Bienzyme Sensors Based on "Electrically Wired" Peroxidase
Abstract
Single layer and bilayer bienzyme electrodes based on the combination of a 3-dimensional redox epoxy network that electrically connects redox centers of bound horseradish peroxidase (HRP) to electrodes with a hydrogen peroxide generating enzyme, the redox centers of which are not connected to the redox epoxy network, are described. In the single layer electrodes, H202 generated by the first enzyme oxidizes the second enzyme HRP, which oxidizes the redox polymer network, that is electrochemically reduced at OmV (SCE). When the redox centers of the H202 generating enzyme are also electrically connected to the redox epoxy network, the substrate reduced redox centers are oxidized by the redox polymer network, thus lowering the cathodic current. Such attenuation is avoided in bilayer electrodes, where the H202 producing enzyme and the redox- epoxy-HRP network are not electrically connected. The single-layer bienzyme electrodes extend the range of amperometric biosensors based on directly redox- epoxy wired enzymes to enzymes that are difficult to electrically connect to redox polymer networks and whose preferred or only co-substrate is oxygen. For a difficult to wire enzyme, choline oxidase, the cathodic current density in the single-layer peroxidase and choline oxidase containing electrode is 80 micro A /sq cm at 10mM choline concentration, while the anodic current density of the directly wired enzyme is only 5 microAmpere /sq cm. Alcohol oxidase is an enzyme that could not be electrically connected to the HRP wiring 3-dimensional redox epoxy network. The anodic current density of its redox epoxy wired electrodes is close to nil, while the cathodic current density, observed in alcohol oxidase and wired peroxidase containing single layer electrodes at 10mM ethanol is 5microAmpere /sq cm. When well wired enzymes such as glucose oxidase or lactate oxidase are utilized in single layer electrodes, limiting cathodic current densities of 60 microAmpere /sq cm are observed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 08, 1993
- Accession Number
- ADA271364
Entities
People
- A. Heller
- F. Battaglini
- M. S. Vreeke
- T. J. Ohara
Organizations
- University of Texas at Austin