Highly efficient FRET-based light-harvesting using nanocrystals

摘要

Dye molecules are widely used for biolabeling in molecular biology because of their high quantum efficiency and stability. Their small size (only a few nanometers) enables their use in bioimaging and biodetection of molecular features, for example, for double stranded deoxyribonucleic acid (DNA). However their narrow absorption spectra (e.g., 450-600 nm for Rhodamine B) limit their efficient pumping beyond their absorption range and place constraints on their use in some important applications such as spectral multiplexing, in which multiple dyes of different colors are simultaneously excited by a single optical source. To effectively extend the absorption range of such dye molecules, nonradiative Forster resonance energy transfer (FRET) can be utilized to transfer excitation energy from nanocrystal donors to acceptor dyes [1]. The use of nanocrystals in dye based applications has been increasing owing to the advantages of nanocrystals including small size, high efficiency, and tunable absorption and emission characteristics [2]. Solubility and emission with high quantum yield in water is an issue for nanocrystals in biological applications. One of the best candidates is CdTe nanocrystals, which are highly efficient and soluble in water as synthesized [3]. These make CdTe a highly preferable choice also for dye related biological applications.