Development of chemiluminescence detection of gold nanoparticles in biological conjugates for immunoassay

By using human immunoglobulin G (IgG), goat-anti-human IgG and rabbit-anti-goat IgG-functionalized gold nanoparticles as an immunoassay model, a chemiluminescence (CL) detection of gold nanoparticles in biological conjugates has been developed. The assay is based on the sandwich-type immunoreaction coupled with CL reaction of AuCl4−-luminol-H2O2 system. The AuCl4−, which is the dissolving product of the gold nanoparticles labeled to the rabbit-anti-goat IgG, served as an analyte in the CL reaction for the indirect measurement of goat-anti-human IgG. The chemiluminescence intensity is proportional to the logarithm of the concentration of goat-anti-human IgG in the range of 5 ng ml−1 to 10 μg ml−1 and the detection limit (3σ) is 1.5 ng ml−1. This method has been successfully applied to the determination of goat-anti-human IgG immune serum samples. As a new chemiluminescence detection method, it shows significant potential for the determination of biological analytes by labeling nanoparticles.