ABSTRACT
The supramolecular self-assembly of pyrene-DNA conjugates into nanostructures is presented. DNA functionalized with different types of pyrene isomers at the 3'-end self-assemble into nano-objects. The shape of the nanostructures is influenced by the type of pyrene isomer appended to the DNA. Multilamellar vesicles are observed with the 1,6- and 1,8-isomers, whereas conjugates of the 2,7-isomer exclusively assemble into spherical nanoparticles. Self-assembled nano-spheres obtained with the 2,7-dialkynyl pyrene isomer were used for the construction of an artificial light-harvesting complex (LHC) in combination with Cy3 as the energy acceptor.
Subject(s)
Nanoparticles , Nanostructures , Nanostructures/chemistry , DNA/chemistry , Pyrenes/chemistryABSTRACT
The precise arrangement of structural subunits is a key factor for the proper shape and function of natural and artificial supramolecular assemblies. In DNA nanotechnology, the geometrically well-defined double-stranded DNA scaffold serves as an element of spatial control for the precise arrangement of functional groups. Here, we describe the supramolecular assembly of chemically modified DNA hybrids into diverse types of architectures. An amphiphilic DNA duplex serves as the sole structural building element of the nanosized supramolecular structures. The morphology of the assemblies is governed by a single subunit of the building block. The chemical nature of this subunit, i.e., polyethylene glycols of different chain length or a carbohydrate moiety, exerts a dramatic influence on the architecture of the assemblies. Cryo-electron microscopy revealed the arrangement of the individual DNA duplexes within the different constructs. Thus, the morphology changes from vesicles to ribbons with increasing length of a linear polyethylene glycol. Astoundingly, attachment of a N-acetylgalactosamine carbohydrate to the DNA duplex moiety produces an unprecedented type of star-shaped architecture. The novel DNA architectures presented herein imply an extension of the current concept of DNA materials and shed new light on the fast-growing field of DNA nanotechnology.
Subject(s)
DNA , Oligonucleotides , Cryoelectron Microscopy , DNA/chemistry , Polyethylene Glycols , NanotechnologyABSTRACT
The supramolecular assembly of DNA conjugates, functionalized with tetraphenylethylene (TPE) sticky ends, into vesicular structures is described. The aggregation-induced emission (AIE) active TPE units allow monitoring the assembly process by fluorescence spectroscopy. The number of TPE modifications in the overhangs of the conjugates influences the supramolecular assembly behavior. A minimum of two TPE residues on each end are required to ensure a well-defined assembly process. The design of the presented DNA-based nanostructures offers tailored functionalization with applications in DNA nanotechnology.
Subject(s)
DNA , Stilbenes , Base Sequence , Nanotechnology , Stilbenes/chemistryABSTRACT
The chemical synthesis and the supramolecular assembly of an aromatic oligoamine are described. The self-assembly of the cationic oligomers in aqueous solution leads to the formation of vesicular objects. The assembly process of the oligomers is monitored by absorption and fluorescence spectroscopy and the formed vesicles are characterized by atomic force and transmission electron microscopy. The electrostatic complementarity of anionic supramolecular polymers sheets and the cationic vesicles is used for a layered assembly process.
ABSTRACT
DNA-organized multi-chromophoric systems containing phenanthrene and pyrene derivatives exhibit a highly efficient excitation energy transfer from phenanthrene (donor) to pyrene (acceptor). The energy transfer also occurs if the phenanthrene antenna is interrupted by intervening DNA base pairs. Artificial light-harvesting complexes composed of up to five phenanthrene-DNA alternations with fluorescence quantum yields as high as 68% are described.
Subject(s)
Energy TransferABSTRACT
The chemical synthesis of molecular probes to identify and study membrane proteins involved in the biological pathway of protein glycosylation is described. Two short-chain glycolipid analogs that mimic the naturally occurring substrate mannosyl phosphoryl dolichol exhibit either photoreactive and clickable properties or allow the use of a fluorescence readout. Both probes consist of a hydrophilic mannose headgroup that is linked to a citronellol derivative via a phosphodiester bridge. Moreover, a novel phosphoramidite chemistry-based method offers a straightforward approach for the non-enzymatic incorporation of the saccharide moiety in an anomerically pure form.
ABSTRACT
The self-assembly of DNA hybrids possessing tetraphenylethylene sticky ends at both sides into vesicular architectures in aqueous medium is demonstrated. Cryo-electron microscopy reveals the formation of different types of morphologies from the amphiphilic DNA-hybrids. Depending on the conditions, either an extended (sheet-like) or a compact (columnar) alignment of the DNA hybrids is observed. The different modes of DNA arrangement lead to the formation of vesicles appearing either as prolate ellipsoids (type I) or as spheres (type II). The type of packing has a significant effect on the accessibility of the DNA, as evidenced by intercalation and light-harvesting experiments. Only the vesicles exhibiting the sheet-like DNA alignment are accessible for intercalation by ethidium bromide or for the integration of chromophore-labelled DNA via a strand exchange process. The dynamic nature of type I vesicles enables their elaboration into artificial light-harvesting complexes by DNA-guided introduction of Cy3-acceptor chromophores. DNA-constructed vesicles of the kind shown here represent versatile intermediates that are amenable to further modification for tailored nanotechnology applications.
Subject(s)
DNA , Nanotechnology , Cryoelectron MicroscopyABSTRACT
An approach combining DNA nanoscaffolds with supramolecular polymers for the efficient and directional propagation of light-harvesting cascades has been developed. A series of photonic wires with different arrangements of fluorophores in DNA-organized nanostructures were linked to light-harvesting supramolecular phenanthrene polymers (SPs) in a self-assembled fashion. Among them, a light-harvesting complex (LHC) composed of SPs and a photonic wire of phenanthrene, Cy3, Cy5, and Cy5.5 chromophores reveals a remarkable energy transfer efficiency of 59 %. Stepwise transfer of the excitation energy collected by the light-harvesting SPs via the intermediate Cy3 and Cy5 chromophores to the final Cy5.5 acceptor proceeds through a Förster resonance energy transfer mechanism. In addition, the light-harvesting properties are documented by antenna effects ranging from 1.4 up to 23 for different LHCs.
Subject(s)
Carbocyanines/chemistry , DNA/chemistry , Fluorescent Dyes/chemistry , Nanostructures/chemistry , Fluorescence Resonance Energy Transfer , Models, Molecular , Phenanthrenes/chemistry , PhotonsABSTRACT
The synthesis and self-assembly of a water-soluble bolaamphiphilic cyclopenta[hi]aceanthrylene derivative is described. Self-assembly in aqueous medium leads to the formation of supramolecular vesicles with intense absorption bands over an extended range of the UV/vis spectral region and a narrow HOMO-LUMO bandgap of 1.65 eV.
ABSTRACT
Vesicle-shaped supramolecular polymers are formed by self-assembly of a DNA duplex containing phenanthrene overhangs at both ends. In the presence of spermine, the phenanthrene overhangs act as sticky ends linking the DNA duplexes together. In aqueous solution, the assembly leads to vesicles with a diameter in the range of 50-200 nm. Fluorescence measurements show that the assembled phenanthrene units act as light-harvesting complexes and transfer absorbed energy to an acceptor, such as pyrene or Cy3, which can either be directly added to the polymer or attached via a complementary DNA strand. The presence of DNA in the nanostructures allows the construction of light-harvesting vesicles that are amenable to derivatization with different functional groups.
Subject(s)
Carbocyanines/chemistry , DNA/chemistry , Energy Transfer , Light , Nanocapsules/chemistry , Phenanthrenes/chemistry , Pyrenes/chemistry , Base Sequence , Models, Molecular , Nanocapsules/ultrastructureABSTRACT
The use of the DNA duplex as a supramolecular scaffold is an established approach for the assembly of chromophore aggregates. In the absence of detailed structural insight, the characterization of thus assembled oligochromophores is, today, largely based on solution-phase spectroscopy. Here, we describe the crystal structures of three DNA-organized chromophore aggregates. DNA hybrids containing non-nucleosidic pyrene and phenanthrene building blocks were co-crystallized with the recently described binding domain of the restriction enzyme BpuJI. Crystal structures of these complexes were determined at 2.7, 1.9 and 1.6 Å resolutions. The structures reveal aromatic stacking interactions between pyrene and/or phenanthrene units within the framework of the B-DNA duplex. In hybrids containing a single modification in each DNA strand near the end of the duplex, the two polyaromatic hydrocarbons are engaged in a face-to-face stacking orientation. Due to crystal packing and steric effects, the terminal GC base pair is disrupted in all three crystal structures, which results in a non-perfect stacking arrangement of the aromatic chromophores in two of the structures. In a hybrid containing a total of three pyrenes, crystal lattice induced end-to-end stacking of individual DNA duplexes leads to the formation of an extended aromatic π-stack containing four co-axially arranged pyrenes. The aromatic planes of the stacked pyrenes are oriented in a parallel way. The study demonstrates the value of co-crystallization of chemically modified DNA with the recombinant binding domain of the restriction enzyme BpuJI for obtaining detailed structural insight into DNA-assembled oligochromophores.
Subject(s)
DNA Restriction Enzymes/chemistry , DNA Restriction Enzymes/metabolism , DNA/chemistry , DNA/metabolism , Phenanthrenes/chemistry , Pyrenes/chemistry , Crystallization , Crystallography, X-Ray , Models, Molecular , Protein Binding , Protein DomainsABSTRACT
A 2,7-disubstituted phosphodiester-linked phenanthrene trimer forms tubular structures in aqueous media. Chromophores are arranged in H-aggregates. Incorporation of small quantities of pyrene results in the development of light-harvesting nanotubes in which phenanthrenes act as antenna chromophores and pyrenes as energy acceptors. Energy collection is most efficient after excitation at the phenanthrene H-band. Fluorescence quantum yields up to 23 % are reached in pyrene doped, supramolecular nanotubes.
ABSTRACT
The understanding and description of collectively excited multichromophores is of crucial importance for many areas of basic and applied research. DNA has been used for the construction of well-defined heterochromophoric stacks. Electronic coupling among non-adjacent chromophores of the same type leads to the co-existence of PDI and pyrene H-aggregates in hybrids composed of alternating chromophore stacks.
Subject(s)
Coloring Agents/chemistry , DNA/chemistry , Imides/chemistry , Perylene/analogs & derivatives , Perylene/chemistry , Pyrenes/chemistry , SpectrophotometryABSTRACT
The efficient collection of solar energy relies on the design and construction of well-organized light-harvesting systems. Herein we report that supramolecular phenanthrene polymers doped with pyrene are effective collectors of light energy. The linear polymers are formed through the assembly of short amphiphilic oligomers in water. Absorption of light by phenanthrene residues is followed by electronic energy transfer along the polymer over long distances (>100â nm) to the accepting pyrene molecules. The high efficiency of the energy transfer, which is documented by large fluorescence quantum yields, suggests a quantum coherent process.
ABSTRACT
Double stranded DNA hybrids containing up to four consecutive, face-to-face stacked porphyrins are described. Non-nucleosidic, 5,15-bisphenyl-substituted porphyrin building blocks were incorporated into complementary oligonucleotide strands. Upon hybridization multiple porphyrins are well accommodated inside the DNA scaffold without disturbing the overall B-DNA structure. The formation of double strands containing up to four free base porphyrins is enabled without compromising duplex stability. UV/vis, fluorescence, and CD spectroscopy demonstrate the formation of porphyrins H-aggregates inside the DNA double helix and provide evidence for the existence of strong excitonic coupling between interstrand stacked porphyrins. H-aggregation results in considerable fluorescence quenching. Most intense CD effects are observed in stacks containing four porphyrins. The findings demonstrate the value of DNA for the controlled formation of molecularly defined porphyrin aggregates.
Subject(s)
DNA/chemistry , Porphyrins/chemistry , Circular Dichroism , Fluorescence , Models, Molecular , Nucleic Acid Conformation , Nucleic Acid HybridizationABSTRACT
Aromatic π-π stacking interactions are ubiquitous in nature, medicinal chemistry and materials sciences. They play a crucial role in the stacking of nucleobases, thus stabilising the DNA double helix. The following paper describes a series of chimeric DNA-polycyclic aromatic hydrocarbon (PAH) hybrids. The PAH building blocks are electron-rich pyrene and electron-poor perylenediimide (PDI), and were incorporated into complementary DNA strands. The hybrids contain different numbers of pyrene-PDI interactions that were found to directly influence duplex stability. As the pyrene-PDI ratio approaches 1:1, the stability of the duplexes increases with an average value of 7.5 °C per pyrene-PDI supramolecular interaction indicating the importance of electrostatic complementarity for aromatic π-π stacking interactions.
ABSTRACT
A light-harvesting complex composed of a π-stacked multichromophoric array in a DNA three-way junction is described. The modular design allows for a ready exchange of non-covalently attached energy acceptors.
Subject(s)
Biomimetic Materials/chemistry , DNA/chemistry , Light-Harvesting Protein Complexes/chemistry , Base Sequence , Models, MolecularABSTRACT
Reading the bands: Amphiphilic pyrene trimers self-assemble into two-dimensional, supramolecular polymers in aqueous medium. Folding and aggregation processes are accompanied by simultaneous development of J- and H-bands and significant changes in the fluorescence properties. The formation of sheet-like nano-structures is confirmed by AFM.
ABSTRACT
Aggregation-induced emission (AIE) was studied by hybridization of dialkynyl-tetraphenylethylene (DATPE) modified DNA strands. Molecular aggregation and fluorescence of DATPEs are controlled by duplex formation.
