Detection of immunoglobulin G based on nanoparticle surface energy transfers from fluorescein isothiocyanate to gold nanoparticles

In this paper, a simple and sensitive approach for human immunoglobulin G (hIgG) detection is described based on nanoparticle surface energy transfer (NSET) from fluorescein isothiocyanate (FITC) to gold nanoparticles (GNPs). The assay consisted of polyclonal goat anti-IgG antibody labeled luminescent FITC as the donor and GNPs as the acceptor. In the initial stage, with the energy transfer from FITC to GNPs, the FITC fluorescence was effectively quenched. Upon the introduction of IgG, effective competitive binding to the polyclonal goat anti-IgG antibody labeled FITC occurred, which significantly hindered the NSET, and thus recovered the fluorescence of FITC. The change in fluorescent intensity produced a novel strategy for the detection of hIgG. The recovered fluorescence of FITC was linearly proportional to the concentration of hIgG in the range of 4.0 × 10−9 to 2.2 × 10−7 g mL−1 with a detection limit of 8.3 × 10−10 g mL−1. This method was applied to the determination of hIgG in human serum samples via a standard addition method, and the recovery rate obtained was 98.7–105.0%.