• Macromolecular Research
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• 제11권4호
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• pp.273-282
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• 2003

A hydrophilic macromolecular network containing hydrophobic moieties has been prepared by free radical copolymerization of acrylamide and styrene in the presence of poly(vinyl alcohol) (PVA) and its potential as controlled drug delivery carrier was evaluated with tetracycline as a model antibiotic drug. The amount of drug was assayed spectrophotometrically. The network was characterized by optical microscopy, infra-red spectroscopy and structural parameters such as average molecular weight between cross1inks ($M_c$), cross1ink density (q) and number of elastically effective chains ($V_e$) were evaluated. It was found that with increasing concentration of PVA, ST and MBA in the hydrogel, the release rate initially increases but after definite concentrations of the above components the release rate falls. In the case of AM, release rate constantly decreases with increasing AM concentration in the hydrogel.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1195-1199
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• 1997

Anthraquinone-2-sulfonate (AQS) release from poly(N-methylpyrrole anthraquinone-2-sulfonate) (PNMP-AQS) was investigated at open circuit and compared with electrochemically stimulated release during potential cycling. It was found that the fast AQS release from PNMP-AQS single layers is substantially retarded and the amounts of spontaneously and electrochemically releasable AQS can be reduced by constructing bilayers, consisting of PNMP-AQS inner layers and PNMP outer layers. PNMP-Cl outer layers exhibited higher effectiveness for entrapping AQS within inner layers than PNMP/poly(styrene slfonate). The effects of outer layer thicknesses on AQS release were also examined with PNMP-AQS:PMP-Cl. The electroactivity enhancement of PNMP-AQS:PNMP-Cl bilayers due to entrapped AQS was confirmed by chronocoulometry.

• 방사성폐기물학회지
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• 제20권3호
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• pp.321-338
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• 2022

The transport of radionuclides at oceanic scales can be assessed using a Lagrangian model. In this review an application of such a model to the Atlantic, Indian and Pacific oceans is described. The transport model, which is fed with water currents provided by global ocean circulation models, includes advection by three-dimensional currents, turbulent mixing, radioactive decay and adsorption/release of radionuclides between water and bed sediments. Adsorption/release processes are described by means of a dynamic model based upon kinetic transfer coefficients. A stochastic method is used to solve turbulent mixing, decay and water/sediment interactions. The main results of these oceanic radionuclide transport studies are summarized in this paper. Particularly, the potential leakage of ¹³⁷Cs from dumped nuclear wastes in the north Atlantic region was studied. Furthermore, hypothetical accidents, similar in magnitude to the Fukushima accident, were simulated for nuclear power plants located around the Indian Ocean coastlines. Finally, the transport of radionuclides resulting from the release of stored water, which was used to cool reactors after the Fukushima accident, was analyzed in the Pacific Ocean.

• 한국산학기술학회논문지
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• 제11권10호
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• pp.4047-4054
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• 2010

실험실 규모의 모사 실험을 통하여 해양 부영양화를 촉진하는 퇴적물의 용출 특성을 연구하였다. 즉 pH, ORP, 질소성분, 인성분 등 주요 환경인자를 분석하고 그에 따른 용출율을 계산하였다. 또한 산소발생제인 과산화칼슘을 이용하여 자연적 용출의 제어효과를 분석하였다. 산소발생제 처리에 따라 호기적 조건으로의 퇴적토 환경변화가 일어났으며 COD, $NH_3$-N의 용출율이 감소하고 질산화 촉진으로 NOx 성분은 증가하였다. 총인과 인산염인도 Ca 이온의 불용화 기작에 의거 감소하였다. 이에 따라 퇴적토의 용출로 인한 해양 부영양화 억제 방법론을 정립하고자한다.

• Macromolecular Research
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• 제13권5호
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• pp.397-402
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• 2005

To explore the potential of shell crosslinked micelle (SCM) as a drug carrier, the drug release behavior of poly($\varepsilon$-caprolactone)-b-poly(acrylic acid) (PCL-b-PAA) SCMs was investigated. PCL-b-PAA was synthesized by ring opening polymerization of $\varepsilon$-caprolactone and atom transfer radical polymerization of tert-butyl acrylate, followed by selective hydrolysis of tert-butyl ester groups to acrylic acid groups. The resulting amphiphilic polymer was used to prepare SCMs by crosslinking of PAA corona via amidation chemistry. The drug release behavior of the SCMs was studied, using pyrene as a model drug, and was compared with that of non-crosslinked micelles, especially below the critical micelle concentration (CMC). When the shell layers were crosslinked, the drug release behavior of the SCMs was successfully modulated at a controlled rate compared with that of the non-crosslinked micelles, which showed a burst release of drug within a short time.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.526-529
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• 2006

The aim of this study was to prepare cyclosporin A-loaded liposome (CyA-Lip) as an oral delivery carrier, with their encapsulation into microspheres based on alginate or extracellular polysaccharide (EPS) p-m10356. The main advantage of liposomes in the microspheres (LIMs) is to improve the restricted drug release property from liposomes and their stability in the stomach environment. Alginate microspheres containing CyA-Lip were prepared with a spray nozzle; CyA-Liploaded EPS microspheres were also prepared using a w/o emulsion method. The shape of the LIMs was spherical and uniform, and the particle size of the alginate-LIMs ranged from 5 to $10\;{\mu}m$, and that of the EPS-LIMs was about $100\;{\mu}m$. In a release test, release rate of CyA in simulated intestinal fluid (SIF) from the LIMs was significantly enhanced compared to that in simulated gastric fluid (SGF). In addition, the CyA release rates were slower from formulations containing the liposomes compared to the microspheres without the liposome. Therefore, alginate-and EPS-LIMs have the potential for the controlled release of CyA and as an oral delivery system.

• Biomolecules & Therapeutics
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• 제29권6호
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• pp.630-636
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• 2021

Eupafolin, a constituent of the aerial parts of Phyla nodiflora, has neuroprotective property. Because reducing the synaptic release of glutamate is crucial to achieving pharmacotherapeutic effects of neuroprotectants, we investigated the effect of eupafolin on glutamate release in rat cerebrocortical synaptosomes and explored the possible mechanism. We discovered that eupafolin depressed 4-aminopyridine (4-AP)-induced glutamate release, and this phenomenon was prevented in the absence of extracellular calcium. Eupafolin inhibition of glutamate release from synaptic vesicles was confirmed through measurement of the release of the fluorescent dye FM 1-43. Eupafolin decreased 4-AP-induced [Ca²⁺]_i elevation and had no effect on synaptosomal membrane potential. The inhibition of P/Q-type Ca²⁺ channels reduced the decrease in glutamate release that was caused by eupafolin, and docking data revealed that eupafolin interacted with P/Q-type Ca²⁺ channels. Additionally, the inhibition of calcium/calmodulin-dependent protein kinase II (CaMKII) prevented the effect of eupafolin on evoked glutamate release. Eupafolin also reduced the 4-AP-induced activation of CaMK II and the subsequent phosphorylation of synapsin I, which is the main presynaptic target of CaMKII. Therefore, eupafolin suppresses P/Q-type Ca²⁺ channels and thereby inhibits CaMKII/synapsin I pathways and the release of glutamate from rat cerebrocortical synaptosomes.

• Journal of Pharmaceutical Investigation
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• 제41권3호
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• pp.185-190
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• 2011

The purpose of this study was to evaluate the phagocytic uptake of surface modified PLGA microspheres containing ovalbumin (OVA) into dendritic cell. In order to find the most suitable formulation for targeted delivery to antigen presenting cells (APC), OVA was encapsulated by a double emulsion solvent evaporation method with three PLGA microspheres (PLGA 50:50, PLGA 75:25 and PLGA 85:15) and two surface modified microspheres by chitosan and sodium dodecyl sulfate (SDS). Physicochemical properties were evaluated in terms of size, zeta potential, encapsulation efficiency, different scanning calorimeter (DSC), x-ray diffraction, morphology, and OVA release test from microspheres. Phagocytic activity was estimated using dendritic cells and analyzed by fluorescence activated cell sorter (FACS). The result showed that zeta potential of PLGA particles was changed to positive by the chitosan modification. The release profile of chitosan modified PLGA microspheres exhibited sustained release after initial burst. The chitosan modified microspheres had higher phagocytic uptake than the other microspheres. Such physicochemical properties and phagocytic uptake studies lead us to conclude that chitosan modified microspheres is more suitable formulation for the targeted delivery of antigens to APC compared with the other microspheres.

• 전기전자학회논문지
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• 제21권3호
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• pp.320-330
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• 2017

Porous nanosilica (PNS) has been identified as a potential candidate for controlled drug delivery. However, unmodified PNS-based carriers exhibited an initial release of loaded bioactive agents, which may limit their potential clinical applications. In this study, the surface of PNS was functionalized with adamantylamine (ADA) via disulfide bonds (-S-S-), PNS-S-S-ADA, which was then modified with cyclodextrin (CD)-heparin (Hep) (CD-Hep), PNS-S-S-CDH, for redox triggered rhodamine B (RhB) delivery. The obtained samples were then characterized by proton nuclear magnetic resonance ($^{1}H\;NMR$), Fourier transform infrared (FTIR), and transmission electron microscope (TEM). These results showed that PNS-S-S-CDH was successfully formed with spherical shape and average diameter of $45.64{\pm}2.33nm$. In addition, RhB was relatively encapsulated in the PNS-S-S-CDH (RhB@PNS-S-S-CDH) and slowly released up to 3 days. The release of RhB, in particular, was triggered due to the cleavage of -S-S- in the presence of dithiothreitol (DTT). It might be anticipated that the modified PNS can be used as redox-responsive drug delivery system in cancer therapy.

• 대한치과교정학회지
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• 제33권5호
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• pp.351-358
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• 2003

니켈과 크롬은 대부분의 교정장치를 제작하는데 사용되는 합금을 구성하는 주요한 금속이다. 그러나 이들 금속은 과민반응, 피부염, 천식 등의 주요한 원인이 되며, 이들 금속의 우발적인 흡입에 의해 암이 유발될 수 있음이 보고된 바 있다 이에 하악 standard edgewise브라켓을 이용한 사분악의 교정장치를 $37^{\circ}C,\;,0.05\%$ NaCl용액에 저장하여 교정장치의 부식에 의해 유리된 니켈과 크롬을 Inductively Coupled Plasma(ICP) spectroanalyzer를 이용하여 측정하였다. 교정장치로부터, 1일 평균 $9.83-70.0{\mu}g/day$의 니켈이 유리되었으나, 크롬은 10ppb 측정한계에서 측정불가능 하였다. 니켈 유리량은 제품에 따라 유의한 차이를 가져왔다 Galvanic조건이나 Sand blasting처리는 니켈 유리량에 증가를 가져왔으나 통계학적으로 유의하지 않았다.