Antibody networks for surface plasmon resonance immunosensors

A technique for preparation of three-dimensional networks of antibodies for surface plasmon resonance biosensors is described. This technique is based on the covalent crosslinking of a multiple molecular layer of monoclonal a ntibodies prepared by alternating adsorption of molecular layers of a posit ively charged antibodies at pH below its isoelectric point and dextran sulf ate polyanion. As a model system, networks of monoclonal antibodies against human choriogonadotropin and horseradish peroxidase were prepared and thei r properties were studied using Fourier transform infrared multiple interna l reflection spectroscopy, ELISA and surface plasmon resonance spectroscopy . Experimental results indicate that a sensor employing a network of antibo dies exhibits an enhanced sensitivity to the respective antigens in compari son with those using two-dimensional monomolecular layers, mainly because o f a higher number of receptors accessible to the antigens and better bindin g properties of antibodies that are not immobilized directly on the sensor surface. (C) 1999 Elsevier Science S.A. All rights reserved.