The detection of human β2-microglobulin by grating coupler immunosensor with three dimensional antibody networks

Immunosensors for the detection of human beta(2)-microglobulin (B2M) were prepared by immobilisation of covalently crosslinked assemblies containing various numbers of molecular layers of monoclonal antibody against B2M (anti-B2M) on the surface of a Ta2O5 grating coupler sensor. The immobilisation procedure consisted of repeated successive adsorption of anti-B2M and dextran sulfate (DS) followed by glutaraldehyde (GA) crosslinking of anti-B2M and washing out DS. The flexibility of the resulting anti-B2M networks was evaluated from the sensor response to the reversible expansion and contraction of the networks induced by changing pH of the ambient solution. A decreased GA concentration and the use of a higher-molecular-mass DS increased the network flexibility, The sensor sensitivity to B2M increased with increasing flexibility of the antibody networks and with increasing number of anti-B2M molecular layers, indicating that B2M can penetrate inside the antibody network. (C) 1999 Elsevier Science S.A. All rights reserved.