Coated glass beads in enzyme linked immunosorbent assays

Successful enzyme linked immuno-sorbent assays (ELISA) were conducted with frosted glass beads coated directly with an immune reactant (antigen or antibody) using glutaraldehyde as cross linking agent. Equally effective ELISA experiments were made by attaching the antigen to a thin layer of gelatin which had been cross-linked over the entire surfaces of the frosted glass beads. The enzyme and substrate used were alkaline phosphatase and p-nitro-phenyl phosphate.