Research by Tokyo Institute of Technology (Professor Masahiro Miyauchi, Faculty of Materials Science and Engineering), Nara Prefectural Medical University (Associate Professor Ryuichi Nakano, Department of Microbial Infectious Diseases), Kanagawa Prefectural Institute of Industrial Technology (Antibacterial and Antiviral Research Group, Research and Development Department) For the first time in the world, the group confirmed the inactivation of the new coronavirus by the visible light responsive photocatalyst material (Cu x O / TiO 2 ). By experimentally clarifying the inactivation conditions, the antiviral effect of the photocatalyst was academically shown.
To prevent the spread of the new coronavirus, it took a lot of labor and time to manually wipe alcohol after using it in various places. The use of ozone gas has been clarified experimentally as a means to solve this problem. However, although these are immediate effects, they are not methods of maintaining a long-lasting antiviral effect, so it is necessary to academically confirm the effects of long-lasting materials on the new coronavirus.
Tokyo Institute of Technology and Kanagawa Prefectural Industrial Technology Research Institute, in collaboration with the University of Tokyo, "Project for Creating a Photocatalytic Industry for Building a Circulating Society" (PL: Professor Kazuhito Hashimoto) of the New Energy and Industrial Technology Development Organization (NEDO) The current NIMS Chairman)) has succeeded in developing a visible light-responsive photocatalytic material [Term 1] that has an extremely high antiviral effect . It has already been reported that this photocatalytic material consists of titanium oxide and copper oxide ( Cu x O / TiO 2 [Term 2] ) and has a high antiviral effect not only under visible light irradiation but also in the absence of light. masu [references 1-2] . The evaluation results of this new coronavirus also revealed that the virus was inactivated by light irradiation (1000 lux) obtained in dark places and everyday spaces, and it became clear that it could help prevent the spread of infection. I will report.
JIS R 1756 has been established as an antiviral performance evaluation test using a visible light responsive photocatalyst. This time, we conducted a test with reference to the test method.
The new coronavirus strain is cultivated, and the test piece (Cu x O / TiO 2 powder supported on glass) placed in the safety cabinet is inoculated with the new coronavirus to be tested. After that, 1000 lux of visible light irradiation (irradiation with a white fluorescent lamp that cuts ultraviolet light of 400 nm or less) was performed. In addition, in order to confirm the effect as a photocatalyst, we also conducted a test in a dark place where there was no light. After a certain period of time, the virus was collected, inoculated into the host cells, judged whether the virus was infected with the cells, and the viral load was calculated.
By irradiating this photocatalyst material with light, the viral load decreased by 2.5 digits (99.7% decrease) in 1 hour, and the viral load of 99.99% or more, which was below the detection limit, decreased in 2 hours. It was also clarified that it is reduced below the detection limit in 4 hours even in the dark. From this, it was found that the new coronavirus can be inactivated by using this photocatalytic material. Based on the results of this research, we believe that it will be possible to impart a lasting antiviral effect to the adhesion of droplets and places touched by people in schools, hospitals and other public facilities used by many people. You can.
(A) Changes in viral load
'(B) An example of virus infection evaluation results. Photo 1: Control. The cells are infected with the new coronavirus, and the destroyed part appears white (the virus is not inactivated). Photo 2: Visible light responsive photocatalytic material. No cell destruction by the new coronavirus is seen (the virus is inactivated).
Figure. Changes in viral load (a) and an example of virus infection evaluation results (b).
[Term 1] Visible light-responsive photocatalyst : A substance that absorbs visible light to generate strong oxidizing power on the surface and oxidatively decomposes odorous components and harmful substances that come into contact with it.
[Term 2] Cu x O / TiO 2 : A composite of copper oxide and titanium dioxide in which Cu x O nanoparticles are supported on the surface of TiO 2 . X of Cu x O has a range of 1 <x <2 and exists in a mixed state of monovalent and divalent copper.
 Masahiro Miyauchi, Kayano Sunada, Kazuhito Hashimoto, "Antiviral Effect of Visible Light-Sensitive Cu x O / TiO 2 Photocatalyst", Catalysts 10 (9), 1093, 2020. (DOI: 10.3390 / catal10091093 outer )
 Masahiro Miyauchi, Hiroshi Irie, Min Liu, Xiaoqing Qiu, Huogen Yu, Kayano Sunada, Kazuhito Hashimoto, "Visible-light-sensitive Photocatalysts: Nanocluster-grafted Titanium Dioxide for Indoor Environmental Remediation", J. Phys. Chem. Lett . 7 , 75-84, 2016. (DOI: 10.1021 / acs.jpclett.5b02041 outer )