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    Control of the Oxygen Dependence of an Implantable Polymer/Enzyme Composite Biosensor for Glutamate


    McMahon, Colm P. and Rocchitta, Gaia and Serra, Pier A. and Kirwan, Sarah and Lowry, John P. and O'Neill, Robert D. (2006) Control of the Oxygen Dependence of an Implantable Polymer/Enzyme Composite Biosensor for Glutamate. Analytical Chemistry, 78 (7). pp. 2352-2359. ISSN 0003-2700

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    Abstract

    Biosensors for glutamate (Glu) were fabricated from Teflon-coated Pt wire (cylinders and disks), modified with the enzyme glutamate oxidase (GluOx) and electrosynthesized polymer PPD, poly(o-phenylenediamine). The polymer/enzyme layer was deposited in two configurations:  enzyme before polymer (GluOx/PPD) and enzyme after polymer (PPD/GluOx). These four biosensor designs were characterized in terms of response time, limit of detection, Michaelis−Menten parameters for Glu (Jmax and KM(Glu)), sensitivity to Glu in the linear response region, and dependence on oxygen concentration, KM(O2). Analysis showed that the two polymer/enzyme configurations behaved similarly on both cylinders and disks. Although the two geometries showed different behaviors, these differences could be explained in terms of higher enzyme loading density on the disks; in many analyses, the four designs behaved like a single population with a range of GluOx loading. Enzyme loading was the key to controlling the KM(O2) values of these first generation biosensors. The counterintuitive, and beneficial, behavior that biosensors with higher GluOx loading displayed a lower oxygen dependence was explained in terms of the effects of enzyme loading on the affinity of GluOx for its anionic substrate. Some differences between the properties of surface immobilized GluOx and glucose oxidase are highlighted.

    Item Type: Article
    Keywords: Oxygen Dependence; Implantable Polymer/Enzyme Composite Biosensor; Glutamate;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Item ID: 8040
    Identification Number: https://doi.org/10.1021/ac0518194
    Depositing User: John Lowry
    Date Deposited: 22 Mar 2017 16:47
    Journal or Publication Title: Analytical Chemistry
    Publisher: American Chemical Society
    Refereed: Yes
    Funders: Science Foundation Ireland (SFI)
    URI:

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