Nanoscale Building Blocks Based on Chemically Modified DNA Helices

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This proposal is located at the interface between nanobiotechnology, chemistry and materials science and focuses on the generation of nanoscale building blocks and nanomechanical devices based on chemically modified DNA. The chemical modifications will help endow DNA with functional characteristics useful in material science and nanobiotechnology such as the ability to change the shape of the nanoscale building blocks in response to an external trigger. The target structure of the proposal is a DNA nanobarrel in which the wall of the barrel is either composed of stacks of DNA-circles or of a coil of an individual DNA duplex. The stacks of DNA-circles and the whorls of the individual DNA duplex will be held together by a multitude of tight yet reversible metal affinity complexes whose constituents are covalently attached to the chemically modified bases of the DNA. Two applications are envisioned for the DNA nanobarrels. (i) Nanobarrels can either serve as nanoscopic building blocks for the creation of lateral assemblies of microscale expansion. These can be employed as templates for the growth of inorganic or metallic nanorods or as nanofiltration membranes with controllable porosity using covalently attached stimulus-responsive polymers. (ii) Nanobarrels composed of a coil of an individual DNA strand can also be used as mechanical nanoscopic coil springs whose expansion is triggered by the controlled opening of the metal affinity bridges and fuelled by electrostatic repulsion between the whorls of the DNA nanobarrels. This type of nanomechanical device might be used as a nanoactuator to increase the distance between two objects or as a biosensor to detect heavy metal ions or toxins.