Figure 5
From: Direct Reading of Bona Fide Barcode Assays for Diagnostics with Smartphone Apps
Preparation of the sandwich immunoassay for hCG performed on the polycarbonate (PC) substrate (see Experimental for details).
After activating the surface of the PC (b,c), a monoclonal antibody specific for the α subunit of hCG is immobilized on the surface via an amide-coupling reaction (d). The target binds (e) and another monoclonal antibody, conjugated to biotin and specific for the β subunit of the hCG is added (f). The Nanogold streptavidin conjugate is added (g) before silver enhancement is used to visualize the signal (h). In the case of the direct biotin-streptavidin assay, NH2-PEG2-biotin is added after the surface activation steps; no antibodies are added. Nanogold streptavidin and silver enhancement is also used.
