Interaction of steroid--peroxidase conjugates with cellulose immunosorbents in aqueous and micellar media.

In 0.1 M bicarbonate buffer (pH 9.0) and in microemulsions of aerosol OT (AOT) and its mixture with Triton X-45 in heptane, antibodies against cortisol (anti-COR) and progesterone (anti-PROG) were covalently immobilized on fine-porous cellulose filters (0.6 cm diameter) after sodium periodate oxidation. Immunosorbents obtained in different media were characterized in terms of antibody-bound density and antigen-binding capacity with respect to peroxidase--steroid conjugates HP--COR-11 and HP--PROG-4 containing 11 molecules of cortisol and four progesterone molecules, respectively. For all immunosorbents antigen-binding capacity expressed as peroxidase activity of immune complexes formed on the solid cellulose phase in aqueous and micellar media was determined. Dissociation constants of immunocomplexes on the cellulose formed in aqueous and micellar media were determined using ELISA. In all cases Kd values in aqueous media were approximately 10-8 M and were significantly lower than corresponding values of dissociation constants of immune complexes in mixed microemulsions of AOT and Triton X-45.