Rapid inactivation of SARS-CoV-2 by titanium dioxide surface coating

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission occurs via airborne droplets and surface contamination. Titanium dioxide (TiO2) coating of surfaces is a promising infection control measure, though to date has not been tested against SARS-CoV-2. Methods: Virus stability was evaluated on TiO2- and TiO2–Ag (Ti:Ag atomic ratio 1:0.04)-coated 45 x 45 mm ceramic tiles. After coating the tiles were stored for 2–4 months before use. We tested the stability of both SARS-CoV-2 Spike pseudotyped virions based on a lentiviral system, as well as fully infectious SARS-CoV-2 virus. For the former, tile surfaces were inoculated with SARS-CoV-2 spike pseudotyped HIV-1 luciferase virus. At intervals virus was recovered from surfaces and target cells infected. For live virus, after illuminating tiles for 0–300 min virus was recovered from surfaces followed by infection of Vero E6 cells. % of infected cells was determined by flow cytometry detecting SARS-CoV-2 nucleocapsid protein 24 h post-infection. Results: After 1 h illumination the pseudotyped viral titre was decreased by four orders of magnitude. There was no significant difference between the TiO2 and TiO2–Ag coatings. Light alone had no significant effect on viral viability. For live SARS-CoV-2, virus was already significantly inactivated on the TiO2 surfaces after 20 min illumination. After 5 h no detectable active virus remained. Significantly, SARS-CoV-2 on the untreated surface was still fully infectious at 5 h post-addition of virus. Overall, tiles coated with TiO2 120 days previously were able to inactivate SARS-CoV-2 under ambient indoor lighting with 87% reduction in titres at 1h and complete loss by 5h exposure. Conclusions: In the context of emerging viral variants with increased transmissibility, TiO2 coatings could be an important tool in containing SARS-CoV-2, particularly in health care facilities where nosocomial infection rates are high.

Recent Advances in Metal-Based Antimicrobial Coatings for High-Touch Surfaces

“…Their preliminary results showed that the genomic RNA of HCov-NL63 cells (a close genetic relative of SARS-CoV-2) were completely degraded after 30 min of UV exposure. Micochova et al [206] also evaluated the efficacy of light-activated TiO 2 and TiO 2 -Ag coatings prepared by spray gun on ceramic tiles, on the infectivity of SARS-CoV-2. They showed that the percentage of the infected SARS-CoV-2 after 1 h was only 15% on the illuminated TiO 2 coating compared to 80% on a polystyrene surface.…”

Application of Electrospun Nonwoven Fibers in Air Filters

“…Disinfecting air, water, and surfaces with the photocatalytic reaction of LED-TiO 2 have been proven useful against many micro-organisms, including human coronavirus, and SARS coronavirus. It was found that the TiO 2 photocatalytic reaction for 20 min inactivated 99.9% of SARS-CoV-2 in aerosols and for 120 min it inactivated 99.9% of SARS-CoV-2 in liquids [126,127].…”

Disinfection and decontamination in the context of SARS‐CoV‐2‐specific data

“… 125 , 130 , 132 , 133 Zinc oxide and titanium dioxide coatings also show antiviral activity. 134 , 135 Antiviral heavy metals found in nutritional supplements may have some efficacy. 136 Quaternary ammonium compound coatings have attracted study.…”