Dr. Trent: Let me put this in context. I came to NASA nearly ten years ago to be part of the then flourishing astrobiology program. One of the fundamental questions in astrobiology is: “What are the physical and chemical limits of life?” or stated another way, “Could life exist in the harsh conditions that exist in worlds beyond Earth?” This question of life’s boundary conditions was directly related to my studies of extremophiles and heat shock proteins, but when I got to NASA, I found myself surrounded by engineers, not biologists or astrobiologists. These engineers were more interested in carbon nanotubes and nanotech than in anything to do with astrobiology. Well, carbon nanotubes are great, but proteins are carbon-based nano-structures, that self-replicate, self-assemble using molecular recognition, are genetically adaptable, and can make amazing structures! They are the building blocks for every living thing from bacteria to blue whales, from enzymes to human consciousness!
About nine year ago, I founded the protein nanotech group at NASA Ames to explore how proteins and their properties can be harnessed for nanotechnology. We began with the rosettasome double ring structures, which are 17 nanometers in diameter with a 10 nm hole in the middle. We knew They could be induced to form crystalline arrays, meaning that under certain conditions rosettasomes attach side-by-side to form a two dimensional crystal—a single layer of ordered rings like a layer of donuts lying side-by-side on a tabletop. We also discovered that rosettasomes can form chains and bundles of chains. So what could we do with these self-assembling nanostructures? We started out using the two dimensional rosettasome structures as templates for organizing nanoparticles with nanoscale accuracy. We used genetic engineering to get the rosettasomes to bind to metallic nanoparticles and made arrays of quantum dots and magnetic particles. The arrays we made led us to the idea of making patterned media for data storage. There are engineers in the hard-drive business that believe that patterned media is their future, but no one knows yet how to make patterns on the scale that’s needed. What we could make with rosettasomes would produce hard drives that could store about 1.5 terabytes per square inch, which is a significant improvement over existing hard-drive technology, but there are still some problems to solve.
NTB: How far off in the future do you think it will be before this type of technology is commercialized?
Dr. Trent: Well, the whole data storage industry is going through an identity crisis as it considers the transition from traditional hard drives to patterned media or some other method for increasing data density and the possibility of using flash memory. There are only a few hard drive manufacturers left and one of them was quite interested in what we were doing with rosettasomes, but things are very competitive in the hard drive business. While I’m still interested in building data storage devices and other electronic applications with protein nanotech, my group has moved on to other more pressing problems. We’re now focusing on biofuels and more specifically producing biofuels from cellulose, which I think could play an important role in our transition away from petroleum.
Cellulose is the most abundant polymer on Earth and it’s composed of glucose. The structure of cellulose makes the glucose pretty difficult to access, which is fortunate for land plants that need cellulose to help them stand upright, but unfortunate for animals that want to use the glucose in cellulose for energy. The animals that do eat plant cellulose break it down using enzymes called cellulases, which are usually made by bacteria living in their stomachs. There are a number of different cellulases that work together to dismantle cellulose systematically. Perhaps not surprising, nature has discovered that the different cellulases function more efficiently if they are arranged next to each other on a scaffold. The enzyme scaffolds that nature has evolved are a bit too complex for us, but the idea of a scaffold was easy to copy by genetically engineering the rosettasome into a cellulase scaffold.