Two-Photon Excitation of Quantum-Dot-Based Fluorescence Resonance Energy Transfer and Its Applications


  • This work was supported by grants from the Office of Naval Research (ONR), DARPA, and NIH. B.R.F., A.R.C., and T.P. were supported by fellowships from the Defense Science and Engineering Graduate Fellowship Program, the National Research Council, and la Fondation pour la Recherche Médicale (Paris), respectively. Supporting Information is available online from Wiley InterScience or from the authors.


original image

Nonradiative fluorescence resonance energy transfer (FRET) between a luminescent quantum dot (QD) donor and a proximal dye brought in close proximity of the QD surface via conjugation with a dye-labeled peptide (or a protein) is shown (see figure). The system is excited with near IR irradiation (well below the absorption band of the QD), via a fast two-photon process, which produces a FRET signal with very low background contribution due to a substantially reduced nonlinear direct excitation of the dye.