• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.23-27
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• 2023

Graphitic carbon nitride (g-C₃N₄) has been used as effective photocatalyst for degradation of antibiotics under visible light irradiation. However, the fast recombination of hole-electron pair may limit their photocatalytic efficiency. In our study, Ag was grafted on g-C₃N₄/g-C₃N₄ isotype heterojunction by a microwave-assisted decomposition method. The structure and physical properties of heterojunction photocatalyst were characterized through X-ray diffraction, UV-DRS, FT-IR, and Photoluminescence analyses. Ag decorated g-C₃N₄/g-C₃N₄ isotype heterojunction exhibited excellent photocatalytic activity for degradation of sulfamethoxazole under irradiation under visible light irradiation within 210 min, which is higher than g-C₃N₄/g-C₃N₄ isotype heterojunction and bulk g-C₃N₄. The addition of Ag may broaden the visible light absorption and restrict the recombination of hole-electron pair because of the surface plasmons resonance, resulting in the improving the photocatalytic activity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.1
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• pp.75-85
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• 2023

This study was conducted to assess the effect of heptapeptide, composed of seven amino acids, on the activation of human hair cells isolated from human hair follicles. We have confirmed that the heptapeptide could bind to Lgr5 from the results of surface plasmon resonance (SPR) analysis. Heptapeptide enhanced the proliferation of human hair follicle dermal papilla cells (HHFDPCs) in a dose dependent manner. It induced the protein level of nuclear β-catenin, and the expressions of β-catenin downstream target genes, including LEF1, Cyc-D1 and c-Myc, in HHFDPCs. Heptapeptide significantly induced the phosphorylation of Akt and ERK, and the mRNA expressions of growth factors, including hepatocyte growth factor (HGF), keratinocyte growth factor (KGF) and vascular endothelial growth factor (VEGF), in HHFDPCs. In addition, heptapeptide significantly increased mRNA expression levels of differentiation-related transcription factors of human hair germinal matrix cells (HHGMCs) and differentiation markers of human hair outer root sheath cells (HHORSCs). Additionally, we investigated the effect of heptapeptide on human hair follicle stem cells (HHFSCs) differentiation and found that the heptapeptide reduced the mRNA and protein levels of stem cell markers, while it increased those levels of differentiation markers. These results have indicated that the heptapeptide promotes proliferation or differentiation of various types of hair follicle constituent cells through the induction of Wnt/β-catenin signaling. From the results, we have suggested that the heptapeptide in this study could be applied as a new functional material for the improvement of hair growth and alopecia.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.67-78
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• 2024

Light absorption has potential as a signal in biochemical analyses due to its simplicity in measurement and interpretational clarity. Among substances that generate absorption signals, gold nanoparticles possess advantages such as chemical stability, biological compatibility, and unique optical properties from the localized surface plasmon resonance (LSPR) in the visible light range. They also exhibit versatility compared to other colorimetric substances effective only for specific target molecules, as they easily conjugate with various detection active substances like antibodies and aptamers. Particularly due to advantages such as low cost, ease of particle synthesis, and high environmental stability compared to enzyme-based colorimetric methods, gold nanoparticles are extensively researched as signal substances in colorimetric assays. This review summarizes various strategies utilizing gold nanoparticles as absorption signal substances, focusing on recent research. Based on the characteristics of gold nanoparticles, where the optical property is influenced by particle morphology, literature is classified and reviewed based on strategies controlling the shape of gold nanoparticles during signal generation. Through this, it is observed that gold nanoparticles, which have been used as absorption signal substances, continue to be actively researched, affirming their potential for broad and continuous improvement in the future.

• KSBB Journal
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• v.24 no.1
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• pp.1-8
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• 2009

In the past decade, we have observed rapid advances in the development of biochips in many fields including medical and environmental monitoring. Biochip experiments involve immobilizing a ligand on a solid substrate surface, and monitoring its interaction with an analyte in a sample solution. Metal nanoparticles can display extinction bands on their surfaces. These charge density oscillations are simply known as the localized surface plasmon resonance (LSPR). The high sensitivity of LSPR has been utilized to design biochips for the label-free detection of biomolecular interactions with various ligands. LSPR-based optical biochips and biosensors are easy to fabricate, and the apparatus cost for the evaluation of optical characteristics is lower than that for the conventional surface plasmon resonance apparatus. Furthermore, the operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in LSPR research and also describe the LSPR-based optical biosensor constructed with a core-shell dielectric nanoparticle biochip for its application to label-free biomolecular detections such as antigen-antibody interaction.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.330-342
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• 2018

The Streptavidin and Biotin system has been studied most extensively as the high affinity non-covalent binding of Biotin to STR ($K_D=10^{-14}M$) and four Biotin binding sites in tetrameric Streptavidin makes this system useful for the production of multivalent antibody. For the application of this system, we cloned Streptavidin amplified from Streptomyces avidinii chromosome by PCR and fused to gene of hAY4 single-chain Fv antibody specific to death receptor 4 (DR4) which is a receptor for tumor necrosis factor ${\alpha}$ related apoptosis induced ligand. The hAY4 single-chain Fv antibody fused to Streptavidin expressed in Escherichia coli showed 43 kDa monomer in heated SDS-PAGE. However, this fusion protein shown in both non-heated SDS-PAGE and Size-exclusion chromatography exhibited 172 kDa as a tetramer suggesting that natural tetramerization of Streptavidin by non-covalent association induced hAY4 single-chain Fv tetramerization. This fusion protein retained a Biotin binding activity similar to natural Streptavidin as shown in Ouchterlony assay and ELISA. Death receptor 4 antigen binding activity of purified hAY4 single-chain Fv fused to Streptavidin was also confirmed by ELISA and Westernblot. In addition, surface plasmon resonance analysis showed 60-fold higher antigen binding affinity of the hAY4-STR than monomeric hAY4 ScFv due to tetramerization. In summary, hAY4 single-chain Fv fused to Streptavidin fusion protein was successfully expressed and purified as a soluble tetramer in E. coli and showed both Biotin and DR4 antigen binding activity suggesting possible production of bifunctional and tetrameric ScFv antibody.