Two scientists in the U.S. have developed a DNA-based system which plays an unbeatable game of tic-tac-toe (noughts and crosses) which they describe in a report published Monday in the journal Nature Biotechnology.
The interactive system, known as Maya, consists of nine wells representing the 3x3 tic-tac-toe board, which contain mixtures of enzymes that are chosen to create a network of 23 molecular logic gates.
The human player has nine different DNA (deoxyribonucleic acid) strands, each one specific to one of the squares on the board. When the player selects one square to play, the DNA strand representing that square is added to each of the nine wells. The Maya system analyzes the play through biochemical reactions occurring in the nine wells.
Because of the careful construction of the enzyme logic gates, each different human move unlocks enzymes in only one well. The move selected by Maya is represented by a fluorescent glow in that well, as molecules in the enzyme mixture are snipped apart. The game then continues with alternate human input and Maya response.
As with a conventional computer tic-tac-toe system, Maya is complex enough to be able to pursue a perfect strategy and thus cannot be beaten, according to scientists Milan Stojanovic of Columbia University and Darko Stefanovic of the University of New Mexico.
The Maya system is an example of the field of DNA computing, where biochemical reactions between molecules rather than movement of electrons through silicon form the basis of a logic system. DNA computing is thought to have potential for solving some mathematically complex problems for which conventional computers are unsuited.