From Nano to Macro through Hierarchical Self-Assembly: The DNA Paradigm.

From atoms to molecules and bio-macromolecules, from organelles to cells, tissues, to the whole living system, nature shows us that the formation of complex systems with emergent properties originates from the hierarchical self-assembly of single components in guided bottom-up processes. By using DNA as a fundamental building block with well-known self-recognition properties, scientists have developed design rules and physical-chemical approaches for the fully programmable construction of highly organized structures with nanosized features. This review highlights the basic principles of hierarchical self-assembly in terms of type and number of distinguishable components and their interaction energies. Such general concepts are then applied to DNA-based systems. After a brief overview of the strategies used until now for the construction of individual DNA units, such as DNA tile motifs and origami structures, their self-association into assemblies of higher order is discussed. Particular emphasis is given to the forces involved in the self-assembly process, understanding and rational combination of which might help to coordinate the single elements of hierarchical structures both in space and time, thus advancing our efforts towards the creation of devices that mimic the complexity and functionality of natural systems.