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Showdown: Copper v. Silver in the Antimicrobial Arena

woman patient in hospital with saline intravenous (iv)Copper is not the only antimicrobial metal used in biocidal coatings. Silver has been known to have antibacterial properties for several hundred years and was used as far back as the days of Hippocrates. However, age does not automatically mean effectiveness and healthcare facilities can’t risk patient safety by choosing the lesser material. Understanding how copper and silver compare and contrast in antimicrobial ability is a big part of making the right decision for protective coatings.

The Methods of Microbial Murder

Copper and silver’s antimicrobial properties take place on a molecular level in almost opposing fashions. Copper works on a bacteria’s exterior while silver strikes from within.

Silver easily reacts with and binds to sulfur, which in bacteria can be found in their proteins. This forces the sulfur groups to bind to the silver instead of each other, preventing the protein from folding into its correct shape. Since bacteria need sulfur to make use of iron properly, this binding interferes with that process as well. The end result of all this disruption is that the bacteria begins producing a reactive oxygen molecule that damages the cell’s interior, DNA, and proteins. In the event this does not kill the bacteria, it becomes weakened for antibiotics to have better effect.

Copper works by disrupting a bacteria’s cellular membrane. Imagine the membrane as a brick wall, but with electricity instead of mortar. Copper is conductive and its presence will disrupt and weaken the electrical bonds holding the bacterial bricks together in the membrane. Once this happens, copper molecules will begin to pull apart pieces of the membrane as it attempts to steal electrons as a result of oxidization caused by the moisture in the air. As the membrane loses its bricks it will weaken and fail, leading to ruptures. Copper ions then flow in through these ruptures and poison the cell from the inside, killing it.

Is Copper or Silver the Better Antimicrobial?

In terms of efficacy, the deciding factor involves how well copper and silver can actually initiate their fatal chains of events. Both metals need to have their molecules oxidized to start having antimicrobial effects but this is not equally easy. Copper is capable of oxidizing in response to ambient moisture in the air of the average room. Silver, on the other hand, doesn’t oxidize as easily and requires either high relative humidity or the moisture to become trapped against the metal.

In other words, copper can kill or disrupt bacteria under the same environmental conditions as silver, but can also provide antimicrobial effects under conditions silver would be less effective or useless in.

Other Considerations

Silver is often thought of as more aesthetically pleasing and silver-coated surfaces are considered more appealing. However, silver is harder to create alloys with than copper and the material is overall more expensive. Copper, by contrast, is easier to be made into an alloy and has antimicrobial effects so long as the metal makes up at least 60% of the compound. This makes copper not only a more reliable antimicrobial, but a more affordable one.

Aereus Technologies is a Canadian Biotech company headquartered in Burlington, Ontario. Their research and development into copper alloy-based technology has resulted in the antimicrobial coating, Aereus Shield™. Contact us at 888-633-8460 to learn more about antimicrobial surfaces and how Aereus Shield™ can help enhance healthcare safety.

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Michelle Berelowitz

Michelle Berelowitz has 15+ years commercializing technology start-ups in the Toronto-Waterloo corridor with strong strategic, operational and management skills within both publicly traded and technology based start-up companies. Michelle has a background in manufacturing, ICT and biotech combined with degrees in political science, finance &strategic management and Masters of Business, Entrepreneurship and Technology from the University of Waterloo.