DNA origami

Friday, August 15, 2008
by Diane Boudreau

Origami is the art of folding paper into shapes like animals or flowers. Some origami artists like to challenge themselves by folding models so tiny they could fit on your fingertip. But even those models are huge compared to Stuart Lindsay’s creations.

Lindsay is a biochemist at ASU. He makes origami with DNA.

DNA is what holds your body’s genetic information. It exists in every cell of every living thing. DNA tells your cells when to reproduce and how to do their jobs. Normally, DNA comes in long strands. But Lindsay bends it into all kinds of different shapes.

A scientist at the California Institute of Technology first invented DNA origami. Since then, other scientists like Lindsay have been using and modifying the process to fit their own research needs.

Clearly, DNA is much too tiny to fold by hand. Instead, scientists design their shapes on a computer, and then use chemistry to do the folding.

The main part of the origami is a long strand of DNA. For instance, the DNA for a virus called M13 is made up of 7,000 DNA bases in a single strand. Lindsay makes folds in the long strand by using smaller pieces of DNA to pull two parts of the strand together in specific places. The small pieces of DNA “staple” the parts together.

“You bend the DNA by using short bits of DNA with ‘sticky’ ends to fasten two sections together,” Lindsay explains. “You pick out where to link two strands together and then find the DNA that will connect there. Out from your computer comes a little ordering list, saying, ‘You need these bits of DNA.’”

After that, he puts the strand of DNA in solution with the sticky bits, heats it all up, cools it down again and—voilá!—custom DNA shapes.

“It’s an unbelievable process,” says Lindsay. “What’s marvelous is you can make self-assembling structures of DNA that have single strands poking out, like a tether line.”

DNA origamiIn fact, Lindsay and ASU chemist Hao Yan created the first DNA arrangement with strands sticking out at specific locations. As an example, they created an array that spells out “ASU” using protruding DNA loops.

Making shapes out of DNA isn’t just for fun. The bits that stick out can be used to attach other substances to the DNA. In this way, DNA origami can be used for countless purposes.

Lindsay is using it to attach silver particles to the DNA. He is trying to create a complex antenna system. He wants to mimic the process that plants use when they capture sunlight.

Normally when we think of antennas, we think about things like TVs and radios. But plants have antennas too—antennas that catch sunlight. These antennas are molecules of chlorophyll—the stuff that makes plants green.

Chlorophyll focuses, transfers, and absorbs light energy from the sun. It sends the energy to reaction centers that turn sunlight and water into fuel that the plant can use. If scientists can figure out how to imitate this process, we will have a clean and renewable way to produce energy.

“There are other molecular solar cells in existence but they aren’t very efficient,” Lindsay explains. “We’re proposing to make nanoscale antennas to collect and focus light more efficiently.”