• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.98-102
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• 2010

Magnolia kobus leaf extract was used for the synthesis of bimetallic Au core-Ag shell nanoparticles. Gold seeds and silver shells were formed by first treating aqueous solution of $HAuCl_4$ and then $AgNO_3$ with the plant leaf extract as reducing agent. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of bimetallic nanoparticles. The synthesized bimetallic nanoparticles were characterized with transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy(XPS). TEM images showed that the bimetallic nanoparticles are a mixture of plate(triangles, pentagons, and hexagons) and spherical structures. The atomic Ag contents of the bimetallic Au/Ag nanoparticles determined from EDS and XPS analysis were 34 and 65 wt%, respectively, suggesting the formation of bimetallic Au core-Ag shell nanostructure. This core-shell type nanostructure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

• Journal of Sensor Science and Technology
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• v.3 no.2
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• pp.50-56
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• 1994

Fiber-optic biosensor for the detection of organophosphorus compounds in a contaminated water was developed, which was the component of pesticides and agricultural agent. The detection principle of designed sensor was the pH variance induced by a reaction of acetylcholinesterase enzyme inhibited by organophosphorus compounds. The pH variance was detected by the optical system to measure the organophosphorus compounds. Litmus was selected as the pH-sensitive dye suitable to the enzyme reaction and a light source to be detected by the optical system. The enzyme entrapped in Ca-alginate gel was immobilized at the inner wall to maintain the high activity of enzyme and to be reused for a long period. The optical fiber was used to miniaturize and control remotely the sensor system. The He-Ne laser with 632 nm was selected as the light source to prevent light intensity fluctuation by the product. Cheap plastic optical fibers were used as the transmission part of the light and the phototransistor was used as the reception part of light based on the wavelength of He-Ne laser. The proposed fiber-optic biosensor has the linear analytical range of 0 ppm-1.5 ppm with response time of 5 minutes.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.140-147
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• 2008

.A new approach for a cloud point extraction-electrothermal atomic absorption spectrometric method was used for determining bismuth. The aqueous analyte was acidified with sulfuric acid (pH 3.0-3.5). Triton X-114 was added as a surfactant and natriumdiethyldithiocarbaminat (Na-DDTC) was used as a complexing agent. After phase separation at 50oC based on the cloud point separation of the mixture, the surfactant-rich phasen was diluted using tetrahydrofuran (THF). Twenty microliters (20 L) of the enriched solution and 10 l of 0.1% (w/v) Pd(NO3)2 as chemical modifier were dispersed into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. After optimizing extraction conditions and instrumental parameters, a preconcentration factor of 195 was obtained for a sample of only 10 mL. The detection limit was 0.04 ng ml-1 and the analytical curve was linear for the concentration range of 0.04-0.70 ng mL-1. Relative standard deviations were <5%. The method was successfully applied for the extraction and determination of bismuth in water samples.

• Macromolecular Research
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• v.16 no.8
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• pp.695-703
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• 2008

Nanoparticles have tremendous potential in cancer prevention, detection and augmenting existing treatments. They can target tumors, carry imaging capability to document the presence of tumors, sense pathophysiological defects in tumor cells, deliver therapeutic genes or drugs based on the tumor characteristics, respond to external triggers to release an appropriate agent, document the tumor response, and identify the residual tumor cells. Nanoparticles < 30 nanometers in diameter show unexpected and unique properties. Furthermore, particles < 5 nanometers in size can easily penetrate cells as well as living tissues and organs. This study evaluated the safety of nano materials in a living body and the relationship between the living tissue and synthetic nano materials by examining the in-vitro cytotoxicity of poly(lactic-co-glycolic) acid (PLGA) nano-spheres and fluorescein isothiocynate(FITC)-labeled dendrimers as polymer nanoparticles. PLGA was chosen because it has been used extensively for biodegradable nanoparticles on account of its outstanding bio-compatibility and its acceptance as an FDA approved material. The dendrimer was chosen because it can carry a molecule that recognizes cancer cells, a therapeutic agent that can kill those cells, and a molecule that recognizes the signals of cell death. Cytotoxicity in L929 mouse fibroblasts was monitored using MTT assay. Microscopic observations were also carried out to observe cell growth. All assays yielded meaningful results and the PLGA nanoparticles showed less cytotoxicity than the dendrimer. These nano-particles ranged in size from 10 to 100 nm according to microscopy and spectroscopic methods.

• Journal of Forest and Environmental Science
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• v.33 no.4
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• pp.342-347
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• 2017

Since the first report of the oak wilt disease at 2004 in Korea, the disease distributed over Korean peninsula and are still giving severe damages. The management of oak wilt disease in Korea has mainly focused on the control of insect vector, Platypus koryoensis. Neverthless the effective method for evaluating the pathogenicity of the pathogen, Raffaelea quercus-mongolicae (Rqm), and for screening chemical or biological agents with strong inhibitory activity against the pathogen, is absolutely necessary, an reliable method is not available so far. This study was conducted to develop the effective method for evaluating the pathogenicity of Rqm in oak trees. The culture suspensions of Rqm were artificially injected to the saplings of Quercus acutissima by using ChemJet tree injector. Three months after treatments, the treated saplings were cut and dipped into 1% fuchsin acid solution. There were significant differences in non-conductive area (%), discoloration area (%) and vertical discoloration length between the pathogen-injected and distilled water-injected control treatments. These results indicated that the pathogen is the causal agent for the dysfunction of water conductive tissue, which will finally result in wilt symptom. Re-isolation of the pathogen and PCR detection using specific primers for the pathogen also confirmed the presence of Rqm in the sapwood chips of the pathogen-injected saplings. These observations would be greatly applied to other related researches for evaluating the pathogenicity of tree wilt pathogens and biocontrol efficacy of the selected antagonistic microorganisms, in case that the wilt symptom is not easily shown by artificial inoculation of the causal agent.

• Environmental Mutagens and Carcinogens
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• v.18 no.2
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• pp.93-97
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• 1998

The results of chromosome aberration test in mammalian cells in culture (Chinese hamster lung fibroblast cells) showed no induction of structural and numerical aberrations by antifungal agents of YH1715 series regardless of metabolic activation. While positive control group (mitomycin C and benzo(a)pyrene) showed structural chromosome aberrations of 37% and 23%, respectively. The in vivo induction of micronuclei was measured in polychromatic erythrocytes in bone marrow of male ddY mouse given YH1715R and YH1729R at 1, 0.5, 0.25 g/kg by p.o. once. After 24 hours, animals were sacrificed and evaluated 40 the incidence of micronucleated polychromatic erythrocytes in whole erythrocytes. Although a positive response for induction of micronuclei in animals treated with mitomycin C demonstrated the sensitivity of the test system for detection of a chemical clastogen, YH1715R did not induce micronuclei in bone marrow of ddY male mice but induced cytotoxicity to bone marrow cells at the highest concentration (1 g/kg, p〈0.05), and YH1729R induced micronuclei in bone marrow of ddY male mice dose dependently (p<0.05) but did not induce cytotoxicity to bone marrow cells.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1727-1732
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• 2007

Phenylacetic acid (PAA) is produced by many bacteria as an antifungal agent and also appears to be an environmentally toxic chemical. The object of this study was to detect PAA using Pseudomonas putida harboring a reporter plasmid that has a PAA-inducible promoter fused to a green fluorescent protein (GFP) gene. Pseudomonas putida KT2440 was used to construct a green fluorescent protein-based reporter fusion using the paaA promoter region to detect the presence of PAA. The reporter strain exhibited a high level of gfp expression in minimal medium containing PAA; however, the level of GFP expression diminished when glucose was added to the medium, whereas other carbon sources, such as succinate and pyruvate, showed no catabolic repression. Interestingly, overexpression of a paaF gene encoding PAA-CoA ligase minimized catabolic repression. The reporter strain could also successfully detect PAA produced by other PAA-producing bacteria. This GFP-based bioreporter provides a useful tool for detecting bacteria producing PAA.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.93-100
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• 2014

Background: Curcumin has has been reported to exert anti-inflammatory, anti-oxidation and anti-angiogenic activity in various types of cancer. It has also been shown to induce apoptosis in leukemia cells. We aimed to unravel the role of the redox pathway in Curcumin mediated apoptosis with a panel of human leukemic cells. Materials and Methods: In this study in vitro cytotoxicity of Curcumin was measured by MTT assay and apoptotic effects were assessed by annexin V/PI, DAPI staining, cell cycle analysis, measurement of caspase activity and PARP cleavage. Effects of Curcumin on intracellular redox balance were assessed using fluorescent probes like $H_2DCFDA$, JC1 and an ApoGSH Glutathione Detection Kit respectively. Results: Curcumin showed differential anti-proliferative and apoptotic effects on different human leukemic cell lines in contrast to minimal effects on normal cells. Curcumin induced apoptosis was associated with the generation of intracellular ROS, loss of mitochondrial membrane potential, intracellular GSH depletion, caspase activation. Conclusions: As Curcumin induces programmed cell death specifically in leukemic cells it holds a great promise as a future therapeutic agent in the treatment of leukemia.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.479-483
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• 2004

An attempt was made to develop a proteinchip for screening of MITF (microphthalmia transcription factor) inhibitor. Binding of MITF to E-box causes transcription of several pigmenting genes including tyrosinase gene. We investigated binding of MITF and its DNA binding site (E-box) using a protein-DNA chip with various detection methods including flurorescence (Cyt3). SPR (surface plasmon resonance) and SPRi (surface plasmon resonance imaging). A fusion protein (MITF-Maltose Binding Protein) was attached on the glass plate by chemical modification. An inhibitory synthetic DNA oligomer, artificially designed based on the E-box sequence, inhibited the binding of MITF and E-box. These results showed the potentials of flurorescence-based MITF protein chip as a microarray for high throughput screening (HTS) system of depigmenting agents.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.207-211
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• 2000

We have studied on the determination of Ni(II) using APDC as a complexing agent in Tween80 micellar medium. The absorption spectrum of Ni(PDC)$_2$ complex in Tween80 medium was better defined and more sensitive than that in chloroform Ni(PDC)$_2$ complex was very stable at pH 7.0 and up to 100 minutes, and could be quantitatively chelated when APDC was added to over 10 times moles of Ni(II). The optimum concentration of Tween80 was 0.1%. The calibration curve of Ni(PDC)$_2$ complex with good linearity(R$^2$=0.9955) was obtained in 0.1% Tween80 medium. The detection limit and the determination limit were 0.09 ${\mu}g$/mL and 0.28 ${\mu}g$/mL, respectively. This technique was applied to the analysis of Suwon stream water samples, and about l00% of recoveries were obtained from the spiked samples. Although the formation of Ni(PDC)$_2$ complex was interfered by various metal ions, this technique could be applied to the practical determination of Ni(II).