Investigating Anti-Bacterial and Anti-COVID-19 Virus Properties and Mode of Action of Pure Mg(OH)2 and Copper-infused Mg(OH)2 Nanoparticles and Coated Polypropylene Surfaces

Abstract

Robust anti-microbial surfaces that are non-toxic to users have widespread application in medical, industrial, and domestic arenas. Magnesium hydroxide has recently gained attention as an anti-microbial compound that is non-toxic, biocompatible, and environmentally friendly. Here we demonstrate melt compound and thermally embossed methods for coating polypropylene with Mg(OH)2 nanoplatelets and copper-infused Mg(OH)2 nanoplatelets. Polypropylene articles coated with Mg(OH)2 nanoplatelets and copper-infused Mg(OH)2 nanoplatelets exhibit a log 8 kill of E.coli within 24 hours. In addition, Mg(OH)2 NPs suspension, at 0.25% reduced SARSCoV-2 virus titers in the solution by 2.5 x 103 PFU/mL or 29.4%, while the Cu-infused Mg(OH)2 NPs suspension, at 0.25% reduced titers by 8.1 x 103 PFU/mL or 95.3%. Fluorescence microscopy revealed that reactive oxygen species (ROS) are produced in bacteria in response to Mg(OH)2 and Cu-infused Mg(OH)2 nanoplatelets which appears to be an important but not the sole mode of anti-microbial action of the nanoplatelets. Plastics with anti-microbial surfaces from where biocides are non-leachable are highly desirable. This work provides a general fabrication strategy for developing anti-microbial plastic surfaces.