• Korean Journal of Microbiology
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• v.47 no.4
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• pp.348-355
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• 2011

Staphylococcus aureus is a major human pathogen that is associated with various types of local and systemic infection. Staphylococcal protin A (SPA), a highly expressed surface component of S. aureus, may have a role in virulence such as activating inflammation and interfering with immune clearance. We examined the effect of recombinant SPA on inflammatory response in human HaCaT keratinocytes. The recombinant SPA protein was prepared using the pET-28a Vector System in Escherichia coli. The expression of pro-inflammatory related adhesion molecules and cytokines in HaCaT cells incubated for 6, 12, and 24 h with SPA (2 ${\mu}g$/ml) was analyzed by comparative RT-PCR or ELISA. The expression of E-selectin, ICAM-1, MCP-1, IL-6 and IL-8 was significantly increased in HaCaT from 6 to 24 h after treatment with SPA. SPA showed the effect on the adhesion-promoting ability of U937 monocytes to HaCaT cells. Our data demonstrate that SPA stimulates inflammatory response of HaCaT cells, implicating an important factor for exacerbation of skin inflammation of immunologic disease.

• Journal of Periodontal and Implant Science
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• v.42 no.3
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• pp.81-87
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• 2012

Purpose: The characteristics of oxidized titanium (Ti) surfaces varied according to treatment conditions such as duration time and temperature. Thermal oxidation can change Ti surface characteristics, which affect many cellular responses such as cell adhesion, proliferation, and differentiation. Thus, this study was conducted to evaluate the surface characteristics and cell response of thermally treated Ti surfaces. Methods: The samples were divided into 4 groups. Control: machined smooth titanium (Ti-S) was untreated. Group I: Ti-S was treated in a furnace at $300^{\circ}C$ for 30 minutes. Group II: Ti-S was treated at $500^{\circ}C$ for 30 minutes. Group III: Ti-S was treated at $750^{\circ}C$ for 30 minutes. A scanning electron microscope, atomic force microscope, and X-ray diffraction were used to assess surface characteristics and chemical composition. The water contact angle and surface energy were measured to assess physical properties. Results: The titanium dioxide ($TiO_2$) thickness increased as the treatment temperature increased. Additional peaks belonging to rutile $TiO_2$ were only found in group III. The contact angle in group III was significantly lower than any of the other groups. The surface energy significantly increased as the treatment temperature increased, especially in group III. In the 3-(4,5-Dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide assay, after 24 hours of incubation, the assessment of cell viability showed that the optical density of the control had a higher tendency than any other group, but there was no significant difference. However, the alkaline phosphatase activity increased as the temperature increased, especially in group III. Conclusions: Consequently, the surface characteristics and biocompatibility increased as the temperature increased. This indicates that surface modification by thermal treatment could be another useful method for medical and dental implants.

• Journal of the Korea Institute of Building Construction
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• v.16 no.2
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• pp.107-115
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• 2016

In this study, the bond strength of metal spraying system by surface treatment of concrete (waterproof/corrosion method) in water treatment facilities was evaluated. The results showed that the system with Sa-P-R-(S) (sanding-perviousness surface hardener-surface roughness agent-metal spraying-sealing) led to the desirable performance. The bond strength, the coefficient of water permeability and air permeability were 3.7MPa, $0.68{\ast}10^{-8}cm/sec$, and $0.45{\ast}10^{-16}m^2$, respectively. In scanning electron microscope analysis, the microstructure of specimen coated with perviousness surface hardener was much denser than that without it. Therefore, the specimen coated with sanding-perviousness surface hardener-surface roughness agent-metal spraying-sealing had the best bond performance and was the most suitable system to concrete surface in water treatment facilities.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.78-78
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• 2013

Recently, many platinoid metals like platinum and ruthenium have been used as an electrode of microelectronic devices because of their low resistivity and high work-function. However the material cost of Ru is very expensive and it usually takes long initial nucleation time on SiO2 during chemical deposition. Therefore many researchers have focused on how to enhance the initial growth rate on SiO2 surface. There are two methods to deposit Ru film with atomic layer deposition (ALD); the one is thermal ALD using dilute oxygen gas as a reactant, and the other is plasma enhanced ALD (PEALD) using NH3 plasma as a reactant. Generally, the film roughness of Ru film deposited by PEALD is smoother than that deposited by thermal ALD. However, the plasma is not favorable in the application of high aspect ratio structure. In this study, we used a bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a metal organic precursor for both thermal and plasma enhanced ALDs. In order to reduce initial nucleation time, we use several methods such as Ar plasma pre-treatment for PEALD and usage of sacrificial RuO2 under layer for thermal ALD. In case of PEALD, some of surface hydroxyls were removed from SiO2 substrate during the Ar plasma treatment. And relatively high surface nitrogen concentration after first NH3 plasma exposure step in ALD process was observed with in-situ Auger electron spectroscopy (AES). This means that surface amine filled the hydroxyl removed sites by the NH3 plasma. Surface amine played a role as a reduction site but not a nucleation site. Therefore, the precursor reduction was enhanced but the adhesion property was degraded. In case of thermal ALD, a Ru film was deposited from Ru precursors on the surface of RuO2 and the RuO2 film was reduced from RuO2/SiO2 interface to Ru during the deposition. The reduction process was controlled by oxygen partial pressure in ambient. Under high oxygen partial pressure, RuO2 was deposited on RuO2/SiO2, and under medium oxygen partial pressure, RuO2 was partially reduced and oxygen concentration in RuO2 film was decreased. Under low oxygen partial pressure, finally RuO2 was disappeared and about 3% of oxygen was remained. Usually rough surface was observed with longer initial nucleation time. However, the Ru deposited with reduction of RuO2 exhibits smooth surface and was deposited quickly because the sacrificial RuO2 has no initial nucleation time on SiO2 and played a role as a buffer layer between Ru and SiO2.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.3
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• pp.150-161
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• 2022

Purpose: To determine the effects of the microgroove-fibronectin complex surface on the expression of various genes related to cellular activity in human gingival fibroblasts. Materials and Methods: Smooth titanium specimens (NE0), acid-treated titanium specimens (E0), microgroove and acid-treated titanium specimens (E60/10), fibronectin-fixed smooth titanium specimens (NE0FN), acid-treated and fibronectin-immobilized titanium specimens (E0FN), and microgroove and acid-treated titanium specimens immobilized with fibronectin (E60/10FN) were prepared. Real-time polymerase chain reaction experiments were conducted on 44 genes related to cell behavior of human gingival fibroblasts. Results: Adhesion and proliferation of human gingival fibroblast on microgroove-fibronectin complex titanium were activated through four types of signaling pathway. Integrin α5, Integrin β1, Integrin β3, Talin-2, which belong to the focal adhesion pathway, AKT1, AKT2, NF-κB, which belong to the PI3K-AKT signaling pathway, MEK2, ERK1, ERK2, which belong to the MAPK signaling pathway, and Cyclin D1, CDK4, CDK6 genes belonging to the cell cycle signaling pathway were upregulated on the microgroove-fibronectin complex titanium surface (E60/10FN). Conclusion: The microgroove-fibronectin complex titanium surface can up-regulate various genes involved in cell behavior.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.257-261
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• 2008

Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.643-649
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• 2012

Coatings composited with alumina and Perfluoro alkoxyalkane (PFA) resin were deposited on stainless steel plate (SUS304) to further improve corrosion resistance. Plate (ca. $10{\mu}m$) and/or nanosize (27~43 nm) alumina used as inorganic additives were mixed in PFA resin to make alumina-fluoro composite coatings. These coatings were deposited on SUS304 plate with wet spray coating and then the film was cured thermally. According to the amount and ratio of the two kinds of alumina having plate morphology and nano size, corrosion resistance of the film was evaluated under strong acids (HF, HCl) and a strong base (NaOH). The film prepared with the addition of 5~10 wt% alumina powders in PFA resin showed corrosion resistance superior to that of pure PFA resin film. However, for the film prepared with alumina content above 10 wt%, the corrosion resistance did not improve with the physical properties, such as surface hardness and adhesion. The film prepared with plate/nanosize (weight ratio = 1/2) alumina especially enhanced the surface hardness and corrosion resistance. This can be explained as showing that the plate and the nanosize alumina dispersed in PFA resin effectively suppressed the penetration of cations and anions due to the long penetration length and fewer defects that accompany the improved surface hardness under a serious environment of 10% HF solution for over 120 hrs.

• Corrosion Science and Technology
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• v.12 no.1
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• pp.27-33
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• 2013

According to its merits about high curing speed and low emission of volatile organic compounds, UV curable inorganic-organic coating technology has been developed as an alternative for toxic and carcinogenic chromate-based treatments for years. It is consistently observed that ultra-thin films offer excellent corrosion protection as well as paint adhesion to metals. Based on the tetra-ethylorthosilicate(TEOS) and methacryloxypropyl trimethoxysilane(MPTMS), inorganic sol was synthesized and formed hybrid networks with UV curable acrylic monomer, 6-hexanediol diacrylate(HDDA), trimethylolpropane triacrylate(TMPTA), pentaerylthritol triacrylate(PETA). Several methods were used to test their properties such as salt spray test, potentiodynamic measurement, tape peel test, etc. It was shown that anti-corrosive property and stability of storage were affected by the molecular ratios of inorganic and organic compounds. It was not only the stability of storage, but had a excellent anti-corrosive, paint adhesive, and anti-solvent properties in a final molar ratios of 0.6/0.04/0.86/0.005 (TEOS/MPTMS/Acetone/HNO3) and 0.08/0.106/0.081/0.02 (TMPTA/HDDA/PETA/photo initiator).

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.378.2-378.2
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• 2016

Biosensors currently suffer from severe non-specific adsorption of proteins, which causes false positive errors in detection through overestimation of the affinity value. Overcoming this technical issue motivates our research. Polyethylene glycol (PEG) is well known for its ability to reduce the adsorption of biomolecules; hence, it is widely used in various areas of medicine and other biological fields. Likewise, amine functionalized surfaces are widely used for biochemical analysis, drug delivery, medical diagnostics and high throughput screening such as biochips. As a result, many coating techniques have been introduced, one of which is plasma polymerization - a powerful coating method due to its uniformity, homogeneity, mechanical and chemical stability, and excellent adhesion to any substrate. In our previous works, we successfully fabricated plasmapolymerized PEG (PP-PEG) films [1] and amine functionalized films [2] using the plasma enhanced chemical vapor deposition (PECVD) technique. In this research, an amine functionalized PP-PEG film was fabricated by using the plasma co-polymerization technique with PEG 200 and ethylenediamine (EDA) as co-precursors. A biocompatible amine functionalized film was surface characterized by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The density of the surface amine functional groups was carried out by quantitative analysis using UV-visible spectroscopy. We found through surface plasmon resonance (SPR) analysis that non-specific protein adsorption was drastically reduced on amine functionalized PP-PEG films. Our functionalized PP-PEG films show considerable potential for biotechnological applications such as biosensors.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.51.2-51.2
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• 2015

Understanding interfacial phenomena has been one of the main research issues not only in semiconductors but only in life sciences. I have been trying to meet the atomic scale surface and interface analysis challenges from semiconductor industries and furthermore to extend the application scope to biomedical areas. Optical imaing has been most widely and successfully used for biomedical imaging but complementary ion beam imaging techniques based on mass spectrometry and ion scattering can provide more detailed molecular specific and nanoscale information In this presentation, I will review the 27 years history of medium energy ion scattering (MEIS) development at KRISS and DGIST for nanoanalysis. A electrostatic MEIS system constructed at KRISS after the FOM, Netherland design had been successfully applied for the gate oxide analysis and quantitative surface analysis. Recenlty, we developed time-of-flight (TOF) MEIS system, for the first time in the world. With TOF-MEIS, we reported quantitative compositional profiling with single atomic layer resolution for 0.5~3 nm CdSe/ZnS conjugated QDs and ultra shallow junctions and FINFET's of As implanted Si. With this new TOF-MEIS nano analysis technique, details of nano-structured materials could be measured quantitatively. Progresses in TOF-MEIS analysis in various nano & bio technology will be discussed. For last 10 years, I have been trying to develop multimodal nanobio imaging techniques for cardiovascular and brain tissues. Firstly, in atherosclerotic plaque imaging, using, coherent anti-stokes raman scattering (CARS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) multimodal analysis showed that increased cholesterol palmitate may contribute to the formation of a necrotic core by increasing cell death. Secondly, surface plasmon resonance imaging ellipsometry (SPRIE) was developed for cell biointerface imaging of cell adhesion, migration, and infiltration dynamics for HUVEC, CASMC, and T cells. Thirdly, we developed an ambient mass spectrometric imaging system for live cells and tissues. Preliminary results on mouse brain hippocampus and hypotahlamus will be presented. In conclusions, multimodal optical and mass spectrometric imaging privides overall structural and morphological information with complementary molecular specific information, which can be a useful methodology for biomedical studies. Future challenges in optical and mass spectrometric imaging for new biomedical applications will be discussed.