• Journal of Microbiology and Biotechnology
• /
• 제16권4호
• /
• pp.505-510
• /
• 2006

A gallocyanine-bound nanoporous titanium dioxide electrode system was investigated to carry out a mediated enzyme reaction. Gallocyanine was bound either directly or through an aminopropylsilane linker to the film of nanoporous titanium dioxide and used as a mediator for nitrate reductase in the mediated enzymatic nitrate reduction. The electrode with the aminopropylsilane linker showed 20% higher efficiency of electron transfer at the same potential than that directly linked. The prepared electrodes showed $0.26{\mu}mol/h$ nitrate reduction at a $100mm^2$ surface of the electrode, and linear current response on nitrate ion concentration up to 1.0 mM, which is very useful as a biosensor of nitrate ion in water.

• 분석과학
• /
• 제29권1호
• /
• pp.35-42
• /
• 2016

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM⁻¹cm⁻².

• 대한화학회지
• /
• 제48권5호
• /
• pp.491-498
• /
• 2004

흑염소의 간-조직과 ferrocene을 탄소반죽 전극에 고정하여 과산화수소를 정량할 수 있는 전극을 만들었다. Ag/AgCl 전극에 대하여 $-0.3{\sim}+0.0\;V$의 전위 범위에서 전극의 감도를 관찰하였으며 전극의 감응시간은 12 s로 나타났다. 전극의 검출한계는 2.25${\times)10^{-6}M$ (S/N＝3)이었으며,1.0${\times}10^{-2 }$M 과산화수소를 이용해 15회 반복 측정한 결과, 상대표준편차는 1.87%이었다. 또한, 방해물질의 영향도 없는 것으로 나타났다. 효소전극의 감도는 19일 사용 후 50%로 감소하였다.

• 전기화학회지
• /
• 제7권2호
• /
• pp.83-88
• /
• 2004

[ $DeniLite^{TM}$ ] laccase immobilized Pt electrode was used for amperometric detection of some catechol derivatives and o-aminophenol (OAP) derivative by means of substrate recycling. In case of catechol derivatives, the obtained sensitivities are 85, 79 and $57 nA/{\mu}M$ with linear ranges of $0.6\~30,\;0.6\~30\;and\; 1\~25 {\mu}M$ and detection limits (S/N=3) of 0.2, 0.2 and $0.3{\mu}M$ for 3,4-dihydroxycinnaminic acid (3,4-DHCA), 3,4-dihydroxybenzoic acid (3,4-DHBA) and 3,4-dihydroxyphenylacetic acid (3,4-DHPAA), respectively. In case of OAP derivative, the obtained sensitivity is $237 nA/{\mu}M$ with linear range of $0.2\~15{\mu}M$ and detection limit of 70 nM for 2-amino-4-chlorophenol (2-A-4-CP). The response time $(t_{90\%})$ is about 2 seconds for each substrate and the long-term stability is around 40-50days for catechol derivatives and 30 days for 2-A-4-CP with retaining $80\%$ of initial activity. The optimal pHs of the sensor for these substrates are in the range of 4.5-5.0, which indicates that stability of the enzymatically oxidized product plays a very important role in substrate recycling. The different sensitivity of the sensor for each substrate can be explained by the electronic effect of the sugstituent on the enzymatically oxidized form.

• 동아시아식생활학회지
• /
• 제22권1호
• /
• pp.88-94
• /
• 2012

Histamine은 발효식품, 등푸른 생선 등 단백질이 많이 함유된 식품에서 잘 생성되는 물질로 이들 식품의 부패 시에는 다량의 histamine이 발생되어 이를 섭취하였을 때 독성을 일으킬 수 있기 때문에 histamine은 어육식품의 선도 저하 또는 부패의 지표로서 사용된다. 따라서 본 연구에서는 신속하며 정확한 histamine 검출을 위한 바이오센서 시스템을 구축하기 위하여 기능화된 MWCNT와 Prussian blue를 사용한 전극을 제작하였으며, 여러 불용성 담체에 효소를 고정화시켜 바이오센서 시스템에 적합한 불용성 담체를 확인하기 위한 연구를 수행하였다. MWCNT-$NH_2$와 Prussian blue가 도입된 전극의 과산화수소에 대한 감응도를 확인한 결과, 검출한계는 $0.1{\mu}M$으로 나타났으며, 각 담체의 효소 고정화도를 측정한 결과, CNBr-activated sepharose 4B는 48.5%, calcium alginate는 40.3%, controlled pore size glass beads는 51.0%를 보였다. 또한 CNBr-activated sepharose 4B, calcium alginate, controlled pore size glass beads로 제작된 효소반응기의 $100{\mu}M$ histamine에 대한 전극 감응도는 각각 120 nA, 110 nA, 140 nA로 나타났다. 따라서 담체의 coupling efficiency, 제작된 효소반응기의 전극 감응도, 선형 관계 등을 고려해 보았을 때 controlled pore size glass beads가 본 연구에서 구축된 바이오센서 시스템에서 가장 적합한 담체인 것으로 확인되었다. 이로써 이들 작업전극과 효소반응기로 구축된 바이오센서는 histamine을 감도 높고 신속하게 측정할 수 있는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
• /
• 제27권5호
• /
• pp.672-678
• /
• 2006

A new approach to fabricate an enzyme electrode was described based on the immobilization of horseradish peroxidase (HRP) on dithiobis-N-succinimidyl propionate (DTSP) self-assembled monolayer (SAM) formed on gold-nanoparticles (Au-NPs) which were electrochemically deposited onto glassy carbon electrode (GCE) surface. The overall surface area and average size of Au-NPs could be controlled by varying deposition time and were examined by Field Emission-Scanning Electron Microscope (FE-SEM). The $O_2$ reduction capability of the surface demonstrated that Au-NPs were thermodynamically stable enough to stay on GCE surface. The immobilized HRP electrode based on Au-NPs/GCE presented faster, more stable and sensitive amperometric response in the reduction of hydrogen peroxide than a HRP immobilized on DTSP/gold plate electrode not containing Au-NPs. The effects of operating potential, mediator concentration, and pH of buffer electrolyte solution on the performance of the HRP biosensor were investigated. In the optimized experimental conditions, the HRP immobilized GCE incorporating smaller-sized Au-NPs showed higher electrocatalytic activity due to the high surface area to volume ratio of Au-NPs in the biosensor. The HRP electrode showed a linear response to $H_2O_2$ in the concentration range of 1.4 $\mu$M-3.1 mM. The apparent Michaelis-Menten constant ($K _M\; ^{app}$) determined for the immobilized HRP electrodes showed a trend to be decreased by decreasing size of Au-NPs electrodeposited onto GCE.

• 한국식품과학회지
• /
• 제44권2호
• /
• pp.141-147
• /
• 2012

BA은 치즈, 와인, 젓갈, 소시지, 된장 등 미생물에 의한 발효과정을 거치는 식품뿐만 아니라 채소류, 과일, 육류와 같은 비발효 식품군에서도 발견된다. 식품 내 BA 오염에 대한 관리를 목적으로 제조공정 및 유통과정에서 신속하게 다량의 시료를 분석하고 제품에 대한 항시 모니터링 기술이 요구된다. 이를 위해 BA 특이항체 및 BA 분해효소를 이용하는 BA 검출 및 센싱 기술이 개발되고 있다. HisN 특이 항체를 이용한 ELISA 키트는 상용화 되었으며 다양한 식품에 적용되고 있다. 산화적 탈아미노반응을 촉매하는 아민산화효소는 항체기반의 ELISA 방식에 비해 다양한 BA 분석에 사용되고 있으며, 효소반응에 의해 생성되는 $H_2O_2$의 산화환원반응에 의해 발생하는 전류를 측정함으로써 BA의 함량을 정량할 수 있는 전류측정식 바이오센서 개발에 적용되고 있다. BA 신속검출을 위한 바이오센서의 개발 연구 동향에 발맞추어 국내 전통발효식품에 적합한 기술개발이 요구되며, 산업현장 적용 연구를 거쳐 국내 전통발효식품의 안전성을 확보해야 할 것으로 판단된다.

• 한국식품위생안전성학회지
• /
• 제32권6호
• /
• pp.447-454
• /
• 2017

본 연구의 목적은 식품 제조 중 표백 및 살균에 사용되는 과산화수소($H_2O_2$)의 잔류 농도 검출에 활용 될 수 있는 유리탄소전극 기반의 바이오센서의 개발이다. 미국 FDA 및 국내 식품의학안전처 등 식품 용 과산화수소(food grade $H_2O_2$)는 국내외적으로 35% $H_2O_2$ 수용액으로 규정한다. 연구에서 개발한 바이오센서는 감응 물질로 사용된 horseradish peroxidase를 graphene oxide와 aniline과 함께 biocomposite를 형성시킨 후 중성 pH에서 본 연구에서 새롭게 개발된 전기화학적 증착법을 수행하여 개발되었다. 센서구조 및 특성 평가를 위하여 SEM, 순환 전압 전류법 등을 수행하였으며 본 연구에서 개발된 바이오센서는 $10-500{\mu}M$ 농도의 $H_2O_2$에 대하여 직선상의 농도 의존적인 반응을 나타내었으며 최저 검출 한계는 $0.12{\mu}M$으로 산출되었다. 본 연구에서 개발된 센서의 전략적 가치는 향후 오징어포, 건어물 등 널리 유통되는 식품 중에 함유된 식품용 $H_2O_2$ 미량을 현장에서 쉽게 분석 할 수 있어서 비용-효과적 측면에서 그 가치가 우수하다는 것을 제시한다.

• Journal of Electrochemical Science and Technology
• /
• 제11권3호
• /
• pp.310-317
• /
• 2020

A development of disposable strip-type galactose sensor for point-of-care testing (POCT) was studied, which was constructed using screen-printed carbon electrodes. Galactose levels were determined by the redox reaction of galactose oxidase in the presence of potassium ferricyanide as an electron transfer mediator in a small sample volume (i.e., less than 1 µL). The optimal performance of biosensor was systematically designated by varying applied potential, operating pH, mediator concentration, and amount of enzyme on the electrode. The sensor system was identified as a highly active for the galactose measurement in terms of the sensitivity (slope = 4.76 ± 0.05 nA/µM) with high sensor-to-sensor reproducibility, the linearity (R² = 0.9915 in galactose concentration range from 0 to 400 µM), and response time (t_95% = <17 s). A lower applied potential (i.e., 0.25 V vs. Ag/AgCl) allowed to minimize interference from readily oxidizable metabolites such as ascorbic acid, acetaminophen, uric acid, and acetoacetic acid. The proposed galactose sensor represents a promising system with advantage for use in POCT.

• Journal of Electrochemical Science and Technology
• /
• 제4권1호
• /
• pp.41-45
• /
• 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.