Isothermal self-assembly of multicomponent and evolutive DNA nanostructures

Thermal annealing is usually needed to direct the assembly of multiple complementary DNA strands into desired entities. 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. In situ, time-resolved observation reveals that this self-assembly is thermodynamically controlled, proceeds through multiple folding pathways and leads to highly reconfigurable nanostructures. It allows a given system to self-select its most stable shape in a large pool of competitive DNA strands. 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. 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. In contrast to conventional thermal annealing approaches, the authors report on the self-assembly of complex mixtures of DNA at room or physiological temperature for generating user-defined programmable nanostructures capable of shape selection and transformation.

Automated summary

Using a magnesium-free buffer, DNA strands and proteins can self-assemble into user-defined nanostructures at room or physiological temperature, without the need for thermal annealing. This isothermal self-assembly is thermodynamically controlled, allows for multiple folding pathways, and results in highly reconfigurable nanostructures. This method expands the possibilities for shape and function in self-assembly and provides a foundation for adaptive nanomachines and nanostructure discovery through evolution.