A reagentless amperometric hydrogen peroxide biosensor based on covalently binding horseradish peroxidase and thionine using a thiol-modified gold electrode

A new approach to construct a reagentless hydrogen peroxide biosensor is described. Horseradish peroxidase and thionine are covalently bound to a cysteamine-assembled gold electrode using glutaraldehyde as a bifunctional reagent. Thionine immobilised in this way can shuttle electrons between the electrode and the redox activity center of the enzyme. The sensor was highly sensitive to hydrogen peroxide with a detection limit of 8.0 x 10(-7) mol l(-1) and a response time of less than 4 s. The effects of the applied potential and the pH values of the buffer solution on the response of the sensor were investigated for optimum analytical performance. (C) 1998 Elsevier Science S.A. All rights reserved.