MAYA, a computing device created by Milan Stojanovic of Columbia University and Darko Stefanovic of the University of New Mexico, cannot do anything more complicated than play a game of tic-tac-toe. Yet if its creators are right, it could be just the thing to put some intelligence into future smart medicines.
MAYA consists of nine wells arranged in a grid that matches the squares on a tic-tac-toe board. If a human player moves to a particular square, a corresponding sequence of DNA molecules is released into all the wells. In one of them, the DNA reacts with a complementary strand and binds to it, activating a fluorescent enzyme. The resulting glow indicates that this is where the computer is making its next move. The process continues until MAYA wins—which happens whenever it goes first. “Conventional computers use the starting and stopping of electric currents at gates to communicate. We use individual molecules,” Stojanovic says. Strictly speaking, MAYA is not a computer at all but an autonomous decision-making machine. In some applications, however, simplicity is an advantage. Stojanovic envisions a day when doctors will inject patients with similar DNA automatons, their logic gates trained to recognize cancerous or diseased cells. When the DNA finds a match, it could release a toxin that kills only those cells.
