General Introduction

Sequence-dependent self-assembly of DNA molecules has been used to develop advanced nanoarchitectures, giving rise to “DNA nanotechnology”. Since Seeman et al. reported branched DNA assemblies, methodologies for fabricating DNA nanostructures have been developed dramatically, represented by DNA origami technique. Dynamic conversion of DNA structures has also been achieved based on strand displacement reactions (SDRs), resulting in DNA-based molecular machines and nanodevices operated by specific sequences of oligonucleotides. Recently, it has gained much attention to construct DNA systems driven by external stimuli instead of nucleic acid strands. In particular, metal ions show unique properties such as reversible complexation, stimuli-responsiveness, and binding specificity. This chapter overviews the history of DNA nanotechnology spanning from early studies of DNA nanostructures to recent examples of dynamic DNA nanodevices. Stimuli-responsive DNA systems are also highlighted, focusing on characteristics of each stimulus. In particular, metal-mediated base pairing is discussed as a strategy for metal-responsive control of DNA assemblies.