Fluorescence resonance energy transfer between two quantum dots with immunocomplexes of antigen and antibody as a bridge.

In this study, 573 nm quantum dots (QDs)-rabbit IgG-goat anti-rabbit IgG-638 nm QDs immunocomplexes were prepared, utilizing antigen-antibody interaction. 573 nm-emitting QDs were conjugated to antigen (rabbit IgG) and 638 nm-emitting QDs were conjugated to antibody (goat anti-rabbit IgG) via electrostatic/hydrophilic self-assembly, respectively. The mutual affinity of the antigen and antibody brought two kinds of QDs close enough to result in fluorescence resonance energy transfer (FRET) between them; the luminescence emission of 573 nm QDs was quenched, while that of 638 nm QDs was enhanced. The luminescence emission of 573 nm QDs could be recovered when the immunocomplexes were exposed to the unlabelled rabbit IgG antigen. The FRET efficiency (E) and the distance between the donor and the acceptor were calculated. Copyright (c) 2006 John Wiley & Sons, Ltd.