Immunoassay for Human IgG Using Antibody-functionalized Silver Nanoparticles

Abstract

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.