"One of the great challenges of nanotechnology remains the assembly of nanoscale objects into more complex systems," said Robert Hamers. “We think that bacteria and other small biological systems can be used as templates for fabricating even more complex systems.”
Hamers and colleagues tested their technique on Bacillus mycoides bacteria. These rod-shaped organisms are typically 800 nm wide and 5 microns long. The scientists used gold electrodes on a silicon wafer to control the movement of the bacteria. Applying a high-frequency field (approximately 1 MHz) attracted bacteria to the electrodes so that they lined up along the length of the electrode.
The team found that they could guide the bacteria towards the gap between the electrodes by applying a small velocity to the water/glycerol solution containing the bacteria. Once the bacteria reached the gap they caused an increase in the current flowing between the electrodes. The team used a second, lower-frequency field to detect this current increase.
“We spend a lot of time making tiny little nanowires and things of that sort, and then we try to direct them into place, but it is very hard,” said Hamers. “However, bacteria and other biological systems can be thought of as nature’s nanowires that can be easily grown and manipulated.”
The scientists believe their technique could also have applications in biosensors, and by exploiting antibody binding to the bacteria, the technique could build up complex nanoscale structures.
“You could even engineer bacteria to have different surface molecules that you could capitalize on,” added Joseph Beck.
The researchers reported their work at the 229th National Meeting of the American Chemical Society in San Diego, US, in March, and in Nano Letters.