The Beauty and Utility of DNA Origami

INTRODUCTION TO DNA ORIGAMI Over the past three decades, DNA, the genetic information carrier in most living organisms, has seen an ever-expanding role as a material for the construction of nanoscale objects. One technique in particular, known as DNA origami, has opened up the ability for researchers to design arbitrarily shaped complex three-dimensional (3D) nanostructures. Origami refers to the art of folding and sculpting a flat sheet of paper into arbitrarily shaped objects. DNA origami is a process of molecular self-folding: a long single-stranded DNA (scaffold), typically M13 phage genomic DNA (!7,000 bp), is folded into prescribed objects by hundreds of short synthetic DNA oligonucleotides, typically 20–60 bp long, which are designed to be complementary to different parts of the scaffold DNA (Figure 1A). The synthetic DNA strands crosslink spatially distant segments of a scaffold together, hence the term ‘‘staples.’’ For a comprehensive elaboration of DNA origami design principles, one can refer to this review article. In the first report of DNA origami in 2006 by Paul Rothemund, planar, arbitrarily shaped, two-dimensional (2D) objects with length scales around 100 nm were constructed (Figure 1B). Topologically, these 2D DNA origamis contained DNA double helices bundled together within a 2D plane by ‘‘crossovers,’’ where DNA strands crossed between neighboring DNA helices. Simple 3D hollow containers—a tetrahedron (Figure 1C) and a cube (Figure 1D)—were constructed in 2009 via the folding of 2D planar DNA origami sheets.