LIVE bacteria could one day act as reconfigurable components for nanoscale electronic circuits, or even a scaffold for building nanomachines.
鈥淣ature has developed these fantastic building blocks,鈥� says Robert Hamers of the University of Wisconsin-Madison. 鈥淥ur approach is to simply grab onto them very gently.鈥� His team have been using electrodes to manipulate individual bacterial cells, they will report in a future issue of Nano Letters.
Their chosen bacterium was Bacillus mycoide, 5 micrometres long and 0.8 wide 鈥� large enough to be visible under an optical microscope. The trick is to apply an electric field to the microbes, so they become polarised and stick to the electrodes. But the idea should also work with smaller bacteria, as a change in the electrical current of the electrode would show they were attached.
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The researchers even persuaded the bacteria to form a conducting bridge between two electrodes, a knack that could perhaps lead to reconfigurable nano-circuitry. 鈥淭he idea of using cells as part of a more complex electronic circuit is very important,鈥� says Hamers.
In his experiments the bacteria attached themselves to a long electrode before being shunted along its length by the motion of the solution in which they are suspended. When the bacteria reach a junction with another electrode, the polarities of the two electrodes securely fix the bugs in place (see Graphic).
At the moment, nanostructures have to be put together manually. But it might be possible to automate the process using bacteria, as components tagged with particular biological molecules will stick to complementary surface proteins on the bacteria. Another use for Hamers-type electrodes would be in biosensors that could detect biological agents such as anthrax from changes in an electrode鈥檚 current as spores become attached.
