![]() ![]() In this work, we show that the major methods of structural DNA nanotechnology, including DNA origamis, DNA nanogrids 33 and SST assemblies, can be operated by the same generic isothermal DNA self-assembly principle, leading to a breadth of user-defined elaborate DNA nanostructures that can be spontaneously formed at room or body temperature, keeping intrinsic reconfigurability and offering the capability of complete shape transformation. ![]() Most of these isothermal approaches were also dedicated to a specific DNA assembly method (for example, DNA origami 3 or single-stranded tile (SST) assembly 4), and lacked a generic character that could offer increased applicability and better understanding of DNA isothermal self-assembly. A few isothermal protocols have been described in the literature but each has limitations such as involving denaturing agents 26, 27, 28, preformed assemblies 29, specific sequence designs 30 or specific working temperatures 31, 32. From a more fundamental viewpoint, it raises the question whether such sophisticated, multicomponent DNA nanostructures could self-assemble flawlessly at constant temperature. It also constitutes an obstacle to one-pot, in situ functionalization with temperature-sensitive entities such as proteins. Thermal annealing thus produces structures that can be actuated once they are formed but are not intrinsically evolutive. This also leads to energetically highly stabilized structures for which dynamic actuation and transformation is possible 12, 13, 14, 15, 16, but typically relies on supplemental action on preformed objects 17, using, for instance, linker strand hybridization 18, 19, 20, strand displacement 21, supramolecular interactions 22, enzymatic editing 23 or photoactuation strategies 24, 25. ![]() Such a thermal treatment hinders any possibility for spontaneous nanostructure formation or evolution under fixed environmental conditions. The assembly of such multicomponent structures is, however, usually directed by a thermal annealing process in which the DNA mixture is first heated above its melting temperature before being slowly cooled down to avoid kinetic traps and ensure proper sequence-specific DNA hybridization 11. By exploiting the sequence-dependent base-pairing principle between synthetic DNA single strands, structural DNA nanotechnology 2 appears as a particularly powerful approach to address this challenge because it makes it possible to programme the assembly of hundreds of different components into elaborate superstructures of desired shape 3, 4, size 5, 6 and site-specific functionality 3, 7, potentially at a large scale 8, leading to a wide range of applications 9, 10. Obtaining multiple-component self-assembling synthetic materials capable of such lifelike functions would arguably expand the applicability, versatility and sustainability of human-made smart materials. In nature, self-assembled systems are key elements of living entities and, contrary to their synthetic counterparts, are usually out-of-equilibrium and multicomponent structures capable of dynamic behaviours such as reconfigurability, adaptation or evolution. They usually have, however, limited intrinsic reconfigurability, and producing the desired structures with more than a few different components is still highly challenging. Synthetic self-assembled materials are usually equilibrium structures resulting from the spatial organization of a repeating single component into a stable supramolecular assembly, such as micelles or colloidal crystals, with a prescribed set of useful properties. Self-assembly is a process whereby naturally occurring or rationally designed entities embed the necessary information to spontaneously interact and self-organize into functional superstructures of interest 1. This method expands the repertoire of shapes and functions attainable by isothermal self-assembly and creates a basis for adaptive nanomachines and nanostructure discovery by evolution. Strikingly, upon the appearance of a new energy minimum, DNA origamis isothermally shift from one initially stable shape to a radically different one, by massive exchange of their constitutive staple strands. It allows a given system to self-select its most stable shape in a large pool of competitive DNA strands. In situ, time-resolved observation reveals that this self-assembly is thermodynamically controlled, proceeds through multiple folding pathways and leads to highly reconfigurable nanostructures. We show that, with a magnesium-free buffer containing NaCl, complex cocktails of DNA strands and proteins can self-assemble isothermally, at room or physiological temperature, into user-defined nanostructures, such as DNA origamis, single-stranded tile assemblies and nanogrids. Thermal annealing is usually needed to direct the assembly of multiple complementary DNA strands into desired entities. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |