We know that DNA makes people and plants and puppies. So why not robots? Could it be possible to make tiny robots out of DNA? In 2006 Paul Rothemund found a way to make all sorts of tiny shapes out of DNA, even miniature smiley faces. He called the technique DNA origami. Here’s how it works. You start with a long piece of single strand DNA, and, you fold it – just like origami – except you have to fix it in place with another tiny piece of DNA called a ‘staple strand’ and then you fold it again, and again, and again until you’ve made a shape (whether it’s a square or a circle or a smiley face). But why bother trying to build with DNA? Well, because DNA folds itself. DNA is made of four chemical bases, shown here by the four colours. The bases always pair up in the same way (green always with blue, red always with yellow) ‘til the two strands line up to form a double helix. So if you make a staple strand with the right pattern of bases it will bind to the single strand piece of DNA automatically. The more staple strands you add, the more stable the structure. If you get a computer to design the DNA, so that it matches up in all the right places, all you have to do is mix the long strand and the short staples together, and the shape folds itself. The first DNA origami creations were all flat shapes. But other DNA nanotechnology groups soon started to develop three dimensional structures. Over the last ten years even more complex shapes have been created. Even DNA bunnies! In 2009, Danish researchers designed a box that can open to release drug molecules. They even fixed a locking mechanism onto the lid: a molecule that acts as a sensor and could detect things like cancer cells to make sure drugs are released in the right place. Scientists are developing DNA structures whose movements can be precisely controlled. And if you combine this machinery with things like sensors and circuits, you’re well on the way to a nano–robot… all made from DNA!