Preventing biofilm formation and removing existing biofilms effectively from dental unit water lines (DUWLs) are crucial to maintaining the quality of dental treatment water for infection control. Several physical and chemical approaches and automatic cleaning systems have been developed to control biofilm formation and output water quality in DUWLs;however, the long-term effect of these approaches is still in doubt, and adverse effects are found to be associated with some of these approaches. Therefore, there is a great need to develop novel approaches for preventing biofilm formation and removing resident biofilms in order to achieve highly effective control of biofilms and output water quality in DUWLs. In this study, a new design concept, inspired by the defense mechanisms employed by our own body against harmful microorganisms in the gastrointestinal tract, is proposed to create material surfaces modified with polymeric materials that have dual functionalities to control biofilm formation as well as to facilitate removal of biofilms. The central hypothesis is that biofilm formation and removal can be effectively controlled by on-demand detachment of antimicrobial and thermo- detachable polymer coatings. Antimicrobial polymers will be coated on interior surfaces of water tubing by thermally cleavable linkers between the coating polymers and surface. The linkers are based on the thermally reversible Diels-Alder chemistry: the covalent bond is formed at room temperature to 600C and cleaved at higher temperatures (>900C), allowing annealing the coatings to anchor the polymers onto surfaces at low temperatures and removing the coatings using hot water or steam vapor. The polymers will prevent or delay biofilm formation by killing bacteria adhered to the surface. Once biofilms are formed after extended periods of use, heating the coating by hot water or steam vapor cleaves the linkages, and the coatings will be detached from the surface. The biofilms on the coatings will be flushed out together with the detached polymers. After biofilm removal, the clean surface will be coated again by the thermally detachable polymers, and the process can be repeated multiple times. To test the hypothesis, two specific aims are proposed: (1) to develop the thermo-detachable antimicrobial coatings and (2) to evaluate biofilm growth and biofilm removal on the polymer coatings. This new coating design is innovative because these coatings will prevent or delay biofilm formation as well as remove formed biofilms efficiently, and this design will allow cleaning inner surfaces of tubing and connectors of DUWLs by flushing hot water/steam vapor, which can be completed without opening tubing systems and the use of chemicals. Recoating the interior surfaces with our polymers will also offer a fresh antimicrobial and detachable coating, which will extend the lifetime of DUWLs substantially. This novel design concept with necessary modifications would also find potential applications in other medical and industrial systems such as medical devices and implants, dental treatment instruments, water-cooling towers, and municipal water systems, where biofilm formation are of significant concern and difficult to remove.
The proposed research will develop thermo-detachable polymeric coatings for dental unit water lines, which can inhibit or delay biofilm growth and facilitate removal of biofilms without extensive use of chemical treatment and physical work. This new coating design will be cost-effective compared to conventional methods and also useful for medical applications and public facilities including medical devices, dental treatment instruments, water-cooling towers, and municipal water systems, where biofilm formation are of significant concern and difficult to remove. Success of this project will have a great impact in medicine and on public health.
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