We report the construction of a DNA-based computational platform that uses a library of catalytic nucleic acids (DNAzymes)10, and their substrates, for the input-guided dynamic assembly of a universal set of logic gates and a half-adder/half-subtractor system.We demonstrate multilayered gate cascades, fan-out gates and parallel logic gate operations. In response to input markers, the system can regulate
the controlled expression of anti-sense molecules, or aptamers, that act as inhibitors for enzymes.

Johann Elbaz, Oleg Lioubashevski, Fuan Wang, Francoise Remacle, Raphael D. Levine and Itamar Willner

Nature Nanotechnology, PUBLISHED ONLINE: 30 MAY 2010 | DOI: 10.1038/NNANO.2010.88

see also http://www.newscientist.com/article/dn18989-dna-logic-gates-herald-injectable-computers.html