β-D-Glucosidase Assisted Gold Dissolution as Non-Optical and Quantifiable Detection Technique for Immunoassays

Authors

  • F. M. Koehler,

    1. Institute of Chemical- and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Fax: (+) 41 44 633 15 71
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  • R. A. Raso,

    1. Institute of Chemical- and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Fax: (+) 41 44 633 15 71
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  • R. N. Grass,

    1. Institute of Chemical- and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Fax: (+) 41 44 633 15 71
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  • W. J. Stark

    Corresponding author
    1. Institute of Chemical- and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Fax: (+) 41 44 633 15 71
    • Institute of Chemical- and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Fax: (+) 41 44 633 15 71.

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Abstract

Immunoassays are used for detecting protein targets for various applications. Here, a modification of immunoassays to allow a purely electrical detection of the target protein concentration is shown. The modification comprises a β-D-glucosidase as reporter enzyme and a cyanogenic glycoside as substrate. The enzymatic reaction produces cyanide in small quantities. For electrical detection of the cyanide, a novel sensor is developed, based on a gold micro wire. The cyanide dissolves the gold wire and changes the electrical resistance of the wire. Monitoring the resistance change allows a quantitative measurement of the target human C-reactive protein (an inflammatory marker) in blood plasma in the physiological relevant concentration range.

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