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.

So, what uses could such a tiny piston be put to? The researchers believe that if several of the nanodevices were joined end-to-end, they could function as a type of simplified artificial muscle tissue, capable of contracting on demand. Also, a surface covered with the pistons could switch between acting as an electrical insulator or conductor, while a larger rod with several helices could be used to create a polymer with adjustable stiffness ... and those are just a few suggestions.

The research, which was led by CNRS' Ivan Huc, was recently published in the journal Science.

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