Antimicrobial activity of cuprous oxide-coated and cupric oxide-coated surfaces

Abstract

Disease can be spread through contact with contaminated surfaces (fomites). For example, fomites have been implicated in the spread of meticillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Antimicrobial surface treatments are a potential method of reducing disease transmission from fomites, and broad-spectrum activity is desirable. To test cuprous oxide (Cu2O) and cupric oxide (CuO) coatings for antimicrobial activity against 12 micro-organisms including bacteria and fungi. We fabricated two surface coatings. The Cu2O coating was fabricated in a simple two-step process using polyurethane to bind the active copper oxide particles; CuO was prepared by heat treatment of Cu2O particles in air to produce cupric oxide (CuO) and to cause early-stage sintering to form a continuous coating. The antimicrobial activity was examined with 10μL of microbial suspension droplets followed by counting cells as colony-forming units (cfu). The coatings rapidly killed nine different micro-organisms, including Gram-negative and Gram-positive bacteria, mycobacteria and fungi. For example, the Cu2O/PU coating killed 99.9997% of P.aeruginosa and 99.9993% of S.aureus after 1h. Efficacy was not reduced after weekly cleanings. The antimicrobial activity of the Cu2O coating was unchanged after abrasion treatment, and the coatings were not cytotoxic to human cells. The combination of broad-spectrum antimicrobial activity, abrasion resistance, and low toxicity of the Cu2O coating suggests potential use in healthcare settings.