In the nick of space: Generalized nucleic acid complementarity and DNA nanotechnology

DNA is the genetic material of living organisms. The properties that make it such an effective molecule for this task also make it a superb molecule for nanoconstruction. One key to using DNA for this purpose is to generalize complementarity and to produce stable complex motifs, such as branched molecules. Combining these species by means of complementary interactions, such as sticky ends, leads to N-connected stick figures whose edges consist of double helical DNA. Zero node removal, a technique that is the reverse of an analytical topological operation, leads to complex fused motifs, such as rigid multi-crossover molecules. These species have been used to produce 2D arrays and a nanomechanical device. DNA is also an ideal molecule for the synthesis of topological targets, because a half-turn of the double helix corresponds to the fundamental crossing unit of these figures. Knots have led to the discovery of the antijunction and mesojunction motifs. Other promising motifs in this system include switchback DNA and polycrossover DNA. Algorithmic assembly and the use of complex complementarities are future goals for DNA nanotechnology.