The DNA of Computing

A joint research project between Bell Labs and the University of Oxford may lead to computers 1,000 times more powerful than today’s machines.

As explained in the August 10 issue of British journal Nature, the researchers have created the first DNA motors – devices which resemble motorized tweezers that are 100,000 times smaller than the head of a pin. According to researchers, DNA is an ideal tool for making nanoscale devices (i.e. devices whose dimensions are on the scale of a nanometre or a billionth of a metre). Scientists believe nanoscale devices may lead to computer chips with billions of transistors, instead of millions which is the typical range of today’s semiconductors.

“We took advantage of how pieces of DNA – with its billions of possible variations – lock together in only one particular way, like pieces of a jigsaw puzzle,” says physicist Bernard Yurke of Bell Labs.

The researchers designed pieces of synthetic DNA that would recognize each other during each step of making the DNA motors. “Because DNA acts as the ‘fuel’ for these motors, they are completely self-sufficient and do not require other chemicals to operate,” Yurke says.

The self-assembling aspect of the DNA motors is crucial for manufacturing nanodevices. “Given the size scale, no other approach appears to be practical,” Yurke says. “This may lead to a test tube based on nanofabrication technology that assembles complex structures, such as electronic circuits, through the orderly addition of molecules.”

Most armchair scientists are familiar with DNA’s double-stranded “twisted ladder” appearance. However, researchers from Bell Labs and Oxford University began by using three single strands, each resembling a ladder sliced down the middle. Strand A has the correct DNA sequence to latch onto half of strand B and half of strand C, thus joining them all together. The hinge sections binding strand A to B and A to C create two arms – AB and AC – which can move freely. The arms are pulled shut by adding a DNA fuel strand, which is designed to attach to the unpaired sections of strands B and C. To re-open the “tweezers”, the fuel strand is removed by adding another strand with the right DNA sequence to pair up with it.

Yurke says the idea for DNA motors came from his observation that molecular-scale protein motors in living organisms are responsible for muscular contraction and moving substances around in cells.

Bell Labs scientists are currently working to attach DNA to electrically conducting molecules to assemble rudimentary molecular-scale electronic circuits.