A team of researchers from Molecular and Medical Virology and Materials Research at Ruhr-Universität Bochum (RUB) in Germany suggest that copper and not silver — both of which have demonstrated bacteria-killing properties — eliminates the COVID-19 virus on surfaces.

Although corrosion causes copper and silver to release positively charged ions into their environment that harm bacteria and subsequently prevent their growth or eliminate them altogether, the researchers are suggesting that the results for eliminating the COVID-19 virus are not the same.

Source: RUB

Noting that some tricks can encourage the release of even more ions, thereby intensifying this bacteria-killing effect, the researchers used a sputtering system wherein the thinnest layers — or tiny nanopatches — of the metals can be applied to a carrier material, the application of which, depending on the sequence or quantity the individual metals are applied, can produce various surface textures. Applying a precious metal like platinum, according to the researchers, encourages silver to corrode even faster and thus release more antibacterial ions.

“In the presence of a more noble metal, the baser metal sacrifices itself, so to speak,” explained the researchers, describing the principle of the sacrificial anode.

Yet, it has previously been undetermined whether or not viruses can be inactivated via this approach, thereby prompting researchers to analyze the antiviral properties of surfaces coated with copper or silver in addition to assorted silver-based sacrificial anodes. Likewise, the team also analyzed copper and silver combinations in terms of possible synergistic effects. As such, the researchers measured the effectiveness of these surfaces against bacteria with the effectiveness of these surfaces against viruses.

Looking at the effect of these surfaces on Staphylococcus aureus, the researchers explained: “Surfaces with sacrificial anode effect, especially nanopatches consisting of silver and platinum as well as the combination of silver and copper, efficiently stopped bacterial growth.” However, with SARS-CoV-2, thin copper layers significantly reduced the viral load after only one hour while sputtered silver surfaces and silver nanopatches reportedly only demonstrated a marginal effect.

“In conclusion: we demonstrated a clear antiviral effect of copper-coated surfaces against SARS-CoV-2 within one hour, while silver-coated surfaces had no effect on viral infectivity,” explained virologist Professor Stephanie Pfänder.

The study, Nanoscale copper and silver thin film systems display differences in antiviral and antibacterial properties, appears in the journal Scientific Reports.