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Energy Transfer in DNA-based Dye Arrays

Our group is investigating the fundamental mechanisms giving rise to the unique and highly efficient energy-transfer properties of multi-chromophoric systems using bulk fluorescence and single-molecule fluorescence techniques including confocal and total internal reflection fluorescence microscopy. The goal is to engineer the light-harvesting potential and energy-transfer pathways using DNA as a scaffold to position multiple chromophores (dyes) in optimal positions. Such DNA nanostructures are a powerful method to construct well-defined arrays of fluorescent dyes which have many applications including biological labeling. Examples of such arrays are the tetrahedral DNA nanostructure and three-way junction motif developed by our collaborators, the Armitage group. These have shown highly-desirable properties like high emissivity, photo-stability and compact size. Being a DNA nano-structure, the size and shape of the label can be easily tuned to match the requirements of each application. In addition, various dyes, including bis-intercalators and covalently-attached dyes are used to make multi-chromophoric arrays using DNA as the scaffold. When multiple dyes are involved a phenomenon known as Förster resonance energy transfer occurs between the two dyes. In this process, the excitation from one dye (the donor) is transferred to the other dye (the acceptor). This causes an increased spectral shift between the excitation light and the emitted light. These arrays are optimized to give the desired properties like brightness and spectral shift by varying the dyes used and their spatial arrangement.