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

Abstract

Nanogold exhibits strong catalytic effect on the slow reaction between glucose and Fehling reagent at 70 °C. The production of Cu 2O 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 Δ I 505 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 Cu 2O–particle RS bioassay was applied to the determination of IgG in serum sample, with high sensitivity, good selectivity, and low cost.