Enhanced ELISA based on carboxymethylated dextran coatings

In a "sandwich" enzyme-linked immunosorbent assay (ELISA) designed to detect an antigen in a complex protein mixture, the antigen is usually captured via an antibody adsorbed to the wells of a microplate. Plate preparation for standard assay involves a passive adsorption of capture antibodies followed by the incubation of blocking agents. Here, we describe a new strategy that replaces these two time-consuming adsorption steps (up to 15 h) by a unique step corresponding to the covalent grafting of the capture antibody on a carboxymethylated dextran (CMD) layer, a single step completed in 15 min. Taking advantage of the CMD low-fouling properties, blocking agent-free buffer solutions can be used as diluent in the improved approach.