Indoor-active photocatalyst for antiviral coating against various
variant types of SARS-CoV-2
Date:
April 15, 2022
Source:
Tokyo Institute of Technology
Summary:
A photocatalyst made using a combination of titanium dioxide
and copper oxide nanoclusters inactivates various variant types
of novel coronavirus SARS-CoV-2. Scientists have developed this
antiviral photocatalyst, in a recent breakthrough, which has been
proven to be effective under both darkness and indoor light.
FULL STORY ========================================================================== Photocatalyst made using a combination of titanium dioxide (TiO2) and
copper oxide (CuxO) nanoclusters inactivates various variant types of
novel coronavirus SARS-CoV-2. Scientists in Nara Medical University,
Kanagawa Institute of Industrial Science and Technology, and Tokyo
Institute of Technology have developed this antiviral photocatalyst,
in a recent breakthrough, which has been proven to be effective under
both darkness and indoor light.
==========================================================================
The novel coronavirus (SARS-CoV-2), responsible for the ongoing
COVID-19 pandemic, has affected millions of people worldwide. The
main transmission pathway of the virus is through droplets released
by infected people into the air. Additionally, these droplets exist
on various surfaces as well. Viral infections mainly occur in indoor environments where many people gather, Antiviral chemicals, such as
alcohol and hydrogen peroxide, are often used to decontaminate regularly touched surfaces. These chemicals essentially render the virus inactive
by breaking down their proteins. However, these chemicals are volatile
in nature and, therefore evaporate away. As a result, the disinfection
process has to be carried out regularly.
Now in a study published in Scientific Reports, a research team of
Nara Medical University, Kanagawa Institute of Industrial Science and Technology, and Tokyo Institute of Technology has developed a solid-state photocatalyst as an alternative defense against the virus. Unlike chemical disinfectants, solid- state coatings remain for a long time, and since
the viral outbreak, have been the subject of intensive research around
the world. Solid-state antiviral coatings have the advantage of being non-toxic, abundant, and chemically and thermally stable.
Many of these solid-state coatings use TiO2 photocatalysts that, when
exposed to ultraviolet (UV) light, cause oxidation reaction that can
destroy organic matter like the spike proteins found on the surfaces of coronaviruses. However, these coatings are activated only when exposed to
UV light, which is not present in typical indoor environments. In most of indoor environments, lightings are usually turned off in the night time,
thus the antiviral material under dark condition is desired.
To get the coating to work under visible light as well dark conditions,
the team has developed a composite consisting of TiO2 and CuxO
nanoclusters. CuxO nanoclusters are composed of a mixed valence number
oxide, in which Cu(I) and Cu(II) species are present. The Cu(II) species
in CuxO contributes to the visible-light-driven photocatalysis reaction, whereas the Cu(I) species plays a crucial role in denaturing virus
proteins, thereby causing their inactivation under dark conditions.
By coating the CuxO/TiO2 powder on a glass, the team showed that it could inactivate even the highly virulent Delta variant of SARS-CoV-2. The team
has also confirmed the inactivation of Alfa, Beta, and Gamma variants
by CuxO/TiO2 in addition to the wild type strain.
The team carefully investigated the antiviral mechanism using sodium
dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), ELISA
assay, and RT-qPCR analysis. These analyses strongly suggest that the
Cu(I) species in CuxO denaturalises spike proteins and also causes RNA fragmentation of SARS-CoV-2, even under dark condition. Furthermore,
white light irradiation causes the photocatalytic oxidation of the
organic molecules of SARS-CoV-2. Based on this antiviral mechanism, the
present antiviral material is not limited to a specific variant of the
virus and will be effective to inactivate various types of a potential
mutant strain.
White light illumination in the present study is usually used as an indoor light apparatus. This can make the CuxO/TiO2 photocatalyst very effective
in reducing the risk of COVID-19 infection in indoor environments,
which are usually subjected to both light and darkness periodically.
Hopefully, this study will take us one step closer to protecting ourselves better against the coronavirus, and adjusting to the post-COVID era.
========================================================================== Story Source: Materials provided by Tokyo_Institute_of_Technology. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Ryuichi Nakano, Akira Yamaguchi, Kayano Sunada, Takeshi Nagai, Akiyo
Nakano, Yuki Suzuki, Hisakazu Yano, Hitoshi Ishiguro, Masahiro
Miyauchi.
Inactivation of various variant types of SARS-CoV-2 by indoor-light-
sensitive TiO2-based photocatalyst. Scientific Reports, 2022; 12
(1) DOI: 10.1038/s41598-022-09402-7 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220414110759.htm
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