Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
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76 巻 , 8 号
選択された号の論文の35件中1~35を表示しています
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論文特集号 生命システムを観る,操る,利用するバイオエレクトロケミストリーの進展
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  • Fumio MIZUTANI, Dai KATO, Ryoji KURITA, Yasuhiro MIE, Yukari SATO, Osa ...
    76 巻 (2008) 8 号 p. 515-521
    公開日: 2012/03/22
    ジャーナル フリー
    This article describes the development of biosensors with chemically-amplified responses. In general, chemical amplification involves a reaction sequence for a substance to generate a relatively large amount of product. Thus a trace concentration of analyte can be caused to yield orders of magnitude higher product concentrations which may be more easily measured than the analyte itself. For biosensor systems to detect biochemical reactions on the transducer surfaces, chemical amplification procedures suitable for concentrating the reaction product on the transducer/test solution interface should be utilized to enhance the sensor response effectively. The amplification procedures, such as enzymatic cycling at the enzyme-modified electrode and the preconcentration of the biochemical reaction product on the electrode surface, are particularly useful for realizing highly-sensitive biosensors. The combination of such amplification techniques with immunoassay protocols has provided simple measuring systems for trace amounts of peptide hormones, such as A- and B-type natriuretic peptides and insulin. These simple and highly-sensitive immunoassay systems are suitable for the purpose of the point-of-care testing.
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  • Yasunori MATSUI, Tatsuya HOSHINO, Masahiro YOSHIZAWA, Hitoshi MUGURUMA
    76 巻 (2008) 8 号 p. 610-613
    公開日: 2012/03/22
    ジャーナル フリー
    We report on an electrochemical nicotin adenine dinucleotide (NADH) sensor that is based on carbon nanotubes (CNT) and plasma-polymerized film (PPF). The configuration of sensing electrode was CNTs sandwiched between two 6 nm thick PPFs made from acetonitrile on sputtered gold thin film. We optimized the CNT concentration for casting formation onto the under PPF layer. The sensor showed high sensitivity (a sensitivity of 240 µA mM−1 cm−2, a detection limit of 3.9 µM at S/N=3, +0.4 V vs. Ag/AgCl), wide dynamic range (a linear response range of 0.009–2.3 mM, a correlation coefficient of 0.993), and rapid response (<7 s in reaching 95% of maximum response). This high performance is attributed that CNTs offer excellent electrocatalytic activity and enhance electron transfer, therefore, PPF and/or plasma process are the electrochemistry-friendly platform for CNT applications.
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  • Yuko OSAWA, Kazunori IKEBUKURO, Natsuki KOBAYASHI, SungWoong HAN, Chik ...
    76 巻 (2008) 8 号 p. 614-618
    公開日: 2012/03/22
    ジャーナル フリー
    The application of voltage has been used to control the movement of charged molecule such as DNA, some proteins and phospholipid in recent year. In this study, we first applied voltage to amyloidogenic protein, α-synuclein, which is related to Parkinson’s disease. To offer the new approach using electric field and new insight into aggregation and fibrillation mechanism of α-synuclein, we tried to control the aggregation of α-synuclein, which has a negative charge, by applying voltage to it. The aggregation of α-synuclein without conformational change occurred rapidly when a voltage of 1 V was applied. The protein did not form amyloid-like fibrils, but it did form small aggregates. These results demonstrate that this technique might be useful not only to efficiently control aggregation of α-syn but also to understand the mechanism of aggregation and fibrillation of α-syn.
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  • Shinichi KOMABA, Toshihiko MITSUHASHI, Soshi SHIRAISHI
    76 巻 (2008) 8 号 p. 619-624
    公開日: 2012/03/22
    ジャーナル フリー
    The nanocomposite enzymatic cathode and anode with carbon nanotube were fabricated and optimized for the application to biofuel cells. The nanocomposite electrodes consisted of polyion complex matrix where enzyme, mediator, and carbon nanotube as an electron transport enhancer were immobilized on the glassy carbon electrode. For the fabrication of anode and cathode, glucose oxidase and tetrathiafulvalene and bilirubin oxidase and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium, respectively, were immobilized together in the polymer matrix. Electrochemical observation confirmed the bioelectrocatalytic ability of glucose oxidation and oxygen reduction at the anode and cathode, respectively, due to the enzymatic activity. The biological-fuel cell fabricated by combining the nanocomposite enzyme electrodes demonstrated open circuit voltage of 0.65 V, and its maximum power was 150 µW cm−2.
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  • Hideaki MATSUOKA, Tamu KOMAZAKI, Yoshiko MUKAI, Mikako SAITO
    76 巻 (2008) 8 号 p. 625-630
    公開日: 2012/03/22
    ジャーナル フリー
    Spatial distribution of intracellular Ca2+ concentration was measured with a spectro-imaging system composed of an image slicer (10×10 channels), a grism, and a high sensitive CCD camera. The Ca2+ concentration of each single protoplast was different from others both at a steady state (10–100 nmol dm−3) and after electric stimulation. Therefore traceable observation of each single-cell was essential, which contrasted conventional methods dealing with an average of many cells. When a pulsing electric stimulation was applied to single-cells of rice protoplast, the transient variation of intracellular Ca2+ concentration was observed and chitinase gene expression followed (16 out of 36 cells, 44.4%). Its significance level was estimated as 90% by χ2-test.
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