[The binding characteristics of antibody with antigen in enzyme immunosensor]

The enzyme immunosensor developed by Aizawa et al for assaying antigens is regarded as a rapid and accurate method for immunoassay. The key point involved in this technique is the binding force of an antigen with a membrane-bound antibody. In this report, a simplified method was adopted to determine the amount of membrane-bound antibody and the binding constant between antigen and membrane-bound antibody. The plot of C* vs C*/A0* facilitates the determination of binding constant K' and the amount of membrane-bound antibody, B0. From the equations expressing competitive binding reactions of labeled and nonlabeled antigen-antibody reactions, the value of K was determined from the value of K' and relative concentrations of antigen and antigen-antibody complex. The determination of K' and K was exemplified by obtaining the data of anti-IgG and anti-hCG antibodies (immobilized on triacetyl cellulose membrane) with their antigens.