Microscopic Cyborgs Could Deliver a Non-Invasive Chemotherapy

If you grew up in the 1990s, you might remember the Magic School Bus episode, “Inside Ralphie.” When Ralphie falls ill, Ms. Frizzle and her students shrink their shapeshifting vehicle, fly into his body and track down the source of the infection.

In a recent study and without Ms. Frizzle, scientists have now invented a steerable microrobot that they hope can deliver cancer-treating drugs to tumors.

Cancer patients receive chemotherapy through IVs. But because the IV delivers the drugs to the entire body, treatment brings a deluge of side-effects. In the new study, researchers report that they can guide medicine-carrying microrobots inside the body using strap-on magnets and control drug delivery using a laser. If it works, they could target tumors precisely and reduce harmful side-effects.

“The therapeutic effects of medical microrobots in seeking and destroying tumor cells could be substantial,” says co-author Metin Sitti of the Max Planck Institute for Intelligent Systems (MPI-IS) in a press release.

The bots are bacterial cyborgs. The team tethered magnetic nanoparticles, called iron oxide, and a locked package of chemotherapeutic drugs to E. coli. They hitched the enhancements on the bacterium using a strong molecular rope that they invented a few years earlier.

The team steered the cyborgs using magnets through narrow labyrinths that mimicked human blood vessels and tumors. Once they reached their destination, they melted the drug casings with a laser. Acid can also unlock the drug parcels. Because tumor cells are highly acidic, experts could deliver drugs automatically in future clinical applications.

“Imagine we would inject such bacteria based microrobots into a cancer patient’s body. With a magnet, we could precisely steer the particles towards the tumor,” says co-author Birgül Akolpoglu of MPI-IS in a press release. “Once enough microrobots surround the tumor, we point a laser.”

This isn’t the first time that scientists turned to bacteria to treat cancer. Since the 1800s, researchers noticed microbes naturally navigated towards tumors because they like acidic environments with low oxygen. But introducing too many pathogens can overload the immune system or unintendedly damage healthy tissues. Piloting with magnets and locking drugs in a safe could create local congregations of bacteria and medicine, to help reduce bodily stress.

The microbial cyborgs are probably cheaper and safer than alternatives like genetic engineering, the researchers say. In the future, scientists can add molecular invisibility cloaks that shield them from the immune system, off-switches that prevent excess drug delivery and brakes that limit bacterial reproduction.

“This on-the-spot delivery would be minimally invasive for the patient, painless [and] bear minimal toxicity,” says co-author Yunus Alapan of MPI-IS.

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