Researchers at Caltech have developed dissolving microrobots capable of delivering life-saving drugs directly to tumor sites. These breakthrough devices, detailed in Science Robotics on December 11, successfully shrank bladder tumors in mice, offering a glimpse into the future of precision medicine.

How the microrobots work

The microrobots, called bioresorbable acoustic microrobots (BAMs), are made of hydrogel with magnetic nanoparticles and therapeutic drugs embedded within them. Using ultrasound imaging and magnetic navigation, researchers can guide these microrobots to specific locations in the body. Once at the target site, they release their drug payload efficiently and dissolve harmlessly.

“Rather than putting a drug into the body and letting it diffuse everywhere, now we can guide our microrobots directly to a tumor site and release the drug in a controlled and efficient way,” said Wei Gao, Caltech’s professor of medical engineering and a lead researcher on the project.

In laboratory tests, the microrobots were administered to mice with bladder tumors. Four treatments over 21 days resulted in a significant reduction in tumor size compared to traditional methods. This marks a promising step in enhancing the effectiveness of cancer therapies while minimizing side effects.

BAMs feature a hydrophilic (attracted to water) outer surface to prevent clumping and a hydrophobic interior to retain an air bubble. This ensures the microrobots can navigate fluids such as blood and stomach acid.

“This asymmetric surface modification, where the inside is hydrophobic, and the outside is hydrophilic, really allows us to use many robots and still trap bubbles for a prolonged period of time in biofluids, such as urine or serum,” explained Gao.

Researchers used two-photon polymerization, an advanced 3D printing technique, to create the microrobots’ precise spherical structure. “This particular shape, this sphere, is very complicated to write,” said Julia R. Greer, a co-corresponding author of the paper and one of the creators of the hydrogel recipe. Greer and her team reportedly worked hard to stop the spheres from collapsing as they were made.

Potential for human use

While the technology shows promise, the team has still yet to explore the use of BAMs for other medical conditions and evaluate their safety in human trials.

“We think this is a very promising platform for drug delivery and precision surgery,” Gao says. “Looking to the future, we could evaluate using this robot as a platform to deliver different types of therapeutic payloads or agents for different conditions. And in the long term, we hope to test this in humans.”

Microrobots like BAMs could transform cancer treatment by targeting tumors with unprecedented precision. Beyond oncology, their potential applications include detoxification, minimally invasive surgery, and disease diagnosis. If successful in humans, these tiny machines could redefine how we approach healthcare, reducing side effects and improving patient outcomes.