DNA is a natural substrate for computing and has been used to implement a diverse set of mathematical problems, logic circuits and robotics. The molecule also interfaces naturally with living systems, and different forms of DNA-based biocomputing have already been demonstrated. Here, we show that DNA origami can be used to fabricate nanoscale robots that are capable of dynamically interacting with each other in a living animal. The interactions generate logical outputs, which are relayed to switch molecular payloads on or off. As a proof of principle, we use the system to create architectures that emulate various logic gates (AND, OR, XOR, NAND, NOT, CNOT and a half adder). Following an ex vivo prototyping phase, we successfully used the DNA origami robots in living cockroaches (Blaberus discoidalis) to control a molecule that targets their cells.
The number of nanobots in the study -- more than in previous experiments -- makes it particularly promising, says Bachelet. "The higher the number of robots present, the more complex the decisions and actions that can be achieved. If you reach a certain threshold of capability, you can perform any kind of computation. In this case, we have gone past that threshold," he says.
The team says it should be possible to scale up the computing power in the cockroach to that of an 8-bit computer, equivalent to a Commodore 64 or Atari 800 from the 1980s. Goni-Moreno agrees that this is feasible. "The mechanism seems easy to scale up so the complexity of the computations will soon become higher," he says.
An obvious benefit of this technology would be cancer treatments, because these must be cell-specific and current treatments are not well-targeted. But a treatment like this in mammals must overcome the immune response triggered when a foreign object enters the body.