A figure in a recent paper from Science made me smile, so I thought I'd share it with you guys. The paper describes a new way of joining nanoscale building blocks together using DNA origami. It's based on the principle that if you have two DNA double helices with a gap in between (see the blue helices in the figure below), another DNA helix that exactly matches the size of the gap (the red helix in the diagram) can snap right in to create an intermolecular bond. While individually, these bonds are somewhat weak, having multiple such interactions together on a building block can create a stable, programmable way of joining blocks of DNA origami together. In the paper, the authors build a few structures to demonstrate the versatility of the technique, but the figure that made me smile was when they built three separate pieces that would assemble into a ~ 100-nm tall "nanorobot." Just like in the cartoon Voltron, the pieces snap together to form a robot-like figure (the diagram of the structure is shown in the 3D model on the left, and electron microscopy images of the actual DNA origami structure are in the circles on the right). The nanorobot itself does not have any applications (it doesn't actually do anything but snap togeter and open and close its arms depending on the salt concentration), but it does look neat. Probably a more useful potential application is shown in other parts of the paper where, for example, they make a box structure that can open and close (perhaps for drug delivery).