Fluorescence resonance energy transfer based immunosensing of human IgG by using quantum Dot/GlgG-gold nanoparticles/IgG conjugation

A novel immunosensor of human immune globulin (IgG) was fabricated based on the fluorescence transfer between luminescent semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs). AuNPs and CdSe/ZnS QDs were respectively labeled with immune reaction pair:lgG and goat anti-human immunoglobulin (GlgG), by optimizing the conditions including pH value and protein amount. In the assembled QD-GlgG-lgG-AuNP fluorescence resonance energy transfer (FRET) immunocomplex system, the presence of AuNP-IgG directly reduced the fluorescence intensity of the GlgG conjugated QDs. As a result, the concentration of AuNP-IgG had a linear relationship with the fluorescence decrease in a range of 0-1.57 μg/mL. Furthermore, the mechanism of the QDs' fluorescence decay has also been discussed and attributed to the light-induced photobleaching. This novel sensing method achieves quantitative detection of trace proteins, suggesting the potential of biomolecule-AuNPs conjugation based analytical methods in furrther application.