Skip to Content

Voyage of the Bacteria Bots

Self-propelled microbots navigate through blood vessels.

The 1966 science-fiction movie Fantastic Voyage famously imagined using a tiny ship to combat disease inside the body. With the advent of nanotechnology, researchers are inching closer to creating something almost as fantastic. A microscopic device that could swim through the bloodstream and directly target the site of disease, such as a tumor, could offer radical new treatments. To get to a tumor, however, such a device would have to be small and agile enough to navigate through a labyrinth of tiny blood vessels, some far thinner than a human hair.

Plot and go: Researchers plot a trajectory for their bacteria-powered microrobots, which are guided using an MRI machine.

Researchers at the École Polytechnique de Montréal, in Canada, led by professor of computer engineering Sylvain Martel, have coupled live, swimming bacteria to microscopic beads to develop a self-propelling device, dubbed a nanobot. While other scientists have previously attached bacteria to microscopic particles to take advantage of their natural propelling motion, Martel’s team is the first to show that such hybrids can be steered through the body using magnetic resonance imaging (MRI).

To do this, Martel used bacteria that naturally contain magnetic particles. In nature, these particles help the bacteria navigate toward deeper water, away from oxygen. “Those nanoparticles form a chain a bit like a magnetic compass needle,” says Martel. But by changing the surrounding magnetic field using an extended set-up coupled to an MRI machine, Martel and his colleagues were able to make the bacteria propel themselves in any direction they wanted.

The bacteria swim using tiny corkscrewlike tails, or flagella, and these particular bacteria are faster and stronger than most, says Martel. What’s more, they are just two microns in diameter–small enough to fit through the smallest blood vessels in the human body. The team treated the polymer beads roughly 150 nanometers in size with antibodies so that the bacteria would attach to them. Ultimately, the researchers plan to modify the beads so that they also carry cancer-killing drugs.

“I think nature has provided an excellent solution to how to make small things swim,” says Bradley Nelson, a professor at ETH Zurich, who has researched the use of artificial flagella. “What’s interesting about Sylvain’s work is that he’s actually using nature to do it and not just learning from it.”

Last year, Martel and his group published research in the journal Applied Physics Letters detailing how they used an MRI machine to maneuver a 1.5-millimeter magnetic bead with a bacteria propeller through the carotid artery of a living pig at 10 centimeters per second. The researchers’ latest work, presented at the IEEE 2008 Biorobotics Conference last week, shows that they can track and steer microbeads and bacteria or bacteria alone through a replica of human blood vessels using the same approach. The group has carried out similar experiments in rats and rabbits, according to Martel.

The bacteria bots wouldn’t be able to make it in larger blood vessels on their own, however. The current would be too strong for them to swim against. So the researchers envisage using a larger, magnetically steerable microvehicle to carry the bots close to a tumor. “The vehicle will be a type of polymer, or possibly another type of material,” says Martel. “We have a way to release the bacteria while the vehicle stays there and dissolves.”

Martel’s vehicle contains magnetic nanoparticles and can be moved at about 200 microns per second. He says that he and his team correct the microvehicle’s course approximately 30 times a second. While they have developed the microvehicle and bacterial microbots independently, they are now working to combine the two technologies. “We think in two years we’ll be able to do that,” says Martel.

“This work is promising but, as with any transformative idea, there are a lot of challenges that need to be addressed,” says Bahareh Behkam, an assistant professor at Virgina Polytechnic Institute, who has also used bacteria to propel microbeads. She suggests that it could be difficult to maintain normal blood flow and to retrieve the magnetic particles from the body after the procedure is complete.

Some researchers also question whether the body’s immune system would attack the bacteria before they could reach a tumor, but Martel defends the approach. “We are very confident from our preliminary tests that this [scenario] will not be an issue,” he says. Because the immune system has not encountered these bacteria before, he says, it would not have time to wipe out the microbots before they reach their target.

Keep Reading

Most Popular

light and shadow on floor
light and shadow on floor

How Facebook and Google fund global misinformation

The tech giants are paying millions of dollars to the operators of clickbait pages, bankrolling the deterioration of information ecosystems around the world.

This new startup has built a record-breaking 256-qubit quantum computer

QuEra Computing, launched by physicists at Harvard and MIT, is trying a different quantum approach to tackle impossibly hard computational tasks.

wet market selling fish
wet market selling fish

This scientist now believes covid started in Wuhan’s wet market. Here’s why.

How a veteran virologist found fresh evidence to back up the theory that covid jumped from animals to humans in a notorious Chinese market—rather than emerged from a lab leak.

protein structures
protein structures

DeepMind says it will release the structure of every protein known to science

The company has already used its protein-folding AI, AlphaFold, to generate structures for the human proteome, as well as yeast, fruit flies, mice, and more.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.