January_2021_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 | J A N U A R Y 2 0 2 1 3 2 MATERIALS SCIENCE AND CORONAVIRUS SERIES SUPERSONICALLY DEPOSITED ANTIVIRAL COPPER COATINGS Enhanced antiviral performance is associated with antipathogenic copper material consolidations obtained using cold spray processing. Bryer C. Sousa* and Danielle L. Cote* Worcester Polytechnic Institute, Massachusetts A s part of the “Materials Science and Coronavirus Series,” Ad- vanced Materials & Process- es readers were introduced to the way copper can assist in the fight against COVID-19 (Can Copper Help Fight COVID-19?, May/June 2020), and a dis- cussion was presented surrounding the renewed interest Cu has enjoyed as of late because of its antimicrobial be- havior (Copper’s Conductivity and An- timicrobial Properties Inspire Renewed Interest, July/August 2020). Most re- cently, Barber et al. pivoted toward the role stainless-steel can play when the commonly found alloyed material in hospitals and medical settings con- tains an adequate amount of Cu and Cu phases via compositional optimization and proper processing as well (Antimi- crobial Copper-Containing Stainless Steels Show Promise, September 2020). The present article shall turn to the en- hanced antimicrobial and antiviral per- formance associated with antipatho- genic Cu material consolidations ob- tained using cold gas-dynamic spray (cold spray) processing. FOMITE TRANSMISSION OF SARS-CoV-2 Before one spends time on the matter of antimicrobial copper coat- ings, contact-mediated (or fomite) transmission of SARS-CoV-2 must be established as a non-negligible trans- mission pathway. Fomite transmission from contaminated high-touch surfac- es is considered a mode for COVID-19 transmission. Since fomite transmission surface [3] . Behzadinasab et al.’s coat- ing was achieved by way of unifying cu- prous oxide particles with polyurethane as a binding agent. Lastly, Hutasoit et al. demonstrated the fact that 96% of the SARS-CoV-2 virions were inactivated upon two hours of incubation time and exposure to an as-deposited Cu cold spray coating [4] . This is consistent with the observation reported in April 2020, by van Doremalen et al. [5] , which noted that viable SARS-CoV-2 was no longer measurable upon four hours of expo- sure to a wrought Cu material. COPPER AS AN ANTIPATHOGENIC MATERIAL Numerable elemental metals, in- cluding Cu, Ag, and Sn, among others, have been classified as oligodynamic [6] ; that is to say they’ve been shown to in- hibit or kill microorganisms. However, copper has been isolated as themost ac- tionable oligodynamic elemental metal studied by the biological community to date. Even though Cu maintains an ap- preciable oligodynamic capacity, many microbial agents shown to be suscepti- ble to copper-based contact killing, in the case of bacteria, or contact inactiva- tion, in the case of viruses, still require trace amounts of Cu to ensure that physiological coherency and homeo- stasis are both maintained [7] . More spe- cifically, Cu acts as a critical trace metal for all aerobic organisms, for example, wherein Cu commonly serves as an en- zymatic cofactor for the catalyzation of various redox reactions [7] . Indeed, this is because of Cu’s ability to cycle between *Member of ASM International of SARS-CoV-2 acts as an indirect dis- ease vector and has been demonstrated numerable times as being non-negligi- ble, surfaces that have been developed to inactivate SARS-CoV-2 will be dis- cussed first; followed by copper as an antiviral surface; contemporary antimi- crobial materials, generally; antipatho- genic copper cold spray coatings; and then the matter of understanding cop- per cold spray’s antimicrobial behav- ior, hereafter. To substantiate the fact that contact-mediated fomite transmis- sion of SARS-CoV-2 plays a non-negligi- ble role in the transference of COVID-19, readers are encouraged to consider the following reference [1] . Since the emergence of SARS- CoV-2 as a lethal infectious agent, which can remain active on common mate- rial surfaces for significant periods of time, researchers and global members of the materials science and engineer- ing community began to develop coat- ing technologies as viral transmission mitigators. Specifically, Mantlo et al. studied Luminore CopperTouch surfac- es to evaluate the inactivation of SARS- CoV-2 and several filoviruses [2] . Mantlo et al. demonstrated the fact that their Luminore CopperTouch surfaces were found to be able to inactivate 99% of SARS-CoV-2 virions before two hours of exposure. Behzadinasab et al. re- ported another copper-based surface that was able to inactivate 99.9% of the SARS-CoV-2 virus after just one hour of exposure, relative to the uncoated surfaces, thus possibly outperforming the Luminore CopperTouch coating/

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