DNA Fuel for Free-Running Nanomachines

More than just a blueprint for life, DNA is proving to be one of the most versatile materials in nanotechnology. A DNA molecule is made from 4 building blocks--the chemical bases A, C, G, and T. Nanotechnologists take advantage of the fact that they can obtain DNA strands with any sequence of bases to design strands that bind together to make novel structures. G always binds to C, and A is similarly complementary to T. Researchers at Bell Labs/Lucent Technologies and the University of Oxford (contact Bernie Yurke, and Andrew Turberfield) have previously constructed short strands of synthetic DNA that bind together to make a simple molecular machine---a pair of molecular tweezers that can be opened and closed by adding additional DNA strands (Yurke et al., Nature, 10 August 2000). Now, they have made a fuel, consisting of DNA loops, that can act as a source of energy for DNA-based molecular motors. The loops react very slowly unless a specially designed DNA strand is present to catalyze the reaction by forcing loops open. They propose that this principle could be used to make a molecular motor (not yet built). The motor would act as a catalyst,pulling open two complementary DNA loops. The opened loops would bind to each other, exerting a force in the process which could for example cause the motor to rotate or move down a track. The motor would slowly deplete the DNA fuel--and run freely until the fuel was exhausted. Possible applications of artificial molecular motors include nanoscale conveyor belts that carry molecular cargo in a nanoscale asssembly line. (Turberfield et al., Physical Review Letters, 21 March 2003).