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.