Immunoassay for Human IgG Using Antibody-functionalized Silver Nanoparticles

A simple colorimetric immunoassay for quantification of human immunoglobulin G (hIgG) is herein described. The assay is based on the aggregation inhibition of silver nanoparticles (AgNP) functionalized with hIgG antibody (anti-hIgG) on the surface. The aggregation is measured in terms of attenuance values ratio at 400 and 530 nm (A(400)/A(530)). A linear response between A(400)/A(530) and hIgG concentration is observed in the range 25 - 200 ng mL(-1), and the detection limit is estimated as 11 ng mL(-1) hIgG.