Researchers make major gains in DNA-based computers
to faster, more accurate tests for diagnosing West Nile Virus and
bird flu more quicker and more accurately.
The development is a step forward for scientists, who have attempted to build computers out of DNA. But getting nano-sized pieces of DNA to act as electrical circuits capable of problem solving like their silicon counterparts has remained a challenge.
Researchers from Columbia University used a computer, MAYA-II (Molecular Array of YES and AND logic gates) that consisted of DNA circuits instead of silicon.
The computer was put through a series of tests including a game of tic-tac-toe against human opponents, winning every time except in the rare event of a tie.
Composed of more than 100 DNA circuits, MAYA-II is quadruple the size of its predecessor, MAYA-I, a similar DNA-based computer developed by the research team three-years ago.
MAYA-II consists of nine cell-culture wells arranged in a pattern that resembles a tic-tac-toe grid. Each well contains a solution of DNA material that is coded with "red" or "green" fluorescent dye.
The computer always makes the first move by activating the centre well. Instead of using buttons or joysticks, a human player makes a "move" by adding a DNA sequence corresponding to their move in the eight remaining wells.
The well chosen for the move by the human player responds by fluorescing green, indicating a match to the player's DNA input. The move also triggers the computer to make a strategic counter-move in one of the remaining wells, which fluoresces red.
The game play continues until the computer eventually wins, as it is pre-programmed to do. Each move takes about 30 minutes.
"This is a big step in DNA computing," said Joanne Macdonald, a virologist at Columbia University's Department of Medicine and leader of the research team.
"These DNA computers won't compete with silicon computing in terms of speed, but their advantage is that they can be used in fluids, such as a sample of blood or in the body, and make decisions at the level of a single cell," she added.
The research team are adamant that their work represents the first "medium-scale integrated molecular circuit," and is the most powerful computing device of its type to date.
The team also said that the new technology could be used in the future, perhaps in five to ten years, to develop instruments that can simultaneously diagnose and treat cancer, diabetes or other diseases
Macdonald is currently using the technology to improve disease diagnostics for West Nile Virus by building a device to quickly and accurately distinguish between various viral strains and hopes to use similar techniques to detect new strains of bird flu.
In the future, she suggests that DNA computers could conceivably be implanted in the body to both diagnose and kill cancer cells or monitor and treat diabetes by dispensing insulin when needed.
The study is scheduled to appear in the November issue of the American Chemical Society's Nano Letters.
