The synthesis and characterization of polymer coated iron oxide microspheres

For biomedical applications drug carrying polymers are coated around magnetic iron oxide particles to form microspheres. In the present study, the iron oxide powder was ball milled. Microspheres were then synthesized by solvent evaporation, resulting in iron oxide particles encapsulated in a polymer and drug coating. Various parameters, such as the duration of milling and agitation speed as well as the polymer concentration were varied. A milling time of 72 h was found to yield a small size and narrow size distribution of particles; the average particle size was about 600 nm. Measurements of the change in grain size and the magnetic properties of the powder with milling time were performed. It was determined that the size of the microspheres was not sensitive to the initial particle size, but it could be decreased by variation of agitation speed or polymer concentration. The agitation speed and polymer concentration of 400 rpm and 0.04 g poly(l-lactic acid) in 8 g dicholoromethane, respectively, was found to yield small, spherical microspheres with a narrow size distribution. The surface morphology and magnetic properties of the microspheres was also analyzed.     

Synthesis and characterization of the iron oxide magnetic particles coated with chitosan biopolymer

Magnetic particles are extremely interesting for several biomedical applications; amongst these are therapeutic applications, such as: hyperthermia and release of drugs. The use of magnetic particles to induce hyperthermia in biological tissues is an important factor in cancer therapy. The aim of this study was to prepare and characterize iron oxide magnetic particles coated with biopolymer chitosan, and also to produce ferrofluids from the magnetic particles. The iron oxide magnetic particles (IOMP) were coated with chitosan (CS) by spray-drying method using two IOMP/coating ratios (IOMP/CS = 1.6 and IOMP/CS = 4.5). The magnetic particles were characterized by way of scanning electronic microscopy and energy-dispersive X-ray. The analysis by energy-dispersive X-ray was carried out to determine the chemical composition of particles in samples. The size distribution the iron oxide magnetic particles uncoated and coated were evaluated by the laser diffraction analysis and image analysis, respectively. Amongst the prepared ferrofluids, the sample IOMP/CS = 1.6 proved to be the one that has brought about the best results in therapeutics applications, such as in hyperthermia treatment. This sample was placed within an alternating magnetic field during 40 min, it was observed that 1 °C heated in 3 min and underwent a temperature variation of 7 °C, since it varied from 25 °C to 32 °C. Considering that the experiment would be carried out at body temperature 37 °C, probably, the temperature variation would be very close to the one reported at 25 °C. In such a way, the cancerous cells would reach 44–45 °C and at such temperatures the cancer cells generally perish.     

TEM characterization of iron-oxide-coated ceramic membranes

Commercially available porous alumina–zirconia–titania ceramic (AZTC) membranes having a titania surface coating were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and the Brunauer–Emmett–Teller (BET) method. TEM photomicrographs showed the as-received AZTC membrane to be a multi-layered structure consisting of a porous alumina–zirconia–titania core having ultrafine pore sizes, coated by an additional layer of nanoporous titania. Electron diffraction studies revealed an amorphous surface titania layer while the underlying AZTC membrane was crystalline. The AZTC membranes were coated 20, 30, 40, 45, or 60 times with iron oxide (Fe₂O₃) nanoparticles, after which the membranes were sintered in air at 900 °C for 30 min. TEM revealed a relatively uniform nanoporous Fe₂O₃ coating on the sintered, coated membranes, where the Fe₂O₃ coating thickness increased with increasing number of layers. Electron diffraction patterns showed the Fe₂O₃ coating to be crystalline in nature. This was confirmed by the XRD results showing the structure to be α-Fe₂O₃, while the AZTC membrane was a mixture of the anatase and rutile phase of TiO₂ as well as ZrO₂ and corundum, Al₂O₃. The average pore size of the underlying AZTC membrane increased after the Fe₂O₃-coated membrane was sintered. The nanoporosity in the sintered Fe₂O₃ coating increased until 40 layers, beyond which no significant increases in the average pore size were observed. The iron-oxide-coated membrane improved catalytic properties when used in combination with ozone to treat water. The optimal benefit, in terms of water treatment efficacy, was found at 40 layers of Fe₂O₃.     

AFM,SEM and XPS characterization of PAN-based carbon fibres etched in oxygen plasmas

Atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) have been used to investigate changes in topography and surface chemical functionality on PAN-based carbon fibres exposed to low-temperature, lowpower, oxygen plasmas. Unsized, type II, Cellion 6000 carbon fibres were treated in oxygen plasmas for 2–60 min at a power of 25 W. Increasing treatment time caused an increase in oxidation from surface alcohol(ether) to carbonyl and carboxyl species, but the total amount of oxidized carbon near the surface remained constant. SEM confirmed that treatments longer than 15 min resulted in pitting on the fibre surface, but even treatments of 60 min did not significantly reduce the overall fibre diameter. AFM showed surface morphology changes after oxygen plasma treatments for 2 and 15 min. 1 m×1 m AFM scans of untreated fibres showed processing grooves with a distribution of depths. Enlarged images along these grooves revealed that their walls were smooth. Oxygen plasma treatments of 2 min roughened fibre surfaces and created holes of the order of 50 nm evenly distributed with a spacing of 150 nm along the bottoms of the grooves. Treatment for 15 min smoothed the overall topography and resulted in smaller holes, of the order of 5–10 nm, with a spacing of < 50 nm. Calculated RMS roughnesses from the AFM data showed an initial increase in roughness with treatment, followed by a decrease to final values lower than those for untreated fibres.     

An investigation of oxide coated cathodes using SEM,AES, XPS and SIMS

In an attempt to extend the life of the oxide-coated cathode and understand its emission mechanism, many cathodes were used to study the transition of nickel base, oxide coating, and the interface using SEM, AES, XPS and SIMS in the electron tubes operating for more than 10,000 h. Some of experimental results support a new point of view which is different from the theory used before.     

High-shrinkage-potential porous glass-ceramic supports for high-temperature oxide ceramic membranes

We have optimized the composition of porous glass-ceramic supports compatible with conducting ceramics and have developed a procedure for the fabrication of such supports. High-shrinkage-potential porous supports in the form of dead-end tubes have been shown to be best suited for designing multilayered selective ceramic membranes. We have assessed the effects of various modifiers on the shrinkage curve of such supports. The factors that play a central role in determining the properties of supports have been identified: the amount of burnout additives determines the macroporosity, the addition of low-melting clay influences the shrinkage potential, leaching influences the microporosity, impregnation with a lanthanum salt determines the shape of the shrinkage curve and reactivity, and modification with Al₂O₃ sol determines the heat resistance of the supports.     

单分散性大粒径磁性复合微球的制备和表征

把聚乙二醇(PEG)和十二烷基磺酸钠(SDS)包裹的自制纳米Fe3O4磁流体加入到分散聚合体系,制备出粒径300～500μm的聚(苯乙烯-二乙烯基苯-甲基丙烯酸)磁性高分子微球并用光学显微镜、红外光谱(FT-IR)、X射线粉末衍射仪(XRD)、振动样品磁强计(VSM)以及热重分析仪(TG)等对其表征。结果表明,其粒径分布均匀,表面光滑且含有羧基,室温比饱和磁化强度达到3.63A·m2/kg,磁流体的包裹率随磁流体用量的增加而增加,最高达到17.07%。     

Synthesis and characterization of multifunctional iron oxide nanoparticles

In order to get high water solubility, monodisperse, superparamagnetic nanoparticles, poly (acrylic acid) was employed to modify Fe3O4 by a high-temperature solution-phase hydrolysis approach. Then, folic acid (FA) and fluorescein isothiocyanate were successively conjugated with prepared magnetic nanoparticles (MNPs). The functional MNPs were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscope (TEM), inductively coupled plasma-atomic emission spectrometer (ICP-AES), and vibrating sample magnetometer (VSM), respectively. The toxicity of the materials was evaluated by selecting NIH/3T3 fibroblast cells and no toxic effect was observed. The fluorescent imaging and targeting property of the MNPs were also realized in vitro and in vivo experiments by confocal laser scanning microscopy (CLSM) and Kodak In-Vivo FX Professional Imaging System, respectively. The results indicated that the final products exhibited interesting magnetic, optical and targeting properties for further potential applications in biological and biomedical fields.     

Removal of heavy metal ions by iron oxide coated sewage sludge

The municipal sewage sludge was modified with iron oxide employed in metal ions removal. The surface modification method was proposed and the effect of parameters in the preparation was studied. The iron oxide coated sludge had higher surface area, pore volume and iron content, compared to uncoated sludge. The suitable conditions for removal of Cu(II), Cd(II), Ni(II) and Pb(II) ions from solutions were investigated using batch method. The suitable pH value in the extraction was 7 for adsorption of Cd(II) and Ni(II), 6 for Cu(II) and 5 for Pb(II) ions. The presence of NaNO(3), Ca(NO(3))(2) and Na(2)SO(4) in metal solution in the concentration of 0.01 M and 0.50 M could reduce the removal efficiency. The adsorption isotherms for the adsorption of the metal ions were defined by Langmuir relation. The maximum adsorption capacity of the iron oxide coated sludge for Cu(II), Cd(II), Ni(II) and Pb(II) was 17.3, 14.7, 7.8 and 42.4 mg g(-1), respectively. The adsorption kinetics for every metal ions followed pseudo-second order model. The metal removal from wastewater by iron oxide coated sludge was also demonstrated.     

Preparation of silica coated iron oxide nanoparticles using non-transferred arc plasma

Silica coated iron oxide nanoparticles were prepared using non-transferred arc plasma. The plasma was discharged with argon. Vapors of iron pentacarbonyl (Fe(CO)₅) and tetraethyl orthosilicate (TEOS, Si(OC₂H₅)₄) were injected into a plasma torch with carrier gas and reacted in the plasma chamber. In addition, two types of reaction chambers that are a hot wall reactor and a cold wall reactor were used to investigate the effect of temperature gradient on the synthesis of silica coated iron oxide nanoparticles. The synthesized nanoparticles were collected on the chamber wall and bottom. Phase compositions of the obtained nanoparticles were characterized by X-ray diffractometer (XRD) and the morphologies and the size distributions of the synthesized particles were analyzed by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Additionally, elements mapping of the coated particles was performed by energy dispersive spectroscopy (EDS). The phase composition of the prepared particles was mainly composed of amorphous silica and polycrystalline Fe₃O₄. It was confirmed that the silica was adsorbed on iron oxide particles or encapsulated iron oxide particles. Furthermore, the mechanism of the formation of silica coated iron oxide in the plasma chamber was predicted.     

纳米铁黄的表面改性及表征

研究了纳米铁黄有机表面改性的影响因素，确定了最优改性剂和改性条件。采用红外光谱（IR）、热分析（TG）、透射电镜（TEM）和分散性实验对表面改性前后的纳米铁黄进行了表征。实验结果表明，以硬脂酸为改性剂、用量为5％、pH值为4、改性时间为1．5h时，改性后的纳米铁黄的亲油化度达到92．6％。红外光谱和热分析显示，硬脂酸以化学键合的方式结合在纳米铁黄的表面，其质量分数约为4％。透射电镜（TEM）和分散性实验表明，经硬脂酸有机表面改性的纳米铁黄具有亲油疏水性能，能较好地分散于有机溶剂二甲苯中。     

Preparation and characterization of thermosensitive PNIPAA-coated iron oxide nanoparticles

A new and facile approach was established to fabricate thermoresponsive poly(N-isopropylacrylamide) (PNIPAA) coated iron oxide nanoparticles in a non-aqueous medium. The morphology and structure of the nanoparticle-doped composite were analyzed by?means of transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and Fourier transformation infrared spectrometry (FTIR). The thermosensitivity of the composite was also investigated. Results indicated that the oil-soluble iron oxide nanoparticles encapsulated with PNIPAA, composed of an inorganic iron oxide core and biocompatible PNIPAA shell, were dispersed well in water and had a sphere-like shape. The PNIPAA-coated iron oxide nanoparticles with such a kind of core-shell structure showed excellent thermosensitivity. Namely, the aqueous suspension of PNIPAA-coated iron oxide nanoparticles dramatically changed from transparent to opaque as the temperature increased from room temperature to 38?°C, showing potential as optical transmittance switch materials and their significance in the fields of protein adsorption and purification controlled release, and drug?delivery.     

Evaluation on cytotoxicity and genotoxicity of the L-glutamic acid coated iron oxide nanoparticles

To evaluate the cytotoxicity and genotoxicity of L-glutamic acid (Glu) coated Fe2O3 nanoparticles (hereafter refer as Glu@MNPs) on Chinese Hamster Lung (CHL) cells using Trypan blue dye exclusion assay, Oxidative stress markers, Comet assay and micronucleus (MN) assay. Results showed a low cytotoxicity with an IC50 was 254.739 microg/ml 36 h post incubation period in CHL cells. Furthermore, Cell redox status is slightly disturbed: Glu@MNPs exposure cause reactive oxygen species production, glutathione depletion and inactivation of some antioxidant enzymes: glutathione reductase, superoxide dismutase, but not catalase. Moreover, no significant genotoxic response was observed in CHL cells over concentration ranges from 8 to 128 microg/mL for all exposure time periods. The results suggest that the Glu@MNPs show biocompatibility In Vitro.     

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe₃O₄), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.     

Bioactivity of gelatin coated magnetic iron oxide nanoparticles: in vitro evaluation

Current research explores formation of bone like apatite on gelatin coated magnetic iron oxide nanoparticles (GIOPs) to evaluate the bioactivity of the material. The GIOPs were soaked in simulated body fluid (SBF) and the apatite formation on the surface was investigated in regular interval of time. Fourier transform-infrared (FT-IR) and x-ray diffraction spectroscopic (XRD) analyses were done to investigate the chemical changes and field emission-scanning electron microscopic (FE-SEM) analysis was done to investigate the morphological changes occurring on the surface of the GIOPs after soaking in different time intervals. The kinetic studies of the apatite growth in SBF suggest that initially calcium and phosphorous ions were deposited to the surface of the GIOPs from the SBF leading to formation of amorphous Ca/P particles. Later, after 9 days of the incubation the amorphous particles were fused to form needle and blade like crystalline structures of bone like apatite.     

Synthesis and characterization of iron oxide nanoparticles dispersed in mesoporous aluminum oxide or silicon oxide

Iron oxide nanoparticles dispersed in aluminum (Al) or silicon (Si) oxides were prepared via a polymeric precursor derived from the Pechini method. The samples were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy, X-ray diffraction, N₂ adsorption/desorption isotherms (Brunauer–Emmett–Teller, BET), M?ssbauer spectroscopy, and vibrating sample magnetometry (VSM). BET analysis shows that the samples are mesoporous materials and have a high surface area. The size of the Fe₂O₃ nanoparticles in Al₂O₃ is smaller than that in SiO₂. M?ssbauer spectra of the samples show that the Fe₂O₃ nanoparticles in Al₂O₃ are non-magnetic at room temperature but magnetic below 50 K. The FeSi samples are magnetic at both room and low temperatures. The magnetic measurements with VSM confirmed this point.     

纳米氧化物/Nafion复合膜的制备与性能表征

分别以SiO2、TiO2、Al2O3和ZnO等纳米氧化物为改性剂,采用流延法制得纳米氧化物/Nafion复合膜.XRD和ATR/FT-IR分析表明纳米氧化物在复合膜均匀分散,也没有发生团聚现象.对复合膜的质子传导和阻醇性能进行了测定,结果发现,纳米氧化物/Nafion复合膜具有较好的质子传导性能;阻醇性能均有较大幅度的提高,且以SiO2和TiO2改性的Nafion膜最为明显,甲醇透过系数分别从约10降低到约10-7和10-8数量级.这说明纳米氧化物/Nafion复合膜是一类较好的直接甲醇燃料电池用质子交换膜材料.     

壳聚糖修饰氧化铁磁性纳米颗粒的制备和性能研究

通过共沉淀法制备氧化铁磁性纳米颗粒,用壳聚糖对其表面进行修饰得到样品(CS@MNPs);表征其形貌结构、尺寸、表面基团、表面电荷、磁学性质和在不同介质中的稳定性等。实验结果表明,CS@MNPs具有典型的立方反尖晶石晶体结构;粒径为16.5nm;在生理(pH值7.4)条件下拥有较高的正电荷(10mV);呈现超顺磁性,对驰豫时间T1、T2,尤其是T2*具有很强的响应;在双蒸馏水和含10%新生牛血清的RPMI 1640培养液中具有良好的稳定性,具有作为磁共振造影剂的潜力。     

Dielectrical and structural characterization of iron oxide added to hydroxyapatite

In this work we report preparation, structural and dielectric analyses of iron oxide added in hydroxyapatite bioceramic (Ca₁₀(PO₄)₆(OH)₂ — HAP). Hydroxyapatite is the main mineral constituent of teeth and bones with excellent biocompatibility with hard and muscle tissues. The samples were prepared through a calcination procedure associated with dry high-energy ball milling process with different iron concentrations (1, 2·5 and 5 wt%). The dielectric analyses were made measuring the sample impedance in the frequency range 1 kHz–10 MHz, at room temperature. The relative permittivity of the ceramics, at 10 MHz, are between 7·13 ± 0·07 (1 wt%) and 6·20 ± 0·11 (5 wt%) while e ⁿ are between 0·0795 ± 0·008 (1 wt%) and 0·067 ± 0·012 (5 wt%). These characteristics were related to the sample microstructures studied by X-ray diffraction and SEM.     

Facile synthesis of magnetic iron oxide nanoparticles and their characterization

Magnetic iron oxide nanoparticles are synthesized by suitable modification of the standard synthetic procedure without use of inert atmosphere and at room temperature. The facile synthesis procedure can be easily scaled up and is of important from industrial point of view for the commercial large scale production of magnetic iron oxide nanoparticles. The synthesized nanoparticles were characterized by thermal, dynamic light scattering, scanning electron microscopy and transmission electron microscopy analyses.