealed that NZIC have a good recovery in repetitive usage for PQ removal in water. (author)
[en] Nanoparticles with large amounts of surface area and unique characteristics that are distinct from their bulk material provide an interesting application in the enhancement of inelastic scattering signal. Surface Enhanced Raman Spectroscopy (SERS) strives to increase the Raman scattering effect when chemical species of interest are in the close proximity of metallic nnaostructures. Gold nanoparticles of various shapes have been used for sensing applications via SERS as they demonstrate the greatest effect of plasmonic behavior in the visible-near IR region of the spectrum. When coupled with other nanoparticles, namely iron oxide nanoparticles, hybrid structures with increased functionality were produced. Multifunctional iron oxide-gold hybrid nanostructures have been created via solution chemistries and investigated for analyte detection of a model analyte. By exploiting their magnetic properties, nanogaps or “hot spots” were rationally created and evaluated for SERS enhancement studies.
[en] In the present work, hematite iron oxide nano-particles are synthesized through a facile wet chemical precipitation route. The phase formation behavior and microstructure evolution of the synthesized nano-particles are studied using infrared spectroscopy in conjunction with x-ray diffraction analyses and electron microscopy. Chemi-resistive type hydrogen sensing characteristics (e.g. response %, response time, recovery time) of hematite iron oxide nano-particulate sensing element are evaluated using an automated, dynamic flow gas sensing measurement set-up. The sensing characteristics are measured by varying the operating temperature (275–350 °C) of the sensor and concentration of hydrogen (250–1660 ppm). From the operating temperature dependence of response and recovery times, we have estimated the respective activation energies for response and recovery processes. (paper)
[en] During the oxidation of iron, poorly crystallized phases are firstly formed: 2- and 6-line ferrihydrite, which presents for the last phase, a similarity with wustite FeO but also with hematite α-Fe2O3. Crystallization increases with time and the solid phase obtained is dependent on temperature and pH. Obviously, high temperature favours the formation of the oxide hematite α-Fe2O3. As for the pH factor, it is more complicated. Low and high values of pH (2-5 and 10-14) favour the formation of goethite α-FeOOH, while obtaining hematite is favoured at neutral pH (values around 7). Goethite or hematite are obtained either through a dissolution-crystallization process or in the solid state, through a topotactic transformation. Given the structural relationships observed between ferrihydrite and wustite and hematite, it is allowed to think that a structural continuity could exist between wustite Fe(1-x)O and hematite via ferrihydrite
[en] Remanent magnetization curves for two samples of iron oxide particles with different size distributions were investigated. It was observed that the isothermal remanent magnetization curve and the DC demagnetization remanence curves are strongly depended on fine particle size. Moreover, it was figured out that remanent curves are quite complicated for the assembly of larger particles. In terms of remanence dependence analysis, it was shown that favourable interaction mechanism for the assembly of iron oxide particles strongly depends on particle size. The isothermal remanent magnetization curves were analysed in terms of the Stoner-Wohlfarth model. It leads to determine particle anisotropy field. It was found that the anisotropy field depends on particle size. It was assumed that observed differences related to different magnetic structure of particles. (paper)
[en] Iron oxide/multiwalled carbon nanotube magnetic composites (denoted as magnetic composites) were synthesized and characterized in detail. The magnetic composites can be separated from aqueous solution easily by using magnetic separation method. The application of magnetic composites in the removal of Eu(III) from large volumes of aqueous solutions was studied. The results indicated that the sorption of Eu(III) on the magnetic composites was strongly dependent on pH values and weakly dependent on ionic strength. The sorption of Eu(III) on the magnetic composites was mainly dominated by inner-sphere surface complexation. The linear sorption isotherms of Eu(III) suggested that Eu(III) sorption on the magnetic composites was far from saturation. The large sorption capacity and the easy magnetic separation method indicate that the magnetic composites may be a promising suitable material in nuclear waste management in future. (author)
[en] Iron oxide nanoparticles (IONPS) have been widely investigated as a platform for a new class of multifunctional theranostic agents. They are considered biocompatible, and some formulations are already available in the market for clinical use. However, contradictory results regarding toxicity of IONPs raise a concern about the potential harm of these nanoparticles. Changes in the nanoparticle (NP) physicochemical properties or exposure media can significantly alter their behavior and, as a consequence, their toxic effects. Here, behavior and two-step RT-qPCR were employed to access the potential toxicological effects of dextran-coated IONPs (CLIO-NH2) and uncoated IONPs (UCIO) in zebrafish larvae. Animals were exposed for 7 days to NP solutions ranging from 0.1–100 μg/mL directly mixed to the system water. UCIO showed high decantation and instability in solution, altering zebrafish mortality but showing no alterations in behavior and molecular expression analysis. CLIO-NH2 exposure did not cause significant mortality or changes in hatching rate of zebrafish larvae; however, behavior and expression profiles of the group exposed to lower concentration (1 μg/mL) presented a tendency to decrease the locomotor activity and apoptotic pathway activation.
[en] This work deals with the partitioning of the cationic amphiphilic drug, propranolol, in the coating of so-called magnetoliposomes (MLs), which consist of nanometre-sized, magnetizable iron oxide cores covered with a phospholipid bilayer. MLs of two types were used: either the ML coat consisted entirely of anionic dimyristoylphosphatidylglycerol, or it was mixed with zwitterionic dimyristoylphosphatidylcholine in a 5/95 molar ratio. To separate sorbed from non-sorbed propranolol, high-gradient magnetophoresis was used. The sorption profiles clearly show that electrostatic interactions play a key role in the sorption process as drug incorporation in the ML coat was favoured by increasing the anionic character of the ML envelope and by reducing the salt concentration of the medium. Also, upon drug binding some phospholipid molecules were expelled from the ML coat. The observations may be of relevance in the biomedical field, i.e. in the development of ML-based, intracellular theranostics