By Liz Stevens, writer, UV+EB Technology
Azodent, Inc., a start-up based out of the University of Colorado, Aurora, Colorado, is a RadTech Class of ’24 member that was founded by scientists Devatha Nair, Michael Schurr, Chaitanya Puranik (all University of Colorado employees) and Steven Inzinna. The company has designed an azobenzene polymer coating that can be used to prevent biofilm accumulation and contamination on medical devices and to provide an array of properties in industrial applications. Azodent’s first target market, however, is dental applications where the coating – a photoresponsive material – can disrupt existing biofilm, selectively inhibit cavity-causing bacteria biofilm and facilitate the regeneration of tissue. UV+EB Technology talked with the company’s Devatha Nair to learn more about this innovative work and its benefits for dentistry.
The Need for Drug-Free Antibacterial Strategies
Bacteria within biofilm in a dental patient’s mouth is much hardier than planktonic bacteria. “Like most bacteria,” said Nair, “cavity-causing bacteria can exist in two states – in the free-floating planktonic state and within biofilms where they display a 10- to 1,000-fold increase in antibiotic resistance.” While planktonic bacteria are less harmful and easy to get rid of by brushing one’s teeth and using oral mouthwashes, bacteria within biofilms are highly structured entities within a matrix that offers maximum resistance to external threats such as immunological responses, conventional antibiotics and disinfectant chemicals.
As bacteria biofilms develop resistance to more and more conventional pharmaceutical antibiotics, there is an increased focus on developing drug-free antibacterial strategies. Azodent’s azobenzene coatings disrupt biofilms with physical movement, offering a treatment against which bacteria most likely cannot evolve a resistance. “We have developed a smart coating that responds to visible light via transient mechanical motion that disrupts biofilms,” said Nair. “This forces the biofilm bacteria back into its more vulnerable planktonic state. Once disrupted, bacteria can be eliminated using traditional treatments.”
Azobenzenes as a Solution
Azobenzenes are straightforward, versatile and biodegradable molecules. While they have been studied and extensively used in industrial applications, and have been employed for their photochemical nature, their photoresponsive capabilities are relatively new avenues of study. “Azobenzenes can be modified to isomerize/respond to a range of wavelengths,” Nair said. “We envision azobenzene coatings that are engineered to respond to different light sources based on the targeted application. Currently, our coatings are optimized to respond to blue light in the visible spectrum, at 420-480 nm for dental applications. However, by varying the functional groups on azobenzenes, they can be made to respond to a range of light/energy sources, including UV and infrared, from high-intensity discharge lamps to lasers and fiber optics.” The energy used to covalently link the coating onto the surface of the tooth can be the same energy that is used to disrupt biofilms. “As the azobenzenes can compete with photoinitiating systems during placement of the coating,” said Nair, “dual-cure initiating systems can be used to ensure that high conversion is achieved by the coating.”
There are two important aspects to Azodent’s coating. One aspect is the ability to induce micromolecular vibrations on the surface of the coating via cyclical trans-cis-trans motion of the azobenzene molecules in response to transient light exposure, which can be used to remove a range of materials from dust particles to biofilms.
Application in Dental Settings
For its dental application, Azodent prompts azobenzene motion to break up bacteria biofilms, dispersing the polymeric bacteria back into its planktonic state, thus leaving it susceptible to eradication with conventional therapies. The mechanical action induced in azobenzenes by photo exposure is photofluidization (trans-cis-trans isomerization), a reversible transition from a solid state to a liquid state in which molecular movement takes place. When the light is switched off, the oscillatory dynamics cease, and the coating returns to its original state. This method of biofilm disruption can be repeatedly initiated to disrupt existing or newly forming biofilm. It is not pathogen-specific and can be used to disrupt multiple pathogens simultaneously. “While we focused on molecules that would respond to visible light for potential biomedical/dental applications,” said Nair, “multiple studies have shown that transient exposure to UV energy, which has more energy than visible light, can be used efficiently to induce controlled molecular vibration at the surface of a coating.”
The other important aspect of Azodent’s coating is the presence of a biomolecule within the coating that can be chosen to selectively target the proliferation, for example, of Streptococcus genus within the oral microbiome. “It is challenging to target a specific genus of bacteria in an oral environment with over 700 known species of microbes,” Nair said. “Traditional anti-bacterial strategies target all types of bacteria, the so-called good strains that are required to maintain a healthy microbiome and the ‘bad’ strains that tend to proliferate, causing dental cavities and diseases.” By targeting the vulnerability of Streptococci to controlled quantities of a carefully chosen biomolecule, which can be continually generated in-situ, Azodent has designed a biocompatible coating that can control the local Streptococci population and prevent cavities.
Azodent’s azobenzenes also can be used to facilitate the regeneration of dental pulp. “The cytocompatible coating provides a matrix that can facilitate cell attachment and growth,” Nair explained, “while simultaneously generating specific biomolecules locally that promote dental pulp regeneration.”
Nair described the dental applications most suited for this treatment. “We see the coating used as a part of implantable devices such as dentures and permanent implants like resin-based restorations,” she said. “The photoresponsive coating can be activated repeatedly via exposure to an appropriate light source, in a dental clinic or for domestic use by customers. For example, once the azocoating is polymerized on the surface of teeth as a sealant or as part of a restoration, a toothbrush modified to shine visible light for 20 seconds can be used to activate the coating and remove biofilms on command.”
Azodent has tapped the features of azobenzenes for the benefit of dental patients, for use on medical devices such as implants, prostheses, catheters and endoscopes, and for deployment in industrial coatings. “There is the potential for this technology to be a game-changer in smart coating,” Nair said. “As light-induced mechanical motion that causes disruption, azobenzene-based coatings can be engineered to remove any unwanted materials, from dust particles on exposed surfaces to biofilms on biomedical implants.”
For more information, visit www.azodent.com.
