Entropy-Driven DNA Networks

A key aspect of electronic circuits is amplification or gain, so that low signals can be distinguished from any persistent background. Zhang et al . (see the Perspective by Bar-Ziv) show how gain can be achieved in biochemical circuits. They have designed complex catalytic networks based on DNA in which the output oligonucleotides that are released go on to act as catalysts for other reactions. The process is designed to be entropy-driven so that the pathways for reactions are well controlled and can be modified at will. Possible applications lie in the field of catalysis, sensor development, the development of an enzyme-free alternative for the polymerase chain reaction, and the construction of nanomachines. D. Y. Zhang, A. J. Turberfield, B. Yurke, E. Winfree, Engineering entropy-driven reactions and networks catalyzed by DNA. Science 318 , 1121-1125 (2007). [Abstract][Full Text] R. Bar-Ziv, DNA circuits get up to speed. Science 318 , 1078-1079 (2007). [Summary][Full Text]