• 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.

• Journal of Information Display
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• v.6 no.2
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• pp.19-24
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• 2005

The density controlled carbon nanotubes (CNTs) are grown on the iron acetate nanoparticles by using the freeze-dry method. The iron-acetate [Fe(II)$(CH_3COO)_2$] solution is used to prepare the catalytic iron nanoparticles. The density of CNTs is controlled in order to enhance the field emission process. Furthermore, the patterning of the iron nanoparticle catalyst-layer for the fabrication of electronic devices is simply achieved by using alkaline solution, TMAH (tetramethylammonium hydroxide). We applied this patterning process of catalyst layer to form the electron emitter with under-gate type triode structure.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.99-104
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• 2006

We introduce a novel contrast mechanism for imaging superparamagnetic iron oxide (SPIO) nanoparticles (average diameter ${\sim}100nm$) using magneto-motive optical Doppler tomography (MM-ODT), which combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect the nanoparticles flowing through a glass capillary tube. A solenoid cone-shaped ferrite core extensively increased the magnetic field strength ($B_{max}=1\;T,\;{\Delta}|B|^2=220T^2/m$) at the tip of the core and also focused the magnetic force on targeted samples. Nanoparticle contrast was demonstrated in a capillary tube filled with the SPIO solution by imaging the Doppler frequency shift which was observed independent of the flow rate and direction. Results suggest that MM-ODT may be a promising technique to enhance SPIO nanoparticle contrast for imaging fluid flow.

• Journal of Environmental Science International
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• v.17 no.7
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• pp.711-717
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• 2008

The use of support materials on the nanoparticle synthesis and applications has advantages in many aspects; resisting the aggregation and gelation of nanoparticles, providing more active sites by dispersing over the supports, and facilitating a filtering process. In order to elucidate the influence of the supports on the nitrate reduction reactivity, the supported iron nanoparticles were prepared by borohydride reduction of an aqueous iron salt in the presence of supports such as activated carbon, silica and polyethylene. The reactivity for nitrate reduction decreased in the order of unsupported Fe(0) > activated carbon(AC) supported Fe(0) > polyethylene(PE) supported Fe(0) ${\ge}$ silica supported Fe(0). Rate constants decrease with increasing initial nitrate concentration implying that the reaction is limited by the surface reaction kinetics.

• Investigative Magnetic Resonance Imaging
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• v.16 no.1
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• pp.31-39
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• 2012

Purpose : To determine the optimal combination of commercially available superparamagnetic iron oxide (SPIO) nanoparticles with transfection agents (TA). Materials and Methods: Protamine sulfate (Pro) and poly-L-lysin (PLL) were incubated with ferumoxide and ferucarbotran in human mesenchymal stem cells at various concentrations, and cellular viability were evaluated. Cellular iron uptake was qualitatively and quantitatively evaluated. Cell visibility was assessed via MR imaging and the T2-relaxation time was calculated. Results: The cellular viabilities with ferucarbotran were more significantly decreased than those with ferumoxide (p < 0.05). Iron uptake with ferumoxide was significantly higher than that for those with with ferucarbotran. The T2-relaxation time was observed to be shorter with ferumoxide in comparison to those with ferucarbotran (p < 0.05). Ferumoxide at a concentration of 25 ${\mu}g$/ml in combination with either Pro or PLL at a concentration of 3.0 ${\mu}g$/ml did not adversely impact cell viability, maximized iron uptake, and exhibited a lower T2-relaxation time in comparison to other combinations. Conclusion: Stem cells with ferumoxide exhibited a higher cellular viability and iron uptake in comparison to ferucarbotran-treated stem cells. A 25 ${\mu}g$/ml of ferumoxide with a 3.0 ${\mu}g$/ml of TA is sufficient to label mesenchymal stem cells.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.355-356
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• 2018

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.1-1
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• 2011

We developed a new generalized synthetic procedure, called as "heat-up process," to produce uniform-sized nanocrystals of many transition metals and oxides without a size selection process. We were able to synthesize uniform magnetite nanocrystals as much as 1 kilogram-scale from the thermolysis of Fe-oleate complex. Clever combination of different nanoscale materials will lead to the development of multifunctional nano-biomedical platforms for simultaneous targeted delivery, fast diagnosis, and efficient therapy. In this presentation, I would like to present some of our group's recent results on the designed fabrication of multifunctional nanostructured materials based on uniform-sized magnetite nanoparticles and their medical applications. Uniform ultrasmall iron oxide nanoparticles of <3 nm were synthesized by thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. These ultrasmall iron oxide nanoparticles exhibited good T1 contrast effect. In in vivo T1 weighted blood pool magnetic resonance imaging (MRI), iron oxide nanoparticles showed longer circulation time than commercial gadolinium complex, enabling high resolution imaging. We used 80 nm-sized ferrimagnetic iron oxide nanocrystals for T2 MRI contrast agent for tracking transplanted pancreatic islet cells and single-cell MR imaging. We reported on the fabrication of monodisperse magnetite nanoparticles immobilized with uniform pore-sized mesoporous silica spheres for simultaneous MRI, fluorescence imaging, and drug delivery. We synthesized hollow magnetite nanocapsules and used them for both the MRI contrast agent and magnetic guided drug delivery vehicle.

• Journal of Biomedical Engineering Research
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• v.38 no.3
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• pp.102-110
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• 2017

Cancer is one of the most challenging human diseases. Current clinical methods have limitations for early-stage cancer diagnosis and effective therapy. Moreover, current surgical methods to remove tumors are not precise enough and chemotherapy destroys normal tissues as well as malignant tumors, resulting in severe side effects such as hair loss, vomiting, diarrhea, and blood disorders. Recently, nanotechnology using nano-sized particles suggests advanced solutions to overcome the limitations. Various nanoparticles have been reported for more accurate diagnosis and minimized side effects. However, current nanoparticles still show limited targeting accuracy for cancer generally below 5% injection dosage. Therefore, herein we report a new nanoparticle inducing device(NID) to guide the nanoparticles externally by using both variable magnetic fields and blood flows. NID can be a promising approach to improve targeting accuracy for drug delivery using iron oxide nanoparticles.

• Journal of Magnetics
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• v.15 no.4
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• pp.179-184
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• 2010

We have investigated the effects of post annealing on iron oxide nanoparticles synthesized by the novel hydrothermal synthesis method with the $FeSO_4{\cdot}7H_2O$. To investigate the post annealing effect, the as-synthesized iron oxide nanoparticles were annealed at different temperatures in a vacuum chamber. The morphological, structural and magnetic properties of the iron oxide nanoparticles were investigated with high resolution X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Mossbauer spectroscopy, and vibrating sample magnetometer analysis. According to the XRD and HRTEM analysis results, as-synthesized iron oxide nanoparticles were only magnetite ($Fe_3O_4$) phase with face-centered cubic structure but post annealed iron oxide nanoparticles at $700^{\circ}C$ were mainly magnetite phase with trivial maghemite ($\gamma-Fe_2O_3$) phase which was induced in the post annealing treatment. The crystallinity of the iron oxide nanoparticles is enhanced by the post annealing treatment. The particle size of the as-synthesized iron oxide nanoparticles was about 5 nm and the particle shape was almost spherical. But the particle size of the post annealed iron oxide nanoparticles at $700^{\circ}C$ was around 25 nm and the particle shape was spherical and irregular. The as-synthesized iron oxide nanoparticles showed superparamagnetic behavior, but post annealed iron oxide nanoparticles at $700^{\circ}C$ did not show superparamagnetic behavior due to the increase of particle size by post annealing treatment. The saturation of magnetization of the as-synthesized nanoparticles, post annealed nanoparticles at $500^{\circ}C$, and post annealed nanoparticles at $700^{\circ}C$ was found to be 3.7 emu/g, 6.1 emu/g, and 7.5 emu/g, respectively. The much smaller saturation magnetization value than one of bulk magnetite can be attributed to spin disorder and/or spin canting, spin pinning at the nanoparticle surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1016-1019
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• 2005

We studied the density control of carbon nanotubes (CNTs) which were grown on the iron nanoparticles prepared from iron-acetate [$Fe(II)(CH_3COO)_2$] solution using freeze-dry method. The density of CNTs was controlled for the enhancement of field emission. The patterning process of iron-acetate catalyst-layer for the fabrication of electronic device was simply achieved by using alkaline solution, TMAH (tetramethylammonium hydroxide). We applied this patterning process of catalyst layer to formation of the electron emitter with under gate type triode structure.