• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.6
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• pp.51-56
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• 2011

The surface of magnetic iron oxide nanoparticles (${\gamma}-Fe_2O_3$) is functionalized ($-NH_2$, -COOH) with bifunctional organic molecules and evaluated using FT-IR (Fourier transform infrared spectroscopy). We immobilize 21-base pair probe DNA and hybridize fluorescence-labeled (Cy5) target DNA onto the functionalized iron oxide nanoparticles. The fluorescence images obtained from a confocal microscopy show that the functionalized iron oxide nanoparticles should detect the hybridization of complementary and noncomplementary DNA.

• Journal of the Korean Magnetics Society
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• v.24 no.1
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• pp.18-21
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• 2014

The microwave absorption ($P_{tot}$), which is the double integration value of ferromagnetic resonance signal, propositional to the saturation magnetization, and the increase of the $P_{tot}$ measured during the thermal reaction time expect the growth process of the nanoparticles. Therefore, in this work, we measured the $P_{tot}$ in order to obtain the growth time of iron oxide nanoparticles after thermal decomposition of $Fe(acac)_3$ precursor at aging temperature $T_a=273$, 300 and $324^{\circ}C$, respectively. The best condition for monodisperse nanoparticles was obtained at $T_a=300^{\circ}C$, which condition showed the most rapid increase of $P_{tot}$ with thermal reaction time. Finally, the rapid growth rate was necessary condition for the synthesis of iron-oxide monodisperse nanoparticles.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.144-150
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• 2013

Hybrid ceramic membrane (HCM) processes that combined ozonation with a ceramic membrane (CM) or a reactive ceramic membrane (RM), an iron oxide nanoparticles (IONs) incorporated-CM were investigated for membrane fouling control. Alumina disc type microfiltration and ultrafiltration membranes doped with IONs by sintering method were tested under varying mass fraction of IONs. Scanning electron microscope (SEM) images showed that IONs were well-doped on the CM surface and doped IONs were approximately 50 nm in size. Change in the pure water permeability of RM was negligible compared to that of CM. These results indicate that IONs incorporation onto CM had little effect on CM performance in terms of the flux. Natural organic matter (NOM) fouling and fouling recovery patterns during HCM processes confirmed that the RM-ozonation process enhanced the destruction of NOM and reduced the extent of fouling more than the CM-ozonation process by hydroxyl radical formation in the presence of IONs on RM. In addition, analyses of NOM in the feed water and the permeate showed that the efficiency of membrane fouling control results from the NOM degradation during HCM processes; leading to removal and transformation of relatively high contents of aromatic, high molecular weight and hydrophobic NOM fractions.

• Polymer(Korea)
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• v.29 no.3
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• pp.266-270
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• 2005

Iron oxide nanoparticles were prepared by the thermal decomposition of iron pentacarbonyl (Fe(CO)$_5$) Poly(vinylpyrrolidone) (PVP) was used as surface-modifying agent to control the size of the iron oxide nanoparticles. The crystalline structure of PVP coated iron oxide nanoparticles was determined by XRD. The size of PVP coated iron oxide nanoparticles was determined by TEM and ELS. The particle sizes of PVP coated iron oxide nanoparticles were controlled by adjusting the molar ratio of PVP/Fe (CO)$_5$, solvent and molecular weight of PVP Particle sizes increased with increasing PVP content. Spherical $50\~100$ nm sized iron oxide nanoclusters were produced when dimethylformamide was used as a solvent. And well-defined 10 nm iron oxide nanoparticles were produced in Carbitol. The prepared PVP coated iron oxide nanoparticles exhibited a well-dispersed property in water. The results obtained in this study confirmed the feasibility of the PVP-coated iron oxide nanoparticles as a biomaterial for MRI contrast agent.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.167-172
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• 2012

In order to analyze the formation mechanism of iron oxide nanoparticles, we measured the heat flow of $Fe(OL)_3$ precursor with temperature, and TEM images and AC susceptibility of aliquots samples sequentially taken from the reaction solution, respectively. The thermal decomposition of two OL-chain from $Fe(OL)_3$ produced the Fe-OL monomer, which were contributed to the formation of iron oxide nanoparticles. In the initial stage of nanoparticles formation, the small iron oxide nanoparticles had ${\gamma}-Fe_2O_3$ structure. However, as the iron oxide nanoparticles were rapidly growth, the iron oxide nanoparticles showed ${\gamma}-Fe_2O_3$-FeO core-shell structure which the FeO layer was formed on the surface of ${\gamma}-Fe_2O_3$ nanoparticles by insufficient oxygen supply from the reaction solution. These nanoparticles were transformed to $Fe_3O_4$ structure by oxidation during long aging time at high temperature. Finally, the $Fe_3O_4$ nanoparticles with high saturation magnetization and stable in the air could be easily synthesized by the thermal decomposition method.

• Clean Technology
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• v.28 no.2
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• pp.110-116
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• 2022

In this study, iron oxide (FeO_x) nanoparticles were synthesized using iron (Fe) by-products recovered from NdFeB permanent magnet scraps, and the effect of heat-treatment temperature on the physical properties of the FeO_x nanoparticles was investigated. In order to prepare the FeO_x nanoparticles, 2.0 M ammonia (NH₄OH) solution was added to an iron by-product solution diluted to c.a. 10 wt% in D.I. water, which led to the precipitation of the iron oxide precursor. Then, the FeO_x nanoparticles were synthesized by heat-treatment at 300 ℃, 400 ℃, 500 ℃ and 600 ℃. After that, the physical properties of the FeO_x nanoparticles were investigated in order to understand the effect of the heat-treatment temperature. The results of the X-ray diffraction (XRD) analysis showed that the diffraction peak in accordance with the <104> direction increased as the heat-treatment increased, and a diffraction peak indicating the α-Fe₂O₃ crystal structure was detected at heat-treatment temperatures above 500 ℃. The BET specific surface area analysis revealed that the specific surface area decreased as the heat-treatment temperature increased to above 400 ℃. Observation with a high resolution transmission electron microscope (HRTEM) showed that rod-shaped nanoparticles were formed, and the size of the nanoparticles showed a tendency to increase as the heat-treatment temperature increased.

• Polymer(Korea)
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• v.36 no.5
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• pp.586-592
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• 2012

Iron oxides ($Fe_3O_4$) are metabolically secreted after endocytosed by cells, indicating no cytotoxicity. Therefore, they are widely used as a contrast agent before photographing of magnetic resonance imaging. In this study, iron oxide nanoparticles are synthesized by the co-precipitation method and subsequently immobilized with a homing peptide (AP), which specifically interacts with interleukin-4 receptor located on the membrane of endothelial and bladder cancer cells. The size of AP-immobilized iron oxide particle is about 39 nm. Intracellular uptake of the AP-immobilized iron oxide nanoparticles was investigated using bladder cancer cells and fibroblasts as the control. As the result, the nanoparticles are specificially uptaken by bladder cancer cells. However, the nanoparticles are not specificially uptaken by fibroblast. It could be said that the AP-immobilized iron oxide nanoparticles have a potential to be used as a contrast agent for early diagnosis of cancer.

• Journal of the Korean Magnetics Society
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• v.24 no.1
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• pp.11-17
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• 2014

We measured the ferromagnetic resonance (FMR) signal using the monodisperse iron oxide nanoparticles with size D=4.67 nm, 5.64 nm and 6.34 nm synthesized by using the thermal decomposition method, respectively. The measured ferromagnetic resonance signals were compared with the calculated ones for superparamagnetic nanoparticles with lognormal volume distribution. The FMR linewidth broadening was propositional to tanh($V^2$), where V was volume of nanoparticles. The narrow linewidth of small size nanoparticles was due to the surface spins, while the broad linewidth of large size nanoparticles was due to the bulk spins affected by the crystalline structure of iron oxide nanoparticles. The superposition of surface and bulk effect was confirmed at D=5.64 nm nanoparticles, which was near the critical size for linewidth transition from surface effect to bulk effect.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.13-18
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• 2016

The ac magnetic susceptibility was measured in iron-oxide nanoparticles with average size of 26 nm, which were uniformly dispersed in organic solvent. The ac magnetic susceptibility measured under zero magnetic fields was well fitted with Debye relaxation model and the relaxation frequency was 370 Hz. The relaxation frequency of the nanoparticles coincided with relaxation time of the Brownian motion, which is due to the viscosity of the liquid medium in which magnetic nanoparticles dwell. The Brown relaxation frequencies were linearly increased with magnetic field.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.325-332
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• 2014

Metallic nanoparticles have attractive properties in biomedical applications such as diagnostics and therapeutics. Cross linked dextran coated iron oxide nanoparticles (SPIONs) and silica coated gadolinium oxide nanoparticles (SPGONs) have been synthesized as a radiosensitizer in the proton beam cancer therapy. The dextran and silicaused for the protective moieties on the SPIONs and SPGONs respectively. Size distributions of synthesized nanoparticles were confirmed 3~5 nm for SPIONs and 30~100 nm for SPGONs by transmission electron microscope (TEM). Cell survival fraction measurement and Western blot assay were performed to evaluate the radiosensitization effects of synthesized radiosensitizer. The calculated radiosensitization of SPIONs and SPGONs at 90 % cell death from the measured cell survival curves were 1.23 and 1.03 respectively. Western blotting results also show the same consistent results that the amount of released cytochrome c from mitochondria was considerably increased for the cancer cells taken up SPIONs.