• 청정기술
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• 제26권1호
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• pp.1-6
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• 2020

초임계 용액 급속팽창법(rapid expansion of supercritical solution, RESS)으로 몰시도민(molsidomine, MOL) 약물이 로딩 된 퍼아세틸-β-사이클로덱스트린(PAc-β-CD) 나노 입자를 제조하였다. 입자는 초임계 용액을 공기 중으로 급속하게 팽창시켜 제조하였다. MOL과 PAc-β-CD (0.5, 1 wt%)의 농도, 추출 온도(45 ~ 60 ℃), 모세관 노즐의 길이(5 ~ 20 mm) 및 내경(Inner diameter, ID) (50 ~ 150 μm), 그리고 분사 거리의 변화에 따라 형성된 입자의 크기와 모폴로지를 조사하였다. MOL과 PAc-β-CD의 상호작용을 ¹H-NMR 분광법으로 확인하였고, 입자 크기는 주사 전자 현미경으로 측정하였다. 온도를 45 ℃에서 60 ℃로 올리거나 노즐 내경을 150 μm에서 50 μm로 줄이면 입자 평균 크기가 증가하였으며, 반면에 일정한 압력(34.5 MPa)과 온도(45 ℃)에서 분사 거리를 늘리면 입자 평균 크기가 감소하는 효과를 나타내었다. 0.5 wt%의 PAc-β-CD 농도로서 초임계 공정을 진행한 결과, 모세관의 길이가 짧고(5 mm) 내경이 작은(50 μm) 조건에서 크기가 가장 작은(165 nm) 입자가 얻어졌다. 제조한 나노 입자는 오일 내에서 분산성과 용해도가 증가하였으며, 포접체 입자에서 MOL이 방출되는 시간이 지연되는 것을 확인하였다.

• 대한화학회지
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• 제55권1호
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• pp.70-80
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• 2011

두 종류의 새로운 팔라디움(II) 착물인 [Pd(phen)(pip-dtc)]$NO_3$와 [Pd(phen)(mor-dtc)]$NO_3$ (여기서 phen은 1,10-페난트롤린, pip-dtc은 피페리딘디티오카르바메이트 음이온, mor-dtc은 모르폴린디티오카르바메이트 음이온을 가리킨다)를 합성하고 원소분석, 분광법(FT-IR, $^1H$ NMR, UV-Vis) 및 전기전도도 측정을 이용하여 특성을 조사하였다. 이 착물들에서, 디티오카르베이트 리간드는 팔라디움 (II) 중심과 두 개의 황 원자와 이중으로 배위 결합을 하고 있다. 이 착물의 세포독성을 K562 세포주를 이용하여 조사하였을 때 $IC_{50}$ 값이 시스플라틴보다 작았기 때문에 착물들의 송아지 흉선 DNA(CT-DNA)와의 결합 모드를 UV 흡광도 차이와 형광 분광법으로 조사하였다. 착물들은 DNA를 변형시키고, 협동결합을 하고, DNA에 끼어 들어간다. 또한 몇 가지 결합 및 열역학적인 변수들이 기술되었다.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1314-1318
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• 2010

The $[Ru(tpy)_2]Cl_2$ (tpy:2,2':6',2"-terpyridine) complex was synthesized and its structure was confirmed by $^1H$-NMR and elemental analysis. Its binding mode toward DNA was compared with the well-known $[Ru(bpy)_3]Cl_2$ (bpy:2,2-bipyridyl), using isotropic absorption, linear dichroism(LD) spectroscopy, and an energy minimization study. Compared to $[Ru(bpy)_3]^{2+}$, the $[Ru(tpy)_2]^{2+}$ complex exhibited very little change in its absorption pattern, especially in the MLCT band, upon binding to DNA. Furthermore, upon DNA binding, both Ru(II) complexes induced a decrease in the LD magnitude in the DNA absorption region. The $[Ru(tpy)_2]^{2+}$ complex produced a strong positive LD signal in the ligand absorption region, which is in contrast with the $[Ru(bpy)_3]^{2+}$ complex. Observed spectral properties led to the conclusion that the interaction between the ligands and DNA bases is negligible for the $[Ru(tpy)_2]^{2+}$ complex, although it formed an adduct with DNA. This conclusion implies that both complexes bind to the surface of DNA, most likely to negatively charged phosphate groups via a simple electrostatic interaction, thereby orienting to exhibit the LD signal. The energy minimization calculation also supported this conclusion.

• Tribology and Lubricants
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• 제31권5호
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• pp.195-204
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• 2015

Several researches are focused on improving the value of fine chemicals based on biomass resources due to environmental and other concerns associated with the use of petroleum-based products. Therefore, the synthesis and application of estolides derived from plant-based waste oil materials and their application as lubricants and as processing oil for butyl rubber products have been studied. Four kinds of estolide were prepared with conversions of 71~92% over 24h using various vegetable oils, as determined by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. FT-IR spectroscopy determines the esterification of estolides using 2-ethylhexyl alcohol. The estolides have iodine values of 35~90, α-ester/α-acid ratios of 0.45~0.55, and total acid number of 114~134 mg KOH g^–1. Four ball wear tests show that the wear scar diameters (WSDs) of estolides as base oil significantly decreased to 0.328~0.494 mm, compared to WSDs of 0.735 and 0.810 mm of WSD for 150N and Yubase 6, respectively, as general base oil. Thus, the estolides have better wear resistance and satisfying design objectives for the engineering of a variety of lubricant base oils.

• Macromolecular Research
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• 제16권8호
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• pp.704-710
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• 2008

Injectable hydrogels are quite promising materials due to their potential to minimize invasive implantation and this provides versatile fitness irrespective of the damaged regions and facilitates the incorporation of bioactive agents or cells. In situ gel formation through stereocomplex formation is a promising candidate for injectable hydrogels. In this paper, a new series of enantiomeric, four-arm, PEG-PLA block copolymers and their stereocomplexed hydrogels were prepared by bulk ring-opening polymerization of D-lactide and L-lactide, respectively, with stannous octoate as a catalyst. The prepared polymers were characterized by $^1H$ nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT IR) spectroscopy, gel permeation chromatography (GPC) and thermal gravitational analysis (TGA), confirming the tailored structure and chain lengths. The swelling and degradation behavior of the hydrogels formed from a selected copolymer series were observed in different concentrations. The degradation rate decreased with increasing polymer content in the solution. The rheological behavior indicated that the prepared hydrogel underwent in situ gelation and had favorable mechanical strength. In addition, its feasibility as an injectable scaffold was evaluated using a media dependence test for cell culture. A Tris solution was more favorable for in situ gel formation than PBS and DMEM solutions were. These results demonstrated the in situ formation of hydrogel through the construction of a stereocomplex with enantiomeric, 4-arm, PEG-PLA copolymers. Overall, enantiomeric, 4-arm, PEG-PLA copolymers are a new species of stereocomplexed hydrogels that are suitable for further research into injectable hydrogels.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.558-564
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• 2013

A simple and effective method is introduced to synthesize a series of polystyrene-b-poly(oligo(ethylene oxide) monomethyl ether methacrylate)-b-polystyrene (PSt-b-POEOMA-b-PSt) triblock copolymers. The structures of PSt-b-POEOMA-b-PSt copolymers were characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ($^1H$ NMR) spectroscopy. The molecular weight and molecular weight distribution of the copolymer were measured by gel permeation chromatography (GPC). Furthermore, the self-assembling and drug-loaded behaviours of three different ratios of PSt-b-POEOMA-b-PSt were studied. These copolymers could readily self-assemble into micelles in aqueous solution. The vitamin E-loaded copolymer micelles were produced by the dialysis method. The micelle size and core-shell structure of the block copolymer micelles and the drug-loaded micelles were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The thermal properties of the copolymer micelles before and after drug-loaded were investigated by different scanning calorimetry (DSC). The results show that the micelle size is slightly increased with increasing the content of hydrophobic segments and the micelles are still core-shell spherical structures after drug-loaded. Moreover, the glass transition temperature (Tg) of polystyrene is reduced after the drug loaded. The drug loading content (DLC) of the copolymer micelles is 70%-80% by ultraviolet (UV) photolithography analysis. These properties indicate the micelles self-assembled from PSt-b-POEOMA-b-PSt copolymers would have potential as carriers for the encapsulation of hydrophobic drugs.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.243-250
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• 2006

Three novel potential metal ion chelating units have been synthesized and characterized: 5-hexylcarbamoyl-3,4-dihydroxythiophene-2-carboxylic acid methyl ester (5), 3-benzyloxy-4-hydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (6), and 3,4-dihydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (7). The crystal structure of 6 was obtained and suggests the presence of three distinct intramolecular hydrogen bonds, namely $[N_{amide}-H{\cdot}{\cdot}{\cdot}O]$ $[O-H{\cdot}{\cdot}{\cdot}O_{amide}]$ and $[N_{amide}-H{\cdot}{\cdot}{\cdot}S]$. Boron chelation with 5, 6 and 7 through the use of $BF_3, \;B(OH)_3 \;or \;B(OMe)_3$ was probed by $^1H$, $^{11}B$, and $^{13}C$ NMR spectroscopy. Technetium (I) chelation with 5, 6 and 7 was also studied via HPLC elutions using $[^{99m}Tc(CO)_3(OH_2)_3]^+$.

• Journal of Microbiology and Biotechnology
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• 제10권3호
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• pp.394-398
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• 2000

A methanol extract of the root of Peucedanum japonicum, used as a medicinal herb, showed an inhibitory effect on mammalian topoisomerase I activity. The methanol extract was suspended in ethyl acetate, and a topoisomerase I inhibitor in the organic soluble fraction was then isolated by silica gel and thin layer chromatography. The topoisomerase I inhibitory compound was indentified as falcarindiol based on the analysis of EI-MS, $^1$H and \ulcornerC NMR spectroscopy. This inhibitory showed cytotoxicity against human leukemia Jurkat T and HL60 cells with an IC\ulcorner value of 7 $\mu\textrm{g}$/ml. These results suggest the possibility of falcarindiol as a new anticancer agent which can be expected to have a synergistic effect on other anticancer drugs. In addition, the present data show that falcarindiol has antifungal, yet not antibacterial, activity.

• Preventive Nutrition and Food Science
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• 제3권4호
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• pp.315-319
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• 1998

Previously, the methanolic extract of Paeonia moutan seeds was found to potently inhibit soybean lipoxy-genase (SLO). Hence to isolate SLO inhibitor, the defattd methaniolic extract of the seeds was consecutively partitioned wiht ether, ethyl acetate,n-butanol ,adn water. The ether souble fraction showing strong inhibitory activity against SLO was further fractionated into a strongly acidic, a weakly acidic, and a neutral fractions. The strongly acidic components of the ether extract were successively subjected to chromatography on a silica gel, Sephadex LH-20, and preparative HPLC. Four phenolic compounds were isolated , and twio of them showing a strong SLO inhibition activity were identified as luteolin (IC50=2.32$\mu\textrm{g}$/ml) and 5,6,4'-trihydroxy-7,3'- dimethoxylflavone (IC50=0.31$\mu\textrm{g}$/ml) by UV, IR, 1H-& 13C-NMR, and MS spectroscopy. In addition, two flavonoids showed significantly antioxidative activity as strong as that of of $\alpha$-tocopherol (p<0.05) in the autoxidation system of linoleic acid. These results suggest that luteolin and 5,6,4'-trihydroxy-7,3'-dimethoxy-flavone may be used as a potential source of anti-inflammatory agents with antioxidative activity.

• 폴리머
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• 제32권4호
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• pp.305-312
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• 2008

A novel TPC-PEG-TPC with active end-groups was obtained from the end-groups of polyethylene glycol (PEG) modified by terephthaloyl chloride (TPC). These active end-groups can link up with a rare earth ion, which is a luminescent center of a rare earth fluorescent complex. Complexes of Eu-PEG with novel ligands (TPC-PEG-PTC) were synthesized by the coordination of the active reactant (as the first ligand) and phenanthroline (as the second ligand) with $Eu^{3+}$.IR, $^1H$-NMR, element analysis, DSC, WAXD, fluorescent spectroscopy, TGA, and SEM were used to characterize the structure and properties of these complexes. The results showed that this type of complex is a heat storage material with the phase change character of polyethylene glycol (PEG) and the luminescent properties of europium. There was no thermal decomposition of the complex of Eu-PEG until $300^{\circ}C$. SEM showed that the complex of Eu-PEG can be dispersed in PE.