Fluorescence resonance energy transfer between FITC and water-soluble CdSe/ZnS quantum dots

Quantum dots had been covalently attached to human IgG by activating agents. The formation of QDs bioconjugates was confirmed by fluorescence spectrum and gel chromatography. Results of circular dichroism showed that the conjugates still maintained biological activity. When goat anti-human IgG labeled with fluorescin isothiocyanate (FITC) was added, the immunocomplex formed and the mutual affinity of the antigen and antibody brought the FITC and QDs close enough. The existing of FRET between FITC (donor) and QDs (acceptor) was further confirmed by observing the changes of their spectra. This investigation provides a new trail of thought for the fluorescence resonance energy transfer (FRET) research based on QDs.