Reciprocating devices are key features in macroscopic machines. We have adapted the DNA PX-JX2 device to a reciprocal format. The PX-JX2 device is a robust sequence-dependent nanomachine, whose state is established by a pair of control strands that set it to be either in the PX state or in the JX2 state. The two states differ by a half-turn rotation between their ends. Here we report the construction of a pair of reciprocal PX-JX2 devices, wherein the control strands leading to the PX state in one device lead to the JX2 state in the other device and vice versa. The formation, transformation, and reciprocal motions of these two device systems are confirmed using gel electrophoresis and atomic force microscopy. This system is likely to be of use for molecular robotic applications where reciprocal motions are of value in addition its inherent contribution to molecular choreography and molecular aesthetics.
Nanowerk has information on these nanoscale DNA pistons.
The synchronous reciprocal motion demonstrated by Seeman's team, i.e. a complete cycle of operation to reach equilibrium, took almost half a day.
Seeman points out that the strategy of using the same control strands to set distinct states of two devices enables many nanoscale capabilities from reciprocating machines to molecular choreography.
"The ability to correlate the motions of molecular devices can lead to complex behavior on the nanoscale" he says. "For example, in a recent device the legs of a bipedal walker (see "A Bipedal DNA Brownian Motor with Coordinated Legs") communicate with each other, producing an autonomous walker."
8 page pdf with supplemental information