Teeny Tiny Tic-Tac-Toe, Anyone?
Just as the steam engine set the stage for the Industrial Revolution, and micro-transistors sparked the digital age, nanoscale devices made from DNA are opening up a new era in biomedical research and materials science.
The journal Science describes the emerging uses of DNA mechanical devices in a “Perspective” article by Khalid Salaita, professor of chemistry, and Aaron Blanchard, a graduate student in the Coulter Department of Biomedical Engineering, a joint program of Georgia Institute of Technology and Emory.
The article heralds a new field, which Blanchard dubbed “DNA mechanotechnology,” to engineer DNA machines that generate, transmit, and sense mechanical forces at the nanoscale. “For a long time,” Salaita says, “scientists have been good at making micro devices, hundreds of times smaller than the width of a human hair. It’s been more challenging to make functional nano devices, thousands of times smaller than that. But using DNA as the component parts is making it possible to build extremely elaborate nano devices because the DNA parts self-assemble.”
DNA, or deoxyribonucleic acid, stores and transmits genetic information as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The DNA bases have a natural affinity to pair up with each other—A with T and C with G. Synthetic strands of DNA can be combined with natural DNA strands from bacteriophages. By moving around the sequence of letters on the strands, researchers can get the DNA strands to bind together in ways that create different shapes. The stiffness of DNA strands can also easily be adjusted, so they remain straight as a piece of dry spaghetti or bend and coil like boiled spaghetti.
The ability to make these precise, three-dimensional structures began as a novelty, nicknamed “DNA origami,” resulting in objects such as a microscopic map of the world and, more recently, the tiniest-ever game of tic-tac-toe, played on a DNA board.
Work on novelty objects continues to provide new insights into the mechanical properties of DNA. These insights are driving the ability to make DNA machines that generate, transmit, and sense mechanical forces. “If you put together these three main components of mechanical devices, you begin to get hammers and cogs and wheels and you can start building nano machines,” Salaita says.
Potential uses for such devices include drug delivery devices in the form of nano- capsules that open up when they reach a target site, nano-computers, and nano-robots working on nanoscale assembly lines. The Salaita Lab is one of about one hundred around the world working at the forefront of DNA mechanotechnology.
