In natural photosynthetic systems, quantum coherent effects contribute to a more efficient energy transfer pathway when light-harvesting chromophores are closely packed or aggregated (Scholes, G.D., et al. Nat. Chem. 2011, 3: 763-774). These effects may be imitated by exploiting the J-aggregation behavior of certain dyes, such as cyanines (Würther, F., et al. Angew. Chem. Int. Ed. 2011, 50: 3376-3410). A proof-of-concept study has established that J-aggregated pseudoisocyanine (PIC) dyes can be rationally attached to DNA scaffolding in what has been termed a “J-bit” (Boulais, E., et al. In Prep.). These “J-bits” are basically stable and controllable J-aggregated dye units which can self-assemble on DNA circuits. In this research, we extend the previous study to determine how to optimize the excitonic behavior, and therefore, the energy transfer in these DNA-dye circuits. Since the geometry of the DNA scaffold can be precisely controlled (Douglas, S. M., et al. Nature 2009, 459: 414-418), the geometry of J-aggregated dyes assembled on the DNA scaffold can also be controlled. Several factors are considered in this excitonic optimization study, including type of cyanine dye, size of “J-bit”, and geometry factors between “J-bits” as well as cyanine dyes within “J-bits”. These factors can be optimized via an in-depth computational study, involving molecular docking and molecular mechanics of the DNA-dye assemblies, and quantum dynamics of the excitonic behavior due to J-aggregation. The best DNA-dye candidates for efficient energy transfer will be experimentally confirmed using spectroscopic techniques. Modeling these DNA-dye excitonic circuits allows a broader view of the various factors involved in efficient energy transfer, and will lead to quicker optimization and implementation of effective nanophotonic technologies.

Optimization of energy transfer in DNA-dye excitonic circuits

251st National Meeting (2016)

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