Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 68 , Issue 11
Showing 1-25 articles out of 25 articles from the selected issue
Visions
Headline
  • Tadashi MATSUNAGA, Tae-Kyu LIM
    2000 Volume 68 Issue 11 Pages 847-852
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    Microbial biofilms are implicated with industrial fouling, corrosion, and hygiene problems. Here, we outline electrochemical control of microbial biofilm accumulation on marine infrastructures preventing biofouling without generating toxic substances. Marine bacteria were killed electrochemically by applying a potential of 1.2 V using conductive paint and TiN film electrode. Most of the cells on the electrode were desorbed within 30 min by applying 0.6 V vs. Ag/AgCI. Prevention of bacterial cell accumulation can be performed by applying alternating potentials. Electrochemical control of bacterial cell accumulation on the electrode was achieved by applying an alternating potential of 1.2 and −0.6 V vs. Ag/AgCl. This method does not result in generation of chlorine or change pH. Electrochemical control of bacterial cell accumulation on electrodes will be applicable not only for seawater applications but also for fresh water systems. This disinfection system may also be used in food and medical process.

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Communications
Technical Paper
  • Yuka TAKAHASHI, Satoshi IGARASHI, Yukie NAKAZAWA, Wakako TSUGAWA, Koji ...
    2000 Volume 68 Issue 11 Pages 907-911
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    In this study, we constructed glucose enzyme sensors with increased thermal stability employing engineered PQQGDH-B. First, we demonstrated the enzyme glucose sensor employing an engineered PQQGDH-B, Ser231 Lys. The residual activity after heat treatment at 60°C for 2 hours of the enzyme electrode employed Ser231Lys was 80% of the initial activity, whereas the electrode employed native PQQGDH-B was 30%. Second, we investigated the effect of cross-linking chemical modification on the thermal stability of PQQGDH-B. The cross-linked PQQGDH-B had high thermal stability and the half life time at 55°C was 63 min whereas that of native enzyme was 4 min. Furthermore, we demonstrated the Flow Injection Analysis (FIA) system for glucose measurement employed the cross-linked PQQGDH-B. The high operational stability of this system showed the very stable responses (SD was within 3%) for 100 times of glucose injection.

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Notes
  • Hirosuke TATSUMI, Katsunori KAWAGUCHI, Kan KATO, Kenji KANO, Tokuji IK ...
    2000 Volume 68 Issue 11 Pages 912-915
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    Respiratory reaction of Thiobacillus ferrooxidans which uses Fe2+ as the substrate in acidic solution was analyzed by a Michaelis-Menten type equation, and the catalytic constant, kB,cat, of the bacterial cell was determined as 3.0×106 S−1 for the first time. The Michaelis constant, Km,Fe, for Fe2+ was determined to be 37 μM, which is much smaller than the values so far reported. In addition to FeSO4, a number of iron complexes (Fe (CN)64−, Fe-citrate, and ferrocene derivatives) functioned as the substrates in the respiration of T. ferrooxidans. The kB,cat values with the iron complexes are in the same order of magnitude as that with Fe2+, 0.71- 3.0×106 s−l, while the Km,Fe values are widespread over the range from 1 μM for Fe(CN)64− to 120 μM for ferrocenecarboxaldehyde.

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  • Tomoaki NISHIMURA, Emi HIFUMI, Tamotsu FUJII, Yoshiyuki NIIMI, Naoyosh ...
    2000 Volume 68 Issue 11 Pages 916-919
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    Adults over 70% of Japanese are infected by Helicobacter pylori causing chronic gastrisis and gastric ulcer. In this study, by employing a unique monoclonal antibody against Helicobacter pylori urease, the bacterium was detected down to 2×107 cell/ml using a SPR apparatus equipping two detecting cells. Ultrasonicated sample of Helicobacter pylori gave a huge improvement in the detection limit rather than the non-ultrasonicated sample by 100 fold. Escherichia coli was hardly detected, suggesting the specific detection of Helicobacter pylori by this measurement system. Using this type of SPR apparatus, the wider concentration of Helicobacter pylori could be detected comparing with the conventional assay kit, while the detection limit of the SPR system was worse by 10 fold.

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  • Mikito YASUZAWA, Shinji FUJII, Akira KUNUGI, Tadao NAKAYA
    2000 Volume 68 Issue 11 Pages 920-923
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    Amperometric glucose sensors were prepared by electropolymerization of a pyrrole derivative having a saccharide unit, 1-(3-D-gluconamidopropyl)pyrrole, in the presence of glucose oxidase (GOD). The response current of the GOD-immobilized electrode was approximately stable for 50 days after an initial loss of signal over the first few days. However, the interference of electroactive compounds such as ascorbic acid, uric acid and acetaminophen to the glucose response was large. Such an interference of electroactive compounds was largely lowered by using the GOD-immobilized electrode with Nafion and PPD films as inner film, but the influence of uric acid still remained. The use of Nafion film as the inner film, was more effective in reducing the interference of electroactive compounds on glucose response than that of poly (o-phenylenediamine), which the use of both film produced the best results in the interference study.

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  • Mikako SAITO, Ayako SAGA, Hideaki MATSUOKA, Danny K. Y. WONG
    2000 Volume 68 Issue 11 Pages 924-926
    Published: November 05, 2000
    Released: November 10, 2019
    JOURNALS OPEN ACCESS

    Acetylene was found more suitable than methane for the fabrication of a glass capillary carbon micro electrode with high fabrication yield and stability. The pyrolysis of acetylene was done at a flow rate of no higher than 1 cm3 min−1 at ca. 1000°C. The fabricated microelectrode was characterized by the cyclic voltammetry in a dopamine solution. The yield of electrode that showed a well-defined sigmoidal profile caused by the oxidation of dopamine became a much higher level (50%) than before by the method using methane.

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