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A Chemical Lift-off Process: Removing Non-Specific Adsorption in an Electrochemical Epstein–Barr Virus Immunoassay

Authors

  • Lutz Stratmann,

    1. Analytische Chemie—Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany), Fax: (+49) 234 3214683
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  • Dr. Magdalena Gebala,

    1. Analytische Chemie—Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany), Fax: (+49) 234 3214683
    2. current address: Biochemistry, Stanford School of Medicine and Beckman Center, B400, 279 W. Campus Dr. MC: 5307, Stanford, CA 94305 (USA)
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  • Prof. Wolfgang Schuhmann

    Corresponding author
    1. Analytische Chemie—Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany), Fax: (+49) 234 3214683
    • Analytische Chemie—Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany), Fax: (+49) 234 3214683

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Abstract

Upon contact of sensor surfaces with complex biological samples containing a variety of different proteins, non-specific adsorption hampers the high-sensitive detection of the analyte in question. To substantially decrease the impact of non-specific adsorption at thiol-based self-assembled monolayers, a chemical lift-off process is introduced. A sequence of local hydrolysis of isooctyl 3-mercaptopropionate, covalent binding of an antigen against the Epstein–Barr virus (EBV), stepwise incubation with a serum sample possibly containing the EBV antibody and an enzyme-labeled anti-human antibody is completed with a lift-off by integral hydrolysis of the remaining ester groups at the self-assembled monolayer. The cleavage of the ester removes any non-specifically bound protein during a following stringent washing step. The substantial improvement of the detection limit of an electrochemical immunoassay against EBV using native recombinant antigens, their immobilization after local deprotection using a scanning electrochemical microscope (SECM) and the local read-out using the generator–collector mode of SECM with redox cycling amplification demonstrates the successful application of the proposed lift-off procedure.

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