A highly sensitive resonance scattering spectral assay for IgG using Fehling reagent–glucose–immunonanogold reaction

Nanogold exhibits strong catalytic effect on the slow reaction between glucose and Fehling reagent at 70 °C. The production of Cu2O particles have two stronger resonance scattering (RS) peaks at 390 nm and 505 nm. The catalytic effect of nanogold-labeled goat anti-human IgG (AuIgG) on the reaction was investigated with the RS technique. Coupled the immunoreaction and the immunonanogold catalytic reaction and centrifugal technique, a highly sensitive and selective RS method was developed for the detection of immunoglobulin G (IgG) as a model. With the concentration of IgG increased, the RS intensity at 505 nm decreased. The decreased intensity at 505 nm ΔI505 nm was proportional to IgG concentration in the range of 0.13–53.3 ng mL−1, with a detection limit of 0.04 ng mL−1 IgG. This new immunonanogold–catalytic Cu2O–particle RS bioassay was applied to the determination of IgG in serum sample, with high sensitivity, good selectivity, and low cost.