Nanoscale computing machine using biological molecules

A group of scientists headed by Professor Ehud Shapiro at the Weizmann Institute of Science has used biological molecules to create a tiny computer - a programmable two-state, two-symbol finite automaton - in a test tube.

This biological nanocomputer is so small that a trillion such computers co-exist and compute in parallel, in a drop the size of 1/10 of a millilitre of watery solution held at room temperature.

Collectively, the computers perform a billion operations per second with greater than 99.8% accuracy per operation while requiring less than a billionth of a Watt of power. This study may lead to future computers that can operate within the human body, interacting with its biochemical environment to yield far-reaching biological and pharmaceutical applications.

The computer's input, output and 'software' are made up of DNA molecules. For 'hardware,' the computer uses two naturally occurring enzymes that manipulate DNA. When mixed together in a solution, the software and hardware molecules operate in harmony on the input molecule to create the output molecule, forming a simple mathematical computing machine, known as a finite automaton.

"The living cell contains incredible molecular machines that manipulate information-encoding molecules such as DNA and RNA in ways that are fundamentally very similar to computation," says Professor Shapiro of the Institute's Computer Science and Applied Mathematics Department and the Biological Chemistry Department.

"Since we do not know how to effectively modify these machines or create new ones just yet, the trick is to find naturally existing machines that, when combined, can be steered to actually compute."

The nanocomputer created by Shapiro's team uses the four DNA bases known as A, G, C and T to encode the input data as well as the program rules underlying the computer software. Both input and software molecules are designed to have one DNA strand longer than the other, resulting in a single-strand overhang called a sticky end.

The nanocomputer created is too simple to have immediate applications, however it may pave the way to future computers that can operate within the human body with unique biological and pharmaceutical applications. "For instance, such a future computer could sense an abnormal biochemical change in the body and decide how to correct it by synthesising and releasing the necessary drug," says Professor Zvi Livneh, a DNA expert from the Institute's Department of Biological Chemistry, who collaborated on this project.

Visit the Weizmann Institute website.