Jonas K Hannestad

Chalmers University of Technology, Göteborg, Vaestra Goetaland, Sweden

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Publications (10)75.94 Total impact

  • Jakob G Woller, Jonas K Hannestad, Bo Albinsson
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    ABSTRACT: Mimicking green plants' and bacteria's extraordinary ability to absorb a vast number of photons and harness their energy is a longstanding goal in artificial photosynthesis. Resonance energy transfer among donor dyes has been shown to play a crucial role on the overall transfer of energy in the natural systems. Here, we present artificial self-assembled light-harvesting complexes consisting of DNA scaffolds, intercalated YO-PRO-1 (YO) donor dyes and a porphyrin acceptor anchored to a lipid bilayer, conceptually mimicking the natural light-harvesting systems. A model system consisting of 39 mer duplex DNA in a linear wire configuration with the porphyrin attached in the middle of the wire is primarily investigated. Utilizing intercalated donor fluorophores to sensitize the excitation of the porphyrin acceptor, we obtain en effective absorption coefficient 12 times larger than for direct excitation of the porphyrin. Based on steady-state and time-resolved emission measurements and Markov chain simulations, we show that YO-to-YO resonance energy transfer substantially contributes to the overall flow of energy to the porphyrin. This increase is explained through energy migration along the wire allowing the excited state energy to transfer to positions closer to the porphyrin. The versatility of DNA as a structural material is demonstrated through the construction of a more complex hexagonal light harvesting scaffold yielding further increase in the effective absorption coefficient. Our results show that, using DNA as a scaffold, we are able to arrange chromophores on a nanometer-scale and in this way facilitate the assembly of efficient light-harvesting systems.
    Journal of the American Chemical Society 01/2013; · 10.68 Impact Factor
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    ABSTRACT: We use single-molecule fluorescence microscopy to monitor individual hybridization reactions between membrane-anchored DNA strands, occurring in nanofluidic lipid monolayer films deposited on Teflon AF substrates. The DNA molecules are labeled with different fluorescent dyes which make it possible to simultaneously monitor the movements of two different molecular species, and thus enabling tracking of both reactants and products. We employ lattice diffusion simulations to determine reaction probabilities upon interaction. The observed hybridization rate of the 40-mer DNA was more than two-fold higher than that of the 20-mer DNA. Since the lateral diffusion coefficient of the two different constructs is nearly identical, the effective molecule radius determines the overall kinetics. This implies that when two DNA molecules approach each other, hydrogen bonding takes place distal from the place where the DNA is anchored to the surface. Strand closure then propagates bidirectionally through a zipper-like mechanism, eventually bringing the lipid anchors together. Comparison with hybridization rates for corresponding DNA sequences in solution reveals that hybridization rates are lower for the lipid-anchored strands and that the dependence on strand length is stronger.
    ACS Nano 12/2012; · 12.03 Impact Factor
  • Bo Albinsson, Jonas K. Hannestad, Karl Börjesson
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    ABSTRACT: Mimicking natural photosynthesis by covalently arranging antenna and charge separation units is a formidable task. Many such beautiful supramolecular complexes have been designed and synthesized with large efforts, some of which are presented in this special issue. The ability to predict relative position of and electronic coupling between the active components in covalent arrays is quite high but there are two obvious drawbacks with the covalent approach. Firstly, as the size grows the complexity of the organic synthesis increases and secondly, sensitivity to light-induced damage becomes a major issue if covalent bonds are broken. Self-assembly of the photoactive components should, in principle, provide a solution to both these issues but generally the ability to predict position and electronic coupling is too low to have the designed properties needed for a functional artificial photosynthetic complex. Here, we present an approach of using DNA as a template for arranging both charge separation units and antenna molecules that govern long-range energy transfer. Of particular interest is the ability of DNA to function as a scaffold for chromophores, either through covalent attachment, or through non-covalent association by means of intercalation or grove binding. Using controlled positioning of dyes, multichromophoric assemblies can be created, capable of long range communication through multi-step energy transfer. This facilitates creation of DNA-based photonic devices for both light harvesting and directed information transfer. The channeled excitation energy can be transformed site specifically to chemical energy by charge separation of DNA linked porphyrins. A two phase system is discussed, in which the DNA is located in buffered solution whereas the hydrophobic porphyrins, responsible for the charge separation reaction, are located in the lipid bilayer of liposomes or supported lipid bilayers.
    Coordination Chemistry Reviews 01/2012; In press. · 11.02 Impact Factor
  • Jonas K Hannestad, Simon R Gerrard, Tom Brown, Bo Albinsson
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    ABSTRACT: Using the principle of self-assembly, a fluorescence-based photonic network is constructed with one input and two spatially and spectrally distinct outputs. A hexagonal DNA nanoassembly is used as a scaffold to host both the input and output dyes. The use of DNA to host functional groups enables spatial resolution on the level of single base pairs, well below the wavelength of light. Communication between the input and output dyes is achieved through excitation energy transfer. Output selection is achieved by the addition of a mediator dye intercalating between the DNA base pairs transferring the excitation energy from input to output through energy hopping. This creates a tool for selective excitation energy transfer on the nanometer scale with spectral and spatial control. The ability to direct excitation energy in a controlled way on the nanometer scale is important for the incorporation of photochemical processes in nanotechnology.
    Small 09/2011; 7(22):3178-85. · 7.82 Impact Factor
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    ABSTRACT: The UV-dissipative mechanisms of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and the 4,7-dideutero derivative (DHICA-d(2)) in buffered H(2)O or D(2)O have been characterized by using ultrafast time-resolved fluorescence spectroscopy. Excitation of the carboxylate anion form, the dominating state at neutral pH, leads to dual fluorescence. The band peaking at lambda=378 nm is caused by emission from the excited initial geometry. The second band around lambda=450 nm is owed to a complex formed between the mono-anion and specific buffer components. In the absence of complex formation, the mono-anion solely decays non-radiatively or by emission with a lifetime of about 2.1 ns. Excitation of the neutral carboxylic acid state, which dominates at acidic pH, leads to a weak emission around lambda=427 nm with a short lifetime of 240 ps. This emission originates from the zwitterionic state, formed upon excitation of the neutral state by sub-ps excited-state intramolecular proton transfer (ESIPT) between the carboxylic acid group and the indole nitrogen. Future studies will unravel whether this also occurs in larger building blocks and ESIPT is a built-in photoprotective mechanism in epidermal eumelanin.
    ChemPhysChem 08/2010; 11(11):2424-31. · 3.35 Impact Factor
  • Biophysical Journal 01/2010; 98(3). · 3.67 Impact Factor
  • Biophysical Journal 12/2009; 98:195. · 3.67 Impact Factor
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    ABSTRACT: We here present a two-dimensional (2D) micro/nano-fluidic technique where reactant-doped liquid-crystal films spread and mix on micro- and nanopatterned substrates. Surface-supported phospholipid monolayers are individually doped with complementary DNA molecules which hybridize when these lipid films mix. Using lipid films to convey reactants reduces the dimensionality of traditional 3D chemistry to 2D, and possibly to 1D by confining the lipid film to nanometer-sized lanes. The hybridization event was observed by FRET using single-molecule-sensitive confocal fluorescence detection. We could successfully detect hybridization in lipid streams on 250 nm wide lanes. Our results show that the number and density of reactants as well as sequence of reactant addition can be controlled within confined liquid crystal films, providing a platform for nanochemistry with potential for kinetic control.
    Nano Letters 09/2009; · 13.03 Impact Factor
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    Jonas K Hannestad, Peter Sandin, Bo Albinsson
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    ABSTRACT: DNA is a promising material for use in nanotechnology; the persistence length of double stranded DNA gives it a rigid structure in the several-nanometer regime, and its four letter alphabet enables addressability. We present the construction of a self-assembled DNA-based photonic wire capable of transporting excitation energy over a distance of more than 20 nm. The wire utilizes DNA as a scaffold for a chromophore with overlapping absorption and emission bands enabling fluorescence resonance energy transfer (FRET) between pairs of chromophores leading to sequential transfer of the excitation energy along the wire. This allows for the creation of a self-assembled photonic wire using straightforward construction and, in addition, allows for a large span in wire lengths without changing the basic components. The intercalating chromophore, YO, is chosen for its homotransfer capability enabling effective diffusive energy migration along the wire without loss in energy. In contrast to heterotransfer, i.e., multistep cascade FRET, where each step renders a photon with less energy than in the previous step, homotransfer preserves the energy in each step. By using injector and detector chromophores at opposite ends of the wire, directionality of the wire is achieved. The efficiency of the wire constructs is examined by steady-state and time-resolved fluorescence measurements and the energy transfer process is simulated using a Markov chain model. We show that it is possible to create two component DNA-based photonic wires capable of long-range energy transfer using a straightforward self-assembly approach.
    Journal of the American Chemical Society 11/2008; 130(47):15889-95. · 10.68 Impact Factor
  • Jonas K Hannestad, Peter Sandin, Bo Albinsson
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    ABSTRACT: DNA is a promising material for use in nanotechnology; the persistence length of double stranded DNA gives it a rigid structure in the several nanometer regime and its four letter alphabet enables addressability. We present the construction of a self-assembled DNA-based photonic wire capable of transporting excitation energy over a distance of more than 20 nm. Our results show that it is possible to create two component DNA-based photonic wires capable of long range energy transfer using a straightforward self-assembly approach.
    Nucleic Acids Symposium Series 02/2008;