Polyurethane With Instant And Persistent Antimicrobial Efficacy Against Bacteria And SARSCoV- 2

ABSTRACT

Purpose/Objectives: Gram-negative bacteria including E. coli and P. aeruginosa can survive for months on dry hard surfaces, and SARS viruses can persist for days. These contaminated surfaces along with patients' damaged skin barriers, due to wounds or central line insertion sites, increase the risk healthcare-acquired infections (HAI) and subsequent serious complications. Furthermore, with increased frequency and duration of hospitalizations due to the current pandemic, the number of HAIs is on the rise. Currently there are no antimicrobial surfaces that provide both instant and long-lasting antimicrobial protection against a broad spectrum of infectious microbes. Liquid- or radiation-based disinfection techniques are kill microbes quickly, but their effect does not last long before needing reapplication. Antimicrobial surfaces based on heavy metals remain antimicrobial for long durations, but complete disinfection can take hours. In this work, we developed a new class of plant-inspired antimicrobial surfaces and wound dressings that incorporate plant secondary metabolites capable of rapid disinfection (> 4-log reduction) of common bacteria and viruses and maintain their efficacy over time (> 6 months). Methodology: We developed a method for stabilizing naturally antimicrobial essential oils components from plants such as, alpha terpineol (AT) and cinnamaldehyde (CMA), within a polyurethane polymer. Using a modified standard method for evaluating the performance of different nonporous solids (ISO 22196) and median tissue culture infection dose assay, these antimicrobial polyurethane coatings were tested and found to be effective in killing E. coli, P. aeruginosa, methicillin-resistant S. aureus (MRSA), and SARS-CoV-2. The durability of the coatings was tested by linear abrasion, UV and airflow exposure. Application methods such as spray coating and dip coating allow the coating to be applied to a variety of surfaces. Results: Polyurethane surfaces containing 35% AT content (PU-35%AT) showed a ∼5.8-log reduction in E. coli colony forming units per cm2 (CFU/cm2) in under 2 minutes, a shorter time than common commercial disinfectants. Additionally, when subjected to 8 consecutive rounds of inoculation the PU- 35%AT surface reduced the E. coli by >99.99% for all 8 rounds. We achieved a ∼5.8-log reduction of MRSA within 5 minutes on PU-60%AT. The PU-35%AT surfaces showed a 4.0-log reduction in SARS-CoV- 2 in 60 minutes. A PU-70%AT showed a 1.6-log reduction after 10 minutes and maintained virucidal capabilities after 2 weeks. PU+35%AT surfaces maintained a ∼5.3-log reduction in CFU/cm2 in MRSA and E. coli after 1000 abrasion cycles, 12 hours of UV exposure, 25 hours of exposure to -17°C, or 5 months of air flow. Lastly, to demonstrate the coating's real world functionality the PU+35%AT coating was successfully applied to a computer keyboard, cell phone screen protector and medical gauze. Conclusion/Significance: This work demonstrates a novel approach for fabricating a broad-spectrum antibacterial and antiviral polymer surface based on plant essential oil components. This antimicrobial polyurethane coating has not only rapid bactericidal and virucidal capabilities but maintains this efficacy over time. Additionally, the coating can be applied to a variety of surfaces including medical gauze to create wound dressings that significantly reduce bacterial burden and decrease chances of HAIs.