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Rotaxanating Metallo-supramolecular Nano-cylinder Helicates to Switch DNA Junction Binding

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posted on 20.11.2020, 15:34 by Catherine A. J. Hooper, Lucia Cardo, James S. Craig, Lazaros Melidis, Aditya Garai, Ross T. Egan, Viktoriia Sadovnikova, Florian Burkert, Louise Male, Nikolas J. Hodges, Douglas F. Browning, Roselyne Rosas, Fengbo Liu, Fillipe V. Rocha, Mauro A. Lima, Simin Liu, David Bardelang, Michael J. Hannon
A class of rotaxane is created, not by encapsulating a conventional linear thread, but rather by wrapping a large cucurbit[10]­uril macrocycle about a three-dimensional, cylindrical, nanosized, self-assembled supramolecular helicate as the axle. The resulting pseudo-rotaxane is readily converted into a proper interlocked rotaxane by adding branch points to the helicate strands that form the surface of the cylinder (like branches and roots on a tree trunk). The supramolecular cylinder that forms the axle is itself a member of a unique and remarkable class of helicate metallo-drugs that bind Y-shaped DNA junction structures and induce cell death. While pseudo-rotaxanation does not modify the DNA-binding properties, proper, mechanically-interlocked rotaxanation transforms the DNA-binding and biological activity of the cylinder. The ability of the cylinder to de-thread from the rotaxane (and thus to bind DNA junction structures) is controlled by the extent of branching: fully-branched cylinders are locked inside the cucurbit[10]­uril macrocycle, while cylinders with incomplete branch points can de-thread from the rotaxane in response to competitor guests. The number of branch points can thus afford kinetic control over the drug de-threading and release.

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