• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.385-386
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• 2008

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 하계학술발표회 논문집
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• pp.231-232
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• 2006

• 한국유변학회:학술대회논문집
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• 한국유변학회 2001년도 춘계 학술발표회 논문집
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• pp.41-44
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• 2001

• Journal of the Optical Society of Korea
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• 제10권3호
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• pp.130-142
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• 2006

Lab-on-a-chip technology is attracting great interest because the miniaturization of reaction systems offers practical advantages over classical bench-top chemical systems. Rapid mixing of the fluids flowing through a microchannel is very important for various applications of microfluidic systems. In addition, highly sensitive on-chip detection techniques are essential for the in situ monitoring of chemical reactions because the detection volume in a channel is extremely small. Recently, a confocal surface enhanced Raman spectroscopic (SERS) technique, for the highly sensitive biological analysis in a microfluidic sensor, has been developed in our research group. Here, a highly precise quantitative measurement can be obtained if continuous flow and homogeneous mixing condition between analytes and silver nano-colloids are maintained. Recently, we also reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). This method overcomes many of the drawbacks of microarray chips, such as long hybridization times and inconvenient immobilization procedures. In this paper, our recent applications of the confocal Raman/fluorescence microscopic technology to a highly sensitive lab-on-a-chip detection will be reviewed.

• Journal of Microbiology and Biotechnology
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• 제18권10호
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• pp.1729-1734
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• 2008

Chitosan, a cationic polysaccharide, has been widely used as a dietary supplement and in a variety of pharmacological and biomedical applications. The antifungal activity and mechanism of action of low molecular weight water-soluble chitosan (LMWS-chitosan) were studied in fungal cells and vesicles containing various compositions of fungal lipids. LMWS-chitosan showed strong antifungal activity against various pathogenic yeasts and hyphae-forming fungi but no hemolytic activity or cytotoxicity against mammalian cells. The degree of calcein leakage was assessed on the basis of lipid composition (PC/CH; 10:1, w/w). Our result showing that LMWS-chitosan interacts with liposomes demonstrated that chitosan induces leakage from zwitterionic lipid vesicles. Confocal microscopy revealed that LMWS-chitosan was located in the plasma membrane. Finally, scanning electron microscopy revealed that LMWS-chitosan causes significant morphological changes on fungal surfaces. Its potent antibiotic activity suggests that LMWS-chitosan is an excellent candidate as a lead compound for the development of novel anti-infective agents.

• 한국생산제조학회지
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• 제18권3호
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• pp.248-254
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• 2009

The worn crater wear geometry of coated tools after machining has been configured by using Confocal Laser Scanning Microscopy(CLSM) and the Wavelet-based filtering technique. The CLSM can be well suited to construct the three-dimensional crater wear on the rake surfaces of coated tips. However, The raw heightness data of HEI(height encoded image) acquired by CLSM must be filtered due to the electronic and imaging noise occurring in constructing the crater image. So the Wavelet-based filtering algorithm is necessary to denoise the shape features in a micro scales so as to realize accurate crater wear topography analysis. The crater wear patterns filtered enable us to predict the crater wear shape in order to study the tool wear evolution. The study shows that the technique by combining the CLSM and Wavelet-based filtering is an excellent one to obtain the geometries of worn tool rake surfaces over a wide range of surface resolution in a micro scale.

• 대한의생명과학회지
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• 제18권2호
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• pp.160-164
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• 2012

The baculovirus/insect cell expression system is of great value for the large-scale production of normal and mutant mammalian passive glucose-transport proteins heterologously for structural and functional studies. In most mammalian cells that express HepG2, this transporter isoform is predominantly located at the cell surface. However, it had been reported that heterologous expression of other membrane proteins using the baculovirus system induced highly vacuolated cytoplasmic membranes. Therefore, how a cell responds to the synthesis of large amounts of a glycoprotein could be an interesting area for investigation. In order to examine the subcellular location of the human HepG2 transport proteins when expressed in insect cells, immunofluorescence studies were carried out. Insect cells were infected with the recombinant baculovirus AcNPVHIS-GT or with wild-type virus at a MOI of 5, or were not exposed to viral infection. A high level of fluorescence displayed in cells infected with the recombinant virus indicated that transporters are expressed abundantly and present on the surface of infected Sf21 cells. The evidence for the specificity of the immunostaining was strengthened by the negative results shown in the negative controls. Distribution of the transporter protein expressed in insect cells was further revealed by making a series of optical sections through an AcNPVHIS-GT-infected cell using a confocal microscope, which permits optical sectioning of cell sample. These sections displayed intense cytoplasmic immunofluorecence surrounding the region occupied by the enlarged nucleus, indicating that the expressed protein was present not only at the cell surface but also throughout the cytoplasmic membranous structures.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.175-180
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• 2010

Nanotechnology is currently receiving considerable attention in various fields of biotechnology. The uptake of nanoparticles by cells for labeling and tracking is a critical process for many biomedical therapeutic applications. However, nanoparticle labeling of porcine hematopoietic cells has not been demonstrated so far. In the present study, silica-coated nanoparticles conjugated with rhodamine B isothiocyanate (SR-RITC) were used to investigate the uptake of nanoparticles by porcine hematopoietic cells. Flow cytometric and confocal microscopic analyses reveled that the cells were efficiently internalized by the silica-coated nanoparticles. Furthermore, biocompatibility tests demonstrated that the SR nanoparticles were not cytotoxic, and they had no impact on proliferation. Our study demonstrates that silica-coated nanoparticles are taken up very rapidly and with high efficiency into porcine hematopoietic cells, with no apparent deleterious effects. Therefore, silica-coated nanoparticles appear to be a promising tool for tracking porcine hematopoietic cells.

• Tribology and Lubricants
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• 제32권1호
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• pp.32-37
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• 2016

The wear characteristics of metal ball and seat in a metal-seated ball valve significantly affect the performances such as leakage and valve torque. In this work, the wear characteristics of metal ball and seat are experimentally investigated. A stainless steel ball and seat with a high corrosion-resistant coating are prepared and a component level test was performed. The hardness and surface roughness of specimens cut from the metal ball and seat are measured before and after the test using a micro-Vickers hardness tester and confocal microscopy, respectively. In order to assess the wear characteristics, the surfaces of the specimens are carefully examined after the test. The confocal microscope data show that the surface roughness values of both the ball and seat increase by a factor of 3-4, which may lead to an increase in valve torque. However, the wear of the seat is found to be more significant than that of the ball. In addition, a comparison of the surfaces of the ball and seat before and after testing revealed that adhesive and abrasive wear are the major wear mechanisms. The results of this study may aid in the design of metal-seated ball valves from the tribological point of view.

• 지질공학
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• 제25권2호
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• pp.165-178
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• 2015

Physical and chemical weathering degrades rock, affecting its structural properties and thus the stability of stone buildings or other structures. Confocal laser scan microscopy (CLSM) is used here to observe temporal changes in the surface roughness of rock samples under simulated accelerated weathering. Samples were pressurized to 50, 55, or 70 MPa using a pressure frame, and subjected to freeze/thaw cycling controlled by a thermostat. The temperature was cycled from -20℃ to 40℃ and back. After each 20 cycles, CLSM was used to assess the change in surface roughness, and roughness factors were calculated to quantify the progression of the surface condition over time. Variations in cross-section line-roughness parameters and surface-roughness parameters were analyzed for specific parts of the sample surfaces at 5× and 50× magnification. The result reveals that the highest and lowest values of the roughness factors are changed according to elapsed time. Freezing/thawing at high pressure caused larger changes in the roughness factor than at low pressure.