title: Photoinactivation of Escherichia coli by sulfur-doped and nitrogen-fluorine-codoped TiO2 nanoparticles under solar simulated light and visible light irradiation.
abstract: Titanium dioxide (TiO2) is one of the most widely used photocatalysts for the degradation of organic contaminants in water and air. Visible light (VL) activated sulfur-doped TiO2 (S-TiO2) and nitrogen-fluorine-codoped TiO2 (N-F-TiO2) were synthesized by sol-gel methods and characterized. Their photoinactivation performance was tested against Escherichia coli under solar simulated light (SSL) and VL irradiation with comparison to commercially available TiO2. Undoped Degussa-Evonik P-25 (P-25) and Sigma-TiO2 showed the highest photocatalytic activity toward E. coli inactivation under SSL irradiation, while S-TiO2 showed a moderate toxicity. After VL irradiation, Sigma-TiO2 showed higher photoinactivation, whereas S-TiO2 and P-25 showed moderate toxicity. Oxidative stress to E. coli occurred via formation of hydroxyl radicals leading to lipid peroxidation as the primary mechanism of bacterial inactivation. Various other biological models, including human keratinocytes (HaCaT), zebrafish liver cells (ZFL), and zebrafish embryos were also used to study the toxicity of TiO2 NPs. In conclusion, N-F-TiO2 did not show any toxicity based on the assay results from all the biological models used in this study, whereas S-TiO2 was toxic to zebrafish embryos under all the test conditions. These findings also demonstrate that the tested TiO2 nanoparticles do not show any adverse effects in HaCaT and ZFL cells.
authors.affiliation: Department of Biology, Jackson State University , Jackson, Mississippi 39217, United States.
authors.forename: Kavitha
authors.initials: K
authors.lastname: Pathakoti
authors.forename: Shavonda
authors.initials: S
authors.lastname: Morrow
authors.forename: Changseok
authors.initials: C
authors.lastname: Han
authors.forename: Miguel
authors.initials: M
authors.lastname: Pelaez
authors.forename: Xiaojia
authors.initials: X
authors.lastname: He
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
authors.forename: Huey-Min
authors.initials: HM
authors.lastname: Hwang
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000528:radiation effects*; D005461:Fluorine / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D015603:Keratinocytes / Q000187:drug effects; D008027:Light; D008099:Liver / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity*; D009584:Nitrogen / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D056951:Photoelectron Spectroscopy; D010782:Photolysis; D017382:Reactive Oxygen Species / Q000378:metabolism; D013455:Sulfur / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D013472:Sunlight; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity*; D014961:X-Ray Diffraction; D015027:Zebrafish / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; C009495:titanium dioxide; D005461:Fluorine; D013455:Sulfur; D014025:Titanium; D009584:Nitrogen