Figure 4.

Agents used for blocking the gold nanoparticle surfaces and their effects on the test line intensity. Antibody‐coated gold nanoparticles were prepared using 1 μg of antibody #8028 and 10 μl of the WRGH1 gold nanoparticle suspension in 100 μl of HEPES (pH 7.0) and recovered by centrifugation. The precipitated particles were subsequently treated in the blocking reagent solutions specified below. Immunochromatographic strips were constructed using these antibody‐coated gold nanoparticles, and the test line intensity was determined in the absence of competing antigen. The blocking reagents used were the following: 1% BSA,; 1% casein,; 1% ovalbumin,; 0.1% PEG,; 0.1% PVP,; 0.1% PVA,; 1% BSA + 0.1% PEG,; 1% BSA + 0.1% PVP,; 1% BSA + 0.1% PVA,; 1% casein + 0.1% PEG,; 1% casein + 0.1% PVP,; and 1% casein + 0.1% PVA,.