Immobilized silver ions as the basis of a highly sensitive microplate immunoassay system

Immunodiagnostic techniques based on the specific interaction of antibody and antigen have become of paramount importance in the clinical, agricultural, food, veterinary, and environmental sectors. One method of increasing immunoassay sensitivity is the use of the specific and irreversible interaction between streptavidin and biotin, a costly proposition. Nevertheless, the streptavidin-biotin system has become a widely used tool of molecular biology in such applications as affinity chromatography, cytometry, nucleic acid research, and diagnostics. A common immunological procedure calls for the use of streptavidin-coated microtiter plates, which are used to capture either biotinylated antibodies or antigens. Since the assay is based on the interaction of streptavidin and biotin, universal kit assay formats are possible for an enzyme-linked immunosorbent assay (ELISA). While streptavidin systems allow for universal ELISA kits and can improve assay sensitivity, coated plates can be costly.; Research examining the behavior of biotin has found that immobilized soft metal ions such as silver will bind biotinylated compounds. It was hypothesized that soft metal ions can be immobilized on the surface of a plastic microtiter plate, and this plate can be used in a cost-effective, highly sensitive immunoassay adaptable for use in the lab as a basis for developing a diagnostic test, in a universal kit format, and in automated assays.; This research has shown that an immobilized silver ion format is a successful and accurate method of performing an immunoassay. Silver ions have been immobilized on the surface of a microplate through an activation protocol that does not adversely affect the optical properties of the microplate. With immobilized silver ions, the ability of the plate to bind biotinylated compounds increases significantly. The silver ion format has been tested using a one step enzyme-labeled biotin technique and a biotinylated antibody immobilization and antigen capture technique. The silver ion method was found to be superior to streptavidin-coated plates, the current best available technology.