• KSBB Journal
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• 제13권1호
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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.

• 분석과학
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• 제5권2호
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• pp.177-184
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• 1992

pH-ISFET와 glucose oxidase막으로 구성되어 있는 포도당센서를 제조하고, 그 감응특성을 조사하였다. pH-ISFET 포도당센서는 pH-ISFET의 gate 위에 glutaraldehyde로서 bovine serum albumin과 glucose oxidase를 고정화시켜서 제작하였다. pH-ISFET 포도당센서의 감응에 미치는 완충용액의 pH 및 농도와 효소의 양의 영향에 대하여 조사였다. 합성생리염수(pH 7.4)로 만든 포도당용액에 대한 감응특성은 다음과 같다. 곧, 직선감응농도 범위, 감응기울기(감도) 및 감응시간은 각각 $1.0{\times}10^{-4}{\sim}6.0{\times}10^{-3}M$, 4.1 mV/decade 및 12~15분이다.

• KSBB Journal
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• 제15권4호
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• pp.388-392
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• 2000

한지자숙폐액을 이용한 Saccharomyces cerevisiae의 배양에 서 glucose의 자동분석 및 첨가에 의해 균농도를 증가시킴으로써 폐액의 재이용성을 향상시키파 하였다 배양액의 glucose를 자동분석하고 자동첨가하기 위하여 ceramic sampler, sampling, ralve, injection valve, glucose oxidase column, debubbler, flow cell과 백금전극, potentiostat, computer와 interface card, 및 tubing pump블로 구성된 glucose 자동분석 및 첨가시스템을 제작하였으며, glucose의 자동분석에는 glucose oxidase를 이용한 on-line FIA법을 채택하였다. 효모의 배양중 glucose자 동분석 및 첨가시스템을 사용하여 glucose를 자동첨가한 결과 배양액의 포도당농도가 $176{\pm}31 mg/L$ 의 낮은 농도로 제어 되었으며, glucose와 $>(NH_4)_2S0_4$의 첨가에 의해 총균수가 3.1 배 증가하였다.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.526-532
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• 2016

In this study, we synthesized a mediator immobilized biocatalyst([FCA/GOx]/PEI/CNT) by surface modification using ferrocene carboxylic acid(FCA), and evaluated its performance as anode catalyst for biofuel cell. Through the application of FCA on glucose oxidase (GOx), the free amine groups on the lysine residue of GOx surface reacted with carboxylic acid of FCA and make amide bond between GOx and FCA. As the result of that, the electron transfer of catalyst was increased up to 1.91 times($0.468mA{\cdot}cm^{-2}$) than the catalyst without surface modification (GOx/PEI/CNT), and high maxium power density of $1.79mA{\cdot}cm^{-2}$ was gained.

• 대한의용생체공학회:의공학회지
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• 제3권2호
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• pp.95-100
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• 1982

Glucose oxidase from A. niger was entrapped in polyacrylamide gel which was used in the enzyme electrode for glucose analysis. The electrode was assembled by placing the gel between the membranes on the surface of a Clark type electrode. In order to make it possible to analyze the experimental results later, the stagnation flow was adopted wheree the governing fluid mechanics were well known. The current increased with the increase concentration in the bulk below a certain level of glucose concentration beyond which no more current increase was observed. This is probably due to the diffusion limitation of oxygen from the bulk solution. Also the current increased witll the enzyme loading in the gel, but the linearity between the current and the glucose concentration was rather limited to a narrow range. Flow rate was found to be very important, which means that film diffusion is very important under the flow rate of 5cm/sec. As a conclusion, enzyme loading, gel layer thickness, stirring speed and bulk concentration of glucose were found to be most improtant parameters in yielding a linar current reponse with respect to the bulk glucose concentration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.100-103
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• 2000

In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidase (GOx) forms a coordinate bond with the polymers backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized the enzyme electrode by electropolymerization added some organic solvent. A formative seeds of film growth is delayed by adding ethanol. The delay is induced by radical transfer between ethanol and pyrrole monomer. The radical transfer shares the contribution of dopant between electrolyte anion and GOx polyanion. This may lead to increase amount of immobilized the enzyme in PPy. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased. We established qualitatively that amount of immobilization can be improved by adding a little ethanol in the synthetic solution. It is due to radical transfer reaction. The radical transfer shares the contribution of dopant between small and fast electrolyte anion and big and slow GOx polyanion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.357-361
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• 1999

GOD electrochemically immobilized in PPy/GOD complex have an effect on redox properties of the complex. In the cyclicvoltammetry, GOD shows the redox reaction at the potential below -0.6Y vs. Ag/AgCI. That leads to new peaks in the cyclicvoltammograms in additional to typical PPy peaks. The pH of electrolyte solution during potential swing decreased to 4.4, and then increased to 10. That suggests the redox of GOD for the cycling. As the concentration of GOD was increased, the anodic wave of the new peaks was strong as much as increased. GOD obstructs the diffusion of electrolyte anion because of its net chain. Insulating property of GOD is cause that it made the faradic impedance of complex large in charge transfer. It suggests that increase of the concentration of GOD be against electrochemical coupling. Therefore, the concentration of GOD and electrochemical coupling should be dealt with each other. The apparent Michaelis-lenten constant ( K\`$_{M}$ ) was determined by 30.7 mmol d $m^{-3}$ fur the PPy/GOD complex. The value is of the same order of magnitude as that for soluble glucose oxidase from Aspergillus Niger.r.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.257-262
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• 2003

A straightforward and effective method is presented for immobilizing enzymes on a microchip platform without chemically modifying a micro-channel or technically microfabricating a column reactor and fluid channel network. The proposed method consists of three steps: the reconstitution of a nitrocellulose (NC) membrane on a plane substrate without a channel network, enzyme immobilization on the NC membrane, and the assembly of another substrate with a fabricated channel network. As a result, enzymes can be stably and efficiently immobilized on a microchip. To evaluate the proposed method, two kinds of enzymatic reaction are applied: a sequential two-step reaction by one enzyme, alkaline phosphatase, and a coupled reaction by two enzymes, glucose oxidase and peroxidase, for a glucose assay.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.529-532
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• 2001

We synthesized polypyrrole (PPy) by electrolysis of the pyrrole monomer solution containing support electrolyte KCl and/or p-toluene sulfonic acid sodium salt (p-TS). The electrochemical behavior was investigated using cyclic voltammetry and AC impedance. In the case of using electrolyte p-75, the redox potential was about -0.3 V vs. Ag/AgCl reference electrode, while the potential was about 0 V for using electrolyte KCl. It is considered as the backbone forms a queue effectively by doping p-TS Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. The AC impedance plot gave a tent of betterment of mass transport. PPy doped with p-TS has improved in mass transport, or diffusion. That is because the PPy doped with p-TS has a good orientation, and is more porous than PPy with KCl.

• 공업화학
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• 제33권2호
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• pp.188-194
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• 2022

본 연구에서는 비파괴적 표면 기능기화 통하여 단일벽 탄소나노튜브(SWCNT) 탄소소재의 특성 변화를 최소화 시킬 수 있는 대면적화 공법을 제안하고, 대면적화 된 SWNT 전자 필름 상에 효소를 집적하여 효소와 SWCNT 전자 필름 간 효율적 전자 전달을 연구하였다. p-terphenyl-4,4"-dithiol, dithiothreitol와 SWCNT의 혼합을 통해 SWCNT 전자 필름의 균일도 및 전하 전달 능력을 향상시키고, 분광학적 분석 및 전기화학적 특성을 평가하여 SWCNT 전자 필름의 향상된 전기화학적 특성을 확인하였다. 전자 필름 상에 고분자 전해질 및 포도당 산화환원 효소를 layer-by-layer 기법으로 효율적으로 집적하여, 최종적으로 음전압 범위에서 구동이 가능한 포도당(glucose) 바이오센서를 구현하였다. 개발된 포도당 바이오센서는 효소와 SWCNT 전자 필름과의 높은 전하 전달 효율을 바탕으로 -0.45 vs. Ag/AgCl 음전압 범위에서 높은 산화환원 신호를 보였을 뿐 아니라 0~1 mM의 낮은 글루코스 농도 변화에서 약 98 ㎂/mM·cm²의 높은 감도를 보였다. 또한 음전압 구동을 통하여, 산화 반응을 일으킬 수 있는 4종의 방해물질(요산, 아스코르빅산, 도파민, 아세타아미노펜) 환경에서 4% 이하의 변화를 보여 높은 선택성을 보였다.