title: Comparison of TiO2 nanoparticle and graphene-TiO2 nanoparticle composite phototoxicity to Daphnia magna and Oryzias latipes.
abstract: With a dramatic rise in complexity, needs of nanotoxicology research go beyond simple forms of nanomaterials. This study compared the phototoxicity of nano-TiO2 and graphene-TiO2 nanocomposite (GNP). GNP was synthesized based on a hydrothermal method, which simultaneously performed the reduction of graphene oxide and nano-TiO2 loading. A series of acute toxicity tests of nano-TiO2, graphene and GNP was performed on two aquatic organisms, Daphnia magna and Oryzias latipes. Fast and substantial agglomeration and sedimentation of nanoparticles in test media and surface attachment of nano-TiO2 and GNP on D. magna surface was observed. Similar phototoxicity of nano-TiO2 and GNP for both species existed, though compared with nano-TiO2, GNP had a 2.3-fold increase in visible light photocatalytic ROS generation. In summary, this study demonstrated the significance of illumination spectrum, particle behavior, and species sensitivity on nanophototoxicity, and the needs for research on increasingly sophisticated functional materials.
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA. Electronic address: li.shibin@epa.gov.
authors.forename: Shibin
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, TX, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Pan
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA.
authors.forename: Lindsay K
authors.initials: LK
authors.lastname: Wallis
authors.affiliation: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, TX, USA.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Fan
authors.affiliation: School of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, Fujian Province, China.
authors.forename: ZuLiang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Nanosafe Inc., Blacksburg, VA, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Diamond
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects*; D054750:Ecotoxicology; D006108:Graphite / Q000737:chemistry / Q000633:toxicity*; D008027:Light; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D009990:Oryzias; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*
chemical_list: C009495:titanium dioxide; D006108:Graphite; D014025:Titanium
keywords: Aquatic organism; Graphene; Nano-TiO(2); Nanocomposite; Phototoxicity