Send in the bacteria

Send in the bacteria

Computer controlled microbes could soon serve as a first line of attack against cancer
July 28, 2010

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The video clip is the stuff of science fiction: a swarm of 5,000 bacteria lift microscopic epoxy bricks and assemble them one by one to form a pyramid, as if they were building a tower of blocks. A computer directs their movement by controlling magnetic fields.
But for Sylvain Martel and his team of researchers at École Polytechnique de Montréal, the first scientists to “train” living bacteria to build a structure, this feat is no futuristic science experiment. It holds real promise as a miraculous tool in the fight against cancer.

“Our primary goal is to use bacteria to carry drugs directly to tumours,” says Martel, director and founder of the NanoRobotics Laboratory and a professor in the department of computer and software engineering and the Institute of Biomedical Engineering. “It’s hard for people to believe that we can control bacteria using a computer. We had to demonstrate that we could control them and make them move blocks in a coordinated fashion in order to show the potential of using bacteria to target a tumour.”

Just as Egypt
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Just as Egypt's Step Pyramid of Djoser was a milestone in the history of man-made structures, Sylvain Martel's nano-pyramid is a milestone in the history of bacteria-made structures.

Martel was inspired by the story of the pyramid of Djoser, built by an estimated 5,000 slaves around 2600 BC, and considered to be the earliest large-scale stone structure known to humankind. He decided to employ 5,000 bacteria in a drop of water as mini workers to construct a similar step pyramid in less than 15 minutes.

“Some of the bacteria lift the brick from underneath, while others push it, using their flagella like a propeller turning at 360 degrees. The principle is similar to tugboats moving a large ship,” says Martel, who, while on his off time, managed to work his way up to becoming the commanding officer of a warship during a 29-year stint with the Canadian Naval Reserve. 

A black arrow pinpoints where a swarm of 5,000
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A black arrow pinpoints where a swarm of 5,000 bacteria will place a block no wider than a strand of hair to complete the base of a pyramid.
Sylvain Martel

Martel’s research in nanorobotics and in micro- and nanosystems is geared mainly to the fields of medicine and bioengineering. This latest achievement follows on the heels of another technological breakthrough in medical robotics to have generated worldwide interest. In 2007, he and researchers from École Polytechnique and the Centre Hospitalier de l’Université de Montréal successfully injected a tiny magnetic device, measuring 1.5 millimetres in diameter, into the carotid artery of a pig, controlling and tracking its travels in the bloodstream with a clinical magnetic resonance imaging (MRI) scanner.  Since then, Martel and his team have been working at reducing the size of the device so it can circulate in smaller blood vessels. This would allow doctors to diagnose and treat areas of the body that current instruments, such as catheters, cannot reach.

“Revolutionary” is how Yu Sun, an engineering professor at the University of Toronto who holds the Canada Research Chair in Micro- and Nano-Engineering Systems, describes Martel’s work.

The final pyramid built by the bacteria in less
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The final pyramid built by the bacteria in less than 15 minutes.
Sylvain Martel

“Not only is he able to drive a micro device accurately in vivo, but he can also use MRI to clearly see where the device or tool is for surgical use. Give him a few more years’ time and he will probably show you that surgery can be done in the Fantastic Voyage way,” referring to the 1966 science fiction movie in which a crew of scientists and doctors aboard a miniaturized submarine is injected into the bloodstream of a critically injured fellow scientist.

Martel’s group is currently experimenting with steering bacteria through the bloodstream of mice with the intent of testing the procedures on humans, likely within a few years, predicts Martel. He is determined to see that the research conducted in his lab does not end up on a shelf.

“I’m trying hard,” he says, “to make sure that what we develop here is eventually used in hospitals and clinics.”

If one day his technology helps save a life, that, adds Martel, will be his ultimate reward.