Researchers Develop Microbots to Help Drugs Reach Blood Clots

Blood clots can obstruct vessels supplying the brain, heart, or lungs, potentially causing stroke, myocardial infarction, or pulmonary embolism. Although catheter-delivered thrombolytic drugs can help dissolve these clots, restricted blood flow may limit drug delivery to the obstruction. To address this challenge, researchers have developed magnetically guided microbots designed to improve drug transport directly to the thrombus.

Researchers at ETH Zurich developed magnetically guided microbots designed to improve drug delivery to blood clots. Measuring approximately 8 micrometers in length, the tiny cocoon-shaped devices are made from a biocompatible gel containing magnetic iron oxide nanoparticles.

The microbots and thrombolytic medication are delivered near the clot through a catheter. An external magnetic control system generates a rotating magnetic field that propels the microbots along the vessel wall in somersault-like movements. This motion creates localized blood flow that helps transport the medication toward the clot, overcoming some of the limitations caused by restricted circulation.

In laboratory tests using a silicone model with vessel-like channels and clots formed from pig blood, medication delivered with the moving microbots dissolved clots six times faster than medication alone. The researchers also collaborated with Charité University Hospital in Berlin to evaluate the approach in live pigs. In arteries blocked by experimentally induced clots, the microbots enhanced thrombolytic activity, doubling the area of restored blood flow after 30 minutes compared with medication alone.

The microbots are manufactured in a rotating magnetic field that aligns iron oxide nanoparticles along their longitudinal axis, allowing them to respond to magnetic fields like tiny compasses. Although the results demonstrate the technology’s potential, it has not yet been tested in humans. Longer-term animal safety studies and further evaluations in specific disease models, including myocardial infarction, are needed before clinical use can be considered.

“To our knowledge, we are the first to show in a clinically relevant large-animal model that the use of microrobots in this way does indeed enhance thrombolysis, i.e., the process of dissolving blood clots,” said Simone Schürle, professor of medical microsystems.

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ETH Zurich