A Surface Coating that Rapidly Inactivates SARS-CoV-2

Abstract

SARS-CoV-2, the virus that causes the disease COVID-19, remains viable on solids for periods of up to 1 week, so one potential route for human infection is via exposure to an infectious dose from a solid. We have fabricated and tested a coating that is designed to reduce the longevity of SARS-CoV-2 on solids. The coating consists of cuprous oxide (Cu₂O) particles bound with polyurethane. After 1 h on coated glass or stainless steel, the viral titer was reduced by about 99.9% on average compared to the uncoated sample. An advantage of a polyurethane-based coating is that polyurethane is already used to coat a large number of everyday objects. Our coating adheres well to glass and stainless steel as well as everyday items that people may fear to touch during a pandemic, such as a doorknob, a pen, and a credit card keypad button. The coating performs well in the cross-hatch durability test and remains intact and active after 13 days of being immersed in water or after exposure to multiple cycles of exposure to the virus and disinfection.

Keywords: COVID-19; Cu2O; SARS-CoV-2; coating; coronavirus; cuprous oxide; virucidal.

Figure 1.

A. Cross section view of the Cu₂O/polyurethane film.

Figure. 2.

Time course of viable titer of SARS-CoV-2 on solids, with and without a coating of cuprous oxide microparticles bound with polyurethane (Cu₂O/PU). Note that the vertical axis in on a log10 scale. Data is shown for coated glass and coated stainless steel. Individual circular data points represent each independent measurement and the × symbol represents the mean of the log of independent measurements. The detection limit was 90 TCID₅₀/mL (shown with a dotted line). Experimental results where virus was not detected are plotted at 90 TCID₅₀/mL and are included in the average as 90 TCID₅₀/mL. SARS-CoV-2 is inactivated much more rapidly on the coated surface than on the bare surface.

Figure. 3.

Time course of viable titer of SARS-CoV-2 on glass coated in Cu₂O/PU that was subjected to 5 cycles of exposure to SARS-CoV-2 plus soaking in 70% ethanol. The uncoated glass was also subjected to the disinfection cycles.