• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1321-1325
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• 2004

Sodium dodecyl sulfate (SDS), an anionic surfactant, can strongly adsorb at the surface of a carbon paste electrode (CPE) via the hydrophobic interaction. In pH 3.0 $Na_2HPO_4$-citric acid buffer (Mcllvaine buffer) and in the presence of SDS, the cationic indole-3-acetic acid (IAA, $pK_a$ = 4.75) was highly accumulated at the CPE surface through the electrostatic interaction between the negative-charged head group of SDS and cationic IAA, compared with that in the absence of SDS. Hence, the oxidation peak current of IAA increases greatly and the oxidation peak potential shifts towards more negative direction. The experimental parameters, such as pH, varieties of surfactants, concentration of SDS, and scan rate were optimized for IAA determination. The oxidation peak current is proportional to the concentration of IAA over the range from $5\;{\times}\;10^{-8}$ mol/L to $2\;{\times}\;10^{-6}$ mol/L. The detection limit is $2\;{\times}\;10^{-8}$ mol/L after 3 min of accumulation. This new voltammetric method was successfully used to detect IAA in some plant leaves.

• 폴리머
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• 제37권6호
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• pp.794-801
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• 2013

Novel microgels of N-isopropylacrylamide (NIPAM)-co-methacrylic acid (MAA) (NIPAM-co-MAA) with different contents of N,N-methylene bis acrylamide (MBA) were prepared by emulsion polymerization technique and were studied by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and zeta potential measurement. Effect of pH, temperature and different salts concentration on the microgel particles was investigated. DLS results have shown that the hydrodynamic radius of the microgel increased upon increasing pH and decreased upon increasing temperature. The swelling/deswelling behaviors as determined by DLS showed the ionic repulsions of the carboxyl group of the methacrylic acid and hydrophobic interaction of NIPAM. The effect of various salts on volume phase transition temperature (VPTT) was also investigated. Upon increasing salt concentration, VPTT became broad and shifted to a lower temperature. Electrophoretic mobility measurements showed an increase with increasing pH and temperature at a constant ionic strength.

• Applied Science and Convergence Technology
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• 제26권6호
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• pp.164-173
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• 2017

Across the most industry, the demand for nanoparticles is increasing. Therefore, many studies have been carried out to synthesize nanoparticles using various methods. The aim of this paper is to introduce an industry-applicable as well as financially and environmentally effective solution plasma process. The solution plasma process involves fewer chemicals than the traditional kit, and can be used to replace many of the chemical agents employed in previous synthesis of nanoparticles into plasma. In this study, this process is compared to the wet-reaction process that has thus far been widely used in the most industry. Furthermore, the solution plasma process has been classified into four different types (in-solution, out of solution, direct type, and remote type), according to its plasma occurrence position and plasma types. Thus, the source of radicals, nanoparticle synthesis, and modification methods are explained for each design. Lastly, unlike nanoparticles with hydrophilic functional groups that are made inside the solution, a nanoparticle synthesis and modification method to create a hydrophobic functional group is also proposed.

• 한국식품영양학회지
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• 제32권2호
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• pp.133-137
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• 2019

Curcumin is a hydrophobic polyphenol extracted from turmeric that exhibits a variety of biological functions has albeit with limited efficacy as a functional food material owing to its low absorption when administered orally. The newly developed curcumin powder formulation exhibits improved absorption rate in vivo. This study evaluates the anti-oxidant effects of $Theracurmin^{(R)}$ (TC), which is highly bio-available in curcumin powder. The antioxidant activity of TC was investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferrous reducing antioxidant power (FRAP) assays, NO radical, superoxide radical, $H_2O_2$ scavenging activity, and total antioxidant capacity (TAC). Additionally, we evaluated the antioxidant activity of TC in high-fat diet (HFD)-fed streptozotocin (STZ)-induced Type 2 diabetic rats. As a result of oral administration of TC for 13 weeks in type 2 diabetic rats, the group administration of 2,000 mg/kg significantly increased FRAP, superoxide dismutase (SOD), and reduced the level of glutathione (GSH) in liver tissue 1.9, 1.2, and 1.2-times, respectively. Furthermore, serum TAC levels increased by 1.3-fold after the rats were administered with a dose of 500 mg/kg. These results were consistent with the in vitro assay results. In conclusion, TC exhibited its potential as a functional food material through its antioxidant properties.

• 폴리머
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• 제27권4호
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• pp.330-339
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• 2003

폴리(스티렌-co-디비닐벤젠) 수지 페닐고리의 클로로메틸화를 통해 메틸렌티올기를 도입한 수지 (I), 폴리(스티렌-co-메틸 메타아크릴레이트-co-디비닐벤젠) 공중합체의 페닐고리와 에스터기에 클로로메틸화 반응을 거쳐 각각 메틸렌티올기를 도입하여 중금속 이온들과의 배위결합에 필요한공간개념을 배려한 수지(II) 및 폴리(스티렌-co-디비닐벤젠) 수지의 페닐고리를 클로로설폰화한 후, 소디움하이드로술파이드로 티오설폰산화한 수지 (III) 등 3가지 종류의 티올계 구상형 수지들을 합성하였다. 이어, 이들 킬레이트 수지들에 대한 중금속 이온의 흡착경향을 평가한 결과, 티올기 함유 I형 킬레이트 수지는 Hg$^{2＋}$에 대해서만 선택적 흡착성을 보였고, 티올기 함유 II형 킬레이트 수지는 Hg$^{2＋}$에 대한 흡착성능이 보다 향상되었으며, Cu$^{2＋}$, Pb$^{2＋}$, C$d^{2＋}$ 및 Cr$^{3+}$ 등의 몇몇 중금속 이온들에 대해서도 약간의 흡착능을 보였다. 다른 한편으로, 친수성의 티오설폰산기 함유 III형 킬레이트 수지는 효율적 흡착체로서 Hg$^{2＋}$, Cu$^{2＋}$, Ni$^{2＋}$, Co$^{2＋}$ 및 Cr$^{3+}$ 등의 중금속 이온들은 물론, 특히 C$d^{2＋}$ 및 Pb$^{2＋}$에 높은 흡착능을 보였다.

• 대한화학회지
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• 제59권5호
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• pp.379-386
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• 2015

양이온성, 비이온성, 양쪽성 계면활성제 및 그들의 혼합 계면활성제용액에서 p-클로로벤조산의 가용화상수(K_s)를 UV-Vis법으로 측정하였다. 계면활성제분자에서 탄소사슬의 길이가 서로 다른 소수성 꼬리-그룹과 친수성인 머리-그룹의 변화가 가용화에 미치는 효과를 조사하였으며, 또한 온도변화에 따른 K_s 값의 변화로부터 여러 가지 열역학적 함수 값들을 계산하고 분석하였다. 그 결과, 모든 계면활성제용액에서 p-클로로벤조산의 가용화에 대한 ΔG^o 값은 모두 음의 값을 그리고 ΔH^o와 ΔS^o의 값은 모두 양의 값을 나타내었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권3호
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• pp.262-267
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• 2006

The objective of this study was to develop new self-organized nanogels as a means of drug delivery in patients with cancer. Pullulan (PUL) and deoxycholic acid (DOCA) were conjugated through an ester linkage between the hydroxyl group in PUL and the carboxyl group in DOCA. Three types of PUL/DOCA conjugates were obtained, differing in the number of DOCA substitutions (DS; 5, 8, or 11) per 100 PUL anhydroglucose units. The physicochemical properties of the resulting nanogels were characterized by dynamic light scattering, transmission electron microscopy, and fluorescence spectroscopy. The mean diameter of DS 11 was the smallest (approx. 100 nm), and the size distribution was unimodal. To determine the organizing behavior of these conjugates, we calculated their critical aggregation concentrations (CACs) in a 0.01-M phosphate buffered saline solution. They were $10.5{\times}10^{-4}mg/mL,\;7.2{\times}10^{-4} mg/mL,\;and\;5.6{\times}10^{-4} mg/mL$ for DS 5, 8, and 11, respectively. This indicates that DOCA can serve as a hydrophobic moiety to create self-organized nanogels. To monitor the drug-releasing behavior of these nanogels, we loaded doxorubicin (DOX) onto the conjugates. The DOX-loading efficiency increased with the degree of DOCA substitution. The release rates of DOX from PUL/DOCA nanogels varied inversely with the DS. We concluded that the PUL/DOCA nanogel has some potential for use as an anticancer drug carrier because of its low CAC and satisfactory drug-loading capacity.

• 펄프종이기술
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• 제47권6호
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• pp.164-169
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• 2015

Nowadays blending ratio of OMG (old magazine) in recovered paper used for manufacturing newspaper have been increased. When large amount of OMG is consumed in newsprint mill, brightness can be improved by inorganic pigments of coating layer. On the other hand decrease in yield of deinking process will be encountered because the pigments can be removed as reject of froth flotation process. Therefore selection of the optimal deinking agent is an important. Non-ionic surfactant have been used widely in newsprint mill. Non-ionic surfactant has amphoteric characteristics. Hydrophilic group is ethylene and propylene oxide that can induce hydrogen bonding with water molecules. In this regard, cloud point is an important parameter in order to control efficiency of deinking process because hydration of the hydrophobic group can be varied according to temperature of a system. In this study, deinking properties of ONP at high blending ratio of OMG was analyzed according to cloud points of non-ionic surfactants. $L^*$, $a^*$, $b^*$, brightness and effective residual ink concentration did not affected by the change of cloud points. Especially, flotation reject decreased significantly according to increase in cloud point of the non-ionic surfactant. Consequently, when a nonionic surfactant having a cloud point higher than the temperature of the system is used, properties of the deinked pulp can be maintained and yield of deinking process can be improved.

• 한국균학회지
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• 제16권3호
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• pp.121-127
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• 1988

흰느타리버섯(Pleurotus cornucopiae(Per.) Rolland)중의 단백질을 선택적으로 분리정제하기 위하여 AH-Sepharose 4B를 출발 물질로 하여 benzoyl-AH-Sepharose 4B를 합성하여 친화성 크로마토그래피하였다. 1) AH-Sepharose 4B 중의 amino기의 capacity는 겔 Iml 당 $9.5{\mu}mol$ 이었으며 합성겔의 리간드인 benzoyl기의 capacity는 겔 1ml당 $9.3{\mu}mol4이었다. 2) 친화성이 있는 단백질의 총 겉보기 분자량은 255,000 돌톤 이었으며, 이는 29,500, 31,500, 34,000, 71,000 및 89,000돌톤 단백질의 복합체였다. 3) 친화성 단백질 중의 아미노산 함량은 비극성 아미노산이 45.68%, 극성 아미노산이 26.93%, 양성 아미노산이 11.81%, 그리고 음성 아미노산이15.58%였다. 4) 소수성 benzoyl기에 친화성이 있는 단백질은 비극성인 것이 선택적으로 분리되었다.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1750-1759
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• 2020

The characterization of cytochrome P450 CYP125A13 from Streptomyces peucetius was conducted using cholesterol as the sole substrate. The in vitro enzymatic assay utilizing putidaredoxin and putidaredoxin reductase from Pseudomonas putida revealed that CYP125A13 bound cholesterol and hydroxylated it. The calculated K_D value, catalytic conversion rates, and Km value were 56.92 ± 11.28 μM, 1.95 nmol min^-1 nmol^-1, and 11.3 ± 2.8 μM, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis showed that carbon 27 of the cholesterol side-chain was hydroxylated, characterizing CYP125A13 as steroid C27-hydroxylase. The homology modeling and docking results also revealed the binding of cholesterol to the active site, facilitated by the hydrophobic amino acids and position of the C27-methyl group near heme. This orientation was favorable for the hydroxylation of the C27-methyl group, supporting the in vitro analysis. This was the first reported case of the hydroxylation of cholesterol at the C-27 position by Streptomyces P450. This study also established the catalytic function of CYP125A13 and provides a solid basis for further studies related to the catabolic potential of Streptomyces species.