Twirling DNA Rings - Swimming Nanomotors Ready for a Kickstart

We propose a rotary DNA nanomachine that shows a continuous rotation with a frequency of 10$^{2}$ -10$^{4}$Hz. The device consists of a minicircle with the DNA sequence chosen appropriately to achieve anisotropic elastic features generating a ratchet potential. The motor can be externally driven via the ratchet effect through periodic temperature oscillations. As a result the ring self-propels through the fluid like a molecular ``ring of smoke" with a speed up to microns per second. Hydrodynamic interactions open the possibility of self-organized collective ratchet behavior in semi-dilute solutions of twirling DNA rings.