• 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.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1800-1808
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• 2013

Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), $^1H$ NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/mL for $PCL_{50}$-b-$PDMAEMA_{68}$, $PCL_{50}$-b-$PDMAEMA_{89}$, $PCL_{50}$-b-$PDMAEMA_{112}$, $PCL_{50}$-b-$PDMAEMA_{89}$ was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at $37^{\circ}C$ by an increase of pH.

• 접착 및 계면
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• 제17권4호
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• pp.149-154
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• 2016

일반적으로, 화학 물리적 변성이 수반되는 멸균방법을 적용하지 못하는 경우 필터여과에 의한 멸균 방법을 주로 사용한다. 하지만 바이러스의 경우 100 nm의 작은 크기로 인해 박테리아 제거에 사용되는 필터여과에 의한 멸균 방법을 적용하기가 어렵다. 본 논문에서는 화학 물리적 변성 없이 바이러스를 비활성화하는 물질 개발을 위하여, 카테콜기가 도입된 헤파린 고분자(Hep-C)를 합성하였다. Hep-C의 바이러스 비활성화 효과를 알아보기 위해서 표면이 노르에피네프린으로 코팅된 조직배양접시에 아데노연관바이러스(Adeno-associated virus; AAV)를 고정화하였으며, 그 위에 다시 Hep-C를 코팅하여 녹색형광단백질(GFP) 유전자를 전달할 수 있는 AAV의 비활성화 정도를 유세포분석기(FACS)를 이용하여 분석하였다. 그 결과 AAV에 Hep-C를 도포하면 99%에 달하는 비활성화 효과를 보였으며, 헤파린 고분자를 도포한 결과에 비해 강한 염 저항성을 확인할 수 있었다. 이러한 결과로 미루어 보아 제조된 Hep-C는 AAV 바이러스 제거의 효과적 방법으로 충분한 가능성을 가짐을 증명하였다.

• Macromolecular Research
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• 제17권5호
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• pp.325-331
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• 2009

The synthesis and the characterization of crosslinked ABC triblock copolymer, i.e. polystyrene-b-poly (hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid), (PS-b-PHEMA-b-PSSA) is reported. PS-b-PHEMA-b-PSSA triblock copolymer at 20:10:70 wt% was sequentially synthesized via atom transfer radical polymerization (ATRP). The middle block was crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA, as demonstrated by FTIR spectroscopy. As increasing amounts of SA, ion exchange capacity (IEC) continuously increased from 2.13 to 2.82 meq/g but water uptake decreased from 181.8 to 82.7%, resulting from the competitive effect between crosslinked structure and the increasing concentration of sulfonic acid group. A maximum proton conductivity of crosslinked triblock copolymer membrane at room temperature reached up to 0.198 S/cm at 3.8 w% of SA, which was more than two-fold higher than that of Nafion 117(0.08 S/cm). Transmission electron microscopy (TEM) analysis clearly showed that the PS-b-PHEMA-b-PSSA triblock copolymer is microphase-separated with a nanometer range and well developed to provide the connectivity of ionic PSSA domains. The membranes exhibited the good thermal properties up to $250^{\circ}C$ presumably resulting from the microphase-separated and crosslinked structure of the membranes, as revealed by thermal gravimetric analysis (TGA).

• 전기학회논문지
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• 제56권9호
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• pp.1561-1565
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• 2007

According to thermal degradation on power transformers, it is known that electrical, mechanical and chemical characteristics for power transformer's oil-paper are changed. In the chemical property, especially, when the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. Also the paper breakdown is accompanied by an increase in the content of various furanic compounds within the dielectric liquid. It is known that furanic components in transformer oil come only from the decomposition of insulating paper rather than from the oil itself. Therefore the analysis of furanic degradation products provides a complementary technique to dissolved gas analysis for monitoring transformers when we evaluate the aging of insulating paper by the total concentration of carbon monoxide and carbon dioxide dissolved in oil only. Recently, the analysis of furanic compounds by high performance liquid chromatography(HPLC) using IEC 61198 method for estimating degradation of paper insulation in power transformers has been used more conveniently for assessment of oil-paper. It is know that the main products which is produced by aging are 2-furfuryl alcohol, 2-furaldehyde(furfural), 2-furoic acid, 2-acetylfuran, 5-methyl-2-furaldehyde, and 5-hydroxymethyl-2-furaldehyde. For investigating the accelerated aging process of oil-paper samples we manufactured accelerating aging equipment and we estimated variation of insulations at $140^{\circ}C$ temp. during 500 hours. Typical transformer proportions of copper, silicon steel and iron have been added to oil-paper insulation during the aging process. The oil-paper insulation samples have been measured at intervals of 100 hours. Finally we have analyzed that 2-furoic acid and 2-acetylfuran products of furanic compounds were detected by HPLC, and their concentrations were increased with accelerated aging time.

• KSBB Journal
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• 제6권3호
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• pp.241-247
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• 1991

본 연구에서는 고정전달자를 갖는 poly(4-vinylpyridine-co-styrene) 고분자막을 합성하여 이를 특성화하고, $Cl^-$ 및 $CCl_3COO$ 의 $H^+$ 및 $OH^-$ 농도차에 따른 능동전달 기구에 대하여 고찰하였다. 시험 범위 내에서 $Cl^-$의 능동전달은 주로 $H^+$ 농도차를 구동력으로 한 병류수송(symprot)이 주가 되었으며 반면에 $CCl_3COO^{-}$의 능동전달은 $OH^-$의 농도차에 의한 향류 수성(antiport)의 영향이 큼을 알 수 있었다. $H^+$ 농도와 $OH^-$ 농도에 의한 음이온의 초기플럭스를 관찰함으로서, 고정전달자와 이온간의 엄형성계수, K와 이온의 막내 확산계수, D는 $Cl^-$의 경우 각각 $4.60{\times}10^2\;mol^{-1}{\cdot}\textrm{cm}^3$ 및 $1.57{\times}10^3{\textrm{cm}^2}/h$, $CCl_3COO^{-}$의 경우 각각 $1.10{\times}10^4\;mol^{-1}{\cdot}\textrm{cm}^3$ 및 $1.44{\times}10^4{\textrm{cm}^2}/h$ 이었다.

• 한국결정성장학회지
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• 제21권6호
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• pp.274-279
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• 2011

연소 반응기를 이용하여 고분자 물질에 함유된 할로겐 원소인 브롬과 염소를 정량하기 위한 조건을 연구하였다. 염소농도 측정의 경우, Mohr법이나 전위차 적정법을 이용한 경우가 산-염기 적정법을 이용한 경우보다 분석 데이터 간 편차가 낮게 나타났다. 또한, 연소 반응기에서 단계별로 포집한 용액에 대한 염소와 브롬 측정 결과, 두 원소 모두 증류수를 흡수액으로 사용할 때, 0.3 M NaOH 수용액을 사용할 때보다 더 높은 회수율을 보였으며, 흡수액/세척액에서의 농도가 가스상의 형태로 배출되는 농도에 비해 높은 것으로 나타났다. 한편, 브롬 함량을 측정할 때, 연소 반응기를 이용한 경우가 XRF나 연소-이온크로마토그래피를 이용한 경우에 비해 농도가 상대적으로 낮게 평가되는 것으로 나타났다.

• 공업화학
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• 제10권1호
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• pp.1-5
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• 1999

알킬비닐에테르와 말레인산디에틸에스테르의 공중합체인 측쇄알킬기의 탄소수나 중합도가 다른 올리고머형 음이온성 계면활성제 ($C_mD-Na$)를 분산제로 사용하고 친수성 안료로서 산화철이나 산화티탄의 미립자에 대한 분산성을 비교검토하였다. 그 결과 올리고머형 계면활성제의 동족체는 안료입자 표면에 알킬기가 흡착되므로써 흡착층을 형성하고 있는 입자에 음의 하전을 띠어 분산거동이 다르지만, $C_4D-Na$는 저농도에서도 우수한 분산능을 나타내었다. 그리고 소수성인 ${\alpha}-Fe_2O_3$와 Anatase $TiO_2$는 0.1% 농도 이상의 범위에서도 측쇄알킬기의 탄소수가 $C_8$ 이상인 것이 분산작용에 양호한 것으로 나타났다.

• 멤브레인
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• 제26권6호
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• pp.463-469
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• 2016

Polyethersulfone (PES) 고분자 상변환막의 성능을 향상시키기 위해 PES 고분자에 나노 크기의 ZnO 무기입자를 함침시킨 혼합기질막(mixed matrix membrane)을 제조하고 특성을 평가하였다. PES-ZnO 혼합기질막은 ZnO 나노입자를 PES 대비 최대 0.375 wt%의 낮은 비율로 첨가시킨 PES-ZnO-NMP(N-methyl-1-pyrrolidone)로 이루어진 캐스팅 용액을 사용하여 상변환법을 통해 제조하였다. 제조된 혼합기질 막의 물성과 특성은 막의 단면구조 관찰, 접촉각 측정, 인장강도 측정, 순수 투과량 측정 및 BSA 단백질 용액의 한외여과 실험을 통해 평가하였다. 이 결과 혼합기질 막은 PES 고분자 matrix에 함유된 ZnO 나노입자로 인해 막의 친수성이 증가하여 막오염 발생이 억제되어 투과량이 증가하였다. ZnO 나노입자는 혼합기질막의 제조에 있어 막오염의 발생 억제와 투과량 증가에 유용하게 사용될 수 있는 무기물 첨가제임을 알 수 있다.

• 한국연소학회지
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• 제7권4호
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• pp.36-44
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• 2002

Carbon molecules with closed-cage structures are called fullerenes $(C_{60},\;C_{70})$, whose applications include super-conductors, sensors, catalysts, optical and electronic device, polymer composites, and biological and medical materials. The synthesis of fullerenes has been recently studied with low-pressure benzene/argon/oxygen flames. The formation of fullerene is known as molecular weight growth processes of PAHs (polycyclic aromatic hydrocarbon). This study presents results of PAHs and fullerene measurements performed in a low-pressure benzene/argon/oxygen normal co-flow laminar diffusion flame. Through the central tube of the burner, benzene vapors carried by argon are injected. The benzene vapors are made in a temperature-controlled bubbler. The burner is located in a chamber, equipped with a sampling system for direct collection of condensable species from the flame, and exhausted to a vacuum pump. Samples of the condensable are analyzed by HPLC (High Performance Liquid Chromatography) to determine the yields of PAHs and fullerene. Also, we computed mole fraction of fullerene and PAHs in a nearly sooting low pressure premixed, one-dimensional benzene/argon/oxygen flame (equivalence ratio ${\Phi}=2.4$, pressure=5.33kPa). The object of computation was to investigate the formation mechanism of fullerenes and PAHs. The computations were performed with CHEMKIN/PREMIX. As a result of this study, fullerenes were synthesized in a low pressure (20torr) $C_6H_6/Ar/O_2$ flames and the highest concentration of fullerene was detected just above the visible surface of a flame.