Delivery of the drug to the right place in the body is no less important than choosing the right drug. To control this process, a team from the California Institute of Technology has developed a tiny medical robot. Of course, these simple microscopic spheres do not look like full-fledged robots, but the creators claim that they can be moved around the body using ultrasound or magnets, which allows targeted delivery of medicine.
Image source: Caltech
Before introducing microbots into the body, it is necessary to ensure that the structure of the bot is resistant to the high or low pH inherent in various body fluids. The bot must also be reliably controlled and release the drug at the desired point in the body. Spent microbots should completely decompose in the body, leaving behind no toxic materials.
The development team from Caltech claims that they were able to successfully solve all of the above problems. The robots they created are made from a biologically inert hydrogel, have high mobility, and their diameter of 30 microns is small enough to penetrate almost any area of the body.
The hydrogel spheres are made by 3D printing using two-photon polymerization (TPP) lithography, a technology pioneered by Caltech’s Institute for Nanoscience. Inside the sphere there is a cavity that contains air microbubbles. The therapeutic load is housed in the outer shell, and the inner vesicle provides excellent contrast for ultrasound imaging, allowing robots to easily track after insertion.
When exposed to the acoustic field created by ultrasound, the microbubbles vibrate, causing the bot to move using the resulting “microflow” from two small holes. The presence of two holes provides the robot with much greater maneuverability. Magnetic particles are embedded in the hydrogel from which the bot is created, which allows it to be controlled using magnetic fields.
Microbots are still laboratory experiments; not a single person has yet been treated with their help. But after sending microbots with chemotherapy drugs to the tumor site, the mice showed a significant reduction in tumor size, while traditional treatments had less effect. The results of the experiment were published in Science Robotics. In the future, developers hope to see the use of this technology in treating people.