• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.943-947
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• 2008

A phosphate-specific and fluorescent probe was prepared for label-free phosphatase assays based on fluorescence polarization. By using the probe, dephosphorylation reactions of DNA and protein substrates by calf intestinal alkaline phosphatase (CIP) could effectively be monitored in real-time. Since this assay method does not require additional materials such as labeled substrates and phosphospecific antibodies to obtain fluorescence polarization signals, it is simple, cost-effective, and expected to be useful not only for measuring activity of phosphatases but also for high-throughput screening of phosphatase inhibitors.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.131-135
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• 2013

A DOTAP analog labeled by NBD on the head group (DTNBD) was designed and synthesized to label DOTAP liposome. The structure was confirmed by $^1H$ NMR and FAB-MS, and the fluorescence of the newly synthesized DT-NBD was observed by fluorescent microscopy. The transfection efficiency of DOTAP liposome containing DT-NBD was comparable to commonly used NBD PE in COS7 and MCF7 cells. Furthermore, the level of cellular uptake and fluorescent intensity of fluorescent liposome containing DT-NBD was higher than NBD PE. Therefore, the novel NBD-labeled DOTAP analog seems to be effectively used for investigation of the cellular interaction and transfection mechanism of DOTAP liposome.

• Applied Microscopy
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• v.51
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• pp.12.1-12.12
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• 2021

Intravital video microscopy permits the observation of microcirculatory blood flow. This often requires fluorescent probes to visualize structures and dynamic processes that cannot be observed with conventional bright-field microscopy. Conventional light microscopes do not allow for simultaneous bright-field and fluorescent imaging. Moreover, in conventional microscopes, only one type of fluorescent label can be observed. This study introduces multispectral intravital video microscopy, which combines bright-field and fluorescence microscopy in a standard light microscope. The technique enables simultaneous real-time observation of fluorescently-labeled structures in relation to their direct physical surroundings. The advancement provides context for the orientation, movement, and function of labeled structures in the microcirculation.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1544-1549
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• 2024

This study presents a fluorescent mechanism for two-step amplification by combining two widely used techniques, exponential amplification reaction (EXPAR) and catalytic hairpin assembly (CHA). Pseudomonas aeruginosa (P. aeruginosa) engaged in competition with the complementary DNA in order to attach to the aptamer that had been fixed on the magnetic beads. The unbound complementary strand in the liquid above was utilized as a trigger sequence to initiate the protective-EXPAR (p-EXPAR) process, resulting in the generation of a substantial quantity of short single-stranded DNA (ssDNA). The amplified ssDNA can initiate the second CHA amplification process, resulting in the generation of many double-stranded DNA (dsDNA) products. The CHA reaction was initiated by the target/trigger DNA, resulting in the release of G-quadruplex sequences. These sequences have the ability to bond with the fluorescent amyloid dye thioflavin T (ThT), generating fluorescence signals. The method employed in this study demonstrated a detection limit of 16 CFU/ml and exhibited a strong linear correlation within the concentration range of 50 CFU/ml to 10⁵ CFU/ml. This method of signal amplification has been effectively utilized to create a fluorescent sensing platform without the need for labels, enabling the detection of P. aeruginosa with high sensitivity.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1345-1358
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• 2017

The impact of overproduction of a heterologous protein on the metabolic system of host Lactococcus lactis was investigated. The protein expression profiles of L. lactis IL1403 containing two near-identical plasmids that expressed high- and low-level of the green fluorescent protein (GFP) were examined via shotgun proteomics. Analysis of the two strains via high-throughput LC-MS/MS proteomics identified the expression of 294 proteins. The relative amount of each protein in the proteome of both strains was determined by label-free quantification using the spectral counting method. Although expression level of most proteins were similar, several significant alterations in metabolic network were identified in the high GFP-producing strain. These changes include alterations in the pyruvate fermentation pathway, oxidative pentose phosphate pathway, and de novo synthesis pathway for pyrimidine RNA. Expression of enzymes for the synthesis of dTDP-rhamnose and N-acetylglucosamine from glucose was suppressed in the high GFP strain. In addition, enzymes involved in the amino acid synthesis or interconversion pathway were downregulated. The most noticeable changes in the high GFP-producing strain were a 3.4-fold increase in the expression of stress response and chaperone proteins and increase of caseinolytic peptidase family proteins. Characterization of these host expression changes witnessed during overexpression of GFP was might suggested the metabolic requirements and networks that may limit protein expression, and will aid in the future development of lactococcal hosts to produce more heterologous protein.

• Molecules and Cells
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• v.44 no.11
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• pp.851-860
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• 2021

Label-free optical diffraction tomography (ODT), an imaging technology that does not require fluorescent labeling or other pre-processing, can overcome the limitations of conventional cell imaging technologies, such as fluorescence and electron microscopy. In this study, we used ODT to characterize the cellular organelles of three different stem cells-namely, human liver derived stem cell, human umbilical cord matrix derived mesenchymal stem cell, and human induced pluripotent stem cell-based on their refractive index and volume of organelles. The physical property of each stem cell was compared with that of fibroblast. Based on our findings, the characteristic physical properties of specific stem cells can be quantitatively distinguished based on their refractive index and volume of cellular organelles. Altogether, the method employed herein could aid in the distinction of living stem cells from normal cells without the use of fluorescence or specific biomarkers.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.551-557
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• 2014

In this study, we demonstrated multimodal nonlinear optical (NLO) microscopy integrated simultaneously with two-photon excitation fluorescence (TPEF), second-harmonic generation (SHG), and coherent anti-Stokes Raman scattering (CARS) in order to obtain targeted cellular and label-free images in an immunofluorescence assay of the atherosclerotic aorta from apolipoprotein E-deficient mice. The multimodal NLO microscope used two laser systems: picosecond (ps) and femtosecond (fs) pulsed lasers. A pair of ps-pulsed lights served for CARS (817 nm and 1064 nm) and SHG (817 nm) images; light from the fs-pulsed laser with the center wavelength of 720 nm was incident into the sample to obtain autofluorescence and targeted molecular TPEF images for high efficiency of fluorescence intensity without cross-talk. For multicolor-targeted TPEF imaging, we stained smooth-muscle cells and macrophages with fluorescent dyes (Alexa Fluor 350 and Alexa Fluor 594) for an immunofluorescence assay. Each depth-sectioned image consisted of $512{\times}512$ pixels with a field of view of $250{\times}250{\mu}m^2$, a lateral resolution of $0.4{\mu}m$, and an axial resolution of $1.3{\mu}m$. We obtained composite multicolor images with conventional label-free NLO images and targeted TPEF images in atherosclerotic-plaque samples. Multicolor 3-D imaging of atherosclerotic-plaque structural and functional composition will be helpful for understanding the pathogenesis of cardiovascular disease.

• International Journal of Oral Biology
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• v.33 no.4
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• pp.125-129
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• 2008

Inositol 1,4,5-trisphosphate ($IP_3$) plays an important role in the release of $Ca^{2+}$ from intracellular stores into the cytoplasm in a variety of cell types. $IP_3$ translocation dynamics have been studied in response to many types of cell signals. However, the dynamics of cytosolic $IP_3$ in salivary acinar cells are unclear. A green fluorescent protein (GFP)-tagged pleckstrin homology domain (PHD) was constructed and introduced into a phospholipase C ${\delta}1$ (PLC ${\delta}1$) transgenic mouse, and then the salivary acinar cells were isolated. GFP-PHD was heterogeneously localized at the plasma membrane and intracellular organelles in submandibular gland and parotid gland cells. Application of trypsin, a G protein-coupled receptor activator, to the two types of cells caused an increase in GFP fluorescence in the cell cytoplasm. The observed time course of trypsin-evoked $IP_3$ movement in acinar cells was independent of cell polarity, and the fluorescent label showed an immediate increase throughout the cells. These results suggest that GFP-PHD in many tissues of transgenic mice, including non-cultured primary cells, can be used as a model for examination of $IP_3$ intracellular dynamics.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.6
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• pp.461-467
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• 2005

Background. 5-(and-6)-carboxy-2',7'-dichlorofluorescein diacetate, succinimidyl ester mixed (CFSE) is the fluorescent labelling agent of living cells and used to trace the cells in vivo after transplatnation of various cells. The CFSE labelled cells can maintain fluorescence for up to 7 days after labelling. The MC3T3-E1 cell line (MC3T3) has been used for many studies about osteoblast, which is well known as a mouse preosteoblast. So the CFSE would be used to trace the transplanted MC3T3. However there are few reports about CFSE labelling of MC3T3. This study is aimed to know about adequate concenturation and incubation time of CFSE to MC3T3. Materials and methods. The MC3T3 was incubated in a humidified atmosphere of 95% air with 5% $CO_2$ at $37^{\circ}C$ using ${\alpha}$-minimal essential medium (${alpha}$-MEM) containing10% FBS and gentamycin. Ten mM CFSE solution in dimethylsulphoxide (DMSO: 1%) was diluted with phosphate buffered saline (PBS) and final concentration of culture medium was, respectively, 5, 10, 15, 20, 25 and 30 ${{\mu}M$. Then the MC3T3 was incubated with CFSE in a humidified atmosphere of 95% air with 5% $CO_2$ at $37^{\circ}C$ for 5, 10, 15, 20, 25, 30, 35, 40 and 45 minutes in each concentration. The fluorescence of CFSE labelled cells was analysed with a inverted fluorescence microscope. The duration of cell labelling was also studied. Trypan blue dye exclusion test was done for cell viability. Results. For concentration between 5 and 10 ${\mu}M$, CFSE did not significantly label the MC3T3 in vitro. The destruction of MC3T3 was observed at the concentration of 20 ${\mu}M$. In the concentration of 15 ${\mu}M$, the best labelling was obtained at an incubation period between 15 and 30 minutes. The MC3T3 labelled with an incubation period of 15 minutes at 15 ${\mu}M$ was still fluorescent 7 days after CFSE labelling. The mean cell viability was 95.93%. Conclusion. These results suggests an incubation period of 15 minutes at 15 ${\mu}M$ of CFSE provides best labelling of MC3T3 in vitro.

• BMB Reports
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• v.48 no.12
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• pp.655-667
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• 2015

Lineage tracing is a widely used method for understanding cellular dynamics in multicellular organisms during processes such as development, adult tissue maintenance, injury repair and tumorigenesis. Advances in tracing or tracking methods, from light microscopy-based live cell tracking to fluorescent label-tracing with two-photon microscopy, together with emerging tissue clearing strategies and intravital imaging approaches have enabled scientists to decipher adult stem and progenitor cell properties in various tissues and in a wide variety of biological processes. Although technical advances have enabled time-controlled genetic labeling and simultaneous live imaging, a number of obstacles still need to be overcome. In this review, we aim to provide an in-depth description of the traditional use of lineage tracing as well as current strategies and upcoming new methods of labeling and imaging.