US Patent 7612184 Polynucleic acid nanomechanical device controlled by hybridization topology

The present invention is directed to a sequence dependent polynucleotide nanomechanical device based on a nucleic acid paranemic crossover (PX) molecule which is a four-stranded structure related to parallel double crossover molecules, except that every possible crossover takes place. Eliminating two crossovers leads to a topoisomer, termed JX2, in which one pair of ends are switched (rotated 180°) while the other pair of ends remain the same. The device can be cycled between the two states, PX and JX2, by replacing single strands that set the state to be PX or JX2.