• Journal of Microbiology and Biotechnology
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• v.9 no.1
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• pp.50-55
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• 1999

To develop a new form of controlled release dosage for administering for indomethacin (IND), two formulations of IND-loaded nanoparticles were designed based on polysaccharide (guar) derivatives. Nanoparticles prepared by the dialysis method were characterized with respect to morphology, size distribution, drug content, and in vitro drug release. Morphological studies by scanning electron microscopy (SEM) indicated that guar acetate (GA) nanoparticles were spherical in shape and had a smooth surface. The particle size distributions of formulation I (40mg of GA) and formulation II (80mg of GA) were shown to be $250.78\pm185.13nm$ and $718\pm145.90nm$ in distilled water ($20$^{\circ}C$), respectively. The drug loading efficiencies of nanoparticles were approximately 26% and 31% for formulations I and II, respectively. The differential scanning calorimetry (DSC) results indicated that the IND was perfectly distributed within GA nanoparticles. We also found, from the X-ray diffractometry analysis, that a decrease in the degree of crystallinity of the drug occurred in the nanoparticles. No changes between the original IND and the released IND from GA nanoparticles were detected by FT-IR. Using guar acetate, it is possible to design nanoparticles which allow the controlled release of IND over an extended period of time.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4113-4116
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• 2011

• Journal of Powder Materials
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• v.19 no.6
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• pp.393-397
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• 2012

$AgNO_3$ has the characteristic is controlling the inhibition or promotion of particle growth by adsorbing onto specific facets of platinum nanoparticles. Therefore, in this study, $AgNO_3$ was added to control the shape of platinum nanoparticles during the liquid phase reduction process. Consequently, platinum cubes were synthesized when $AgNO_3$ of 1.1 mol% (with respect to the Pt concentration) was added into the solution. Platinum octahedrons were synthesized when 32 mol% (with respect to the Pt concentration) was added into the solution. These results demonstrate that the metal salt $AgNO_3$, effectively controlled the relative growth rates of each facet of Pt nano particles.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1583-1586
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• 2011

Silver nanoparticles (<10 nm) were prepared in ultrasonic vibration-induced nanodroplets of isopropyl alcohol (IPA) in combination with hydrophobic room temperature ionic liquids (RTILs). The Ag-precursor used were silver (I) complex, Ag$_2$(ehac)$_2$(eha)$_2$ (ehac = 2-ethylhexylammonium carbamate; eha = 2-ethylhexylamine), in IPA, while 1-butyl-3-methylimidazolium-based ionic liquids bearing $SbF_6^-$, $PF_6^-$ and $NTf_2^-$ as counter anions were used as RTILs. During sonication for 10-90 min at room temperature, uniform silver nanoparticles with mean sizes of 2 to 8 nm were rapidly synthesized. Transmission electron micrographs also confirmed that silver nanoparticles have a spherical shape and diverse sizes depending on the reaction time (10-90 min).

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.32-36
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• 2003

Co nanoparticles were prepared by the reverse micelle technique (NaBH₄reduction of cobalt chloride in a reversed micelle solution of didodecyldimethylammoniumbromide (DDAB)/toluene). The size and the shape of Co nanoparticles could be easily controlled by changing the water contents and micelle concentrations, and the solubility of Co nanoparticles was systematically tuned by choosing appropriate surface capping organic ligand molecules. Furthermore, a novel nanofabrication process was clearly demonstrated, which generated oxide over-coated Co nanorods from Co nanoparticles in organic solution by slow oxidation with an external magnetic field.

• Journal of Powder Materials
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• v.11 no.3
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• pp.242-246
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• 2004

FePt nanoparticles for high-density magnetic recording media were synthesized by the simultaneous chemical reduction of Fe(acac) $_2$ and Pt(acac) $_2$ with 1,2-hexadecanediol as the reducing reagent. TEM images showed that the shape of as-synthesized FePt nanoparticle was spherical and average particle size was 3 nm. Also, SAD pattern showed that crystal structure was disordered FCC (face centered cubic). These FCC structured nanoparticles were transformed FCT (face centered tetragonal) structure by annealing at 55$0^{\circ}C$ for 30 min in Ar atmosphere. XRD analysis revealed that as-synthesized FePt nanoparticles were transformed from disordered FCC to ordered FCT. Finally, the coercivity of 2 kOe for FePt nanoparticles with FCT structure was obtained by VSM measurement.

• Macromolecular Research
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• v.16 no.2
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• pp.85-102
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• 2008

The development of reliable synthetic routes to polymer nanomaterials with well-defined size and morphology is a critical research topic in contemporary materials science. The ability to generate nanometer-sized polymer materials can offer unprecedented, interesting insights into the physical and chemical properties of the corresponding materials. In addition, control over shape and geometry of polymer nanoparticles affords versatile polymer nanostructures, encompassing nanospheres, core-shell nanoparticles, hollow nanoparticles, nanorods/fibers, nanotubes, and nanoporous materials. This review summarizes a diverse range of synthetic methods (broadly, hard template synthesis, soft template synthesis, and template-free synthesis) for fabricating polymer nanomaterials. The basic concepts and significant issues with respect to the synthetic strategies and tools are briefly introduced, and the examples of some of the outstanding research are highlighted. Our aim is to present a comprehensive review of research activities that concentrate on fabrication of various kinds of polymer nanoparticles.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.318.1-318.1
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• 2014

Metal nano-crystals have been received much attentions owing to their excellent catalytic property and surface plasmon effect. In the last decade, many studies on synthesizing well-dispersive nanoparticles and on understanding their distinct physical properties have been performed. There were tremendous reports revealing the electrochemical activities and enhancement of surface plasmonic effect were dependent mainly on the size, shape, and composition. So far, most fabrication methods have been based on vacuum based deposition techniques, such as chemical vapor deposition and electron-beam evaporation, and then annealed them to transform into the nanoparticles. Recently, there were several reports regarding to the photoinduced nano-crystal synthesis as an effective way to produce the metal nanoparticles. In this study, we report synchrotron x-ray mediated synthesis of Au nanoparticles on ZnO nanowires. ZnO nanowires were fabricated by hydrothermal method, and then they were dip into a solution having Au clusters. Detailed structural evolution of Au nanoparticles was investigated using scanning electron microscopy and photoluminescence measurements. The results on formation of well-dispersive Au nanoparticles on ZnO nanowires will be presented.

• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1061-1068
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• 2010

The biological synthesis of nanoparticles has gained considerable attention in view of their excellent biocompatibility and low toxicity. We isolated and purified rhamnolipids from Pseudomonas aeruginosa strain BS-161R, and these purified rhamnolipids were used to synthesize silver nanoparticles. The purified rhamnolipids were further characterized and the structure was elucidated based on one- and two-dimensional $^1H$ and $^{13}C$ NMR, FT-IR, and HR-MS spectral data. Purified rhamnolipids in a pseudoternary system of n-heptane and water system along with n-butanol as a cosurfactant were added to the aqueous solutions of silver nitrate and sodium borohydride to form reverse micelles. When these micelles were mixed, they resulted in the rapid formation of silver nanoparticles. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDS). The nanoparticles formed had a sharp adsorption peak at 410 nm, which is characteristic of surface plasmon resonance of the silver nanoparticles. The nanoparticles were monodispersed, with an average particle size of 15.1 nm (${\sigma}={\pm}5.82$ nm), and spherical in shape. The EDS analysis revealed the presence of elemental silver signal in the synthesized nanoparticles. The formed silver nanoparticles exhibited good antibiotic activity against both Grampositive and Gram-negative pathogens and Candida albicans, suggesting their broad-spectrum antimicrobial activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.133-133
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• 2013

For both oxygen reduction (ORR) and hydrogen oxidation reactions (HOR) of proton electrolyte membrane fuel cells (PEMFCs), alloying Pt with another transition metal usually results in a higher activity relative to pure Pt, mainly due to electronic modification of Pt and bifunctional behaviour of alloy surface for ORR and HOR, respectively. However, activity and stability are closely related to the preparation of alloy nanoparticles. Preparation conditions of alloy nanoparticles have strong influence on surface composition, oxidation state, nanoparticle size, shape, and contamination, which result from a large difference in redox priority of metal precursors, intrinsic properties of metals, increasedreactivity of nanocrystallites, and interactions with constituents for the synthesis such as solvent, stabilizer, and reducing agent, etc. Carbon-supported Pt-Ni alloy nanoparticles were prepared by the borohydride reduction method in anhydrous solvent. Pt-Ru alloy nanoparticles supported on carbon black were also prepared by the similar synthetic method to that of Pt-Ni. Since electrocatalytic reactions are strongly dependent on the surface structure of metal catalysts, the atom-leveled design of the surface structure plays a significant role in a high catalytic activity and the utilization of electrocatalysts. Therefore, surface-modified electrocatalysts have attracted much attention due to their unique structure and new electronic and electrocatalytic properties. The carbon-supported Au and Pd nanoparticles were adapted as the substrate and the successive reduction process was used for depositing Pt and PtM (M=Ru, Pd, and Rh) bimetallic elements on the surface of Au and Pd nanoparticles. Distinct features of the overlayers for electrocatalytic activities including methanol oxidation, formic acid oxidation, and oxygen reduction were investigated.