In their setup, the multi-layered strands of DNA into biochemical logic gates that can perform the basic Boolean AND, OR and NOR operations executed by today's transistor-based computer processors. Like the silicon-based integrated circuits, these molecular logic gates produce binary, or on-or-off, output signals, using binary signals as inputs.

Computational operations are conducted by DNA sequence binding and replication. The pre-engineered DNA molecules are immersed in a solution in a test tube. When they bump into one another, they can bind and produce offspring molecules that, in turn, can connect to other strands of DNA, producing a logic chain.

The researchers have also developed a compiler, which maps user-manipulated logic operations to the DNA circuits.

The work is a follow-up from earlier tests, carried out in 2006, which used a total of 12 DNA molecules. Since then, the researchers concentrated on making the process simpler and more reliable, which could lead to larger DNA-based systems.

The researchers' particular approach has a number of advantages, explained Reif, who was not involved in the research. One is simplicity. The biochemical reactions needed to encode the DNA are well-established. The process is also inherently scalable, meaning it could be used as a basis for much larger systems.