Molecular machines could be capable of quantum mechanical tunnelling – something normally seen in very tiny particles like electrons and atoms. That’s the claim of researchers at the University of California, Riverside who have made and studied “two-legged” and “four-legged” nanomachines.
The tunnelling behaviour has never before been seen in devices so big and is a fundamental departure from mechanics in the macroscopic world, says team leader Ludwig Bartels. It also means that such machines could move much faster than expected.
Molecular machines are found everywhere in biology. For example, the acid in our stomachs is produced by a proton pump in cells that line the stomach. And in every cell in the body, proteins are dragged to the place where they are needed using kinesin motors. These biological motors consist of thousands of atoms and are much too big to be studied using computer models.
Bartels’ team wanted to understand the basic principles behind natural molecular machines so that could develop similar, artificial devices. The researchers, together with chemist Michael Marsella, made small, easy-to-study, molecules that can “walk” and carry “cargo” when placed on a flat copper surface held in vacuum. “This is a very much more simplified set-up than in biology, where molecules need to attach themselves everywhere in 3D and where all kinds of other molecules are floating by,” explains Bartels.