May/June_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 0 2 1 *Member of ASM International PERSPECTIVE CAN COPPER HELP FIGHT COVID-19? Experts on copper and microbiology recommend the expanded use of copper alloys in public spaces to reduce the spread of COVID-19 and minimize future pandemics. Harold T. Michels,* consultant and retired senior vice president, Copper Development Association, Manhasset, New York Corinne A. Michels, distinguished professor emerita, Queens College — CUNY, Flushing, New York A 3D atomic scale map, or molecular structure, of the 2019-nCoV spike protein. The protein takes on two different shapes, called conformations—one before it infects a host cell, and another during infection. This structure represents the protein before it infects a cell, called the prefusion conformation. Courtesy of Jason McLellan/University of Texas at Austin. C opper can be a powerful weapon in the fight against COVID-19 and future pandemics, but we have to use it. Throughout history, copper was recognized for its antimicrobial ac- tivity [1] . With the advent of antibiotics, the value of copper as a medical treat- ment was pushed aside and lost from our collective knowledge base. While the world focuses on treating those with COVID-19 and developing test- ing kits and vaccines, prevention will soon take greater prominence. An ev- er-increasing body of research in- dicates that copper alloys have the potential to control the spread of in- fectious disease and blunt the impact of future pandemics. “An ounce of pre- vention is better than a pound of cure.” INACTIVATION STUDIES A recent, highly publicized New England Journal of Medicine article authored by van Doremalen et al. [2] re- ported that Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the newly emerged strain of corona- virus that causes COVID-19 infections, retains infectivity in aerosols and on a variety of common surfaces for extend- ed periods of time. Most significantly, while the virus remained infective on plastic and 304 stainless steel for up to 48-72 hours, inactivation was observed in 4 hours on a 99.9% copper alloy. This finding was largely overlooked by me- dia reports. Another coronavirus, Human Cor- onavirus 229E (Hu-CoV-229E) caus- es a broad spectrum of lung disorders. An article published in 2015 authored by Warnes et al. [3] showed that Hu-CoV-229E remained infectious following exposure to polytetrafluoro- ethylene(PTFEorTeflon),poly- vinyl chloride (PVC), ceramic tile, glass, silicone rubber, and stainless steel, but was ra- pidly inactivated on copper and on a range of copper-zinc and copper-nickel alloys. Complete loss of infectious activity was reached after as little as a five-minute expo- sure, depending on the par- ticular alloy tested. Not only was the inactivation rapid but it was accompanied by the ir- reversible destruction of viral RNA and massive structural damages. Figure 1, taken from Warnes et al. [3] , is rich in con- tent and calls for a detailed ex- planation. In the experimental protocol, a small sample of a suspension of virus particles was spread onto a 1 cm 2 cou- pon of metal of the indica- ted composition. After a desig- nated time, the virus particles were washed from the surface of the coupon and the number of infectious viruses remaining was determined. This number is expressed as the number of plaque forming units (pfu) per coupon. Figure 1 plots the number of pfu (on a logarithmic scale) versus the time of ex- posure to the alloy surface. COPPER ALLOY PERFORMANCE Figure 1a shows a series of brass- es ranging from 60 to 95% Cu (balance Zn), C110 (100%), Z130 (100% Zn), and S304 Stainless Steel (18% Cr – 8% Ni), which served as the experimental con- trol. Both S304 and Z130 displayed no