• 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.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.264-270
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• 1999

Enzyme electrodes for amperometric measurement of glucose were prepared by immobilization of glucose oxidase on an Immobilon-AV Affinity membrane and attachement to a Pt electrodes. The electrochemical oxidation of Hz02 was monitored at +0.8V vs. Ag/AgCl. Response was linear from 0.2 mM to 20mM. The detection limit was 10m3 mM. Response time, the optimum pH and life time of enzyme immobilized membrane was 12 seconds, pH 5.5(CH3COONaJCH3COOH) and about 27 days, respectively. When the enzyme electrode was applied for the determinaion of glucose with amperometric method, other physiolosical materials have not interfered. Also, we compared the result with that from AOAC(Association of Offical Analytical Chemists) method, measuring the glucose in sweet potato. The relative error was 0.1%.

• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.65-70
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• 2006

An amperometric glucose biosensor has been developed based on the use of the nanoporous composite film of sol-gel-derived zirconia and perfluorosulfonated ionomer, Nafion, for the encapsulation of glucose oxidase (GOx) on a platinized glassy carbon electrode. Zirconium isopropoxide (ZrOPr) was used as a sol-gel precursor for the preparation of zirconia/Nafion composite film and the performance of the resulting glucose biosensor was tuned by controlling the water content in the acid-catalyzed hydrolysis of sol-gel stock solution. The presence of Nafion polymer in the sol-gel-derived zirconia in the biosensor resulted in faster response time and higher sensitivity compared to those obtained at the pure zirconia- and pure Nafion-based biosensors. Because of the nanoporous nature of the composite film, the glucose biosensor based on the zirconia/Nafion composite film can reach 95% of steady-state current less than 5 s. In addition, the biosensor responds to glucose linearly in the range of 0.03-15.08 mM with a sensitivity of 3.40 $\mu$A/mM and the detection limit of 0.037 mM (S/N = 3). Moreover, the biosensor exhibited good sensor-to-sensor reproducibility (~5%) and long-term stability (90% of its original activity retained after 4 weeks) when stored in 50 mM phosphate buffer at pH 7 at 4 ${^{\circ}C}$.

• Korean Journal of Food Science and Technology
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• v.44 no.2
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• pp.141-147
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• 2012

Biogenic amines have been used as chemical indicators to estimate bacterial spoilage of foods, particularly fish and fish products, cheese, and fermented foods. So far many chromatography methods have been developed to detect biogenic amines in foods. Although these instrumental analyses exhibit good sensitivity, they cannot be used as rapid detection methods due to the chemical treatment of the samples and the time-consuming process involved. For the rapid and simple detection of biogenic amines, enzyme linked immunosorbent assay kits are commercially available. In addition, analytical systems with enzyme-based amperometric biosensor detection have been increasingly developed. The biosensors used to detect the biogenic amines are based on the action of either amine oxidases or amine dehydrogenases that catalyzes the oxidative deamination of biogenic amines to the corresponding aldehydes and ammonia. This review mainly focused on the principle, development, and applications of the detection methods for rapid detection of biogenic amines in foods.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1460-1461
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• 2008

마이크로칩 형태에서의 모세관 전기영동과 전류법을 이용하여 디옥시리보핵산(DNA) 단편들의 분리 검출하는 실험을 하였다. 마이크로 채널이 형성된 PDMS(polydimethylsiloxane)와 금 전극이 형성된 유리 기판을 접합하여 마이크로칩을 제작하였다. 20V/cm의 전계를 인가하여 100bp-1.5kbp 길이의 DNA 단편을 모세관 전기영동 하였을 때 250초내에 분리 검출되는 것을 확인하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.449-452
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• 2005

We fabricated an electrochemical detector (ECD) to catalyze redox reaction efficiently by electrodepositing Prussian blue (PB) on the indium tin oxide (ITO) electrode. Capillary electrophoresis (CE) and amperometric method were used. We investigated the PB surface properties by topography from atomic force microscopy (AFM). Also PB film thickness calibration with respect to deposition time and voltage was used to get better PB surFace. The PB thin film of dense and smooth surface could catalyze redox reaction efficiently. Comparing with CE-ECD microchip using bare-lTO electrode, proposed CE-ECD microchip using PB deposited electrode has shown better sensitivity by determining the detected peak current from the electropherograms while the concentration of tested analyzes was maintained the same. It is verified that detection limit can be lowered for 0.01 mM of dopamine and catechol respectively.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1175-1180
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• 2013

A microfabricated electrochemical cell comprising PDMS-based microchannel and in-channel gold microelectrodes was fabricated as a sensitive and a miniature alternative to the conventional electroanalytical systems. A reproducible fabrication procedure enabled patterning of multiple microelectrodes integrated within a PDMS-based fluidic network. The active area of each electrode was $200{\mu}m{\times}200{\mu}m$ with a gap of $200{\mu}m$ between the electrodes which resulted in a higher signal to noise ratio. Also, the PDMS layer served the purpose of shielding the electrical interferences to the measurements. Analytes such as potassium ferrocyanide; amino acid: cysteine and nucleoside: guanosine were characterized using the fabricated cell. The microchip was comparable to bulk electrochemical systems and its applicability was also demonstrated with flow injection based rapid amperometric detection of DNA samples. The device so developed shall find use as a disposable electrochemical cell for rapid and sensitive analysis of electroactive species in various industrial and research applications.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.952-957
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• 1997

Modified polymeric composite electrodes having highly dispersed CuO particles through the electrode matrix were prepared for LCEC or flow injection analysis of carbohydrates. The composite electrodes were prepared by incorporating carbon black and highly dispersed copper oxide particles in polystyrene matrix cross-linked with divinylbenzene. The analytical characteristics of the electrodes for LCEC and flow injection analysis of carbohydrates were evaluated. Improved performance in LCEC and flow injection analysis of carbohydrates is demonstrated in terms of sensitivity, reproducibility, stability and surface renewability. It was possible to get improved performance of the electrodes as well as adaptability of the electrodes for practical applications by employing highly dispersed catalyst particles through the electrode matrix and robust polymeric electrode matrix.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.18-25
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• 2014

A Pt nanoparticle-decorated multiwall carbon nanotube (Pt-MWNT) electrode was prepared on Nafion by a hot-pressing at relatively low temperature. This electrode exhibited an intricate entangled, nanoporous structure as a result of gathering highly anisotropic Pt-MWNTs. Individual Pt nanoparticles were confirmed to have a polycrystalline face-centered cubic structure with an average crystal size of around 3.5 nm. From the cyclic voltammograms for hydrogen redox reactions, the Pt-MWNT electrode was found to have a similar electrochemical behavior to polycrystalline Pt, and a specific electrochemical surface area of $2170cm^2mg^{-1}$. Upon exposure to hydrogen analyte, the Pt-MWNT/Nafion electrode demon-strated a very high sensitivity of $3.60{\mu}A\;ppm^{-1}$ and an excellent linear response over the concentration range of 100-1000 ppm. Moreover, this electrode was also evaluated in terms of response and recovery times, reproducibility, and long-term stability. Obtained results revealed good sensing performance in hydrogen detection.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.385-390
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• 2002

Laccase could be successfully assembled on an amine-derivatized platinum electrode by glutaraldehyde coupling. The enzyme layer formed on the surface does not communicate electron directly with the electrode, but the enzymatic activity of the surf ace could be followed by electrochemical detection of enzymatically oxidized products. The well-known laccase substrates, ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) and PPD (p-phenylenediamine) were used. ABTS can be detected down to 0.5 ${\mu}M$ with linear response up to 15 ${\mu}M$ and current sensitivity of 75 nA/ ${\mu}M.$ PPD showed better response with detection limit of 0.05 ${\mu}M$, linear response up to 20 ${\mu}M$, and current sensitivity of 340 nA/ ${\mu}M$ with the same electrode. The sensor responses fit well to the Michaelis-Menten equation and apparent $K_M$ values are 0.16 mM for ABTS and 0.055 mM for PPD, which show the enzymatic reaction is the rate-determining step. The laccase electrode we developed is very stable and more than 80% of initial activity was still maintained after 2 months of uses.