Immobilization of anti-horseradish peroxidase on glyoxyl-agarose proceeds rapidly, and after the immobilization, it was found that the antibody captured almost the same amount of peroxidase than the free antibody. After boiling the antibodies in the presence of SDS and mercaptoethanol, more than 95% of the immobilized antibodies presented the four subunits attached to the support. The reduction of the preparation converts the glyoxyl groups into very hydrophilic and inert hydroxyl-groups. That way, the final support was fully unable to adsorb any protein under any condition, and the only adsorbed proteins on the immobilized antibody are these recognized by the antibody. The immobilized antibody maintained intact their capacity to capture peroxidase after 20 weeks of storage at 4 degrees C. The high functionality of the immobilized antibody and the fully inert surface suggest that this technique may be a very suitable one to immobilize antibodies for biosensor design or immunochromatographic matrices. (C) 2008 Elsevier Ltd. All rights reserved.