Exploiting Plasmon-Mediated Energy Transfer To Enhance End-to-End Efficiency in a DNA Origami Energy Transfer Array

DNA origami technology can produce various 2D/3D nanoscale platforms capable of controlling external ligand spatial arrangements with nanometer accuracy. In this report, a rectangular-shaped two-dimensional DNA origami nanoplatform (DNA 2D-sheet) was synthesized to spatially arrange chromophores and a gold nanoparticle (AuNP) for the creation of biomimetic energy transfer (EnT) array. Specifically, three different chromophores (Alexa Fluor 488 (A488), Alexa Fluor 546 (A546), and a zinc(II) tetraphenylporphyrin derivative, ZnTPEP), arranged near 5 or 10 nm AuNPs on a DNA 2D-sheet, have shown the enhancement of EnT toward the center of the light harvesting array. This design provides a platform to study the mechanistic properties of AuNP-chromophore interactions which include enhancement and quenching effects due to the plasmonic AuNP electric field. Different regions of the electric field were probed by varying the AuNP-chromophore spacing. Along with the fluorescence enhancement effects on the chromophores due to the AuNP electric field, we propose that bidirectional energy transfer, including Forster resonance energy transfer (FRET), to and plasmon resonance energy transfer (PRET) from the AuNP must be occurring which contribute to the overall efficiency of EnT within the arrays. This study attempts to experimentally measure and quantitatively predict the complex interactions of chromophores and nanoparticles for future utilization in highly efficient energy capture arrays.