• 한국환경과학회지
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• 제23권10호
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• pp.1745-1753
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• 2014

Sediment microbial fuel cell (SMFC), equipped with Zn, Al, Cu, Fe or graphite felt (GF) anode and marine sediment, was performed. Graphite felt was used as a common cathode. SMFC was single chambered and did not use any redox mediator. The aim of this work was to find efficient anodic material. Oxidation reduction potential (ORP), cell voltage, current density, power density, pH and chemical oxygen demand (COD) were measured for SMFC's performance.. The order of maximum power density was $913mWm^{-2}$ for Zn, $646mWm^{-2}$ for Fe, $387.8mWm^{-2}$ for Cu, $266mWm^{-2}$ for Al, and $127mWm^{-2}$ for graphite felt (GF). The current density over voltage was found to be strongly correlated with metal electrodes, but the graphite felt electrode, in which relatively weaker electricity was observed because of its bio-oriented mechanism. Metal corrosion reactions and/or a complicated microbial electron transfer mechanism acting around the anodic compartment may facilitate to generate electricity. We presume that more sophisticated selection of anodic material can lead to better performance in SMFC.

• Korean Chemical Engineering Research
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• 제54권2호
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• pp.171-174
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• 2016

효소 전극 cathode와 PEMFC용 전극 anode를 이용하여 효소연료전지를 구동하였다. 효소 cathode는 그래파이트 분말과 효소로서 Laccase, 산화환원 매개체로서 ABTS를 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. cathode 제조조건을 변화시키며 OCV를 측정해 효소 cathode 제조 최적조건을 찾았다. 효소 cathode 압축 시 최적 압력은 4.0 bar 였다. 효소 cathode에서 그래파이트가 95%일 때 최고의 OCV를 나타냈다. cathode기질 용액의 최적 글루코스 농도는 0.4 mol/l이었다.

• 전기화학회지
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• 제8권3호
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• pp.117-124
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• 2005

Electrochemical oxidation of ethanol at nickel electrodes has been studied in 1 M KOH solution containing 0.20M ethanol using electrochemical impedance spectroscopy. Equivalent circuits have been worked out by simulating the impedance data, and the results were used to model the oxidation of ethanol as well as the passivation of the electrode. The maximum rate of oxidation of $Ni(OH)_2$ to NiOOH was observed at about 0.37V vs. Ag/AgCl reference electrode, while the maximum rate of ethanol oxidation at the Ni electrode was observed at about 0.42V, The charge-transfer resistance for oxidation of the electrode itself became smaller in the presence of ethanol than in its absence. These results suggest that the $\beta-Ni(OH)_2/\beta-NiOOH$ redox couple is acting as an effective electron transfer mediator far ethanol oxidation. The kinetic parameters also were obtained by the experimental and simulated results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1520-1522
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• 2003

Molecular self-assembled of surfactant viologen are of recent interest because they can from functional electrodes as well as micellar assemblies, which can be Profitably utilized for display devices, photoelectrochemical studies and electrocatalysis as electron acceptor or electron mediator. Fromherz et al studied the self-assembly of thiol and disulfide derivatives of viologens bearing long n-alkyl chains on Au electrode surface. The electrochemical behavior of self-assembled viologen monolayer has been investigated with QCM, which has been known as nano-gram order mass detector. The self-assembly process of viologen was monitored using resonant frequency (${\Delta}$F) and resonant resistance (R). The redox process of viologen was observed with resonant frequency (${\Delta}$F).

• Molecules and Cells
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• 제46권3호
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• pp.165-175
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• 2023

The transcription factor Nrf2 was originally identified as a master regulator of redox homeostasis, as it governs the expression of a battery of genes involved in mitigating oxidative and electrophilic stress. However, the central role of Nrf2 in dictating multiple facets of the cellular stress response has defined the Nrf2 pathway as a general mediator of cell survival. Recent studies have indicated that Nrf2 regulates the expression of genes controlling ferroptosis, an iron-and lipid peroxidation-dependent form of cell death. While Nrf2 was initially thought to have anti-ferroptotic function primarily through regulation of the antioxidant response, accumulating evidence has indicated that Nrf2 also exerts anti-ferroptotic effects via regulation of key aspects of iron and lipid metabolism. In this review, we will explore the emerging role of Nrf2 in mediating iron homeostasis and lipid peroxidation, where several Nrf2 target genes have been identified that encode critical proteins involved in these pathways. A better understanding of the mechanistic relationship between Nrf2 and ferroptosis, including how genetic and/or pharmacological manipulation of Nrf2 affect the ferroptotic response, should facilitate the development of new therapies that can be used to treat ferroptosis-associated diseases.

• 전기화학회지
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• 제17권1호
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• pp.30-36
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• 2014

산화/환원 매개체는 혈당 센서의 구성에서 전극과 효소 반응의 전자 전달 매개체로서 중요한 역할을 담당한다. 본 연구에서는 기존의 산화/환원 매개체보다 전자 전달 반응이 용이하며, 높은 민감도를 위해 페레이트에 아닐린을 결합시켜, 1차 아민기를 갖는 $Fe(CN)_5$-aminopyridine를 합성하였다. 합성된 $Fe(CN)_5$-aminopyridine 는 순환 전압 전류 법과 분광학적 방법을 이용하여 합성 결과를 확인하였다. 합성된 물질과 포도당을 측정하기 위한 당 탈 수소 효소를 ITO 전극위에 고정시켜 효소전극을 제작하였고, 또한 신호 증폭을 위하여 금 나노 입자를 함께 고정시켰다. 금 나노 입자가 고정된 효소 전극은 그렇지 않은 전극에 비해 약 2배 가량의 전류 밀도가 증가함을 확인하였다. 만들어진 효소 전극에서 포도당의 농도 별 산화 촉매 전류를 순환 전압 전류 법으로 측정한 결과 0.4 V (vs. Ag/AgCl)에서 전기적 신호가 발생되었으며, 포도당 0~10 mM의 농도 범위에서 전기적 신호가 선형 증가함을 확인할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.179-183
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• 2015

In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ($[GOx/GNR]_nPEI/CNT$). To investigate the impact of $[GOx/GNR]_nPEI/CNT$ on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that $[GOx/GNR/PEI]_2/CNT$ is the best layer. Its glucose sensitivity is $13.315{\mu}AmM^{-1}cm^{-2}$. When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within $[GOx/GNR/PEI]_2/CNT$, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the $[GOx/GNR/PEI]_3/CNT$ is limited to the surface reaction and the reaction is quasi-reversible.

• 한국미생물·생명공학회지
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• 제48권4호
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• pp.463-470
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• 2020

삼림지역의 고목에서 분리한 JS18 균주는 합성 멜라닌을 탈색하는 세포 외 분비효소를 생산했다. JS18 균주의 internal transcribed spacer (ITS) 염기서열을 분석하고 계통학적으로 확인한 결과 본 균주는 Trametes velutina로 동정되었다. JS18 균주는 laccase 활성을 나타냈지만 manganese peroxidase 및 lignin peroxidase 활성은 나타내지 않았다. 본 균주를 회분배양한 결과 멜라닌 탈색 활성은 laccase 활성으로부터 유래하는 것으로 확인되었다. Laccase 유도인자로써 Syringic acid 및 CuSO4를 첨가하고 25℃에서 7일간 배양한 결과 배양상등액에서 98 U/ml의 laccase 활성을 나타내었다. GYP 배지에서 배양한 T. velutina의 배양상등액에서 ammonium sulfate 침전, Hi-trap Q Sepharose 컬럼 및 gel filtration을 이용하여 효소를 정제하였고, SDS-PAGE에서 약 67 kDa의 분자량을 나타내었다. 정제된 효소의 멜라닌 탈색율은 효소 단독으로는 24 시간 만에 단지 4% 만을 나타내는 반면, HBT의 존재 하에서는 80%로 향상되었다. 또한 1.5 mM HBT의 농도에서는 최대 81%의 멜라닌 탈색율을 나타내었다. 본 효소의 멜라닌 탈색에 대한 최적 pH 및 온도는 각각 5.0와 37℃를 나타내었다. 본 연구에서는 T. velutina JS18 유래 laccase가 촉매하는 멜라닌 탈색 반응에서 redox mediator로써 HBT의 적용 가능성을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1120-1127
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• 2017

Marasmius scorodonius secretes an extracellular laccase in potato dextrose broth, and this enzyme was purified up to 206-fold using $(NH_4)_2SO_4$ precipitation and a Hi-trap Q Sepharose column. The molecular mass of the purified laccase was estimated to be ~67 kDa by SDS-PAGE. The UV/vis spectrum of the enzyme was nontypical for laccases, and metal content analysis revealed that the enzyme contains 1 mole of Fe and Zn and 2 moles of Cu per mole of protein. The optimal pH for the enzymatic activity was 3.4, 4.0, and 4.6 with 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate) (ABTS), guaiacol, and 2,6-dimethoxy phenol as the substrate, respectively. The optimal temperature of the enzyme was $75^{\circ}C$ with ABTS as the substrate. The enzyme was stable in the presence of some metal ions such as $Ca^{2+}$, $Cu^{2+}$, $Ni^{2+}$, $Mg^{2+}$, $Mn^{2+}$, $Ba^{2+}$, $Co^{2+}$, and $Zn^{2+}$ at a low concentration (1 mM), whereas $Fe^{2+}$ completely inhibited the enzymatic activity. The enzymatic reaction was strongly inhibited by metal chelators and thiol compounds except for EDTA. This enzyme directly decolorized Congo red, Malachite green, Crystal violet, and Methylene green dyes at various decolorization rates of 63-90%. In the presence of 1-hydroxybenzotriazole as a redox mediator, the decolorization of Reactive orange 16 and Remazol brilliant blue R was also achieved.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.667-671
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• 2015

Anode는 효소를 이용한 효소전극과 cathode는 PEMFC용 전극을 이용해 효소연료전지를 구동하였다. 효소 anode는 graphite 분말과 효소로서 글루코스 산화제, 전자매개체로 ferrocene을 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. Anode 제조조건을 변화시키며 성능을 측정해 효소 anode 제조 최적조건을 찾았다. 효소 anode 압축 시 최적 압력은 8.89 MPa이고, 효소 anode의 graphite 성분비가 60%일 때 최고의 출력밀도를 나타냈다. Anode 기질 용액의 최적 glucose 농도는 1.7mol/l이었다. 효소 anode는 Nafion 용액에 1초, 2회 침지에 의해 안정화되었다.