7 research outputs found
Complex multicomponent patterns rendered on a 3D DNA-barrel pegboard
DNA origami, in which a long scaffold strand is assembled with a many short staple strands into parallel arrays of double helices, has proven a powerful method for custom nanofabrication. However, currently the design and optimization of custom 3D DNA-origami shapes is a barrier to rapid application to new areas. Here we introduce a modular barrel architecture, and demonstrate hierarchical assembly of a 100 megadalton DNA-origami barrel of similar to 90nm diameter and similar to 250nm height, that provides a rhombic-lattice canvas of a thousand pixels each, with pitch of similar to 8nm, on its inner and outer surfaces. Complex patterns rendered on these surfaces were resolved using up to twelve rounds of Exchange-PAINT super-resolution microscopy. We envision these structures as versatile nanoscale pegboards for applications requiring complex 3D arrangements of matter, which will serve to promote rapid uptake of this technology in diverse fields beyond specialist groups working in DNA nanotechnology
Homochiral and <i>meso</i> Figure Eight Knots and a Solomon Link
A homochiral
naphthalenediimide-based building block forms in water
a disulfide library of macrocycles containing topological isomers.
We attempted to identify each of these isomers, and explored the mechanisms
leading to their formation. The two most abundant species of the library
were assigned as a topologically chiral Solomon link (60% of the library,
as measured by high-performance liquid chromatography (HPLC)) and
a topologically achiral figure eight knot (18% by HPLC), competing
products with formally different geometries but remarkably similar
4-fold symmetries. In contrast, a racemic mixture of building blocks
gives the near-quantitative formation of another new and more stable
structure, assigned as a <i>meso</i> figure eight knot.
Taken together, these results seem to uncover a correlation between
the point chirality of the building block used and the topological
chirality of the major structure formed. These and the earlier discovery
of a trefoil knot also suggest that the number of rigid components
in the building block may translate into corresponding knot symmetry
and could set the basis of a new strategy for constructing complex
topologies
Thermodynamics of Supramolecular Naphthalenediimide Nanotube Formation: The Influence of Solvents, Side Chains, and Guest Templates
Amino-acid functionalized naphthalenediimides self-assemble into hydrogen-bonded supramolecular helical nanotubes via a noncooperative, isodesmic process; the self-assembly of ordered helical systems is usually realized through a cooperative process. This unexpected behavior was rationalized as a manifestation of entropy–enthalpy compensation. Fundamental insights into the thermodynamics governing this self-assembly were obtained through the fitting of the isodesmic model to <sup>1</sup>H NMR spectrometry and circular dichroism spectroscopy measurements. Furthermore, we have extended the application of this mathematical model, for the first time, to quantitatively estimate the effect of guests, solvents, and side chains on the stability of the supramolecular nanotube; most significantly, we demonstrate that C<sub>60</sub> acts as a template to stabilize the nanotube assembly and thereby substantially increase the degree of polymerization
Structural Parameters Governing the Dynamic Combinatorial Synthesis of Catenanes in Water
We report the first dynamic combinatorial synthesis in
water of
an all-acceptor [2]catenane and of different types of donor–acceptor
[2] and [3]catenanes. Linking two electron-deficient
motifs within one building block using a series of homologous alkyl
chains provides efficient and selective access to a variety of catenanes
and offers an unprecedented opportunity to explore the parameters
that govern their synthesis in water. In this series, catenane assembly
is controlled by a fine balance between kinetics and thermodynamics
and subtle variations in the building block structure, such as the
linker length and building block chirality. A remarkable and unexpected
odd–even effect with respect to the number of atoms in the
alkyl linker is reported
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Oligolysine-based coating protects DNA nanostructures from low-salt denaturation and nuclease degradation
DNA nanostructures have evoked great interest as potential therapeutics and diagnostics due to ease and robustness of programming their shapes, site-specific functionalizations and responsive behaviours. However, their utility in biological fluids can be compromised through denaturation induced by physiological salt concentrations and degradation mediated by nucleases. Here we demonstrate that DNA nanostructures coated by oligolysines to 0.5:1 N:P (ratio of nitrogen in lysine to phosphorus in DNA), are stable in low salt and up to tenfold more resistant to DNase I digestion than when uncoated. Higher N:P ratios can lead to aggregation, but this can be circumvented by coating instead with an oligolysine-PEG copolymer, enabling up to a 1,000-fold protection against digestion by serum nucleases. Oligolysine-PEG-stabilized DNA nanostructures survive uptake into endosomal compartments and, in a mouse model, exhibit a modest increase in pharmacokinetic bioavailability. Thus, oligolysine-PEG is a one-step, structure-independent approach that provides low-cost and effective protection of DNA nanostructures for in vivo applications