| The unique optical properties of quantum dots (QDs) are of interest in the development of nucleic acid diagnostics. The potential for a simultaneous two-colour diagnostic scheme for nucleic acids operating on the basis of fluorescence resonance energy transfer (FRET) has been demonstrated. Upon ultraviolet excitation, two-colours of CdSe/ZnS quantum dots with conjugated oligonucleotide probes acted as energy donors yielding FRET-sensitized acceptor emission upon hybridization with fluorophore labeled target oligonucleotides. The use of an intercalating dye to improve signal-to-noise was also demonstrated. The major limitation of the system was the non-specific adsorption of oligonucleotides, which was characterized extensively. Adsorptive interactions were found to affect the conformation of oligonucleotides conjugated to QDs, the kinetics of hybridization with QD-DNA conjugates, and the thermal stability of those hybrids. In addition, it was found that thiol-alkyl-acid capped QDs exhibited pKa correlated ligand-chromism and radiative decay rate-driven changes in quantum yield. |
