Water-Repellent TiO₂-Organic Dye-Based Air Filters for Efficient Visible-Light-Activated Photochemical Inactivation against Bioaerosols

Abstract

Recently, bioaerosols, including the 2019 novel coronavirus, pose a serious threat to global public health. Herein, we introduce a visible-light-activated (VLA) antimicrobial air filter functionalized with titanium dioxide (TiO2)-crystal violet (CV) nanocomposites facilitating abandoned visible light from sunlight or indoor lights. The TiO2-CV based VLA antimicrobial air filters exhibit a potent inactivation rate of ~99.98% and filtration efficiency of ~99.9% against various bioaerosols. Under visible-light, the CV is involved in overall inactivation by inducing reactive oxygen species production both directly (CV itself) and indirectly (in combination with TiO2). Moreover, the susceptibility of the CV to humidity was significantly improved by forming a hydrophobic molecular layer on the TiO2 surface, highlighting its potential applicability in real environments such as exhaled or humid air. We believe this work can open a new avenue for designing and realizing practical antimicrobial technology using ubiquitous visible-light energy against the threat of infectious bioaerosols.

A review of methods to reduce the probability of the airborne spread of COVID-19 in ventilation systems and enclosed spaces

“… The mechanisms of bacterial and viral inactivation are not completely understood. Filter Coatings ( Joe et al, 2014 ; Park and Hwang, 2014 ; Heo et al, 2020 ; Pazokifard et al, 2012 ; Woo et al, 2012 ; Pyankov et al, 2012 ; Chen and Liang, 2020 ; Ziental et al, 2020 ; Monge et al, 2010 ; Skyspring, 2021 ; Sigma-Aldrich, 2021 ) Relatively easy to incorporate coated filters into an existing HVAC system. The nanoparticle field is currently growing and will continue to expand in applications and available technology.…”

“…In the cited study, the added coating increased particle filtration efficiency by 33 % and the antiviral efficiency was 92 % overall, where the inactivation of the viral particles from the CNTs was attributed to mechanical damage of the cell's surface upon contact. Alternatively, titanium dioxide (TiO 2 ) and crystal-violet nanocomposites (CV) may be used to create an air filter that is visible-light-activated for viral particle inactivation ( Heo et al, 2020 ). Using visible light, the filter coating produces ROS with the CV-TiO 2 combination, resulting in a 99.98 % inactivation and a 99.99 % filtration rate.…”

Dewetted Silver Nanoparticle-Dispersed WO3 Heterojunction Nanostructures on Glass Fibers for Efficient Visible-Light-Active Photocatalysis by Magnetron Sputtering

“… 13 Heo et al exploited filter fibers for antimicrobial applications using TiO 2 nanoparticle coverage through a simple aerosol deposition method, which is impressive in this COVID-19 pandemic situation. 14 …”

Distribution of Bioaerosols in Association With Particulate Matter: A Review on Emerging Public Health Threat in Asian Megacities

“…The application of nanotechnology can significantly contribute to the efficiency improvement of bioaerosol inactivation. Recent research on visible-light-activated (VLA) antimicrobial air filters equipped with TiO 2 -crystal violet nanocomposites shows <99.9% bioaerosol inactivation (Heo et al, 2021). Application of Iron Oxide nanowire-based filter significantly inactivated airborne bacteria.…”