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Abstract:

The rational design of complementary DNA sequences can be used to create nanostructures that self-assemble with nanometer precision. DNA nanostructures have been imaged by atomic force microscopy and electron microscopy. Small-angle X-ray scattering (SAXS) provides complementary structural information on the ensemble-averaged state of DNA nanostructures in solution. Here we demonstrate that SAXS can distinguish between different single-layer DNA origami tiles that look identical when immobilized on a mica surface and imaged with atomic force microscopy. We use SAXS to quantify the magnitude of global twist of DNA origami tiles with different crossover periodicities: these measurements highlight the extreme structural sensitivity of single-layer origami to the location of strand crossovers. We also use SAXS to quantify the distance between pairs of gold nanoparticles tethered to specific locations on a DNA origami tile and use this method to measure the overall dimensions and geometry of the DNA nanostructure in solution. Finally, we use indirect Fourier methods, which have long been used for the interpretation of SAXS data from biomolecules, to measure the distance between DNA helix pairs in a DNA origami nanotube. Together, these results provide important methodological advances in the use of SAXS to analyze DNA nanostructures in solution and insights into the structures of single-layer DNA origami.

Abstract:

We report the design and assembly of chiral DNA nanotubes with well‐defined and addressable inside and outside surfaces. We demonstrate that the outside surface can be functionalised with a chiral arrangement of gold nanoparticles to create a plasmonic device and that the inside surface can be functionalised with a track for a molecular motor allowing transport of a cargo within the central cavity.

Abstract:

The performance of biosensors strongly depends on the nanoarchitecture of the biosensing surface. In many studies the bioreceptor density, orientation and accessibility are often overlooked, resulting in suboptimal biosensing devices. Here, DNA origami structures were decorated with aptamers and studied as a novel tool to structure the biosensor surface with nanoscale precision, favoring interaction between target and aptamer. Using this novel method to engineer biosensing interfaces of two in-house developed biosensing platforms, we were able to accurately detect the presence of a specific target and to compete with existing biosensors in reproducibility, SNR and LOD, without the need for backfilling.