A novel enzyme biosensor for the detection of protein is presented. The bio
sensor was made from a screen-printed three-electrode configuration. Amino
acid oxidase was immobilized with glutaraldehyde and polyethylenimine on a
working electrode made of rodinised carbon. A protease was immobilized on a
n immunodyne membrane and was placed on the electrode. A protein sample was
deposited on the membrane, and was subsequently hydrolyzed to amino acids
in the presence of the protease. This in turn produced hydrogen peroxide by
the immobilized amino acid oxidase. The oxidation of hydrogen peroxide was
then detected at +400 mV vs. an Ag/AgCl reference electrode. The method wa
s very effective at detecting a very low level of protein. The sensor does
not require any washing step. The sensor works with only 40 mu l of sample
per detection, and may be used on-site as a disposable sensor using a hand-
held meter. The electrodes are also stable for more than 6 weeks. (C) 2000
Elsevier Science B.V. All rights reserved.