• 분석과학
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• 제20권1호
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• pp.49-54
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• 2007

For the practical use as a biosensor, a rubber electrode bound by polybutadiene was newly devised for the determination of hydrogen peroxide. Then its electrochemical behaviors were investigated. The signal could be obtained at low electrode potential between 0.0 ~ -0.5 V (vs. Ag/AgCl) with a detection limit of $1.4{\times}10^{-4}M$ and its potential dependence was linear in the experimental range. Especially its Lineweaver-Burk plot showed a very good linearity giving the evidence of a good enzyme immobilization on the surface of the electrode. And mechanical stability of the electrode resulted from using rubber binder presented a new possibility for the practical use of biosensor.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3077-3083
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• 2010

The electrochemical detection of As(III) was investigated on a platinum-iron(III) nanoparticles modified multiwalled carbon nanotube on glassy carbon electrode(nanoPt-Fe(III)/MWCNT/GCE) in 0.1 M $H_2SO_4$. The nanoPt-Fe(III)/MWCNT/GCE was prepared via continuous potential cycling in the range from -0.8 to 0.7 V (vs. Ag/AgCl), in 0.1 M KCl solution containing 0.9 mM $K_2PtCl_6$ and 0.6 mM $FeCl_3$. The Pt nanoparticles and iron oxide were co-electrodeposited into the MWCNT-Nafion composite film on GCE. The resulting electrode was examined by cyclic voltammetry (CV), scanning electron microscopy (SEM), and anodic stripping voltammetry (ASV). For the detection of As(III), the nanoPt-Fe(III)/MWCNT/GCE showed low detection limit of 10 nM (0.75 ppb) and high sensitivity of $4.76\;{\mu}A{\mu}M^{-1}$, while the World Health Organization's guideline value of arsenic for drinking water is 10 ppb. It is worth to note that the electrode presents no interference from copper ion, which is the most serious interfering species in arsenic detection.

• 센서학회지
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• 제28권1호
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• pp.47-51
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• 2019

Sweat-based glucose sensors are being widely investigated and researched as they facilitate painless and continuous measurement. However, because the concentration of sweat glucose is almost a hundred times lower than that of blood glucose, it is important to develop electrochemical sensing electrode materials that are highly sensitive to glucose molecules for the detection of low concentrations of glucose. The preparation of a flexible and ultra-sensitive sensor for detection of sweat glucose is presented in this study. Oxygen and nitrogen are removed from the surface of a polyimide film by exposure to a CO2 laser; hence, laser-induced graphene (LIG) is formed. The fabricated LIG electrode showed favorable properties of high roughness and good stability, flexibility, and conductivity. After the laser scanning, Pt nanoparticles (PtNP) with good catalytic behavior were electrodeposited and the glucose sensor thus developed, with a LIG/PtNP hybrid electrode, exhibited a high order of sensitivity and detection limit for sweat glucose.

• 전기화학회지
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• 제16권2호
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• pp.74-80
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• 2013

세 가지 종류의 카복실산(포름산, 아세트산, 프로피온산) 용액 하에서 양극산화 반응을 통한 나노 다공성 금(nanoporous gold, NPG) 구조의 형성과 NPG 전극 표면 상의 전기화학적 글루코오스 산화반응을 관찰하였다. 세 가지 카복실산 용액 조건 중에서 포름산 용액 조건하의 양극산화를 통해 형성된 NPG 전극에서 글루코오스의 산화 활성이 가장 우수하였다. 포름산 용액 조건하의 양극산화 과정에서 가장 우수한 글루코오스 산화 활성을 얻기 위한 최적 조건은 인가전위 5.0 V와 반응시간 4시간이었다. 카복실산 용액 하에서 형성된 NPG 상의 전기화학적 글루코오스 산화 활성을 염소이온의 부재 및 존재 하 조건에서 관찰하고, 이를 옥살산 용액 하에서 형성된 NPG 상의 거동과 비교 분석하였다. 포름산 용액 하에서 최적 조건으로 형성된 NPG 전극상에서 글루코오스의 전류법 검출 응용을 제시하였다.

• 전기화학회지
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• 제10권3호
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• pp.190-195
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• 2007

본 연구는 뇨 속에 있는 에피네피린을 선택적으로 정량하기 위한 새로운 전기화학적 센서를 제작하고 그 특성을 연구한 것이다. 전극의 제작은 유리질 탄소전극에 촉매능이 있는 니켈(II)거대고리 착물을 전착시킨 후, 그 위에 생체적합성이 좋으며 음의 하전을 띤 polyuretane benzyl L-glutamate(PUBLG)로 막을 입힌 이중 폴리머 전극이다. 이 전극은 뇨 속에 있는 많은 방해물질에 대하여 좋은 선택성을 보였으며, 우수한 장기 안정성을 보였다. 최적 실험조건하에서 이 전극을 이용한 에피네피린의 정량범위는 $8.0\;{\times}\;10^{-7}\;M$에서 $2.0\;{\times}\;10^{-4}\;M$이고, 검출한계는 $1.0\;{\times}\;10^{-7}\;M$이다. 완충용액으로 5 배 희석한 뇨 시료에서 에피네피린의 회수율은 6 회 측정에서 $101.5({\pm}3.2)%$ 이었다.

• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.68-75
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• 2016

In this study a new, simple, precise, accurate and economic electrochemical method was developed and validated for the voltammetric determination of zolpidem (ZP) using disposable pencil graphite (PG) electrode. The anodic oxidation of ZP on the surface of the PG electrode was examined in a britton robinson (BR) buffer. Square wave and cyclic voltammetry were used as electrochemical techniques in the potential range of 0-1.2 V in the pH 8 BR buffer. In cyclic voltammetry studies, the diffusion coefficient of ZP oxidation was found to be 3.6×10^-6 cm² s^-1. On the other hand, the ZP has shown a well-defined irreversible anodic peak at 0.98 V in the square wave voltammetry mode. The PG electrode, primarily being graphite which has a large active surface area gives rise to increasing peak current with respect to ZP electrooxidation. PG electrode showed an electrocatalytic effect in anodic oxidation of ZP. A linear relationship between catalytic current response and ZP concentration was obtained over a concentration range of 10-30 μM with R.S.D. values ranging from 0.29-3.89. Limits of detection and quantitation were found to be 1 and 3 μM, respectively. Finally, the PG electrode was successfully used to determine ZP in standard and tablet dosage forms with a mean recovery of 100.69 %.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.915-920
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• 2008

In this paper the electrochemical behaviors of hydroquinone ($H_2Q$) were investigated on a carbon paste electrode using room temperature ionic liquid N-butylpyridinium hexafluorophosphate ($BPPF_6$) as binder (ILCPE) and further applied to $H_2Q$ determination. In pH 2.5 phosphate buffer solution (PBS), the electrochemical response of H2Q was greatly improved on the IL-CPE with a pair of well-defined quasi-reversible redox peaks appeared, which was attributed to the electrocatalytic activity of IL-CPE to the $H_2Q$. The redox peak potentials were located at 0.340 V (Epa) and 0.240 V (Epc) (vs. the saturated calomel electrode, SCE), respectively. The formal potential ($E^0$') was calculated as 0.290 V and the peak-to-peak separation (${\Delta}E_p$) was 0.100 V. The electrochemical parameters of $H_2Q$ on the IL-CPE were further calculated by cyclic voltammetry. Under the selected conditions the anodic peak current was linear with $H_2Q$ concentration over the range from $5.0\;{{\times}}\;10^{-6}$ to $5.0\;{\times}\;10^{-3}\;mol\;L^{-1}$ with the detection limit as $2.5\;{\times}\;10^{-6}\;mol\;L^{-1}$ (3$\sigma$ ) by cyclic voltammetry. The proposed method was successful applied to determination of $H_2Q$ content in a synthetic wastewater sample without the interferences of commonly coexisting substances.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.928-932
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• 2008

A glassy carbon electrode (GCE) modified with poly(p-aminobenzene sulfonic acid) [Poly(p-ABSA)] film is fabricated by voltammetric technique in phosphate buffer solution (pH 8.0) containing $5.0\;{\times}\;10^{-3}\;mol\;L^{-1}$p- ABSA. Electrochemical behaviors of tryptophan at the Poly(p-ABSA) film electrode are investigated with voltammetry. The results indicate that the electrochemical response of tryptophan is improved significantly in the presence of poly(p-ABSA) film. Compared with the bare glassy carbon electrode, the Poly(p-ABSA) film electrode remarkably enhances the irreversible oxidation peak current of tryptophan. Some parameters such as voltammetric sweeping segments for the electrochemical polymerization, pH, accumulation potential and accumulation time are optimized. Under the optimal conditions, the oxidation peak current is proportional to tryptophan concentration in the range of $1.0\;{\times}\;10^{-7}$ to $1.0\;{\times}\;10^{-6}\;mol\;L^{-1}$, and $2.0\;{\times}\;10^{-6}$ to $1.0\;{\times}\;10^{-5}\;mol\;L^{-1}$ with a detection limit of $7.0\;{\times}\;10^{-8}\;mol\;L^{-1}$. The proposed procedure is successfully applied to the determination of tryptophan in a commercial amino acid oral solution.

• Korean Chemical Engineering Research
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• 제57권5호
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• pp.606-610
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• 2019

본 연구에서 우리는 보론 도핑된 다이아몬드 나노물질을 이용하여 유연성 탄소 섬유 기반의 전극(CF-BDD 전극)을 개발하고, 이를 비효소적 글루코스 센서에 적용하여 전기화학적 특성을 확인하였다. 이 전극은 탄소 섬유 표면에 정전하 자기조립법을 이용하여 BDD 층을 증착하여 제작하였다. 이 전극 물질의 표면 구조는 주사전자 현미경(SEM)을 이용하여 분석하였으며, 전기화학적 특성 및 센싱 성능 분석은 시간대전류법(CA)와 순환전압 전류법(CV), 전기화학 임피던스(EIS)으로 실행하였다. 제작된 CF-BDD 전극은 산화-환원 화학종과 전극 계면 간의 effective direct electron transfer와 large effective surface area, high catalytic activity의 우수한 특성들을 보였다. 결과적으로, CF 센서와 비교에서 CF-BDD 센서는 더 넓은 선형 농도 범위(3.75~50 mM)와 더 빠른 감응 시간(3초 이내), 더 높은 감도(388.8 nA/mM) 등의 향상된 센싱 특성을 보였다. 따라서, 본 연구에서 개발된 전극 물질은 다양한 전기화학 센서 뿐 아니라, 웨어러블 센서 소재로도 활용 가능할 것으로 기대된다.

• Molecules and Cells
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• 제39권11호
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• pp.807-813
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• 2016

Escherichia coli are important indicator organisms, used routinely for the monitoring of water and food safety. For quick, sensitive and real-time detection of E. coli we developed a 2'F modified RNA aptamer Ec3, by Cell-SELEX. The 31 nucleotide truncated Ec3 demonstrated improved binding and low nano-molar affinity to E. coli. The aptamer developed by us out-performs the commercial antibody and aptamer used for E. coli detection. Ec3(31) aptamer based E. coli detection was done using three different detection formats and the assay sensitivities were determined. Conventional Ec3(31)-biotin-streptavidin magnetic separation could detect E. coli with a limit of detection of $1.3{\times}10^6CFU/ml$. Although, optical analytic technique, biolayer interferometry, did not improve the sensitivity of detection for whole cells, a very significant improvement in the detection was seen with the E. coli cell lysate ($5{\times}10^4CFU/ml$). Finally we developed Electrochemical Impedance Spectroscopy (EIS) gap capacitance biosensor that has detection limits of $2{\times}10^4CFU/mL$ of E. coli cells, without any labeling and signal amplification techniques. We believe that our developed method can step towards more complex and real sample application.