AAAS: Wires and batteries made of viruses
Well, Angela Belcher’s talk was, predictably, very cool. She’s a bioengineer at MIT and one of those researchers who really seems to capture the ethos of the institute: think of something crazy, and then figure out a way to do it. The gist of her work is this:
Biological organisms embody a lot of the characteristics that engineers would like to achieve. They heal themselves. They assemble themselves. They correct themselves. But evolution is an opportunistic enterprise, and living creatures build their materials out of the ingredients around them. Unfortunately, the ingredients we use in important mechanical structures like, say, semiconductors, aren’t terribly abundant. That’s where Belcher comes in: “Maybe we can give organisms the opportunity to work with the rest of the periodic table,” Belcher said today.
So Belcher’s lab set about screening through libraries containing billions of short amino acid chains (called peptides) to find those that can bind to things like semiconductors or magnetic materials. (The high-throughput screen is necessary Belcher noted: organisms started building biomaterials 500 million years ago. It took them 50 million years to 'get good at it,' she said, but her funders want updates every three months.)
Once she finds the right amino acid sequences, it’s relatively easy to work back to the DNA sequence that would encode then. Shove that DNA sequence into a virus, and voila, you’ve made a virus that can bind to a semiconductor.
How do you use it? Belcher’s lab has found peptides that bind to the specific chemical structures found at certain semiconductor deformities. Another peptide can bind to stress fractures in engine blocks. So you can make viruses that express the peptides as well as a fluorescent tag, spray them on a semiconductor or an airplane engine, and look for the fluorescence. If you see it, maybe you don't want to fly that plane.
Belcher gave other examples of how she creates viruses that are coated with peptides that bind gold, for example, or colbalt oxide. The result is a conducting nanowire made of viruses. She’s also made a viral battery that can run an LED light. Take a look through her papers for the details there -- I'm off to the next session.