Evolution could generate new semiconducting structures: The team chose silicateins – proteins that build the silica skeletons of marine sponges – as the basis for their work. Using DNA amplification techniques, they grew millions of strands of DNA that code for silicateins. Mutations arise naturally during the process, so the final pool of DNA contained enough variation to ensure that some of the silicateins would build different kinds of mineral structures.
The researchers then attached the DNA to polystyrene microbeads and placed them in a solution containing a silicon-rich compound. Bawazer's team was looking to select proteins that could draw silicon out of the solution to build silica structures around the beads, while still allowing access to the DNA on the surface of the bead. This would make it easy to collect and amplify the DNA that made the most promising structures. The end product? Proteins that built silica structures unlike any seen in nature.