Copper works effectively against Sars-Cov-2 on surfaces - silver does not

The material that makes up a surface influences how long viruses and bacteria can remain contagious on it.
Credit: RUB, Marquard

Silver and copper ions kill many pathogens. For example, implants or medical instruments are coated with these metals. Researchers from Molecular and Medical Virology and Materials Research at the Ruhr University Bochum (RUB) have worked with the surgical research of the BG to determine whether they can help curb the Covid 19 pandemic by rendering Sars-Cov-2 harmless. University Hospital Bergmannsheil Bochum examined. They could show that a copper coating eliminates the virus. But this does not apply to silver. The team reports in the journal Scientific Reports May 2022.

Unedler material sacrifices itself

Copper and silver release positively charged ions to their environment through corrosion, which are harmful to bacteria in various ways and prevent their growth or completely kill them. This effect has long been used, for example by coating implants with these metals in order to avoid bacterial infections. Tricks can be used to ensure that even more ions become free and increase this effect. So, the team around materials researcher Prof. Dr. Alfred Ludwig a so-called sputtering system, with which the thinnest layers or tiny nanofleaks of the metals can be applied to a carrier material. Depending on the order or quantity in which the individual metals are applied, different surface conditions arise. If you also apply a precious metal such as platinum, silver corrodes even faster and releases more antibacterial ions. "In the presence of a more noble metal, the less noble metal sacrifices itself, so to speak," explains Ludwig the principle of the sacrificial anode. The efficiency of such sacrificial anode systems against bacteria was demonstrated by the team of surgical research led by Prof. Dr. Manfred Köller and Dr. Marina Breisch has already demonstrated and published it many times.

So far, it has not been examined in detail whether viruses can also be rendered harmless. "Therefore, we examined the antiviral properties of surfaces coated with copper or silver as well as various silver-based sacrificial anodes, and also looked at the combinations of copper and silver with a view to possible synergy effects," said Virologist Prof. Dr. Stephanie Pfänder. The team compared the effectiveness of these surfaces against bacteria with that against viruses.

Silver nanofleaks do not impress the virus

The effect of the surfaces on the bacterium Staphylococcus aureus reports Dr. Marina Breisch: “Surfaces with a sacrificial anode effect, especially nanofleaks consisting of silver and platinum, and the combination of silver and copper efficiently stopped bacterial growth. "The situation was different with Sars-Cov-2: thin layers of copper significantly reduced the viral load after just one hour. Sputtered silver surfaces, on the other hand, had only a minor effect, and silver nanofleaks did not impress the virus either. "In summary, we could demonstrate a clear antiviral effect of copper-coated surfaces against Sars-Cov-2 within an hour, while silver-coated surfaces had no effect on viral infectivity," said Stephanie Pfänder.

The successful interdisciplinary collaboration between materials research, clinical microbiology and virology is to be further deepened in future studies in order to identify further materials with the broadest possible antimicrobial effect.

Source/Credit: Ruhr University Bochum

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