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DNA may replace silicon in computers

MADISON, Wis.-University of Wisconsin-Madison scientists are researching a new technology that replaces silicon with DNA in computer chips. The DNA gives the new computer chips the ability to store much more information than the silicon variety.

Over the past three years, professors Lloyd Smith and Robert Corn have been exploring DNA's storage capabilities in comparison with the current models of computers. Smith and Corn currently work in the chemistry department.

"Silicon computer chips are becoming smaller and smaller, in fact, approaching the size of molecules and leaving less room for storage," Corn said.

New computers would take advantage of DNA molecules' capacity for storing large amounts of information regardless of DNA's small size.

According to a recent UW press release, it has been estimated that only one gram of dried DNA can hold as much information as a trillion CDs.

"Conventional silicon computers use electrical charges to represent information," Corn said, "but DNA computers have information stored in the chemistry of the DNA as patterns."

Current computer systems use electronic impulses to represent information. A positive impulse, or electrical charge, would be represented by the number one and a negative charge represented by a zero. Computers then use mathematical formulas to manipulate the binary code and produce possible solutions to equations.

Instead of using positive and negative charges, DNA molecules use combination patterns of four nitrogen bases to produce possible solutions. The difference means the smaller DNA computer chip is capable of finding more possibilities.

Scientists then manipulate the DNA on a smooth glass surface to tailor the DNA to only include answers that solve mathematical problems.

"We use an enzyme called x-nuclease to chew up the single-stranded DNA and leave the double-stranded ones," Corn said. "The double strands are the 'good answers' to mathematical problems. Then we do it again and again until each mathematical computation has a biochemical equivalent."

The tailored DNA can then be fixed to a computer chip.

Smith, Corn and other scientists have recorded their work in the Jan. 13 edition of the scientific journal "Nature."

In the article, Corn and several other scientists describe their experiments involving surface chemistry to easily manipulate DNA on a solid glass surface using enzymes like x-nuclease.

Smith said DNA computers are still far from overtaking the silicon chip, but the new chemistry provides an opportunity to scale up current computers in the years to come.