This article takes a comprehensive look at the burgeoning field of DNA nanotechnology, in which scientists arrange the four building blocks of DNA – molecules of adenine (A), guanine (G), cytosine (C), and thymine (T) – so that they assemble themselves into whatever structures the researchers want to build. It’s an endeavor that represents nanotechnology’s closest attempt to build materials atom by atom from the ground up, but critics have been quick to wonder about the point of it all. Ned Seeman, an x-ray crystallographer at New York University (NYU), United States, who has spent more than a decade working in the field, said, “People always say, ‘Yeah, that’s cute. So what? What are you going to do with it?’” DNA nanotechnology is now beginning to find its footing, with applications that are helping researchers map the atomic structure of proteins and compute inside cells, and even start tracking and curing diseases. Andrew Turberfield, a physicist at the University of Oxford in the United Kingdom, said, “We’re still playing around. But we’ve gotten good enough that we can do some interesting things.” Someday, this emerging technology may move beyond basic science to find real-world applications, such as a DNA origami nanorobot that will seek out and destroy cancer cells, but as of yet, DNA nanotechnology has not reached that level of maturity. According to William Shih, a DNA nanotech expert at Harvard Medical School, also in the U.S., “In the next 5 years, this is where we’re going to make a real contribution, getting control over small collections of individual molecules.”