The assemblies of molecules designed as a part of targeted therapies presently under development - such as those used to attack cancer cells without harming normal cells - are increasing in sophistication. It won't be too much longer before we can call them robots, and either way this field is the basis for a wide range of medicine that is far more effective and far more safe than anything available today: researchers "have developed a robotic device made from DNA that potentially could 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. ... A research team [used] what they call the DNA origami method, in which complex three-dimensional shapes and objects are constructed by folding strands of DNA. In this case, the 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 can recognize and seek out combinations of cell-surface proteins, including disease markers. When the latches find their targets they reconfigure, causing the two halves of the barrel to 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. The investigators used this system to deliver instructions, which were encoded in antibody fragments, to two different types of cancer cells - leukemia and lymphoma. In each case, the message to the cell was to activate its 'suicide switch' - a standard feature that allows aging or abnormal cells to be eliminated. And since leukemia and lymphoma cells speak different languages, the messages were written in different antibody combinations. ... We can finally integrate sensing and logical computing functions via complex, yet predictable, nanostructures - some of the first hybrids of structural DNA, antibodies, aptamers, and metal atomic clusters - aimed at useful, very specific targeting of human cancers."