ONE-STEP IMMOBILIZATION OF IMMUNOGLOBULIN-G AND POTENTIAL OF THE METHOD FOR APPLICATION IN IMMUNOSENSORS

Stable monolayers of antibodies incorporated in a polymer monolayer ar e prepared on the subphase of a Langmuir-Blodgett trough. Both copolyg lutamate (Cpg) and photopolymerized phthalocyaninato-polysiloxane (Pcp s) derivatives are ideal matrices for embedding immunoglobulin G (IgG) . One-step immobilization of the biofilm onto several substrates is ac hieved by the vertical dipping technique. So far 30 optical waveguides can be coated within 10 min. Polymethyl methacrylate (PMMA) is found to be a suitable substrate for obtaining highly reproducible transfer ratios. Enzyme-linked immunosorbent assays are performed to determine the density and stability of active immobilized antibodies and to esti mate specificity with regard to the suitable antigen. The specific bin ding capacity is comparable to that of the widely used silanization pr ocedure via aminoalkyltrialkoxysilanes. First successful tests of the irradiation of the mixed photopolymer-immunoglobulin G layers are repo rted. Photochemical crosslinking is monitored by the film area decreas e with irradiation time and both the density and stability of active i mmobilized antibodies are significantly enhanced in comparison with le ss or non-crosslinked films. Using an evanescent wave biosensor, laser diode-induced fluorescence emission is detected to observe the reacti on of the immobilized antibodies with antigens linked to a fluorescent dye.