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 antibodies prepared by alternating adsorption of molecular layers of a positively charged antibodies at pH below its isoelectric point and dextran sulfate polyanion. As a model system, networks of monoclonal antibodies against human choriogonadotropin and horseradish peroxidase were prepared and their properties were studied using Fourier transform infrared multiple internal reflection spectroscopy, ELISA and surface plasmon resonance spectroscopy. Experimental results indicate that a sensor employing a network of antibodies exhibits an enhanced sensitivity to the respective antigens in comparison with those using two-dimensional monomolecular layers, mainly because of a higher number of receptors accessible to the antigens and better binding properties of antibodies that are not immobilized directly on the sensor surface.