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What's a DNA robot, and how could it change medicine?

Hunting Cancer With DNA Robots
Behold, the DNA robot. The purple fragments represent the antibody payload.
Behold, the DNA robot. The purple fragments represent the antibody payload.

So what will hunt out the cancerous cells in our body and terminate them with minimal collateral damage? We'll need a robot -- one made out of DNA (deoxyribonucleic acid).

As you can tell from the illustration, the DNA robot doesn't look all that much like a typical bucket-of-bolts automaton. He has neither the charm of a WALL-E nor the deadly symmetry of a U.S. Air Force Predator Drone, but there's a very good reason. In order to build a robot at such a small scale, you have to build it out of small things. The material of choice in this machine is DNA itself.

DNA, of course, is the blueprint for most forms of organic life. The way you look, the way you think -- all of it's contained in a code of chemical bases. But DNA is more than just information. Since complementary sequences of DNA can bind together, individual molecules can self-assemble into complex shapes and structures. Develop a machine out of this stuff and you benefit from a building material that's both readily available and self-assembling. You'll save lives, and you'll also save research and development money.

Using a method called DNA origami, researchers at Harvard's Wyss Institute for Biologically Inspired Engineering folded strands of synthetic DNA into a barrel-shaped cage roughly 35 nanometers in diameter [source: Katsnelson]. By contrast, a strand of human hair is only 20,000 nanometers wide [source: EPA].

This cage holds up to 12 payload molecules inside it, such as cell-destroying antibodies [source: Katsnelson]. On the outside, two aptamers keep the cage from flying open and releasing the deadly payload. Aptamers are short DNA strands with special sequences for recognizing specific molecules. Think of them as locks holding the basket closed.

When the DNA robot comes in contact with targeted cancer cell, the locks spring open, the cage flies open and the antibody destroys the target cell. In 2012, the Wyss Institute research team reported "almost zero collateral damage" after releasing its bots on a mixture of target cells and bystander cells [source: Bachlet].

The technology promises to revolutionize health care with smart, targeted drugs and even more complex nanomachines to police our insides. Scientists have a number of hurdles to overcome as they fine-tune their DNA robot designs, however.

For starters, it currently takes weeks to fold together complex DNA structures. And if these nano-size hot pockets of destruction are to get any work done, it will help if we don't pee them out an hour later. Researchers are working on modifications to prevent the bot from hitting the kidneys or liver before it carries out its attack on targeted cells.

Still, the fact remains: We're building tiny robotic weapons to aid the endless war between the denizens of your body and the endless hordes that strive to conquer it. The technology, like the future, is here.

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