Researchers at Harvard University have developed a robotic device made from DNA that could potentially seek out specific cell targets within a complex mixture of cell types and deliver important molecular instructions, such as telling cancer cells to self-destruct. Inspired by the mechanics of the body's own immune system, the technology might one day be used to program immune responses to treat various diseases. Using the DNA origami method, researchers created a nanosized robot in the form of an open barrel whose two halves are connected by a hinge. The DNA barrel, which acts as a container, is held shut by special DNA latches that seek out combinations of cell-surface proteins, including disease markers. When the latches find their targets, the two halves of the barrel swing open and expose its payload. The container can hold various types of payloads, including specific molecules with encoded instructions that can interact with specific cell surface signaling receptors.