Hemoglobin immobilization on the Clark electrode for development of a hydrogen peroxide biosensor

31st Congress of the Federation-of-European-Biochemical-Societies (FEBS) -- JUN 24-29, 2006 -- Istanbul, TURKEYWOS: 000238914002310Federat European Biochem So

Development of a catalase based biosensor for alcohol determination in beer samples

WOS: 000186127200006PubMed ID: 18969169An amperometric biosensor based on catalase enzyme for alcohol determination was developed. To construct the biosensor catalase was immobilized by using gelatin and glutaraldehyde on a Clark type dissolved oxygen (DO) probe covered with a teflon membrane which is sensitive for oxygen. The working principle of the biosensor depends on two reactions, which one is related to another, catalyzed by catalase enzyme. In the first reaction catalase catalyzes the degradation of hydrogen peroxide and oxygen is produced and also a steady-state DO concentration occurs in a few minutes. When ethanol added to the medium catalase catalyzes the degradation of both hydrogen peroxide and ethanol and this results in a new steady-state DO concentration. Difference for first and the last steady-state DO concentration occurred in the interval surface of DO probe membrane, which related to ethanol concentration, are detected by the biosensor. The biosensor response depends linearly on ethanol concentration between 0.05 and 1.0 mM with a detection limit of 0.05 mM and a response time of 3 min. In the optimization studies of the biosensor phosphate buffer (pH 7.0; 50 mM) and 35 degreesC were established as providing the optimum working conditions. In the characterization studies of the biosensor some parameters such as reproducibility, substrate specificity, operational and storage stability were carried out. Finally, by using the biosensor developed and enzimatic-spectrophotometric method alcohol concentration of some alcoholic drinks were determined and results were compared. (C) 2003 Elsevier Science B.V. All rights reserved

Enzyme electrode based on oxalate oxidase immobilized in gelatin for specific determination of oxalate.

PubMed ID: 8144172A biosensor for the specific determination of oxalate was developed using oxalate oxidase (EC 1.2.3.4) from barley (Hordeum vulgare) seedling roots in combination with a dissolved oxygen probe. Oxalate oxidase immobilized with gelatin using glutaraldehyde and fixed on pretreated teflon membrane served as an enzyme electrode. The electrode response was maximum when 50 mM succinate buffer was used at pH 3.2 and 35 degrees C. The biosensor response depends linearly on oxalate concentration between 5 x 10(-6)-2 x 10(-4) M with response time 30 sec and substrate specificity of the oxalate oxidase electrode of 100%. The sensor is stable for more than 3 months during which time more than 400 assays can be performed