Use of cellulose ethers as peptide antigen carriers in the ELISA

A procedure for surface immobilisation of peptides is described. Insulin, a model for peptide antigens, was covalently coupled to alkyl-hydroxyalkyl-cellulose ethers. The cellulose-insulin conjugate was then adsorbed to the plastic surface of microtitre wells and was used as antigen in an ELISA assay. The adsorbed conjugate was shown to be stable in undiluted plasma or serum whereas adsorbed insulin was removed from the surface by incubation in undiluted serum or plasma. Adsorption of serum albumin or cellulose ether polymers to the microtitre plates followed by incubation with whole blood, showed that adsorbed albumin but not the cellulose ether was exchanged by fibrinogen at the surface. The results indicate that coupling of peptides to alkyl-hydroxyalkyl-cellulose ethers is an efficient means of immobilising peptide antigens to hydrophobic surfaces.