title: Photocatalytic inactivation of diarrheal viruses by visible-light-catalytic titanium dioxide.
abstract: Titanium dioxide (TiO2) that had been irradiated with visible light (VL) was demonstrated to inactivate rotavirus, astrovirus, and feline calicivirus (FCV). The virus titers were dramatically reduced after exposure for 24 hrs to the VL-catalytic TiO2. The addition of bovine serum albumin could protect the virus against inactivation by VL-catalytic TiO2 in a dose-dependent manner. This finding implied that the VL-catalytic TiO2 products might somehow interact initially with the viral proteins in the process of virus inactivation. Moreover, we showed partial degradation of the rotaviral dsRNA genome. This was more prominent when the virus was exposed to the VL-catalytic TiO2 treatment for at least 2 days. An attempt was made to elucidate the mechanism underlying the inactivation of the viruses. It was found that upon activation of TiO2 with VL by using a white fluorescent lamp, the reactive oxygen species such as superoxide anions (O2-) and hydroxyl radicals (*OH) were generated in a significant amount after stimulation for 8, 16, and 24 hrs. We therefore assume that virus inactivation by VL-catalytic TiO2 might occur through the generation of O2- and *OH followed by damage to the viral protein and genome. This is the first report, to the best of our knowledge, demonstrating the inactivation of rotavirus, astrovirus and FCV by the presence of TiO2 film under VL as well as describing its mechanism.
authors.affiliation: Department of Developmental Medical Sciences, Institute of International Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Sang
authors.forename: Tung Gia
authors.initials: TG
authors.lastname: Phan
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sugihara
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Yagyu
authors.forename: Shoko
authors.initials: S
authors.lastname: Okitsu
authors.forename: Niwat
authors.initials: N
authors.lastname: Maneekarn
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushijima
mesh_terms: D000818:Animals; D052676:Avastrovirus / Q000187:drug effects / Q000528:radiation effects; D017927:Calicivirus, Feline / Q000187:drug effects / Q000528:radiation effects; D002384:Catalysis; D002460:Cell Line; D002478:Cells, Cultured; D003967:Diarrhea / Q000821:virology*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D008027:Light; D016877:Oxidants / Q000378:metabolism; D010777:Photochemistry; D012401:Rotavirus / Q000187:drug effects / Q000528:radiation effects; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*; D014780:Viruses / Q000187:drug effects* / Q000528:radiation effects*