Researchers develop microrobots to break up plaque

PHILADELPHIA, U.S.: The fight against plaque has been a long-running battle. In a discovery that might give dentists the upper edge, researchers from the University of Pennsylvania have developed a swarm of microrobots, directed by magnets, that can break apart and remove dental biofilm from a tooth. The innovation arose from a cross-disciplinary partnership among dentists, biologists and engineers.

Lead researcher Prof. Hyun Koo, from the University of Pennsylvania School of Dental Medicine (Penn Dental Medicine), said the development was truly a synergistic and multidisciplinary interaction. “We’re leveraging the expertise of microbiologists and clinician-scientists as well as engineers to design the best microbial eradication system possible. This is important to other biomedical fields facing drug-resistant biofilms as we approach a post-antibiotic era,” he explained.

This collaboration came about after Koo and his colleagues made headway in breaking down the biofilm matrix by using iron oxide-containing nanoparticles that work catalytically, activating hydrogen peroxide to release free radicals that can kill bacteria and destroy biofilms in a targeted fashion. Serendipitously, the Penn Dental Medicine team found that groups at Penn Engineering, led by Dr. Edward Steager, Prof. Vijay Kumar and Prof. Kathleen Stebe, were working with a robotic platform that used very similar iron oxide nanoparticles as building blocks for microrobots. The engineers control the movement of these robots using a magnetic field, allowing a tether-free way to steer them.

Together, the cross-school team designed, optimized and tested two types of robotic systems, which the group called catalytic antimicrobial robots, or CARs. One system works on surfaces and the other operates inside confined spaces. After testing the robots on biofilms growing either on a flat glass surface or in enclosed glass tubes, the researchers tested the removal of biofilm from hard-to-reach parts of a human tooth. According to the researchers, the CARs were able to degrade and remove bacterial biofilms not just from a tooth surface but also from one of the most difficult-to-access parts of a tooth, the isthmus.

“Existing treatments for biofilms are ineffective because they are incapable of simultaneously degrading the protective matrix, killing the embedded bacteria and physically removing the biodegraded products,” noted Koo. “These robots can do all three at once very effectively, leaving no trace of biofilm whatsoever.”

“Treating biofilms that occur on teeth requires a great deal of manual labor, both on the part of the consumer and the professional. We hope to improve treatment options as well as reduce the difficulty of care,” said Steager.

The team now hopes to move its invention into clinical application and has received support from the Penn Center for Health, Devices and Technology, an initiative supported by the Perelman School of Medicine, Penn Engineering and the Office of the Vice Provost for Research at the University of Pennsylvania.