Just like a regular-sized device requires a regular-sized motor to operate, a nanodevice likewise requires a molecular-scale motor.
In some cases, that motor takes the form of a piston, and building a piston that’s just a few nanometers long … well, it’s pretty hard. It can and has been done, but it’s an extremely fiddly process. Now, scientists from France’s Centre National de la Recherche Scientifique (CNRS) and the Université de Bordeaux, along with colleagues in China, have developed a molecular piston that is capable of assembling itself.
The CNRS/U Bordeaux piston consists of a slender rod-shaped molecule, around which is wrapped a helix-shaped molecule, that slides along the length of the rod. Both molecules are made from organic compounds, which were synthesized specifically for the project.
Previously with such pistons, a nanoscale ring would have to be manually placed around the rod. In this case, the helicoidal molecule was engineered to spontaneously wind itself around the rod, while still staying flexible enough to maintain a decent range of movement.
The helix moves along the rod in response to the acidity of the piston’s environment. If the acidity is increased, the helix is drawn toward one end of the rod, while if it’s decreased, the helix moves toward the other end.