'Bug-driven robots' to administer drugs

Computer simulations are based on bacterial 'motors'

Scientists are in a race to create the first microscopic "submarines" which can whizz through the bloodstream attacking disease.

We could conceivably have micro-organisms power nanomachinery for extended periods of time

Eldrid Sequeira, Utah State University

Nanotechnology researchers in both Europe and the US have created computer simulations of the mini subs and some believe prototypes are less than a year away.

A team from Utah State University is examining the prospect of using bacteria to propel small structures to deliver drugs to particular parts of the body.

According to Eldrid Sequeira from the university's mechanical engineering department, bacteria such as salmonella and E. coli may be the perfect "motors" for the subs.

Tiny biomotors

As the bacteria swam through the bloodstream they could push or pull a tiny disc, sealed within a liquid-filled cylinder.

These discs could be drugs to treat tumours or break down the material lining blocked arteries.

Speaking at the Foresight conference on nanotechnology in Maryland, he said: "Depending on the design we implement and with recent advances in nanoscale fabrication techniques, we could conceivably have micro-organisms power nanomachinery for extended periods of time."

Eventually, the Utah team believe they could build biomotors using only the flagella from the bacteria which would mean the biomotors would be even smaller - around 100 nanometres (billionths of a metre).

Various methods

The team hope that their current computer simulations will be followed up with a prototype in a few months, probably using a wild strain of the salmonella bacterium.

According to New Scientist magazine, commercial manufacturers are also working on similar technology.

US company Renaissance Technologies plans to start making medical robots smaller than a millimetre in diameter within a year. And a German firm, MicroTEC, is exploring the use of external magnetic fields as a power source for microscopic motors to travel around the body.

In the UK, one of the main areas of work is in seeking effective systems that will target powerful drugs directly at tumours without causing side effects throughout the body.