Asahi Kasei & Nara Medical University Confirm 226 nm UVC LED Efficacy Against SARS-CoV-2 & Verify Reduced Effect on Animal Sk...
14 Juni 2021 - 3:00PM
Business Wire
Asahi Kasei announces the results of joint research with Nara
Medical University regarding the efficacy of 226 nm ultraviolet-C
(UVC) LEDs in the inactivation of the coronavirus (SARS-CoV-2) that
causes COVID-19, and its effects on animal skin cells. This is the
first study in the world conducted with LEDs of this wavelength,
and the results confirm that the 226 nm UVC LEDs are able to
quickly inactivate SARS-CoV-2 while having significantly less
effect on animal skin cells than 270 nm UVC LEDs.
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Figure 1 and Figure 2 references
indicating the efficacy of 226 nm UVC LEDs against SARS-CoV-2, the
virus that causes COVID-19. (Graphic: Business Wire)
Combating Pathogens with UVC Light
The inactivation (killing) of viruses and other pathogens using
UV light rather than chemical disinfectants has drawn greater
attention with the COVID-19 pandemic. Nevertheless, it has been
necessary to prevent light from conventional mercury UV lamps (254
nm) and UVC LEDs (260–280 nm) from directly irradiating human skin
due to risk of harmful effects. In contrast, UV excimer lamps with
a wavelength of 222 nm were introduced last year showing negligible
effect on the human body. However, LEDs are more compact and allow
greater flexibility in design, have less risk of breaking, and have
a quicker startup time than traditional lamps, opening up new
potential for smaller, safer, and more responsive applications of
UVC light.
Crystal IS, Inc., an Asahi Kasei company, has commercialized
Klaran™ UVC LEDs in the 260–270 nm wavelength range, and is now
supporting the advanced research by Asahi Kasei to reach shorter
wavelengths. Recently, Asahi Kasei’s Corporate Research &
Development was able to create 226 nm UVC LED prototypes, and tests
were conducted for these LEDs regarding their efficacy for
inactivating SARS-CoV-2 as well as their effects on animal skin
cells.
About the Tests
One hundred of the 226 nm UVC LEDs were placed on a panel in a
10 × 10 array as shown in Figure 1. For comparison, a similar array
of 270 nm UVC LEDs was also prepared. All of the UVC LEDs used in
this study were created from the proprietary aluminum nitride (AlN)
substrate and pseudomorphic aluminum gallium nitride (AlGaN)
technology of Crystal IS.
- 226 nm UVC LED Efficacy for Inactivating
SARS-CoV-2 Liquid containing viable SARS-CoV-2 was injected
into a Petri dish and then dried. Panel arrays of 226 nm and 270 nm
UVC LEDs were activated at the same output (440 μW/cm2).
Afterwards, the virus was collected, and the amount of contagion
was measured by the plaque technique*1. The results, shown in
Figure 2, indicate that in approximately 6 seconds, 99.9% of the
virus was inactivated by both 226 nm and 270 nm UVC LEDs.
- Evaluating the Effects on Animal Skin
Cells An additional experiment was conducted on mouse skin
cells to estimate the damage that 226 nm UVC LED light has on
animal skin compared with 270 nm light. Figure 3 shows the flow of
the experiment. The mouse skin cells were arranged in two layers
which were then exposed to either 226 nm or 270 nm UVC LED light at
a dosage of 100 mJ/cm2 and 500 mJ/cm2. After the exposure, the
upper layer of the cells was removed and the relative fraction of
living cells in the bottom layer was evaluated by measuring the
absorbance (optical density) after applying an MTT reagent*2 dye to
the cells on the bottom layer. The dark colored dye indicates the
amount of living cells that remain. The results shown in Figure 4
and Figure 5 indicate that the 226 nm UVC LED light had little to
no effect at 100 mJ/cm2, and even at 500 mJ/cm2 there was
significantly less effect on the cells of the bottom layer compared
to that of the 270 nm UVC LED light.
Result Overview
The above results indicate that 226 nm UVC LEDs can quickly
inactivate SARS-CoV-2 while having significantly less effect on
animal skin cells compared to the current generation of 270 nm UVC
LEDs for disinfection. This suggests the possibility that 226 nm
UVC LEDs may be safely used to disinfect hands or objects where
there are people nearby. Moving forward, further advancements in
technology will be necessary before the power of the light emitted
from 226 nm UVC LEDs can be improved enough for commercialization.
Continued research development by Asahi Kasei is progressing to
make this possible.
Additional Information
- All the biological experiments were conducted on the campus of
Nara Medical University in Bio Safety Level 3 (BSL3) testing
facilities under appropriate means to safely contain the active
virus. Furthermore, airborne viruses or their effects on humans
were not tested.
- Strain of novel coronavirus tested: SARS-CoV-2; 2019-nCoV
JPN/TY/WK-521
*1 Plaque technique: A method of measuring virus volumes after
the degeneration of virus infected cells. *2 MTT reagent:
Tetrazolium salt. Becomes colored when enzymes within the
mitochondria are deoxidized indicating that the cells are still
viable.
About Asahi Kasei
The Asahi Kasei Group contributes to life and living for people
around the world. Since its foundation in 1922 with ammonia and
cellulose fiber businesses, Asahi Kasei has consistently grown
through the proactive transformation of its business portfolio to
meet the evolving needs of every age. With more than 40,000
employees around the world, the company contributes to a
sustainable society by providing solutions to the world's
challenges through its three business sectors of Material, Homes,
and Health Care. Its health care operations include devices and
systems for acute critical care, dialysis, therapeutic apheresis,
transfusion, and manufacture of biotherapeutics, as well as
pharmaceuticals and diagnostic reagents. For more information,
visit www.asahi-kasei.com.
About Crystal IS
Crystal IS, an Asahi Kasei company, is a pioneer in the
development and commercialization of UVC LEDs based on its
proprietary Aluminum Nitride substrate technology. Devices grown on
Aluminum Nitride can more effectively (technically and
economically) emit at deeper ultraviolet (UVC) wavelengths than
devices grown on sapphire. Crystal IS products are used to produce
high performance UVC LEDs for disinfection and environmental
monitoring in a variety of applications that enhance and sustain
life and living around the world. www.cisuvc.com
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Asahi Kasei Media Inquiries ATTN: Jonathan Todd Asahi
Kasei America, Inc. aka-info@ak-america.com
https://www.asahi-kasei.com