PHOTOACTIVATABLE CROSS-LINKED POLYACRYLAMIDE FOR THE SITE-SELECTIVE IMMOBILIZATION OF ANTIGENS AND ANTIBODIES

This paper describes the synthesis, characterization, and photochemica l behavior of a new light-activated material for the photoimmobilizati on of antigens. The material is a derivative of cross-linked polyacryl amide that incorporates photoactive o-nitrobenzyl carbamates. When irr adiated, the polymer undergoes a photochemical rearrangement to produc e primary amines that can be used as molecular attachment sites. We mo nitored the photoconversion of thin (1-2 mu m) polymer films that were deposited on silicon wafers or fused silica substrates using FT IR sp ectroscopy and UV-vis spectroscopy. To produce patterned polymer-modif ied substrates, we irradiated the material using a photolithographic m ask;. This process yielded 10-mu m lines of photogenerated amines, to which an amine-reactive antigen (2,4,6-trintrobenzenesulfonic acid) wa s covalently bound. When we used this antigen-patterned substrate in a competitive fluorescence immunoassay containing tetramethylrhodamine- labeled anti 2,4-dinitrophenyl antibodies and 2,4-dinitrophenol, conce ntrations of 2,4-dinitrophenol as low as 2.3 mu g/mL were detectable.