PROTEIN-A LANGMUIR-BLODGETT-FILM FOR ANTIBODY IMMOBILIZATION AND ITS USE IN OPTICAL IMMUNOSENSING

Protein A molecular membrane has been developed as a versatile matrix for immobilization of an antibody molecule. Protein A, having specific affinity to the Fc part of IgG, was spread on the air/water interface and prepared in a stable monolayer by an LB film technique. The prote in A monolayer was transferred onto an alkylsilanized hydrophobic synt hetic quartz plate. Anti-human IgG antibody was self-assembled on the protein A LB film. The antigen-binding affinity of the protein A-bound antibody was assessed by fluorescein immunoassay. An optical immunose nsor was constructed using the antibody plate. Fluorescein isothiocyan ate was used as the label. The optical immunosensor response in fluore scence intensity was inversely proportional to the amount of human IgG in the sample. Human IgG was detected in the concentration range from 10(-4) to 10(-7) g mL(-1).