GLIDING bacteria have been put to work spinning a microscopic 鈥渉amster wheel鈥� to power a rotary motor. The system is the first microengine to combine bacteria with silicon components and could eventually be used to transport blood samples around so-called lab-on-a-chip devices to help diagnose diseases.
The biomotors are powered by nothing but glucose. They can also repair themselves and, of course, reproduce, says team leader Yuichi Hiratsuka of the University of Tokyo, Japan. 鈥淚t is easy to obtain enormous numbers of living cells by self-reproduction in a simple nutrient within a few days, without any laborious purification processes.鈥�
The researchers powered their motor using Mycoplasma mobile bacteria. The pear-shaped organisms, around 1 micrometre long, can move over solid surfaces at speeds of up to 5 micrometres per second, making them among the fastest moving of all bacteria.
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鈥淭he engine could be used to transport blood samples around diagnostic devices鈥�
The M. mobile were coaxed around a circular silicon track, which was connected to a silicon dioxide rotor. The bacteria tend to follow any wall they encounter, so the researchers etched the surface of the wall to start them off travelling in the same direction so that their efforts didn鈥檛 cancel each other out. The circular wall then kept the bacteria travelling in that direction.
By chemically modifying the bacteria鈥檚 outer surface, the team made them grip the surface and spin the rotor at a rate of around two rotations per minute as they crawled around its perimeter (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0604122103).
Mark Leake, who investigates biological motors at the Bionanotechnology Interdisciplinary Research Centre at the University of Oxford, hails the research as a significant advance. 鈥淢icro-organisms have had millions of years to evolve ingenious strategies to explore and move around. By harnessing this ability and fusing it with the high-precision technology of the silicon-chip industry, we can start to design useful hybrid devices on the microscopic scale,鈥� he says. 鈥淭hese could be used in miniature devices to diagnose different medical conditions from a single drop of blood.鈥�
