A quantum dot is a nanoscale semiconductor that can trap a single electron. They’re the front-runner for providing power to nano-devices, but getting them to cluster in an orderly fashion is really, really hard. Unless you use engineered virii:
The researchers tackled the problem by using a rod-like virus that infects and reproduces in bacteria. They created viruses that were about six nanometres in diameter and 880 nm in length. The viruses had a peptide sequence at one end that would bind to zinc sulphide – changing this peptide would mean quantum dots could be made from other materials.
Then they took the viruses and mixed them in a solution containing zinc sulphide. Each virus assembled a nanocrystal of about 20 nm diameter at one end that had the ability to function as a quantum dot. What is more, when the concentration was just right, the viruses all lined up evenly spaced and end to end, similar to the way molecules in a polymer order themselves.
When Belcher allowed the solution to dry on a substrate, she ended up with a thin, transparent film composed entirely of viruses and nanoparticles, with an area of several square centimetres. It was solid enough to handle with forceps without breaking.
(Thanks, Bill!)