A capacitive immunosensor for detection of cholera toxin

Mahmoud Labib, Martin Hedström, Magdy Amin, Bo Mattiasson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Contamination of food with biological toxins aswell as their potential use asweapons of mass destruction has created an urge for rapid and cost effective analytical techniques capable of detecting trace amounts of these toxins. This paper describes the development of a sensitive method for detection of cholera toxin (CT) using a flow-injection capacitive immunosensor based on self-assembled monolayers. The sensing surface consists of monoclonal antibodies against the B subunit of CT (anti-CT), immobilized on a gold transducer. Experimental results showthat the immunosensor responded linearly to CT concentrations in the range from 1.0×10−13 to 1.0×10−10 M under optimized conditions. The limit of detection (LOD) was 1.0×10−14 M. Two more analytical methods were employed for detection of CT using the same antibody namely, sandwich ELISA and surface plasmon resonance (SPR)-based immunosensor. The former had an LOD of 1.2×10−12 M and a working range from3.7×10−11 to 2.9×10−10 M whereas, the latter had an LOD of 1.0×10−11 M and a linearity ranging from 1.0×10−9 to 1.0×10−6 M. These results demonstrate that the developed capacitive immunosensor system has a higher sensitivity than the other two techniques. The binding affinity of CT to the immobilized anti-CT was determined using the SPR-based immunosensor and an association constant (KA) of 1.4×109 M−1 was estimated.
    Original languageEnglish
    Pages (from-to)255-261
    JournalAnalytica Chimica Acta
    Volume634
    Issue number2
    DOIs
    Publication statusPublished - 2009

    Subject classification (UKÄ)

    • Analytical Chemistry

    Free keywords

    • Surface plasmon resonance
    • Cholera toxin
    • Capacitive immunosensor
    • Enzyme-linked immunosorbent assays

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