• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3208-3212
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• 2012

Controlled drug delivery systems employing microparticles offer lots of advantages over conventional drug dosage formulations. Microencapsulation technique have been conducted with biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA) and poly(lactic acid) (PLA) for its adjustable biodegradability and biocompatibility. In this study, we evaluated two techniques, oil-in-water (o/w) emulsion solvent evaporation and spray drying, for preparation of polymeric microparticles encapsulating a newly synthesized drug, SS-AG20, for the long-term drug delivery of this low-molecular-weight drug with a very short half-life. Drug-loaded microparticles prepared by the solvent evaporation method showed a smoother morphology; however, relatively poor encapsulation efficiency and drastic initial burst were discovered as drawbacks. Spray-dried drug-loaded microparticles had an imperfect surface with pores and distorted portions so that its initial burst was critical (70.05-87.16%) when the preparation was carried out with a 5% polymeric solution. By increasing the concentration of the polymer, the morphology was refined and undesirable initial burst was circumvented (burst was reduced to 35.93-74.85%) while retaining high encapsulation efficiency. Moreover, by encapsulating the drug with various biodegradable polymers using the spray drying method, gradual and sustained drug release, for up to 2 weeks, was achieved.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.145-148
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• 2012

Spherical silica aerogel powders were fabricated via an emulsion polymerization method from a water glass. A water-in-oil emulsion, in which droplets of a silicic acid solution are emulsified with span 80 (surfactant) in n-hexane, was produced by a high power homogenizer. After gelation, the surface of the spherical silica hydrogels was modified using a TMCS (trimethylchlorosilane)/n-hexane solution followed by solvent exchange from water to n-hexane. Hydrophobic silica wet gel droplets were dried at 80 ℃ under ambient pressure. A perfect spherical silica aerogel powder between1 to 12 ㎛ in diameter was obtained and its size can be controlled by mixing speed. The tapping density, pore volume, and BET surface area of the silica aerogel powder were approximately 0.08 g·cm-3, 3.5 ㎤·g-1 and 742 ㎡·g-1, respectively.

• 한국세라믹학회지
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• 제27권8호
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• pp.955-964
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• 1990

A new process of emulsiion-spray pyrolysis for synthesizing ceramic powders was developed and the characteristics of Al2O3-20w/o ZrO2 composite powders prepared by this method were investigated. The composite powders synthesized in this study were spherical dense particles with 0.1~0.4${\mu}{\textrm}{m}$ of diameter. As found in powders derived by the emulsion-hot kerosene drying method, all zirconia in Al2O3-20w/o ZrO2 powders heat-treated at 120$0^{\circ}C$ was in the tetragonal form at room temperature. The relative density and the fracture toughness of composites sintered at 1$650^{\circ}C$ for 4hrs were 95% and 5.2MPa.m1/2, respectively.

• Journal of Pharmaceutical Investigation
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• 제31권4호
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• pp.241-256
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• 2001

Alginate microspheres, containing fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) or green fluorescent protein (GFP) were prepared and used as a model drug to develop the oral vaccine delivery system. The alginate microspheres were coated with poly-L-lysine or chitosan. Two methods, w/o-emulsion and spray, were used to prepare alginate microspheres. To optimize preparation conditions, effects of several factors on the particle size and particle morphology of microsphere, and loading efficiency of model antigen were investigated. In both preparation methods, the particle size and the loading efficiency were enhanced when the concentration of sodium alginate increased. In the w/o-emulsion preparation method, as the concentration of Span 80 was increased from 0.5% to 2%, the particle size was decreased, but the loading efficiency was increased. The higher the emulsification speed was, the smaller the particle size and loading efficiency were. The concentration of calcium chloride did not show any effect on the particle size and loading efficiency. In the spray preparation method, the particle size was increased as the nozzle pressure $(from\;1\;kgf/m^2\;to\;3\;kgf/m^2)$ and spray rate was raised. Increasing calcium chloride concentration (<7%) decreased the particle size, in contrast to no effect of calcium chloride concentration on the w/o-emulsion preparation method. Alginate microspheres prepared by two methods were different in the particle size and loading efficiency, the particle size of microspheres prepared by the spray method was about $2-6\;{\mu}m$, larger than that prepared by the w/o emulsion method $(about\;2{\mu}m)$, and the loading efficiency was also higher with spray method. Furthermore, drying process for the microspheres prepared by the spray was simpler and easier, compared with the w/o emulsion preparation. Therefore, the spray method was chosen to prepare alginate microspheres for further experiments. Release pattern of FITC-BSA in alginate microspheres was evaluated in simulated intestinal fluid and PBS (phosphate buffered saline). Dissolution rate of FITC-BSA from alginate/chitosan microsphere was lower than that from alginate microsphere and alginate/poly-L-lysine microsphere. By confocal laser scanning microscope, it was revealed that alginate/FITC-poly-L-lysine microspheres were present in close apposition epithelium of the Peyer's patches of rabbits following inoculation into lumen of intestine, which proved that microspheres could be taken up by Peyer's patch. In conclusion, it is suggested that alginate microsphere prepared by spray method, showing a particle size of & $10\;{\mu}m$ and a high loading efficiency, can be used as a model drug for the development of oral vaccine delivery system.

• Journal of Pharmaceutical Investigation
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• 제31권4호
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• pp.257-263
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• 2001

The microspheres have been developed as a new drug delivery system. Although many particulate drug carriers, such as liposome, niosome and emulsion, have been introduced, injectable and biodegradable microspheres appears to be a particularly ideal delivery system because the local anesthesia is not necessary for the insertion of large implants and for the removal of the device after the drug release is finished. Biodegradable microspheres with nicotine and triamcinolone acetonide are prepared and evaluated. As biodegradible polymers, PLA (M.W. 15,000, PLA-0015), PLGA (M.W. 17,000, RG 502) and PLGA (M.W. 8,600, RG 502H) are used. This study attempted to prepare and evaluate the nicotine and triamcinolone acetonide-incorporated microspheres, which were prepared by two methods, solvent-evaporation and spray-drying methods. The microspheres, as a disperse system for injections, were evaluated by particle size, size distribution, entrapment efficiency, and in vitro drug release patterns. The differences of preparation method, partition coefficient, types of polymer, and preparation conditions of microspheres influence the particle size, entrapment efficiency, and in vitro drug release patterns.

• 한국결정성장학회지
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• 제15권2호
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• pp.51-56
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• 2005

We prepared orthorhombic $LiMnO_2$ by emulsion drying method. The thermo-gravimetric measurement and X-ray diffraction studies indicated that the orthorhombic $LiMnO_2$ phase was formed above $800^{\circ}C$ by oxygen evaporation process from $LiMn_2O_4$ and $Li_2MnO_3$. In this process, we could control the ordering of $LiMnO_2$ with heating rate. It was observed that electrochemical properties depended on the ordering of this material; the ordered one exhibited good capacity retention, whereas the disordered one suffered capacity fading upon cycling, especially in the 3 V region. Transmission electron microscopic (TEM) study showed that this difference is related with difference in the stress relieving effects in the samples.

• 한국재료학회지
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• 제1권2호
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• pp.71-76
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• 1991

The superconducting powders in $YBa_2Cu_3O_{7-x}$ and Bi-Pb-Sr-Ca-Cu-O system were easily prepared from water in oil type emulsion by loading each cation into the aqueous phase. In $YBa_2Cu_3O_{7-x}$ system, the superconducting orthorhombic phase was formed by calcining at $750^{\circ}C$ for 10h in $O_2$. The size of the superconducting phase powders was submicron. The density of the sintered specimen using this powders was about 95% of the theoretical density and the resistance sharply decreases at about 90K, In Bi-Pb-Sr-Ca-Cu-O system the low Tc phase($(Bi, Pb)_2Sr_2Ca_1Cu_2O_y$) was formed by calcining at $800^{\circ}C$ for 10h in a low oxygen partial pressure of 1/20 atm The shape of clacined powder is thin plate of which size is about $2\mu\textrm{m}$ and thickness is smaller than $\mu\textrm{m}$. It was observed that the high Tc phase ($(Bi, Pb)_2Sr_2Ca_2Cu_3O_y$) was formed by sintering at $850^{\circ}C$ for 30h in oxygen pressure of 1/20 atm without intermediary grinding. The above sintered sample exhibited superconductivity with a Tc(zero)=105K.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.236.3-237
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• 2003

Fine particles of water-soluble pharmaceuticals were prepared using a new micronization method, Carbon Dioxide Assisted Nebulization in a Bubble Dryer(CAN-BD). The process utilized mixtures of CO$_2$ in aqueous solution at supercritical conditions to form an emulsion. The aerosols were dried with pre-heated nitrogen, and the drying chamber was operated at near atmospheric pressure. The dry particles were collected on membrane filter at the bottom of the drying chamber. Several processing parameters such as flow rate, temperature, pressure, solid concentration and processing scale were accessed using NaCl, human serum albumin, and granulocyte-colony stimulating factor as model pharmaceuticals. (omitted)

• 폴리머
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• 제25권3호
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• pp.318-326
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• 2001

본 연구에서는 세포 배양시 감염방지용으로 널리 쓰이는 겐타마이신 설페이트(GS)가 서방화된 다공성 PLLA 지지체를 유화동결건조방법으로 제조하였다 이들의 물성을 전자현미경 및 수은다공도계로 특성결정하였고, 적심성은 푸른염색 수용액으로 관찰하였으며, 방출거동은 high performance liquid chromatography (HPLC)를 이용하여 측정하였다. GS가 5, 10 및 20%가 포접된 PLLA 지지체의 다공도는 80~90%이었으며 평균다공크기 범위는 30~57 ${\mu}{\textrm}{m}$ 그리고 가장 큰 것으로는 150${\mu}{\textrm}{m}$이상의 것도 관찰되었다. 전체적인 다공도의 모양은 다공과 다공사이의 연결이 양호하고 대부분이 열린 셀 구조를 하고 있는 것으로 나타났다. 대조군에 비해 GS의 농도가 증가함에 따라 PLLA 지지체의 다공도가 감소하는 것으로 보아 GS내의 설페이트 부분은 친수성 역할 그리고 겐타마이신 부분은 소수성 역할을 수행하는 계면활성제의 역할에 기인한 것으로 사료된다. PLLA 지지체의 방출거동은 GS의 농도가 증가함에 따라 방출되는 양이 증가하였고, 적심성 또한 향상되어 세포배양시 긍정적 효과를 끼칠 것으로 예상되었다.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.51-55
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• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.