Antigen-binding activity of antibodies immobilized on styrene copolymer beads

An important element of the Kodak thin-film immunoassay is antibody immobilized on small polymer beads. Monodisperse styrene copolymer beads offer a well-defined, high surface area substrate for covalent immobilization of monoclonal antibodies. The authors have used the ability of an immobilized monoclonal antibody directed against phenobarbitol, Phe 1.9, to recognize an antigen-enzyme conjugate to determine the extent of antibody activity retention and find that the packing density of antibody at the surface and the copolymer composition are important variables. For polystyrene homopolymer and some copolymers, antibody retention is greater as the packing density at the surface increases. Small changes in the copolymer composition, such as addition of 1% acrylamide or 10% acrylic acid, significantly increase the retention of binding activity of the antibody. The chemistry for covalent coupling of the antibody to the surface is also important. Phe 1.9 coupled to chloromethyl styrene copolymer beads retains less activity than when coupled to vinyl sulfone copolymer beads. Monodisperse sytrene copolymer beads provide great flexibility in the design of rapid immunoassays since a copolymer bead can be tailored to the specific requirements of the antibody and the analyte.