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

BACKGROUND

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.

AIM

To test cuprous oxide (CuO) and cupric oxide (CuO) coatings for antimicrobial activity against 12 micro-organisms including bacteria and fungi.

METHODS

We fabricated two surface coatings. The CuO 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 CuO 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 10 μL of microbial suspension droplets followed by counting cells as colony-forming units (cfu).

FINDINGS

The coatings rapidly killed nine different micro-organisms, including Gram-negative and Gram-positive bacteria, mycobacteria and fungi. For example, the CuO/PU coating killed 99.9997% of P. aeruginosa and 99.9993% of S. aureus after 1 h. Efficacy was not reduced after weekly cleanings. The antimicrobial activity of the CuO coating was unchanged after abrasion treatment, and the coatings were not cytotoxic to human cells.

CONCLUSION

The combination of broad-spectrum antimicrobial activity, abrasion resistance, and low toxicity of the CuO coating suggests potential use in healthcare settings.