RIVERSIDE, Calif. Molecular machines can be found everywhere in nature, for example, transporting proteins through cells and aiding metabolism. To develop artificial molecular machines, scientists need to understand the rules that govern mechanics at the molecular or nanometer scale (a nanometer is a billionth of a meter).
To address this challenge, a research team at the University of California, Riverside studied a class of molecular machines that 'walk' across a flat metal surface. They considered both bipedal machines that walk on two 'legs' and quadrupedal ones that walk on four.
"We made a horse-like structure with four 'hooves' to study how molecular machinery can organize the motion of multiple parts," said Ludwig Bartels, a professor of chemistry, whose lab led the research. "A couple of years ago, we discovered how we can transport carbon dioxide molecules along a straight line across a surface using a molecular machine with two 'feet' that moved one step at a time. For the new research, we wanted to create a species that can carry more cargo which means it would need more legs. But if a species has more than two legs, how will it organize their motion?"
Bartels and colleagues performed experiments in the lab and found that the quadrupedal molecules use a pacing gait both legs on one side of the molecule move together, followed next by the two legs on the opposite side of the molecule. The species they created moved reliably along a line, not rotating to the side or veering off course. The researchers also simulated a trotting of the species, in which diagonally opposite hooves move together, and found that this form of movement distorted the species far too much to be viable.
Having established how the molecule moves, the researchers next addressed a fundamental question about molecular machinery: Does a molecule or port
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University of California - Riverside