Published: April 11, 2019 By

Researchers working together across the University of Colorado system are developing a technique that would quickly and easily remove antibiotic-resistant bacteria in dentistry and other potential applications.

The work, recently highlighted in American Chemical Society Publications, deals with the removal of biofilms through dynamic, photo-responsive layers. Biofilms are communities of bacteria that attach to a surface, linking together into a matrix. Biofilms can be found on organic materials like your teeth or inorganic materials like the slime that covers river rocks. These formations of bacteria are less sensitive to traditional antibiotics, making them generally harder to eradicate during medial treatment. That is especially important because of growing antibiotic resistance worldwide due to over prescription and use. 

In the paper, CU’s team outlines a technique for removing biofilms that involves layering the chemical compound acrylated azobenzene on a tooth during restoration for example. That layer will stay dormant until activated by light of specific wavelengths — say every morning on your toothbrush — destroying the bacteria without a drug and simultaneously slowing future film growth. The paper shows this process can be used successfully to remove biofilms from the surface of glassy materials in response to light from a common dental lamp and outlines possible avenues for future research and application.

The work is being led by Devatha Nair, an assistant professor at the University of Colorado School of Dental Medicine on the Anschutz Medical Campus. The team includes researchers from the dental school as well as CU Boulder’s College of Engineering and Applied Science. Funding comes from the National Health Institute among other sources.

Nair, a CU CEAS mechanical engineering alumna, said the project is incredibly promising because the technique is not specific to one strain of bacteria.

“The opto-mechanical response we elicit and use to remove the biofilms is not microorganism specific and is easily repeatable. It can also be engineered to remove a host of bacteria, microorganisms and biofilms,” she said. “It’s also unlikely that the bacteria could undergo an evolutionary adaptation to ‘out-evolve’ this process.”

Assistant Professor Krithika Baskaran, also in the dental school, and Associate Professor Michael Schurr in the Department of Immunology and Microbiology are assisting with the research at Anschutz. Over all, the team is working on the implementation of this phenomena in dental materials, surgical instruments and medical devices. 

While dentistry is the main area of interest right now, CU Boulder Professor Bob McLeod and Associate Professor Sean Shaheen in the Electrical, Computer and Energy Engineering Department are designing experiments to better understand the fundamental aspects of this behavior. The idea is to study it further so that the same process can be slightly modified and perfected based on the type of bacteria targeted and the surface it is on. This would broaden the applications Shaheen said. 

"Why the opto-mechanical response works so well to remove the bacteria is not fully clear at this time,” said Shaheen, who is also serving as the interam director of the Multi-Functional materials Interdiciplinary Research Theme at the college. “It may be due to fundamental, dynamical forces at the molecular level, or a longer-range response at the materials level, or a complex response of the bacteria’s outer cell membrane structures. In any case, it is something that works but is in need of a better explanation. It’s a good problem to have."

Recently, the International Association of Dental Researchers selected the team’s work on smart coatings as one of 10 international finalists for a new investigator award. The final decisions will be made later this year at a conference.

Nair said the work would continue as the team attempts to optimize the process on various surfaces and against different biofilms, especially those composed of multiple-species.