Watching DNA nanotechnology at the speed of light

Light-driven photophysical and photochemical transformations are key phenomena underlying numerous processes, including photosynthesis, vision, photovoltaic light harvesting. The development of mode-locked femtosecond lasers has revolutionized the way that chemists think about interactions with molecular systems. Utilizing coherent pulses can allow direct observation processes such as exciton transport, vibrational motion, electron transfer on their characteristic timescales, ranging from femtoseconds to picoseconds, via ultrafast spectroscopy. Natural photosynthetic systems plants, algae, bacteria use nanoscale arrangements biological chromophores harvest near-unity quantum efficiency picosecond timescale.1Blankenship R.E. Molecular Mechanisms Photosynthesis. John Wiley & Sons, 2014Google Scholar Ultrafast spectroscopy been used unravel dynamics associated this transport process in varying structural motifs. From these studies, design principles be emulated synthetic have emerged.2Schlau-Cohen G.S. Akihito I. Fleming G.R. Two-dimensional electronic photosynthesis: Fundamentals applications light-harvesting.Chem. Phys. 2011; 386: 1-22https://doi.org/10.1016/j.chemphys.2011.04.025Crossref Scopus (124) Google However, protein machinery is challenging modify limited biologically relevant pigments, which hindered exploration engineering for optimizing condensed-phase dynamics. In issue Chem, my colleagues I develop a tunable DNA origami platform controlling excitonic systems, biomimetic We time-resolved computational methods explore parameters driving energy circuits.3Hart S.M. Chen W.J. Banal J.L. Bricker W.P. Dodin A. Markova L. Vyborna Y. Willard A.P. Häner R. Bathe M. Schlau-Cohen Engineering couplings using scaffolds.Chem. 2021; 7: 752-773Abstract Full Text PDF (14) By incorporating multiple into DNA, we were able generate delocalized excited states similar those found natural light-harvesting basis fast efficient harvesting lies careful optimization both coupling between system-bath environment. These dictated by chromophore placement interaction surrounding pocket our achieved required control over leveraging predictable base pairing structure formation interchromophore spacing To quantify short-timescale coupling, turned 2D map out temporal spectral resolution. This method utilizes four non-collinear geometry (Figure 1A) correlation excitation emission frequencies 1B) how correlations change function time after photoexcitation. approach immensely useful unraveling spectrally congested previously related technique, transient grating spectroscopy, excited-state non-DNA-bound chromophores.4Hart Identification nonradiative decay pathways Cy3.J. Chem. Lett. 2020; 11: 5000-5007https://doi.org/10.1021/acs.jpclett.0c01201Crossref PubMed (11) leveraged correlative nature technique two ways. First, controlled nucleotide neighboring chromophores. correlating frequency vibronic cross peaks spectrum conjunction simulations, tune weak regime (tens wavenumbers) strong (several hundred wavenumbers). second examination spectrum, lineshape extract frequency-frequency function, readout femtosecond-timescale interaction. evidence sub-picosecond diffusion modes yet observed minimal differences short-time variation motifs nanometer length scale. indicates bath variations longer timescales drive energy-transfer system, suggesting could followed other systematic work highlights utility nanostructures serving artificial harvesters. also paves toward integration devices computation, imaging, charge transport. Control extent delocalization particularly implications modular computing components, driven measured methods. Advances multiplexed imaging approaches made studies coupled future, small-scale nanoengineered will hopefully inform construction more scalable metal-organic frameworks, semiconducting polymers, supramolecular constructs. scaffoldsHart et al.ChemJanuary 14, 2021In BriefExcitonic condensed phase electrodynamic Here, DNA-based characterize multidimensional single-molecule simulations. Leveraging tunability platform, role Full-Text Open ArchiveCelebrating differences: A nanotechnologyWei Jia ChenChemMarch 1, BriefIn Potential Energy article, group graduate student Wei Crystal describes advantages expertise across disparate areas research combine fluorescence nanotechnology modeling fundamental concepts underlie capture transfer. rigidity scaffolds photophysics turn leads efficiency. ArchiveWeaving strands energyJames BanalChemMarch BriefDNA self-assembly provides diverse toolbox program spatiotemporal characteristics aggregates carefully dissecting complex behavior excitons condensed-matter James vignette dye steer Archive