Nanowires grow on viral templates

When materials scientist Angela Belcher set out to build electronic circuits using building blocks the size of viruses, she took the challenge quite literally. The Massachusetts Institute of Technology researcher has made semiconducting nanowires with the help of the microbes themselves.

Nanowires fashioned into billions of transistors on a microchip could someday drive tiny, ultra-fast computers. Because these building blocks are so minuscule, however, assembling them into functioning circuits is a big challenge.

Belcher and some other researchers are now harnessing the self-assembling power of biological materials to construct these complex devices (SN: 7/5/03, p. 7: Microbial Materials). Belcher and her colleagues used a bacteriophage–a narrow virus that infects bacteria. With genetic engineering techniques, the researchers raised a population of phages that produce specific proteins on their coats. Some of these proteins attract cadmium sulfide particles, while others bind bits of zinc sulfide. In the presence of these semiconductor particles, small crystals grew all along the phages’ shafts.

Next, the researchers placed the crystal-coated phages on a silicon surface and subjected them to a heat treatment that killed off the virus while fusing the crystals into a semiconducting nanowire. The scientists report their work in the Jan. 9 Science.

The next challenge, says Belcher, is to tailor the phages so that they can self-assemble into functioning transistors. One tactic the researchers could pursue is to genetically engineer phages to produce specific proteins around their tips that would automatically attach to pairs of tiny gold electrodes on the surface of a chip.


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