Photoactivatable Cross-Linked Polyacrylamide for the Site-Selective Immobilization of Antigens and Antibodies

Abstract

This paper describes the synthesis, characterization, and photochemical behavior of a new light-activated material for the photoimmobilization of antigens. The material is a derivative of cross-linked polyacrylamide that incorporates photoactive o -nitrobenzyl carbamates. When irradiated, the polymer undergoes a photochemical rearrangement to produce primary amines that can be used as molecular attachment sites. We monitored the photoconversion of thin (1−2 μm) polymer films that were deposited on silicon wafers or fused silica substrates using FT IR spectroscopy and UV−vis spectroscopy. To produce patterned polymer-modified substrates, we irradiated the material using a photolithographic mask. This process yielded 10-μm lines of photogenerated amines, to which an amine-reactive antigen (2,4,6-trintrobenzenesulfonic acid) was 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, concentrations of 2,4-dinitrophenol as low as 2.3 μg/mL were detectable.