[Efficacy of inactivating viruses by photocatalytically reacting nonwoven titanium dioxide fabric].

Titanium dioxide (TiO2) photocatalysis causes oxidative destruction dependent on electrons excited by < or = 400 nm ultraviolet (UV) rays. Many studies have covered the destruction of organics and bacteria and bacteriophage inactivation by photocatalysis. We studied the inactivation by new nonwoven siliconized titanium dioxide fabric of the feline calicivirus F9 (FCV-F9), human adenovirus GB (HAdv3-GB), and influenza A and B virus (A/New Caledonia, B/Shandong, and 5 clinical strains). We spotted 10 microL of viral suspensions containing infectious 5 log10 50% tissue culture doses (TCID50) onto 1 cm2 pieces of TiO2-coated nonwoven control fabric treated or not treated with UV light (lambda(max), 365 nm, 1,100-1,300 microW/cm2). We then measured the virus titers of 50 microL of viral suspension recovered from these fabrics. FCV-F9 and HAdv3-GB infectivity titers were reduced by over 3.5 log10 TCID50 after 30 min of irradiation, but influenza viral titer was reduced to where it was undetectable even without UV irradiation. Comparing individual viral titer reduction due to nonwoven fabric contact without UV irradiation exposure, showed that FCV-F9 and HAdv3-GB titer infectivity was not reduced. In contrast, influenza A and B titer infectivity was reduced to 2 log10 TCID50 after 5 min of contact with the nonwoven fabric and to 3 log10 TCID50 after 30 min of contact. Titers of 6 of 7 influenza A and B strains were reduced by over 4 log10 TCID50 within 30 min. Siliconized TiO2-coated nonwoven fabric thus efficiently inactivated FCV-F9 and HAdV-GB and absorbed influenza viruses.