• Biomedical Science Letters
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• v.9 no.4
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• pp.195-201
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• 2003

Aromatic hydrocarbons are of major concern among genotoxic chemicals due to their toxicity and persistence. Some microorganisms can utilize aromatic hydrocarbons as carbon and energy sources by inducing expression of catabolic operon(s). The XylR regulatory protein activates transcription of the catabolic enzymes to degrade BTEX (benzene, toluene, ethylbenzene, and xylene) from its cognate promoters, Pu and Ps upon exposure of the cells to the aromatic hydrocarbons. The activity of XylR on the promoters was previously monitored using luciferase luc reporter system. The xylR, its promoter Pr and the promoter Po for the phenolic compound catabolic operon were introduced upstream of firefly luciferase luc in the pGL3b vector to generate about 7.1 kb of pXRBTEX. Here E. coli harboring the plasmid was freeze-dried under various conditions to fin,d optimal conditions for storage and transport. The cell viability and luciferase activity were maintained better, when the cells were freeze-dried at -7$0^{\circ}C$ in the addition of the 10% skim milk or 12% sucrose. However, coaddition of protectants such as 10% skim milk plus 10% glucose or 12% sucrose plus 10% glucose, resulted in much better viability and bioluminescence activity compared with the effect of single addition of each protectant. In addition, it was shown that the freeze-dried cells maintained almost intact bioluminescent activities and cell viability for at least 1 week after freeze-drying. This work demonstrated that the properly freeze-dried recombinant bacterial cells could be utilized as a whole-cell biosensor for simple and rapid monitoring of BTEX in the environment.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.65-72
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• 2002

This study was to determine the optimum conditions of malt extracting temperature, extracting time of malt in water, ratio of malt to water, and rice volume of malt extract water on saccharification in producing sikhe (sweet rice drink) using central composite design of response surface methodology. Glucose and maltose were analyzed by a biosensor having dual cathode system. The optimum temperatures of malt extracting for glucose and maltose were 60 and $55^{\circ}C$. The saccharification power for the two sugars was highest when malt powder soaked for 6.5 and 5.75 hour, respectively. And ratios of malt to water for optimum saccharification were 1 : 6.3 to 1 : 8.8, respectively. The optimum volumes of malt extracting to rice for the two sugars were 0.48% and 0.6%, respectively. The application of response surface methodology to sikhe processing showed a good correlation with high significance.

• KSBB Journal
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• v.32 no.1
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• pp.35-45
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• 2017

In this work the optical fiber glucose and lactate biosensors were developed by using fluorescent dye and enzyme immobilized on the end tip of an optical fiber. 3-Glycidyloxypropyl)methyldiethoxysilane (GPTMS), (3-Aminopropyl) trimethoxysilane (APTMS) and Methyltrimethoxysilane (MTMS) were used to immobilize glucose oxidase (GOD), lactate oxidase (LOD) and ruthenium(II) complex (tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II), $Ru(dpp)_3^{2+}$) as oxygen sensitive fluorescent dye. MTMS sol-gel was an excellent supporting material for the immobilization of $Ru(dpp)_3^{2+}$, GOD, and LOD on the optical fiber. Storage stability of the optical fiber glucose sensor was kept constant over 20 days, while the optical fiber lactate sensor had constant storage stability over 17 days. The optical fiber glucose and lactate biosensors also maintained good operational stability for 20 hours and 14 hours, respectively. The activities of the immobilized enzymes were most excellent at pH 7 and at $25^{\circ}C$. On-line monitoring of glucose and lactate in a simulated process was performed with the optical fiber glucose and lactate biosensors. On-line monitoring results were agreed with those of off-line data measured with high performance liquid chromatography (HPLC).

• Journal of Electrochemical Science and Technology
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• v.4 no.1
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• pp.41-45
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• 2013

Platinum is a well known element which shows a significant electrocatalytic activity in many important applications. In glucose sensor, because of the poisoning effect of reaction intermediates and the low surface area, the electrocatalytic activity towards the glucose oxidation is low which cause the low sensitivity. So, we fabricate a nanoporous PtZn alloy electrode by deposition-dissolution method. It provides a high active surface and a large enzyme encapsulating space per unit area when it used for an enzymatic glucose sensor. Glucose oxidase was immobilized on the electrode surface by capping with PEDOT composite and PPDA. The composite and PPDA also can exclude the interference ion such as ascorbic acid and uric acid to improve the selectivity. The surface area was determined by cyclic voltametry method and the surface structure and the element were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX), respectively. The sensitivity is $13.5{\mu}A/mM\;cm^2$. It is a remarkable value with such simply prepared senor has high selectivity.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.724-730
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• 2015

For ex-vivo diabetic control, the voltammetric diagnosis of glucose (GU) was conducted with a modified carbon nanotube paste electrode, using handheld analytical circuits. The optimum analytical conditions were attained within the 0.5-4.0 ug/L working range and at the 0.06 ug/L detection limit, which system was interfaced to the feedback circuits and was applied to human urine for diabetic-patient diagnosis. It can be used for ex-vivo flow control analysis, vascular flow detection and other medicinal assays. The equations of the patients' urine are y=36.65x+12.13 and $R^2=0.987$, those of the healthy person of y= 2.5x+10.9 and $R^2=0.928$ (patients: 118 ug/L; healthy person: 12.34 ug/L).

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.210-217
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• 2014

For ex-vivo diabetic control, the voltammetric diagnosis of glucose (GU) was conducted with a modified carbon nanotube paste electrode, using handheld analytical circuits. The optimum analytical conditions were attained within the 0.5-4.0 ug/L working range and at the 0.06 ug/L detection limit, which system was interfaced to the feedback circuits and was applied to human urine for diabetic-patient diagnosis. It can be used for ex-vivo flow control analysis, vascular flow detection, and other medicinal assays.

• Archives of Plastic Surgery
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• v.48 no.4
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• pp.392-394
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• 2021

A 33-year-old man presented to the plastic surgery department for foreign body removal 1 month after the insertion of a continuous glucose monitoring (CGM) sensor (Dexcom G5) in the left upper arm. The patient had used the CGM system for 5 years, and the insertion was done in the usual manner. The entire sensor wire was visible on simple radiography and ultrasonography. In the operating room, and the sensor wire was identified in the intermuscular septum and removed. No foreign body reaction or inflammatory signs were found around the CGM, and the extracted wire measured 2.5 cm. Thus, it was assumed that the whole sensor wire was detached from the transmitter, not fractured. No remnant foreign body was observed on follow-up simple radiography.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.22-34
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• 1998

The purpose of this study is to develop biosensor for determination of glucose, lactate, and ethanol in foods and food-stuffs simultaneously. The multiple cathode system was prepared with an oxygen electrode having one anode and hexagonal cathode. Glucose oxidase, mutarotase, lactate oxidase, alcohol oxidase and catalase were used for immobilization to determine glucose, lactate, and ethanol. These components including ethanol were simultaneously determined by the immobilized enzymes in the multiple cathode system. The determination of the components by enzyme sensor was based on the maximum slope of oxygen consumption from enzyme reaction of each sensor part. The response time for analysis was 1 min. The optimum condition for glucose, lactate and ethanol sensor was found to be 0.1 M potassium phosphate buffer, pH 7.0 at $40^{\circ}C$. Interferences of various sugars and organic acids were investigated. Less than 10% of error was found in determination of the components except organic acids. This difference was compensated by the modified equation. This system was confirmed by conventional methods. It was concluded that the multiple cathode system of this study is for an effective method to determine sugar, organic acid, ethanol simultaneously in foods.

• KSBB Journal
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• v.13 no.1
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• pp.52-57
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• 1998

The present work proposes a simple electrochemical method applicable to any immobilization processes of oxidase using a Clark type oxygen electrode as a base transducer. The present work suggests an optimal immobilization technique among three different methods of glucose oxidase(GOD) onto one side of $37[\mu}$mthick blend membranes, composed o 80% of cellulose triacetate and 20% of polycaprolactone, on the basis of the maximum Michaelis-Menten parameter(Vm) determined by either steady state or transient analyses. The electrode system was made of disk type gold cathode(4mm diameter) and Ag/AgCl anode. One side of the blend membrane was in contact with the cathode surface while the other side was immobilized with GOD either in covalent-bond or cross-linked forms, the latter being covered by $25{\mu}$m thick dialysis membrane of cellulose acetate. The resultant current density was on-line monitored by a potentiostat while glucose level was varied from 1 to 20 mM. The present study shows that direct cross-linking of GOD with glutaraldehyde was mostly preferred for fabrication of glucose sensor, on the basis of resultant kinetic parameters from either steady state or transient analyses.

• KSBB Journal
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• v.10 no.4
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• pp.468-474
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• 1995

The disposable glucose bio-sensor using composite of CTA and PCL membrane was developed for measurement of glucose. The most effective membrane was composed of CTA/PCL(80/20, w/w) and glutaraldehyde one-step immobilization method ($10{\mu}m$ thickness) for glucose sensor gave the best result among various methods, considering oxygen permeability and electronic sensitivity. A scanning electron micrograph of the cross-section of a typical asymmetric CTA/PCL composite membrane showed that the membrane fused with a dense layer covered with a GOD-glutaraldehyde. Glucose oxidase immoblilized on the membrane showed the linearity between difference of absolute amperometric values and glucose concentrations within 7mM when the GOD immobilized electrode was used. About 35% of activity was remained after 8 days when the tyrosinase was immobilized on CTA/PCL (80/20) membrane.