A membrane-based electrochemical inummosensor sensitive towards proteins is described, based on nanoporous alumina-modified platinum wire electrodes. The sensing mechanism depends on the blocking of pore channels when the protein antigen molecules bind to antibody molecules attached to the channel walls, impeding the diffusion of redox probe, ferrocenemethanol, towards the sensing platinum wire overlaid by the nanoporous alumina film. The antibody and antigen used in this work were anti-glucose oxidase and glucose oxidase, respectively. The immunosensor showed a low limit of detection of 100 ng L-1 antigen concentration and was selective towards glucose oxidase protein in the presence of another protein, glucothione S-transferase. (c) 2007 Elsevier Ltd. All rights reserved.