Use of rabbit antiboty IgG bound onto plain and aminoalkylsilyl glass surface for the enzyme-linked sandwich immunoassay.

Rabbit antibody IgG was bound onto aminoalkylsilyl or plain glass rods by simple adsorption. For comparison, rabbit antibody IgG was also bound onto glutaraldehyde-activated aminoalkylsilyl glass rods. These antibody-glass rods were tested by the sandwich procedure using Fab' fragments of rabbit antibody conjugated with beta-D-galactosidase from Escherichia coli. The glutaraldehyde-activated aminoalkylsilyl glass showed the largest capacity to bind antigen and the plain glass showed the smallest. However, the antibody-glass rods prepared by simple adsorption were as useful for the sandwich immunoassay of macromolecular antigens as those prepared with glutaraldehyde. With all the antibody-glass rods prepared, 0.1 to 10 fmol of ornithine delta-aminotransferase from rat liver and 2,4-dinitrophenyl human IgG were measurable. More than 10 fmol of the antigens may be measurable with larger amounts of the antibody-beta-D-galactosidase complexes, although the non-specific binding of the complexes to the solid phase increases to limit the sensitivity of the immunoassay.