On the Antimicrobial Properties and Endurance of Eugenol and 2-Phenylphenol Functionalized Sol-Gel Coatings

Preventing microbiological surface contamination in public spaces is nowadays of high priority. The proliferation of a viral or a bacterial infection may arise through air, water, or direct contact with infected surfaces. Chemical sanitization is one of the most effective approaches to avoid the proliferation of microorganisms. However, extended contact with chemicals for cleaning purposes such as chlorine, hydrogen peroxide or ethanol may lead to long-term diseases as well as drowsiness or respiratory issues, not to mention environmental issues associated to their use. As a potentially safer alternative, in the present work, the efficacy and endurance of the antimicrobial activity of different sol-gel coatings were studied, where one or two biocides were added to the coating matrix resulting on active groups exposed on the surface. Specifically, the coating formulations consisted of a hybrid silica-titania-methacrylate matrix, where aromatic liquid eugenol was added with a double function: as a complexing agent for the chelation of the reaction precursor titanium isopropoxide, and as a biocide. In addition, 2-Phenylphenol, ECHA approved biocide, has also been incorporated to the coating matrix. The antibacterial effect of these coatings was confirmed on gram-positive (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). Additionally, the coatings were non cyto-toxic and displayed virucidal activity. Overall, our data support the efficacy of the tested sol-gel coatings and suggest that added features may be required to improve endurance of the antimicrobial effects on operational conditions.