An acoustic plate mode study of complementary and non-complementary antigen/antibody reactions

Acoustic plate mode sensors have been used to monitor immunochemical reactions as a function of antigen concentration. In the studies, antibodies were covalently linked to the gold-coated sensing surface via mercaptoethanol, aminosilane and glutaraldehyde. Two antigen/antibody model systems have been used which differ in their ability to mutually bind one another. For sensor operation at about 150 MHZ a detection limit of about 0.5 μg/ml was obtained in both cases. No significant difference between the two systems was found for the value of the binding constants. They amount to about 1.10⁸ 1/mol and fall well into the range of binding constants reported for homogeneous immunoassays. A comparison of the sensor response obtained for the two model systems shows that about 70% of the immobilized antibodies are active