'Molecular Sex' Used to Evolve Novel Computer Ingredients
CREDIT: Kendra Short
Using "molecular sex," for the first time scientists have evolved enzymes to synthesize semiconductor materials potentially useful in future devices.
The enzymes in questions are known as silicateins, proteins that help form the silica skeletons in marine sponges. Silica, also known as silicon dioxide, is the primary material in sand and a starting material for most commercially manufactured semiconductors, the materials at the heart of modern electronic circuits.
To mimic how nature creates new silicateins, the researchers took DNA encoding these proteins and recombined them in what Bawazer called "molecular sex" to create millions of novel genetic blueprints for silicateins, including ones not found in nature. (Real-life sex similarly involves mixing two sets of genes to produce offspring that are blends of both parents.)
After the scientists generated a host of silicateins, they selected ones with desired properties. They created microscopic plastic beads that each had a novel silicatein enzyme and the gene encoding that enzyme on the outside of the bead. These beads were then placed in emulsions where the enzymes could react with chemicals in their surroundings, such as silicon or titanium, to generate mineral particles of silicon dioxide or titanium dioxide on the surface of the beads.
The researchers took out the beads that performed the best — say, generated the greatest amount of mineral particles — and analyzed their DNA and enzymes. This process of subjecting enzymes to an outside challenge and getting survivors that perform best is a basic step of evolution.
"In the realm of human technologies it would be a new method, but it's an ancient approach in nature," said researcher Lukmaan Bawazer, a biotechnologist at the University of Leeds in England, who conducted this research while at the University of California, Santa Barbara.
The process of directed evolution yielded a multitude of silicateins with unique properties. For example, some of the proteins generated crystalline materials, unlike their "parents." Others assembled themselves into sheets that generated dispersed mineral particles, as opposed to the clumps of particles typically formed by natural silicateins.
"We demonstrated that semiconductor materials that form the basis of electronic components, such as silicon dioxide, which can be used in optical fibers, and titanium dioxide, which is used in dye-sensitized solar cells, are amenable to being engineered via enzymatic synthesis and genetic evolution," Bawazer told InnovationNewsDaily.
Silicateins are complex molecules, potentially making them far more capable than more traditional industrial synthetic approaches. In addition, varying what traits scientists want to evolve the enzymes toward can lead to materials with a variety of novel desirable properties, such as magnetization or fluorescence.
"We can begin carefully designing new environmental pressures to genetically evolve specific material properties," Bawazer said.
Bawazer, Daniel Morse and their colleagues detailed their findings online June 7 in the journal Proceedings of the National Academy of Sciences.