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 (A400 /A530 ). A linear response between A400 /A530 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.