• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.15-21
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• 2011

Threelectrodes systems were used in stripping voltammetry (SW) and cyclic voltammetry (CV) instead of the expensive platinum and Ag/AgCl reference electrodes. Moreover, the electrolyte solution was used with deep seawater, which can reduce water pollution, is more eco-friendly, and has a lower cost. The analytical optimum parameters measured via CV and SW and with working ranges were obtained from 10 to 80 ug/L using fluorine immobilized on a graphite pencil electrode (FE). Under the optimum conditions, the analytical detection limit of 6.30 ug/LAu was obtained. The results of the study can be applied to diagnostic assay for natural minerals and human finger tissue.

• Journal of Environmental Science International
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• v.19 no.8
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• pp.941-949
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• 2010

The three electrode system was used to detect the pesticide fenitrothion ($C_9H_{12}NO_5PS$. MW=277.24) using cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). The working electrode was mercury immobilized on a carbon nanotube paste electrode (Hg-CNTPE). At the optimized condition, the limit of detection (LoD) was 0.6 ppt ($2.16{\times}10^{-12}\;M$), and the relative standard deviation was 0.035% (n=15). And there is more sensitive in detecting fenitrothion than common type carbon nanotube paste electrode. When it was implanted into the brain of live fish (carp), the existence of fenitrothion was measured without any destruction or damage of tissue.

• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.502-507
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• 2011

A voltammetric assay of phenol ions was investigated using three electrode systems of graphite pencil working, reference and counter electrodes. Under optimum analytical parameters, square wave stripping working ranges were attained at a mili range of 10~80 mg/L and a micro range of 20~90 ug/L using seawater electrolyte. The developed sensor was applied to tap water and the human body system of a smoker. It was found that the methods can be applied to in vivo fluid or medicinal diagnosis.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.515-519
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• 2007

Neurotransmitter glycine in the nano gram range was analyzed using a paste electrode (PE) in cyclic voltammetry (CV) and square-wave stripping voltammetry (SWSV). An anodic peak caused by oxidation of the glycine ion appeared at the 0.4 V (versus Ag/AgCl/KCl) potential in a 0.1 M NH4H2PO4 electrolyte solution. At optimized conditions, the working range of the SWSV and CV concentration was found to be 5-60 ngL-1 glycine; precision of R2 = 0.9816 (SWSV) and 0.9986 (CV); and detection limit of 0.65 ngL-1 (5.82 × 10-12 molL-1) (S/N = 3). The optimized conditions were applied to an assay in a fish brain tissue and a living brain cell in real time.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.491-498
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• 2004

The response characteristics of the bioelectrode developed by the co-immobilization of black goat liver tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined ($-0.3{\sim}+0.0\;V$ vs. Ag/AgCl), the response time was relatively short (t95%=12 s) and it responded in the wide range of pH. The detection limit was 2.25${\times)10^{-6}M$ and a relative standard deviation of the measurements which were repeated 15 times using 1.0${\times}10^{-2 }$M hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 50% of the original value in 19 days of continuous use.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.369-374
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• 2017

The curtailment of production cost is important for the mass production of biosensors. Since horseradish peroxidase, which is a key material of enzyme electrodes for hydrogen peroxide analysis is rather expensive, this has been a limiting factor for fabricating carbon paste based enzyme electrodes. In this paper, the acacia leaf tissue as a zymogen easily obtainable in our living environment was used as an alternative to horseradish peroxidase for developing a hydrogen peroxide sensor and the electrochemical properties were evaluated. Ten or more electrochemical parameters alongside the other experimental results acquired by the potentiostatic method demonstrated that our enzyme electrodes can be used for the quantitative analysis of hydrogen peroxide. This also indicates that acacia leaves can take the place of the marketed peroxidase.

• Toxicological Research
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• v.29 no.4
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• pp.293-298
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• 2013

A method of detecting lead was developed using square wave anodic stripping voltammetry (SWASV) with DNA-carbon nanotube paste electrode (CNTPE). The results indicated a sensitive oxidation peak current of lead on the DNA-CNTPE. The curves were obtained within a concentration range of 50 $ngL^{-1}-20mgL^{-1}$ with preconcentration time of 100, 200, and 400 sec at the concentration of $mgL^{-1}$, ${\mu}gL^{-1}$, and $ngL^{-1}$, respectively. The observed relative standard deviation was 0.101% (n = 12) in the lead concentration of 30.0 ${\mu}gL^{-1}$ under optimum conditions. The low detection limit (S/N) was pegged at 8 $ngL^{-1}$ ($2.6{\times}10^{-8}M$). Results showed that the developed method can be used in real-time assay in vivo without requiring any pretreatment and pharmaceutical samples, and food samples, as well as other materials requiring water source contamination analyses.

• Journal of Biomedical Engineering Research
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• v.40 no.1
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• pp.1-6
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• 2019

Human mesenchymal stem cells (hMSC) are multipotent stromal cells that have great potential to differentiate into a variety of cell types such as osteocytes, chondrocytes, and myocytes. Although there have been many studies on their clinical availability, little is known about how intracellular signals can be modulated by topographic features of the extracellular matrix (ECM). In this study, we investigated whether and how microwavy-patterned extracellular matrix (ECM) could affect the signaling activity of focal adhesion kinase (FAK), a key cellular adhesion protein. The fluorescence resonance energy transfer (FRET)-based FAK biosensor-transfected cells are incubated on microwavy-patterned surfaces and then platelet derived growth factor (PDGF) are treated to trigger FAK signals, followed by monitoring through live-cell FRET imaging in real time. As a result, we report that PDGF-induced FAK was highly activated in cells cultured on microwavy-patterned surface with L or M type, while inhibited by H type-patterned surface. In further studies, PDGF-induced FAK signals are regulated by functional support of actin filaments, microtubules, myosin-related proteins, suggesting that PDGF-induced FAK signals in hMSC upon microwavy surfaces are dependent on cytoskeleton (CSK)-actomyosin networks. Thus, our findings not only provide new insight on molecular mechanisms on how FAK signals can be regulated by distinct topographical cues of the ECM, but also may offer advantages in potential applications for regenerative medicine and tissue engineering.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.114-118
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• 2011

Even though the carbon paste electrode bound with mineral oil is useful for research about the characteristics of enzymes, it remains far from practical uses because the lack of mechanical hardness limits its practical use. When the rubber liquefied in toluene was used as a binder of carbon powder in lab, it is confirmed that the mechanical robustness of the electrode is guaranteed. In order to confirm whether it shows quantitative electrochemical behaviors or not, its kinetic parameters, e.g. the symmetry factor (${\alpha}=0.28$), the exchange current density ($i_0=4.06{\mu}A/cm^2$), the capacity of the double layer ($C_d=2.11{\times}10^{-3}F$), the Michaelis constant ($K_M=2.45{\times}10^{-3}M$), and the time constant (${\tau}_B=0.077sec$) were investigated. Our experimental observations prove that the chloroprene rubber is a promising binder for the practical use of a carbon paste electrode.