Establishing the Virucidal Properties of a Copper-Nickel-Zinc Alloy using a Genetically Modified Insect Virus
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Date
2019-08-28
Authors
Walji, Sadru-Dean
Journal Title
Journal ISSN
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Publisher
University of Waterloo
Abstract
Healthcare associated infections (HAIs) cause a significant financial burden on the healthcare industry. To reduce incidence of HAIs, strategies for cleaning and infection control have been developed to target common transmission routes. Surfaces that are frequently touched, so called high-touch surfaces, have been identified as a key transmission route. High-touch surfaces are cleaned inconsistently, and frequent disinfection of these surfaces is impractical.
Copper and its alloys have been shown to have contact biocidal properties and pose a solution to inconsistent and infrequent cleaning of high-touch surfaces. However, the virucidal properties of these surfaces are poorly understood due to variability in literature methods. The goals of this thesis are assess the virucidal properties of a copper(65)-nickel(18)-zinc(17) alloy designed to replace stainless steel high-touch surfaces, investigate factors that may diminish the virucidal properties, evaluate virucidal activity of each alloy component, and characterize leaching of metals from the alloy.
The copper alloy was shown to have a strong virucidal activity under clean and moderate soiling conditions (>4-log) for virus droplets or dried virus onto the surface. Multiple exposures of the surface to virus found that the surface was unable to inactivate virus droplets (<1-log) while dried virus was repeatably inactivated (>3-log), regardless of no or moderate soiling. Heavy soiling reduced inactivation below an acceptable efficacy threshold (<1-log). Copper, nickel, and zinc were identified as the primary metals being released (leached) by the surface and causing virucidal activity. These metals were further investigated as ion solutions.
Virucidal tests of copper, nickel, and zinc ions found that copper and nickel were significantly virucidal (Cu,Ni p<0.05; Zn p>0.1). Concentration of the leached metal ions was dependent on the solution applied to the surface. The driving force behind leaching could not be identified but osmolarity, chlorine content, and protein load of the solution were ruled out.
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Keywords
virucidal, alloy, healthcare-associated infections, self-sterilizing surface, high-touch surface, contact biocide