How Thermal Sprayed Copper Can Be Effective Against COVID-19

Copper, the first metal manipulated by humans to make everything from tools to jewelry, is now making headlines for another reason — its antimicrobial properties.

AWS Publications | May 27, 2021 | Tech and Industries
Welding Digest ►  How Thermal Sprayed Copper Can Be Effective Against COVID-19

Copper, the first metal manipulated by humans to make everything from tools to jewelry, is now making headlines for another reason — its antimicrobial properties.

A recent United States government-funded study conducted by researchers at the National Institute of Health (NIH) and the Centers for Disease Control and Prevention (CDC) shows that the SARS-CoV-2 virus, which causes COVID-19, remained viable for up to two to three days on plastic and stainless-steel surfaces but only up to four hours on copper (Ref. 1).

Highly effective antimicrobial and antivirus coatings of copper and copper alloys for frequently touched surfaces can be produced by thermal spraying.

 

Mankind’s First Metal

The Stone Age lasted for more than three million years until around 10,000 years ago when our ancestors began working metals they found on the ground or in ground waters. The three metals were gold, meteoric iron, and copper, and they were easily worked (hammered) to make ornaments and replace tools previously made out of stone.

 

Bronze and Brass

The first recorded medicinal uses for copper were discovered in an Egyptian papyrus written between 2600 and 2200 B.C.E. Now known as the Edwin Smith Papyrus, named after the dealer who purchased it in 1862, the document is the oldest known surgical treatise on trauma. In it is recorded the use of copper to sterilize wounds, cure headaches, calm epileptic seizures, and sterilize drinking water (Figure 1). Other documents found from this era show writings of soldiers who used shavings from their copper alloy knives and swords in their wounds to aid in healing and prevent infection. By this time, it was known that copper bowls, cups, and pitchers prevented water from getting a green slime on the surface and reduced bouts of diarrhea (Ref. 3).

Figure 2-May-27-2021-05-56-39-84-PMFigure 1: The Edwin Smith Papyrus, the world's oldest surviving surgical document. The text describes anatomical observations and the examination, diagnosis, treatment, and prognosis of 48 types of medical problems in exquisite detail. (Source: Jeff Dahl/Public Domain.)

 

Antimicrobial Copper

Doctor Victor Burq is credited with discovering copper’s antimicrobial properties during a cholera outbreak in Paris between 1854 and 1855. He observed that significantly fewer deaths from cholera had occurred among jewelers, goldsmiths, or musicians who played brass instruments. Burq later wrote, “Copper or its alloys, brass and bronze, applied literally and pregnantly to the skin in the cholera epidemic are effective means of prevention which should not be neglected.” It would be many years later when his studies would be verified by the scientific community (Ref. 4).

Since then, it has been well established that copper has inherent antimicrobial properties that do not diminish with time. An example of this are the brass railings at Penn Station in New York City. The railings were installed in 1910 and even though most of the station was demolished in 1963, a few structures from the original building still exist. The railings were tested and found to be just as effective as an antimicrobial today as they were in 1910.

 

Present Day

Currently, the United States Environmental Protection Agency (EPA) has registered more than 500 copper alloys as antimicrobial. There is a strict protocol to follow to register an alloy product or coating as antimicrobial (see epa.gov for details). With this registration comes the responsibility to advertise the antimicrobial products or coatings using required verbiage. An excerpt is as follows:

“Laboratory testing has shown that when cleaned regularly:

[This [product] [surface] continuously reduces bacterial contamination, achieving 99.9% reduction within two hours of exposure.]

[This [product] surface kills greater than 99.9% of Gram-negative and Gram-positive bacteria within two hours of exposure.]

[This [product] surface delivers continuous and ongoing antibacterial action remaining effective in killing greater than 99.9% of bacteria within two hours, even after repeated wet and dry abrasion and re-contamination.]… The use of a copper surface is a supplement to and not a substitute for standard infection control practices…” (Ref 5).

Copper continues to be incorporated into many forms for various uses. As an example, Cupron Inc., Richmond, Va., has a proprietary and EPA-registered technology for blending copper into polymers and fibers. Some of the products that have been produced are textiles used in various garments, such as anti-fungal socks. Cupron also produces reusable medical textiles, such as patient bed linens, gowns, blankets, and towels, as well as reusable knit and woven face masks (Figure 2) The Sentara Hospital Group, Norfolk, Va., installed Cupron medical textiles and EOS Surfaces biocidal copper hard surfaces in all 12 of their hospitals over a four-year period from 2013 to 2017 (Refs. 6–9).

Figure 3-3Figure 2: Copper-infused hospital linens. (Photo courtesy of Cupron Inc.)

 

Copper and Thermal Spray

A critical reason for using copper antimicrobials in the healthcare industry is the reduction of healthcare-associated infections (HAIs). The CDC reports that in 2015, there were an estimated 687,000 HAIs in U.S. acute care hospitals and approximately 72,000 hospital patients with HAIs had died. The cost to hospitals approached $45 billion. In a 2010 to 2011 study funded by the U.S. Department of Defense, copper components were installed at three medical centers  — Medical University of South Carolina, the Memorial Sloan-Kettering Cancer Center, and the Ralph H. Johnson Veterans Affairs Medical Center. It was shown that HAIs were reduced by as much as 58%.

Why is it not more prevalent? It is a daunting and expensive task to replace all the plastic and stainless steel handrails, IV stands, door handles, faucets, call buttons, etc. that exist in a hospital environment with copper/copper alloy products. Offering a thermal spray solution could be a less expensive option. To increase the use of thermal spray antimicrobial coatings in healthcare requires proof of efficacy against known pathogens; collaboration with such government agencies as the CDC, NIH, and the U.S. Department of Health and Human Servies; cost comparisons of coatings vs. copper alloy components; retrofitting costs and time; partnering with component manufacturers and end users; and education and training in the maintenance and cleaning of coatings (Refs. 10–13).

There are numerous publications on the efficacy of copper/copper alloys against various pathogens, as well as the utilization of thermal spray. Some are listed in the references and resources below. Additionally, there are numerous companies that have and continue to thermal spray components with copper and copper alloys. The following are just a few organizations offering and studying antimicrobial coatings for the healthcare industry.

Aereus Technologies, Toronto, Canada offers EPA-registered CuVerro Shield™. It uses a proprietary thermal fabrication technique to heat the copper alloy, permanently binding CuVerro® antimicrobial copper to any shape or form during the manufacturing process, which starts and ends as solid copper (Ref. 14) (Figure 3).

Figure 4Figure 3: Stretcher handles with CuVerro Shield™ antimicrobial copper coating. (Photo courtesy of Washington Hose Company EMS (WHC EMS) of Coatesville, Pa.)

 

Bed Techs Inc., Greendale, Ind., and LuminOre®, Nassau Bay, Tex., have partnered to market Bed Tech’s Ever-Clean™ antimicrobial hospital bed utilizing LuminOre’s cold spray copper technology (Ref. 15) (Figure 4).

Figure 5Figure 4: Bed Techs’s Ever-Clean™ antimicrobial copper technologies from LuminOre on a hospital bed. (Photo courtesty of Bed Techs Inc.)

 

In addition, TST Engineered Coatings Solutions, Sun Prairie, Wis., has developed a family of antimicrobial coatings made with elemental alloys of silver, copper, and iodine. The coatings can be applied to most materials, including metals, plastics, and composites (Ref. 16).

The Centre for Advanced Coating Technologies, University of Toronto (Ref. 17), has been studying the antibacterial properties of wire-arc sprayed copper alloy coatings for ten years and it continues to work closely with industry, other universities, and research facilities.

 

What about COVID-19?

Copper has proven to be an effective antimicrobial against such pathogens as Salmonella enterica, Listeria, Influenza A virus, Staphylococcus Aureus, Methicillin-Resistant Staphylococcus Aureus (MRSA), Escherichia coli, and others. But what about COVID-19? There is documented proof that copper is effective against the earlier discovered Human Coronavirus 229E; therefore, it is theorized that copper could be effective against COVID-19.

A recent letter was submitted to the New England Journal of Medicine in March 2020 documenting preliminary results to this effect (Ref. 1). The work was jointly undertaken by the NIH, CDC, Princeton University, and UCLA. It compared the time that aerosol COVID-19 remains viable on various surfaces including plastic, stainless steel, cardboard, and copper. The best results were achieved on copper (4 h vs. 24 h for cardboard and one to three days on the other surfaces). It is expected that updates from this promising research will be provided over the coming months.

 

The Future of Copper

Since its discovery 10,000 years ago, copper continues to prove its value as a natural antimicrobial against an ever-growing list of pathogens. It is hopeful then that copper and copper coatings can be added to our toolbox in the fight against COVID-19.

 

References

1. “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1.” New England Journal of Medicine. Letter published on March 17, 2020, signed by Doremalen, Bushmaker, Morris, Holbrook, Gamble, Williamson, Tamin, Lloyd-Smith, and de Witt.

2. Copper Development Association. A Timeline of Copper Technologies, copper.org

3. Morrison, J. 2020. Copper’s virus-killing powers were known even to the ancients. Smithsonian Magazine.

4. Bexxon Global. Copper and Cholera: A Fateful Beginning. bexxonglobal.com/copper-spray.html

5. United States Environmental Protection Agency (EPA) / EPA Antimicrobial Stewardship Website for Copper Alloys, epa.gov / copperalloystewardship.com/epa-registration

6. Cupron Inc., cupron.com

7. Cupron Medical Textiles, cupronmedicaltextiles.com/2017-copper-patient-gowns-linens/

8. EOS Surfaces LLC, eoscu.com/healthcare-environments/

9. Sentara Hospital System, Virginia, sentara.com/

10. Kevil, B. 2020. Copper is great at killing superbugs — So why don’t hospitals use it. University of Southampton, Canadian Architect.

11. United States Center for Disease Control and Prevention, cdc.gov

12. United States National Institutes of Health, nih.gov

13. United States Department of Health & Human Services, hhs.gov

14. Aereus Technologies, aereustech.com/index.php/products-applications/

15. LuminOre Copper Touch, luminorect.com

16. TST Engineered Coatings Solutions, tstcoatings.com/

17. Centre for Advanced Coating Technologies, University of Toronto, cact.utoronto.ca/fields-of-research/anti-microbial-copper-based-alloys-coatings/

18. Warnes, S. L., Little, Z. R., Keevil, C. W. 2015. Human coronavirus 229E remains infectious on common touch surface materials. American Society for Microbiology.

19. Michels, H. T., and Michels, C. A. 2020. Can copper help fight COVID-19? Advanced Materials & Processes Digital Edition.

 

Resources

1. Antimicrobial copper facts, antimicrobialcopper.org

2. Miller, K. A potential ally in the fight against bacteria and viruses? Copper. InsideHook March 18, 2020.

3. da Silva, F. S., et al. Corrosion resistance and antibacterial properties of copper coating deposited by cold gas spray. Surface and Coatings Technology March 15, 2019, pp. 292–301.

4. Kocaman, A., and Keles, O. 2019. Antibacterial efficacy of wire arc sprayed copper coatings against various pathogens. Istanbul Technical University, Journal of Thermal Spray Technology 28(3): 504–513.

5. Champagne, V., Sundberg, D., and Helfritch, D. 2019. Kinetically deposited copper antimicrobial surfaces. Coatings April 17, 2019.

6. Jahani, B., Brooks, A., and Azarmi, F. 2018. Development of antibacterial surfaces via thermal spray coating technologies. North Dakota State University, Biomed Sciences Instruments 54(1).

7. Wrona, A., Bilewski, K., et al. 2017. Antimicrobial properties of protective coatings produced by plasma spraying technique. Surface & Coatings Technology pp. 332–340.

8. Champagne, V., and Helfritch, D. 2013. A demonstration of the antimicrobial effectiveness of various copper surfaces. Journal of Biological Engineering.

9. Grass, G., Rensing, C., and Solioz, M. 2011. Metallic copper as an antimicrobial surface. American Society for Microbiology.

 

This article was written by Jean Mozolic for the American Welding Society.