All aboard the nanotrain
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Getting kinetic with motorised molecules - kinesin |
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Speaking at the Foresight Conference on Nanotechnology in October, US bioengineers described motor proteins that drive the intracellular railroad system and their aim to use this molecular machinery in micron-scale devices with moving parts driven by protein motors for nanotechnology.
Russell Stewart and his colleagues in the Department of Bioengineering, at the University of Utah in Salt Lake City, hope to exploit nature's lead in nanotechnology by mimicking kinesin motor proteins. They describe these proteins as powering an intracellular railroad system based on the microtubule cytoskeleton, they are like "nanometre-scale engines running on nanometre-scale tracks," Stewart said. They want to be able to take this micromachinery out of the living cell and integrate it into micron-scale devices with moving parts powered by the cellular engines.
The microtubule tracks Stewart pointed out are hollow tubes, 24 nanometres diameter, formed by the self-assembly of tubulin protein subunits. The kinesin engines are coupled to nature's cellular fuel molecule, adenosine triphosphate (ATP) the energy from which is released by hydrolysis. For each ATP it hydrolyses, Stewart explained, kinesin moves eight nanometres along the microtubule surface with a remarkable force of up to 6 piconewtons (pN). A pN is a million-millionth of a Newton, which sounds small but Stewart reckons power densities can be produced that are large enough to push tiny gears, levers and rotors. Stewart's team have already been able to "flip" 5 micrometre silicon chips.
