Immunoassay with multicomponent protein microarrays fabricated by electrospray deposition.

Two new techniques were recently developed in these laboratories for fabrication of protein microarrays: electrospray deposition of dry proteins and covalent linking of proteins from dry deposits to a dextran-grafted surface. Here we apply these techniques to simultaneously fabricate 1200 identical microarrays. Each microarray, 0.6 x 0.6 mm2 in size, consists of 28 different protein antigens and allergens deposited as spots, 30-40 microm in diameter. The ability of the microarrays to detect IgG antibodies in plasma samples from mice immunized with different sets of antigens and IgE antibodies in human plasmas was examined using ELISA. Comparison of the microarray-based ELISAs with standard ELISAs in microtiter plates established that both techniques provided identical responses in 88% of all the antibody/antigen interactions tested. Both techniques showed similar antibody detecting sensitivity defined by the maximum dilution of serum at which a reliable signal distinguishable from the background was obtained.