The development of the new approach, funded by the U.S. National Science Foundation, is a significant step in the march toward controlling biological systems with standard information-processing techniques. One day, DNA computing could execute logical functions much like regular silicon-based computers do today. But DNA computers would be much smaller and more easily integrated into biological systems, such as the human body. For example, biological circuits could be directly embedded in cells or tissues to detect and treat diseases.

Caltech researchers Erik Winfree and Lulu Qian of their work in the June 3 issue of Science. "This is basically a technology foundations paper," Winfree wrote in an e-mail.

While simple DNA computational systems , this demonstration system is larger than other prototypes to date.

"The approach adopted by Qian and Winfree marks an important advance in DNA-based computations," wrote John Reif, a professor of computer science at Duke University, in a commentary .

The researchers formed 130 different synthetic DNA strands that can be used to compose logic circuits. From this source material, they created one 74-molecule, four-bit circuit that can compute the square root of any number up to 15 and round down the resulting answer to the nearest integer.