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- 검색키워드
- 저자 : ( Daham Jeong ) (검색결과 20 건)
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Jeong, Daham,Joo, Sang-Woo,Hu, Yiluo,Shinde, Vijay Vilas,Cho, Eunae,Jung, Seunho Elsevier 2018 European polymer journal Vol.105 No.-
<P><B>Abstract</B></P> <P>Carboxymethyl cellulose (CMC)-based hydrogels have superabsorbent properties but low mechanical strength. Variation of other hydrogel components might improve the mechanical strength, but has been occasionally seen to decrease the swelling and drug-loading capacity. To address these problems, we designed a dual-component system, consisting of both carboxymethyl β-cyclodextrin (cmβCD) and CMC. We synthesized the hydrogels by crosslinking βCD or cmβCD with both cellulose (CEL) and CMC to evaluate their intrinsic mechanical strength and swelling capacity. The characteristic structure and morphology of each hydrogel was determined by Fourier- transform infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy, and field emission scanning electron microscopy. The storage modulus of the cmβCD/CMC gel was nearly eight-fold higher than that of the CMC gel only in rheology tests; the compressive strength was also enhanced while still retaining high swelling ability. We also investigated the drug-loading capacity and subsequent release properties, using tetracycline as a drug model. The cmβCD/CMC hydrogels showed the most effective tetracycline-loading capacity with the highest antibacterial activity among all hydrogels. They also showed the highest mechanical strength and the best drug release properties apart from the appreciable swelling capacity. Furthermore, cmβCD/CMC hydrogels are non-cytotoxic towards human dermal fibroblasts, suggesting their safe use as nontoxic, bio-friendly, and effective drug delivery systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The superabsorbent CMC-based hydrogel containing cmβCD was successfully synthesized. </LI> <LI> The storage modulus of cmβCD/CMC gel was about eight-fold higher than CMC gel. </LI> <LI> The cmβCD/CMC gel obtained displayed high performance in compressive strength. </LI> <LI> The cmβCD/CMC-based hydrogel enhanced the drug-loading capacity due to complexation. </LI> <LI> The cmβCD/CMC gel has non-cytotoxicity on human dermal fibroblast cell. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Jeong, Daham,Joo, Sang-Woo,Shinde, Vijay Vilas,Jung, Seunho Elsevier 2018 Carbohydrate Polymers Vol.198 No.-
<P><B>Abstract</B></P> <P>A novel self-healing hydrogel was prepared from a cationic β-cyclodextrin oligomer allyl ether [C(βCD−OM)AE] using a triple cross-linking strategy combining electrostatic interaction, host–guest complexation, and CC bonds as the macrocrosslinker. Here, the C(βCD−OM)AE@Ad gel was successfully prepared by polymerization of synthesized C(βCD−OM)AE, 1-adamantyl acrylate, and acrylic acid. The triple cross-linked hydrogel shows multi-functionality of high mechanical strength, enhanced stability, cytocompatibility, pH responsiveness as well as self-healing ability. Based on the cooperative and synergetic forces of non-covalent and covalent bonds, the C(βCD−OM)AE@Ad gel shows a high tensile strain up to 1,590%, and the self-healed gel could restore up to 84% of its initial length within 24 h. Furthermore, drug release in the hydrogel was controlled by the surrounding pH and slowly released. The present work reveals the cooperativity of multiple cross-links for a 3D structured polymeric material, and the developed self-healable hydrogel can possibly be applied in various biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Triple cross-linked cationic βCD oligomer allyl ether hydrogel was newly synthesized. </LI> <LI> That hydrogel was composed of CC bonds, ionic bonds and host-guest interactions. </LI> <LI> That hydrogel showed the self-healing ability as well as high mechanical strength. </LI> <LI> That self-healing ability was restored up to 84% of its initial length within 24 h. </LI> <LI> That self-healing hydrogel also showed the pH-dependent drug release profile. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Biosourced cyclosophoraose-driven acceleration of click reaction in H<sub>2</sub>O
Cho, Eunae,Jeong, Daham,Dindulkar, Someshwar D.,Jung, Seunho THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.59 No.-
<P><B>Abstract</B></P> <P>Here, we report biosourced cyclosophoraose (CyS)-promoted click reaction of organic azides and alkynes in water, where CyS, rhizobial cyclic β-1,2 glucan molecules containing 17–23 glucoses, dramatically decreased the reaction time from hours to minutes <I>via</I> the solubilization of aromatic alkynes. This catalytic system was successfully applied to the copper-mediated Huisgen 1,3-dipolar cycloaddition reaction using <I>in situ</I>-generated azide. The developed strategy yielded 1,4-disubstituted-1,2,3-triazoles after a short reaction time without bases from a room-temperature aqueous medium, and the products were purified simply by precipitation without requiring further column purifications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A facile synthetic strategy of 1,4-disubstituted-1,2,3-triazoles in H<SUB>2</SUB>O is reported. </LI> <LI> Cyclosophoraoses purified from <I>Rhizobium</I> species promoted the click reaction of azide and alkyne in water. </LI> <LI> The supramolecular catalytic system provides a simple, workup-free, and green catalytic platform for aqueous click reaction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Properties and current applications of bacterial cyclic β-glucans and their derivatives
Cho, Eunae,Jeong, Daham,Choi, Youngjin,Jung, Seunho KLUWER ACADEMIC PUBLISHERS 2016 JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHE Vol. No.
<P>Cyclic beta-glucans are unique constituents that are found in the periplasmic space and extracellular media of Agrobacterium, Rhizobium, Bradyrhizobium, Rhodobacter, Xanthomonas, and Ralstonia species. Based on their glycosidic linkages, they are classified into three groups composed of cyclic beta-(1,2), beta-(1,3)-beta-(1,6), and beta-(1,2)-alpha-(1,6) linked glucans. Their degrees of polymerization vary ranging from 10 to 40 glucose residues, and the backbone structure can be modified with non-sugar moieties. Since the macrocyclic oligosaccharides possess their own characteristics such as inherent three-dimensional structures, hydrogen bonding, and complex-forming abilities, various possible applications would be of interest in the field of green chemistry, separation science, pharmaceutical, and food industries. In this review, we have addressed the properties and current applications of bio-sourced cyclic beta-glucans and their derivatives.</P>
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Cho, Eunae,Jeong, Daham,Paik, Hyun-Dong,Jung, Seunho Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.8
Dimeric ${\beta}$-cyclodextrin linked by a thioether bridge was synthesized from a reaction of mono-6-iodo-6-deoxy-${\beta}$-cyclodextrin with sodium sulfide, and the structure was analyzed using nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The effects of thioether-bridged dimeric ${\beta}$-CD on the aqueous solubility of flavonols (myricetin, quercetin, and kaempferol) were investigated by ultraviolet-visible spectroscopy. The aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 33.6-, 12.4-, and 10.5-fold following the addition of 9 mM of thioether-bridged dimeric ${\beta}$-CD. In comparison, the aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 5.4-, 3.3-, and 2.7-fold using the same concentration of monomeric ${\beta}$-cyclodextrin. Furthermore, the formation of flavonol/thioether-bridged dimeric ${\beta}$-CD inclusion complexes was confirmed with nuclear magnetic resonance, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The results showed that the nature of the complexes significantly differed from that of free flavonols. Herein, we suggest that the thioether-bridged dimeric ${\beta}$-CD can act as an effective complexing agent for flavonols.
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Dindulkar, Someshwar D.,Jeong, Daham,Cho, Eunae,Kim, Dongjin,Jung, Seunho The Royal Society of Chemistry 2016 GREEN CHEMISTRY Vol.18 No.12
<P>As a novel biosourced saccharide catalyst, microbial cyclosophoraose, a cyclic beta-(1,2) glucan, was used for the synthesis of therapeutically important versatile indolyl 4H-chromenes via a one pot three-component Knoevenagel-Michael addition-cyclization reaction of salicylaldehyde, 1,3-cyclohexanedione/ dimedone, and indoles in water under neutral conditions. A possible reaction mechanism through molecular complexation is suggested based on 2D ROESY NMR spectroscopic analysis. Moreover, green chemistry metric calculations were carried out for a model reaction, indicating the satisfactory greener approach of this method, with a low E-factor (0.18) and high atom economy (AE = 91.20%). The key features of this protocol are based on two critical factors where the first is to use a novel eco-friendly supramolecular carbohydrate catalyst and the second is its fine green properties such as compatibility with various substituted reactants, recyclability of the catalyst, chromatography-free purification, high product selectivity, and clean conversion with moderate to excellent yields in an aqueous medium.</P>
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Tahir, Muhammad Nazir,Jeong, Daham,Kim, Hwanhee,Yu, Jae-Hyuk,Cho, Eunae,Jung, Seunho Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.1
Glass discs functionalized with alkynyl (GDA) terminated monolayers were prepared and incubated in $AgNO_3$ solution (GDA-Ag). The modified functional glass surfaces were characterized by X-ray photoelectron microscopy (XPS). The potential of GDA and GDA-Ag as antimicrobial surfaces was investigated. Anti-microbial efficacies of GDA against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Candida albicans was relatively low ranging from 4.67 to 17.00%. However, the GDA-Ag was very effective and its antimicrobial efficacy ranged from 99.90 to 99.99% against the same set of microbial strains except for C. albicans where it was 95.50%. The durability of the Ag bonded to the terminal alkynyl groups was studied by placing the GDA-Ag in PBS buffer solution (pH 7.4) for two weeks. Initially, the silver release was relatively fast, with 40.05 ppb of silver released in first 24 h followed by a very slow and constant release. To study the potential of GDA-Ag for medical applications, in vitro cytotoxicity of GDA-Ag against Human Embryonic Kidney 293 (HEK293) cell lines was studied using WST-assay. The cytotoxicity of the GDA-Ag was very low (5%) and was almost comparable to the control (blank glass disc) indicating that GDA-Ag has a promising potential for medical applications.
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Shinde, Vijay Vilas,Jeong, Daham,Jung, Seunho THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 Journal of Industrial and Engineering Chemistry Vol.68 No.-
<P><B>Abstract</B></P> <P>Well-modified amino-appended β-cyclodextrin (AA-β-CD) with an amino group at the primary face of the β-CD was synthesized and used in the catalytic synthesis of chromeno pyrimido[1,2-b]indazol as supramolecular catalysts in water for the first time. AA-β-CD was characterized by FT-IR, NMR, MALDI-TOF mass spectrometry, and SEM analysis. A possible reaction mechanism featuring molecular complexation was suggested based on 2D NMR (ROESY) spectroscopy, FE-SEM, DSC, and FT-IR. Advantages such as operational simplicity, recyclability of the catalysts, and accessibility in aqueous medium render this protocol eco-friendly.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amino-appended β-cyclodextrin (AA-β-CD) as a supramolecular organic base catalyst were synthesized. </LI> <LI> AA-β-CD catalyzed the synthesis of chromeno pyrimido[1,2-b]indazol derivatives. </LI> <LI> AA-β-CD as a catalyst can be easily recovered and reused. </LI> <LI> Reaction mechanism was elucidated extensively by spectroscopic analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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