Publications by authors named "Kyung Do Suh"

21 Publications

  • Page 1 of 1

Ultraviolet photodetector using pn junction formed by transferrable hollow n-TiO nano-spheres monolayer.

Opt Express 2017 Dec;25(25):30843-30850

We report an ultraviolet (UV) photodetector with a universally transferable monolayer film with ordered hollow TiO spheres on p-GaN. After forming a TiO monolayer film by unidirectional rubbing of hollow TiO spheres on a polydimethylsiloxane (PDMS) supporting plate, we used a 5% polyvinyl alcohol (PVA) aqueous solution to transfer the film onto the target substrate. The PVA/TiO monolayer film was detached from the PDMS film and transferred to the p-GaN/AlO substrate. To investigate the effects of crystallized phases of the TiO hollow spheres, anatase and rutile TiO sphere monolayers prepared by combining template synthesis and thermal treatment. The responsiveness of the UV photodetectors using anatase and rutile hollow n-TiO monolayer/p-GaN was 0.203 A/W at 312 nm and 0.093 A/W at 327 nm, respectively.
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http://dx.doi.org/10.1364/OE.25.030843DOI Listing
December 2017

Correction: Highly lithium-ion conductive battery separators from thermally rearranged polybenzoxazole.

Chem Commun (Camb) 2015 Feb;51(16):3474

School of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Korea.

Correction for 'Highly lithium-ion conductive battery separators from thermally rearranged polybenzoxazole' by Moon Joo Lee et al., Chem. Commun., 2015, 51, 2068-2071.
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http://dx.doi.org/10.1039/c5cc90064fDOI Listing
February 2015

Highly lithium-ion conductive battery separators from thermally rearranged polybenzoxazole.

Chem Commun (Camb) 2015 Feb;51(11):2068-71

School of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Korea.

High power density lithium ion battery (HLIB) separators were fabricated for the first time from thermally rearranged poly(benzoxazole-co-imide) (TR-PBOI) nanofibrous membranes coated with TR-PBOI nanoparticles, which show distinct thermal and dimensional stabilities as well as excellent cycle retention and rate capability.
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http://dx.doi.org/10.1039/c4cc09411eDOI Listing
February 2015

Method for detecting the reactivity of chemicals towards peptides as an alternative test method for assessing skin sensitization potential.

Toxicol Lett 2014 Feb 19;225(1):185-91. Epub 2013 Dec 19.

AmorePacific Corporation R&D Unit, Yongin-si, Republic of Korea. Electronic address:

Cosmetics are normally composed of various ingredients. Some cosmetic ingredients can act as chemical haptens reacting toward proteins or peptides of human skin and they can provoke an immunologic reaction, called as skin sensitization. This haptenation process is very important step of inducing skin sensitization and evaluating the sensitizing potentials of cosmetic ingredients is very important for consumer safety. Therefore, animal alternative methods focusing on monitoring haptenation potential are undergoing vigorous research. To examine the further usefulness of spectrophotometric methods to monitor reactivity of chemicals toward peptides for cosmetic ingredients. Forty chemicals (25 sensitizers and 15 non-sensitizers) were reacted with 2 synthetic peptides, e.g., the cysteine peptides (Ac-RFAACAA-COOH) with free thiol group and the lysine peptides (Ac-RFAAKAA-COOH) with free amine group. Unreacted peptides can be detected after incubating with 5,5'-dithiobis-2-nitrobenzoic acid or fluorescamine™ as detection reagents for free thiol and amine group, respectively. Chemicals were categorized as sensitizers when they induced more than 10% depletion of cysteine peptides or more than 30% depletion of lysine peptides. The sensitivity, specificity, and accuracy were 80.0%, 86.7% and 82.5%, respectively. These results demonstrate that spectrophotometric methods can be an easy, fast, and high-throughput screening tools predicting the skin sensitization potential of chemical including cosmetic ingredient.
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http://dx.doi.org/10.1016/j.toxlet.2013.12.007DOI Listing
February 2014

One-pot template-free synthesis of monodisperse hollow hydrogel microspheres and their resulting properties.

Macromol Rapid Commun 2013 Aug 9;34(15):1243-8. Epub 2013 Jul 9.

Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791, Republic of Korea.

Monodisperse poly(methacrylic acid/ethyleneglycoldimethacrylate) (MAA/EGDMA) hollow microcapsules, which exhibit pH-responsive behavior, are prepared by diffusion of cationic surfactants and hydrophobic interaction. During the association of the negatively charged hydrogel microspheres and an oppositely charged surfactant (cetyltrimethylammonium bromide, CTA(+)B), the hydrophobic polymer-surfactant complexes that form are separated from the internal water; consequently, a hollow structure can be formed. Confocal laser scanning microscopy, UV spectro-scopy and zeta potential are employed to study the formation of the hollow structure during the diffusion of the cationic surfactant. The controlled release behavior of methylene blue as a model drug from the as-prepared poly(MAA/EGDMA) microcapsules with a hollow structure is investigated under different pH conditions. The hollow structure can be retained, even during repetitive pH changes.
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http://dx.doi.org/10.1002/marc.201300330DOI Listing
August 2013

Biofilm-forming ability of Staphylococcus aureus strains isolated from human skin.

J Dermatol Sci 2013 Aug 17;71(2):130-7. Epub 2013 Apr 17.

Amore-Pacific Co. R&D Center 314-1, Bora-dong, Giheung-gu, Yongin-si, Gyeonggi-Do 446-729, Republic of Korea.

Background: Staphylococcus aureus produces various toxins and enzymes, and its presence can exacerbate skin conditions. Previous studies have shown that S. aureus is involved in skin deterioration, even in normal tissue. Biofilm strains show much greater resistance to antimicrobial agents and therefore require a much higher concentration of biocide than planktonic counterparts.

Objective: As such, alternative strategies and more effective therapeutic agents against biofilm-producing S. aureus in skin are of great interest. Therefore, we turned our attention to differences in 50 clinical biofilm strains isolated from human facial skin.

Methods: Based on S. aureus density on facial skin, we divided donors into two groups: relatively low density (LSG) and high density (HSG). In general, strong biofilm-forming strains were detected in the HSG donors. Two strains from each of the groups were submitted to gene microarray analysis to investigate expression differences and confirmed by RT-PCR.

Results: In total, 111 of 7775 genes were differentially expressed between low (SA2 and SA7) vs. high (SA10 and SA33) biofilm-forming clinical strains. These genes include already well-known as biofilm formation related genes like icaABCD and lrgAB, and newly identified genes (sdrC, sspBCP) by RT-PCR. Comparison of gene expression differences between the two groups available at NCBI Gene Expression Omnibus accession number GSE44268.

Conclusion: Our results suggest that S. aureus density in the skin is closely related to biofilm-forming ability, and we have identified several potential target genes that may be involved in regulating biofilm formation in situ.
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http://dx.doi.org/10.1016/j.jdermsci.2013.04.004DOI Listing
August 2013

Depigmenting activities of kojic acid derivatives without tyrosinase inhibitory activities.

Bioorg Med Chem Lett 2012 Jun 16;22(12):4159-62. Epub 2012 Apr 16.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

We synthesized benzoate ester derivatives of kojic acid with and without adamantane moiety. Benzoate derivatives 2a-e that did not contain an adamantane moiety showed potent tyrosinase inhibitory activities. However, depigmenting activity was not noted in a cell-based assay. Contrasting results were obtained for benzoate derivatives (3a-e) containing an adamantane moiety. Compounds 3a-e showed potent depigmenting activities without tyrosinase inhibitory activities. To the best of our knowledge, this is the first study showing the depigmenting activities of kojic acid derivatives without tyrosinase inhibitory activities.
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http://dx.doi.org/10.1016/j.bmcl.2012.04.046DOI Listing
June 2012

Monodisperse conducting colloidal dipoles with symmetric dimer structure for enhancing electrorheology properties.

J Colloid Interface Sci 2012 May 4;374(1):18-24. Epub 2012 Feb 4.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

This study introduces an electrorheological (ER) approach that allows us to obtain remarkably enhanced ER properties by using monodisperse colloidal dimer particles. Two sets of colloidal particles, which are spheres and symmetric dimers, were synthesized employing the seeded polymerization technique. The aspect ratio of dimer particles was ~1.43. Then, the surface of the particles was coated with polyaniline by using the chemically oxidative polymerization method. After preparation of the particle suspensions having the same particle volume and concentration, their ER behavior was investigated with changing the electric field strength. At the same experimental condition, both shear stress and shear yield stress of the dimer particle suspension remarkably increased, compared with those of the spherical particle suspension. This attributes to the fact that the shape anisotropy of suspending particles effectively led to increase in the dipole moment under the electric field, thus resulting in formation of a well-structured colloidal chains between the electrodes.
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http://dx.doi.org/10.1016/j.jcis.2012.01.055DOI Listing
May 2012

Depigmenting activity of new kojic acid derivative obtained as a side product in the synthesis of cinnamate of kojic acid.

Bioorg Med Chem Lett 2012 Mar 21;22(5):2004-7. Epub 2012 Jan 21.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

We synthesized cinnamate derivatives of kojic acid for use as depigmenting agents by various esterification methods. The cinnamate of 5-position of kojic acid (6) was obtained by EDC coupling, DCC coupling, acid chloride, and mixed anhydride methods. To obtain the cinnamate of the 2-position of kojic acid (7), we carried out the nucleophilic addition of the potassium salt of cinnamic acid to kojyl chloride. In this reaction, we discovered the occurrence of a side reaction and identified the structure of the side product thus formed. We evaluated the depigmenting activities of both the side product and the cinnamate derivatives of kojic acid. Interestingly, the side product (11) showed more potent depigmenting activity (IC(50)=23.51μM) than compound 7 (IC(50)>100μM) which is the mother compound of the side product. However, it has no tyrosinase inhibitory activity. Compound 6, the cinnamate of 5-position of kojic acid, also showed moderate depigmenting activity (IC(50)=46.64μM) without tyrosinase inhibitory activity. Production of this side product (11) may have originated from the proton exchange between the potassium salt of cinnamic acid and kojyl chloride. We then efficiently reduced the yield of the side product by controlling the equilibrium of the potassium salt of cinnamic acid. The addition of cinnamic acid greatly reduced the amount of the side product produced.
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http://dx.doi.org/10.1016/j.bmcl.2012.01.032DOI Listing
March 2012

Discrete dipole moments and enhanced electro-rheological properties of dumbbell-shaped, non-spherical particles.

Macromol Rapid Commun 2010 Nov 20;31(22):1987-91. Epub 2010 Sep 20.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

In this study, uniform dumbbell-shaped non-spherical particles are produced by seeded polymerization, and the electro-rheological (ER) properties are compared to those of spherical-shaped particles after surface coating with functionalized multiwall carbon nanotubes (f-MWCNTs). The non-spherical particles formed linear chains under an applied electric field. The yield stress of the non-spherical particles is five-times as high as that of the spherical particles. The enhanced ER properties of the dumbbell-shaped non-spherical particles are attributed to the discrete dipole moments, which are found to depend on the morphology.
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http://dx.doi.org/10.1002/marc.201000302DOI Listing
November 2010

A facile process for generating monolithic-structured nano-silica/polystyrene multi-core/shell microspheres by a seeded sol-gel process method.

J Colloid Interface Sci 2010 Oct 11;350(2):581-5. Epub 2010 Jul 11.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

Monodisperse "monolithic-structured" organic-inorganic composite microspheres were produced by a seeded sol-gel process method. A large number of nano-silica particles were generated and dispersed in the inner domains of the obtained microspheres. Seed particles were prepared by dispersion co-polymerization of styrene and (trimethoxysilyl)propyl 2-methylprop-2-enoate (TMSPM). The seed particles were swollen with an emulsified tetraethoxysilane (TEOS) in 0.25 wt.% sodium dodecylsulfate (SDS) aqueous solutions. Then the sol-gel reaction was conducted with ammonium hydroxide after completion of the swelling process. In contrast to conventional methods, the sol-gel reaction occurred in the inner space of the prepared template particles and monolithic-structured nano-silica and polystyrene organic-inorganic composite microspheres were obtained. The synthetic procedure for composite particles was studied by utilizing transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and thermo-gravimetric analysis (TGA).
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http://dx.doi.org/10.1016/j.jcis.2010.07.006DOI Listing
October 2010

The design of polymer-based nanocarriers for effective transdermal delivery.

Macromol Biosci 2010 Oct;10(10):1171-6

School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea.

This study reports a facile and practical means to non-invasively deliver biologically active ingredients through the skin using polymer-based nanocarriers. For this, polymer nanocapsules were fabricated with different surface charges as well as glass transition temperatures and we observed their ability to deliver the encapsulated active ingredient, coenzyme Q10, through the skin layer. Direct imaging of a probe molecule, Nile Red, and a matrix polymer labeled with fluorescence moiety, Lucifer Yellow, allowed us to demonstrate that the probe molecule readily permeates into the deep skin, while the matrix polymer stays in the stratum corneum layer due to electrostatic interactions. Quantitative characterization of the penetrating amount of coenzyme Q10 using the Frantz cell method proved that, to achieve improved delivery efficiency, the nanocapsule should have a low glass transition temperature as well as positive surface charges.
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http://dx.doi.org/10.1002/mabi.201000097DOI Listing
October 2010

Fabrication and characterization of pseudo-ceramide-based liposomal membranes.

Colloids Surf B Biointerfaces 2009 Oct 27;73(2):207-11. Epub 2009 May 27.

Amore-Pacific Co R&D Center, Yongin-si, Gyeonggi-Do 446-729, Republic of Korea.

We present a facile and straightforward method to fabricate liposomal membranes with a significantly stable lamellar structure consisting of pseudo-ceramide, fatty acid, and cholesterol. Characterizing their membrane properties, in which we have used differential scanning calorimetry, X-ray diffraction, and FT-IR spectra, enables us to demonstrate that pseudo-ceramide with appropriate amounts of stearic acid and cholesterol can assemble to form a stable lamellar alpha-phase. Moreover, we show that cholesterol is indeed important and plays a role in controlling the melting entropy of lipid membranes, which is attributed to a disordered molecular packing, thus creating more flexible liposomal membranes. This approach to use pseudo-ceramide offers a useful means to fabricate a variety of biocompatible liposomes with controllable membrane properties, which enlarges their applicability in the field of drug delivery, dermatology, and cosmetics.
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http://dx.doi.org/10.1016/j.colsurfb.2009.05.019DOI Listing
October 2009

Control over micro-fluidity of liposomal membranes by hybridizing metal nanoparticles.

Colloids Surf B Biointerfaces 2009 Apr 25;70(1):108-13. Epub 2008 Dec 25.

Amore-Pacific Co. R&D Center, 314-1, Bora-dong, Giheung-gu, Yongin-si, Gyeonggi-Do, 446-729, South Korea.

This study introduces a facile method to hybridize metal nanoparticles with lipid vesicles, which allows us to control over their membrane micro-fluidity. We have fabricated these hybrid liposomes by directly hybridizing metal nanoparticles with lipid bilayers solely consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC). For this, we have used the dehydration and rehydration method. Characterizing their morphology and micro-fluidity, in which we have used electron microscopy and fluorescence anisotropy spectroscopy, enables us to demonstrate that metal nanoparticles with different surface properties create interactions with either phosphorus end groups or hydrophobic tails of DPPC, thereby resulting in decrease in micro-fluidity of the assembled lipid membranes, especially for the hydrophobic layers. Our approach to hybridize metal nanoparticles in between lipid layers offers a flexible means that allows us to obtain a liposome system with more controllable membrane properties.
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http://dx.doi.org/10.1016/j.colsurfb.2008.12.024DOI Listing
April 2009

Electrorheological properties of carbon nanotube/ polyelectrolyte composite silica nanoparticles by layer-by-layer self-assembly.

J Nanosci Nanotechnol 2008 Aug;8(8):3895-9

Division of Inorganic Chemistry Exam, Bureau of Chemistry and Biotechnology Exam, Korean Intellectual Property Office (KIPO), Daejeon 302-701, South Korea.

Multiwall carbon nanotubes (MCNTs)/silica (SiO2) composite particles were prepared by layer-by-layer (LbL) self-assembly method using polyelectrolytes and functionalized MCNTs (fMCNTs). The fMCNTs prepared by chemical oxidation method were incorporated on the outermost layer of polyelectrolyte-coated SiO2 particles. The amount of fMCNTs was varied by LbL self assembly. In the process the number of fMCNT layers on SiO2 particles could be controlled. The fMCNT-coated SiO2 particles were characterized by zeta-potential analysis, transmission electron microscopy (TEM), and optical microscopy (OM). In addition, the electrorheological (ER) properties of multilayers containing fMCNTs on silica particles were investigated under controlled electric fields. The ER properties of the composite particles were influenced by the amount of fMCNTs in multilayers.
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http://dx.doi.org/10.1166/jnn.2008.203DOI Listing
August 2008

A facile approach to synthesize uniform hydrogel shells with controllable loading and releasing properties.

Chem Commun (Camb) 2008 Feb 21(8):984-6. Epub 2008 Jan 21.

Division of Chemical Engineering, College of Engineering, Hanyang University, Seoul 133-791, Republic of Korea.

We present a facile and straightforward method to synthesize uniform poly(vinyl amine) hydrogel shells with excellent loading capability for active materials and controllable responsiveness to applied stimuli, providing tunable releasing properties.
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http://dx.doi.org/10.1039/b715557cDOI Listing
February 2008

Quantitative characterization of degradation behaviors of antioxidants stabilized in lipid particles.

Talanta 2007 Mar 4;71(5):2129-33. Epub 2006 Oct 4.

Amore-Pacific Co. R&D Center, 314-1, Bora-dong, Giheung-gu, Yongin-si, Gyeonggi-do 449-729, South Korea.

This study describes a flexible approach that allows us to characterize the long-term stability of antioxidants by using a thermodynamically extended Arrhenius equation. We use retinol, Vitamin A, as a model antioxidant and its degradation behaviors are characterized for both stabilized and non-stabilized systems; in this study, by using a fluid bed technique, we immobilize the retinol in lipid particles, thus increasing its thermal stability in complex formulations, such as aqueous polymer gels and emulsions. Our approach demonstrates that the degradation behaviors of the retinol show a functional relationship with temperature and time, which makes it possible to use the Arrhenius approach. This result allows us to precisely characterize the stability of antioxidants in complex formulations for long time.
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http://dx.doi.org/10.1016/j.talanta.2006.09.006DOI Listing
March 2007

Bidisperse electrorheological fluids using hydrolyzed styrene-acrylonitrile copolymer particles: synergistic effect of mixed particle size.

Langmuir 2004 Mar;20(6):2429-34

College of Engineering, Hanyang University, Seoul 133-791, South Korea.

Monodisperse micron-sized styrene-acrylonitrile copolymer (SAN) particles with three different sizes (about 5, 10, and 15 microm) were prepared by a two-step seeded polymerization and used for a study of bidisperse electrorheological (ER) suspensions. The effect of the particle size and the size-mixing fraction on ER properties was studied with varying the size of these monodisperse copolymer particles. When the two particle sizes were mixed, the suspension generally showed a decrease in the shear yield stress, reaching a minimum value. However, a bidisperse ER suspension of large particles containing a small fraction of fine particles showed an interesting synergy effect of size mixing on ER response, giving enhanced yield stresses over the other size-mixing fractions. This synergistic ER suspension also showed a great increase in the viscoelastic property. The current density of suspensions was maximum at the synergistic bidisperse suspension. This synergy effect in a particular bidisperse suspension was investigated in view of the structure model consideration and was concluded to be due to a close packing and a peculiar structural ordering at an optimum size ratio and mixing fraction.
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http://dx.doi.org/10.1021/la030248cDOI Listing
March 2004

The stabilization of L-ascorbic acid in aqueous solution and water-in-oil-in-water double emulsion by controlling pH and electrolyte concentration.

J Cosmet Sci 2004 Jan-Feb;55(1):1-12

Amore Pacific Corporation R&D Center, 314-1 Bora-ri, Giheung-eup, Yongin-si, Gyeonggi-do 449-729, Korea.

This study presents a new approach that can stabilize effectively L-ascorbic acid in water-in-oil-in-water (w/o/w) double emulsions. Basically, the behavior of L-ascorbic acid in the aqueous phase was observed, considering its molecular deformation. Then, it was found that the stability determined in the aqueous phase by high-performance liquid chromatography (HPLC) showed that the collapse of ionization of L-ascorbic acid played a crucial role in protecting the molecular deformation. Then, the stable aqueous system was incorporated into the internal aqueous phase of the double emulsions. From the HPLC analysis, it was observed that the L-ascorbic acid in an appropriate system showed high molecular stability for a long time. Moreover, in the measurement of in vitro skin permeation, the L-ascorbic acid stabilized in this study showed considerable skin permeation ability, indicating its potential applicability in pharmaceutics and cosmetics.
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May 2004

Nano-structured biphasic polymer film on the hair surface from PEGylated polymer latexes.

J Cosmet Sci 2003 Nov-Dec;54(6):569-77

Amore-Pacific R&D Center, 314-1, Bora-ri, Giheung-eup, Yongin-si, Gyeonggi-do 449-726, South Korea.

In this study, biphasic polymer latexes were synthesized by surfactant-free-emulsion polymerization of butyl methacrylate, poly(ethylene glycol) methyl ether methacrylate, and 2-(methacryloyloxy) ethyl trimethyl ammonium chloride. The latexes synthesized were composed of hydrophobic core phase and hydrophilic shell phase. Nano-structured film morphology could be obtained by annealing the biphasic polymer latexes between the two transition temperatures. It was found that the unique film morphology gave a viscoelastic property to the film. Scanning electron microscope and atomic force microscope images revealed that the biphasic polymer latexes deposited effectively onto the entire hair surface upon conditioning with 1 wt% polymer concentration in water. Consequently, they formed a smooth polymer membrane thereon, showing a high potential for a new hair cosmetic ingredient.
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March 2004