These tiny robots could help treat cancer: study

Robots are good for lots of things: shopping, emotional support, even goofy viral internet challenges.

Soon, scientists hope, they’ll also be used to battle cancer — by deploying microscopic bots through our bodies to attack tumors.

“The microrobot concept is really cool because you can get micromachinery right to where you need it,” says Lihong Wang, researcher at Caltech’s Division of Engineering and Applied Science. He and his partner Wei Gao are developing bots that could deliver treatment to hard-to-reach parts of the body, specifically the digestive tract. Wang says the technology could be used for targeted drug delivery, or eventually even perform “microsurgery.”

The microbots are made of magnesium and, save a small unprotected portion, coated with a gold and a parylene polymer that would withstand the stomach’s digestive enzymes. The uncoated area exposes the metal to digestive fluids, which react with magnesium to create tiny bubbles. These bubbles, scientists say, would act as a sort of propeller for the bead bots.

To make bots clinically useful, Wang and Gao applied a layer of medicine between the metal ball and the polymer coat. For added protection through the gut’s harsh environment, the entire bot is enveloped in paraffin wax.

But the most astonishing part about this method is the way they tell the microbots where to go. For this, Wang uses a technique he developed called photoacoustic computed tomography (PACT).

Infrared laser light travels through tissues to reach red blood cells, which cause oxygen-rich hemoglobin molecules to vibrate. Sensors near the skin detect the vibrations and analyze the data to create an internal image of the microbots’ surroundings — including nearby tumors.

When the scientists see their microbots — which appear clearly in PACT images — near the tumor, they use a high-power continuous-wave near-infrared laser to help push them along. The metal sphere absorbs the light which causes the wax to melt, exposing the uncoated area of the bot and thus propelling them with bubbles as close to their intended target as possible.

“These micromotors can penetrate the mucus of the digestive tract and stay there for a long time. This improves medicine delivery,” says Gao. “But because they’re made of magnesium, they’re biocompatible and biodegradable.”

Successful animal tests have encouraged Gao and Wang, whose work was published this week in Science Robotics, to push their research ahead, and eventually treat other parts of the human body.

“We demonstrated the concept that you can reach the diseased area and activate the microrobots,” Gao says. “The next step is evaluating the therapeutic effect of them.”

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