title: Metal oxide nanoparticles with low toxicity.
abstract: A number of different nanomaterials produced and incorporated into various products are rising. However, their environmental hazards are frequently unknown. Here we consider three different metal oxide compounds (SnO2, In2O3, and Al2O3), which have not been extensively studied and are expected to have low toxicity. This study aimed to comprehensively characterize the physicochemical properties of these nanomaterials and investigate their toxicity on bacteria (Escherichia coli) under UV illumination and in the dark, as well as on a marine diatom (Skeletonema costatum) under ambient illumination/dark (16-8h) cycles. The material properties responsible for their low toxicity have been identified based on comprehensive experimental characterizations and comparison to a metal oxide exhibiting significant toxicity under illumination (anatase TiO2). The metal oxide materials investigated exhibited significant difference in surface properties and interaction with the living organisms. In order for a material to exhibit significant toxicity, it needs to be able to both form a stable suspension in the culture medium and to interact with the cell walls of the test organism. Our results indicated that the observed low toxicities of the three nanomaterials could be attributed to the limited interaction between the nanoparticles and cell walls of the test organisms. This could occur either due to the lack of significant attachment between nanoparticles and cell walls, or due to their tendency to aggregate in solution.
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong; Department of Physics, South University of Science and Technology of China, Shenzhen, China.
authors.forename: Alan Man Ching
authors.initials: AM
authors.lastname: Ng
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong; Department of Physics, South University of Science and Technology of China, Shenzhen, China.
authors.forename: Mu Yao
authors.initials: MY
authors.lastname: Guo
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Yu Hang
authors.initials: YH
authors.lastname: Leung
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Charis M N
authors.initials: CM
authors.lastname: Chan
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Stella W Y
authors.initials: SW
authors.lastname: Wong
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Mana M N
authors.initials: MM
authors.lastname: Yung
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Angel P Y
authors.initials: AP
authors.lastname: Ma
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: dalek@hku.hk.
authors.forename: Aleksandra B
authors.initials: AB
authors.lastname: Djurišić
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Frederick C C
authors.initials: FC
authors.lastname: Leung
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Kenneth M Y
authors.initials: KM
authors.lastname: Leung
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Wai Kin
authors.initials: WK
authors.lastname: Chan
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Hung Kay
authors.initials: HK
authors.lastname: Lee
mesh_terms: D000537:Aluminum Oxide / Q000633:toxicity; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000633:toxicity; D002462:Cell Membrane / Q000187:drug effects; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects*; D017377:Diatoms / Q000187:drug effects; D054750:Ecotoxicology / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects; D007204:Indium / Q000633:toxicity; D008070:Lipopolysaccharides / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D017382:Reactive Oxygen Species / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D017971:Tin Compounds / Q000633:toxicity; D014025:Titanium / Q000633:toxicity; D014466:Ultraviolet Rays
chemical_list: D000900:Anti-Bacterial Agents; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D017971:Tin Compounds; D007204:Indium; C009495:titanium dioxide; C047711:indium oxide; D014025:Titanium; C045358:stannic oxide; D000537:Aluminum Oxide
keywords: Ecotoxicity; Metal oxide nanoparticles; Toxicity