title: The bactericidal effect of TiO2 photocatalysis involves adsorption onto catalyst and the loss of membrane integrity.
abstract: The bactericidal effect of photocatalysis with TiO2 is well recognized, although its mode of action is still poorly characterized. It may involve oxidation, as illuminated TiO2 generates reactive oxygen species. Here we analyze the bactericidal effect of illuminated TiO2 in NaCl-KCl or sodium phosphate solutions. We found that adsorption of bacteria on the catalyst occurred immediately in NaCl-KCl solution, whereas it was delayed in the sodium phosphate solution. We also show that the rate of adsorption of cells onto TiO2 is positively correlated with its bactericidal effect. Importantly, adsorption was consistently associated with a reduction or loss of bacterial membrane integrity, as revealed by flow cytometry. Our work suggests that adsorption of cells onto aggregated TiO2, followed by loss of membrane integrity, is key to the bactericidal effect of photocatalysis.
authors.affiliation: ENAC-Laboratory for Environmental Biotechnology, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland. gaetan.gogniat@epfl.ch
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Gogniat
authors.forename: Melilotus
authors.initials: M
authors.lastname: Thyssen
authors.forename: Michel
authors.initials: M
authors.lastname: Denis
authors.forename: Cesar
authors.initials: C
authors.lastname: Pulgarin
authors.forename: Sam
authors.initials: S
authors.lastname: Dukan
mesh_terms: D000327:Adsorption; D002384:Catalysis; D002462:Cell Membrane / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects*; D017665:Hydroxyl Radical; D010777:Photochemistry; D014025:Titanium / Q000494:pharmacology*
chemical_list: C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium