• Journal of Powder Materials
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• v.30 no.1
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• pp.47-52
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• 2023

The purpose of this study is to develop and evaluate amorphous spray-dried microparticles (SDM) containing levosulpiride to increase its solubility. SDM are prepared via solvent evaporation using polyvinylpyrrolidone (PVP) as the water-soluble polymer and Cremophor RH40 as the surfactant. The SDM is prepared by varying the amounts of PVP and Cremophor RH40, and its physicochemical properties, solubility, and dissolution are confirmed. All levosulpiride-loaded SDMs converted the crystalline drug into an amorphous form, significantly improving drug solubility and dissolution compared with the drug alone. SDM consisting of drug/PVP/Cremophor RH40 in a weight ratio of 5:10:3, with increased solubility (720 ± 36 vs. 1822 ± 51 ㎍/mL) and dissolution rate (10.3 ± 2.2 vs. 92.6 ± 6.0%) compared with drug alone, shows potential as a commercial drug for improved oral bioavailability of levosulpiride.

• Medical Lasers
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• v.8 no.2
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• pp.97-100
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• 2019

Facial pores are a visible topographic feature of skin surfaces and are generally the enlarged openings of pilosebaceous follicles. Enlarged facial pores can be a significant cosmetic problem, particularly for women. Recently, gold nanoshell-mediated photothermal therapy (PTT) has been reported to be effective in treating recurrent acne. The treatment of enlarged facial pores with gold nanoshell-mediated PTT produced excellent results with no side effects. The two cases reported here demonstrate the possibility of gold nanoshell-mediated PTT as a safe and effective treatment for enlarged facial pores.

• Clean Technology
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• v.25 no.4
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• pp.283-288
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• 2019

Monodisperse microparticles has been particularly enabling for various applications in the encapsulation and delivery of pharmaceutical agents. The microfluidic devices are attractive candidates to produce highly uniform droplets that serve as templates to form monodisperse microparticles. The microfluidic devices that have micro-scale channel allow precise control of the balance between surface tension and viscous forces in two-phase flows. One of its essential abilities is to generate highly monodisperse droplets. In this paper, a microfluidic approach for preparing monodisperse polycaprolactone (PCL) microparticles is presented. The microfluidic devices that have a flow-focusing generator are manufactured by soft-lithography using polydimethylsiloxane (PDMS). The crucial factors in the droplet generation are the controllability of size and monodispersity of the microdroplets. For this, the volumetric flow rates of the dispersed phase of oil solution and the continuous phase of water to generate monodisperse droplets are optimized. As a result, the optimal flow condition for droplet dripping region that is able to generate uniform droplet is found. Furthermore, the droplets containing PCL polymer by solvent evaporation after collection of droplet from device is solidified to generate the microparticle. The particle size can be controlled by tuning the flow rate and the size of the microchannel. The monodispersity of the PCL particles is measured by a coefficient of variation (CV) below 5%.

• Journal of Life Science
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• v.26 no.1
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• pp.59-67
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• 2016

Platycodon grandiflorum A. De Candolle (Korean name, ‘Doraji’) is a perennial plant containing various triterpenoid saponins. The roots of this plant have traditionally been used as a food material in Korea. Here, we prepared a fermented P. grandiflorum extract (PG). Although it was previously reported that P. grandiflorum A. extract has a variety of physiological functionalities, including anti-inflammatory and anti-oxidant activities, little is known about its vascular functions. In this study, we executed a series of experiments to identify the effect of PG on endothelial cells. PG at a high concentration (100 μg/ml) was found to induce cell detachment, whereas PG at a low concentration (0.1 μg/ml) appeared to promote cell proliferation and migration in bovine aortic endothelial cells. The cell detachment induced by the high concentration was not associated with cell death, such as apoptosis, necrosis, and autophagy. In addition, we found that PG at the high concentration formed a small vesicular structure called an endothelial microparticle (EMP). The EMP was prepared by centrifugal fractionation and determined with flow cytometry and a microscope. Interestingly, PG-induced cell detachment was found to be mediated by EMP. We furthermore determined that PG at the low concentration activated Akt, a crucial cell-signaling molecule, and then controlled cell proliferation and migration. Overall, our findings suggest that PG at low doses maintains vascular stability by promoting endothelial cell proliferation, and enhances the efficacy of wound healing by cell proliferation and migration activity.

• Clean Technology
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• v.13 no.1 s.36
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• pp.34-45
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• 2007

Phase behavior of the ternary systems of water-insoluble simvastatin drug, which is well known to be effective drugs for hypercholesterolemia therapy, in solvent mixtures of dichloromethane and supercritical carbon dioxide was investigated to present a guideline of establishing operating conditions in the particle formation of the drugs by a supercritical anti-solvent recrystallization process utilizing dichloromethane as a solvent and carbon dioxide as an anti-solvent. The solubilities of simvastatin in the mixtures of dichloromethane and carbon dioxide were determined as functions of temperature, pressure and solvent composition by measuring the cloud points of the ternary mixtures at various conditions using a high-pressure phase equilibrium apparatus equipped with a variable-volume view cell. The solubility of the drug increased as the dichloromethane composition in solution and the system pressure increases at a fixed temperature. A lower solubility of the drug was obtained at a higher temperature. The second half of this work is focused on the particle formation of the simvastatin drug by a supercritical anti-solvent recrystallization process in a cylindrical high-pressure vessel equipped with an impeller. Microparticles of the simvastatin drug were prepared as functions of pressure (8 MPa to 12 MPa), temperature (303.15 K, 313,15 K), feed flow rate of carbon dioxide, and stirring speed (up to 3000 rpm), in order to observe the effect of those process parameters on the size and shape of the drug microparticles recrystallized.

• KSBB Journal
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• v.26 no.4
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• pp.333-340
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• 2011

In this study, gemcitabine-loaded methoxy poly(ethylene glycol)-b-poly(L-lactide) (MPEG-PLLA) microparticles with different PEG block lengths were prepared by a W/O/W double emulsion technique. The present study focuses on the investigation of the influence of various preparative parameters such as the ratio of internal water phase and oil phase, polymer concentration, solvent composition of organic phase and salt concentration of external water phase on the morphology and encapsulation efficiency of the microparticles. The microparticles fabricated at high volume ratios of internal water phase to oil phase and at high polymer concentrations showed a relatively high encapsulation efficiency and low porosity. When a dichloromethane/ethyl acetate mixture was used as solvent, both the encapsulation efficiency and drug loading of the microparticles decreased as the level of ethyl acetate increased. The addition of a salt (NaCl) to the external water phase significantly improved the encapsulation efficiency up to 40%, and the microparticles became more spherical with their size and porosity decreased.

• Journal of the Korean Society of Combustion
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• v.11 no.4
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• pp.9-13
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• 2006

Recent advances in energetic materials modeling and high-resolution hydrocode simulation enable enhanced computational analysis of bio-medical treatments that utilize high-pressure shock waves. Of particular interest is in designing devices that use such technology in medical treatments. For example, the generated micro shock waves with peak pressure on orders of 10 GPa can be used for treatments such as kidney stone removal, transdermal micro-particle delivery, and cancer cell removal. In this work, we present a new computational methodology for applying the high explosive dynamics to bio-medical treatments by making use of high pressure shock physics and multi-material wave interactions. The preliminary calculations conducted by the in-house code, GIBBS2D, captures various features that are observed from the actual experiments under the similar test conditions. We expect to gain novel insights in applying explosive shock wave physics to the bio-medical science involving drug injection. Our forthcoming papers will illustrate the quantitative comparison of the modeled results against the experimental data.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1382-1388
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• 2014

Proteus vulgaris K80 lipase was expressed in Escherichia coli BL21 (DE3) cells and immobilized on amine-terminated magnetic microparticles (Mag-MPs). The immobilization yield and activity retention were 84.15% and 7.87%, respectively. A homology model of lipase K80 was constructed using P. mirabilis lipase as the template. Many lysine residues were located on the protein surface, remote from active sites. The biochemical characteristics of immobilized lipase K80 were compared with the soluble free form of lipase K80. The optimum temperature of K80-Mag-MPs was $60^{\circ}C$, which was $20^{\circ}C$ higher than that of the soluble form. K80-Mag-MPs also tended to be more stable than the soluble form at elevated temperatures and a broad range of pH. K80-Mag-MP maintained its stable form at up to $40^{\circ}C$ and in a pH range of 5.0-10.0, whereas soluble K80 maintained its activity up to $35^{\circ}C$ and pH 6.0-10.0. K80-Mag-MPs had broader substrate specificity compared with that of soluble K80. K80-Mag-MPs showed about 80% residual relative activity after five recovery trials. These results indicate the potential benefit of K80-Mag-MPs as a biocatalyst in various industries.

• Elastomers and Composites
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• v.35 no.4
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• pp.281-287
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• 2000

Waterborne polyurethane(PU) microgel dispersions were synthesized with different mole ratio of polytetramethylene glycol(PTMG) to dimethylol propionic acid(DMPA). Particle size distribution, thermal and mechanical properties of the PU microgels were investigated. Particle size of the microgels was distributed in the range of $98{\sim}$680{\mu}m$ and decreased with increasing the mole ratio of DMPA and 1,2,6-hexanetriol. Glass transition temperature and melting temperature of the microgels were in the range of $-79.7 {\sim}-78.1^{\circ}C$, $22{\sim}24^{\circ}C$ respectively. Tensile strength and elongation of the PU microgel films were maximum in the case of 60/40 mole ratio of PTMG/DMPA.

• KSBB Journal
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• v.26 no.1
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• pp.69-77
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• 2011

In this study, poly (L-lactic acid) (PLLA) microparticles containing gemcitabine hydrochloride were prepared by a supercritical fluid process, called aerosol solvent extraction system (ASES), utilizing supercritical carbon dioxide as antisolvent. The influence of process parameters such as temperature, pressure, $CO_2$ and solution flow rate, solution concentration, and feed ratio of drug to polymer on the morphology and characteristics of the microparticles was studied in detail. The gemcitabine-loaded microparticles exhibited a spherical shape with a smooth surface. The entrapment efficiency of gemcitabine increased with increasing temperature, solution concentration and $CO_2$ flow rate and with decreasing drug/polymer feed ratio. The maximum drug loading obtained from the ASES process was found to be about 11%. The ASES-processed PLLA microparticles containing gemcitabine showed a relatively high initial burst due to the presence of surface pores on the microparticles and the poor affinity between drug and polymer.