DNA based computers – research moves forward

Caltech researchers have broken some new barriers and have produced the most sophisticated DNA based computer to date – a system that can calculate the square roots of numbers as high as 15. This system is created from 74 strands of DNA that make up 12 logic gates, similar to those in a silicon based computer.

The system obviously isn't as fast that the computer we use daily, and it can take up to 10 hours to get each result for instance. These findings are important however because it is a project which is two decades in development.

The plans for this new technology isn't to replace silicon technology, but instead to create systems which can interact directly with components within living cells.

Scientists hope that this technology will be able to help cure diseases and to monitor cells within people. Erik Winfree the senior author of the study and Caltech bioengineer is very significant for future development and Leonard M. Adleman, a USC computer scientist said his work “is crossing the gulf between chemistry in the laboratory and chemistry in the cell. The goal is no longer to be massively fast, or to do a lot of operations. The goal is to be able to carry out computations and algorithms in a wet molecular environment.”

The system which was created by Winfree and his colleague Lulu Qian is based around the principle that constructing segments of DNA to ‘construct segments of DNA with specific sequences rapidly and reliably, along with the ability of single DNA strands to bind to other strands if they have DNA sequences that chemically match one another.'

They have developed a DNA strand family which can be programmed with ‘not' ‘or' ‘and' commands which work in a similar manner to silicon based technology. Winfree said that the strands of DNA can be reconfigured easily to rewire the circuit.

Winfree and Qian created elements to in a test tube system which can calculate the square roots of numbers from 1 to 15, or in digital terms, 0000 to 1111. Four coloured molecules then reveal the two digit answer in 00, 01, 10 or 11 terms.

Although this seems such a basic thing to achieve, it is the stepping stone for more sophisticated results in the future. Winfree said the system could be made to be 20 times bigger, although there are penalties with speed, as it will be proportionally (20 times) slower. There are ways to help with performance by possibly attaching the DNA strands to some type of fixed substrate to hold them in close proximity so that ‘individual molecules would not have to slowly diffuse to the next step in the reaction.'

He added ‘We hope that, by having localized reactions, even with a very large circuit we wouldn't introduce delays'

Kitguru says: the start of something big for the future? this could be breakthrough technology for the health care industry, but it is some time away from mainstream.

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