title: Effects of humic acid and ionic strength on TiO₂ nanoparticles sublethal toxicity to zebrafish.
abstract: The stability and bioavailability of titanium dioxide nanoparticles (TiO2 NPs) suspension could be modified by the physicochemical properties of solution. In the present study, the effect of humic acid (HA) and ionic strength (by adding NaCl) on aggregation and sedimentation of TiO2 NPs suspension were investigated. Accordingly, the sublethal toxicity of TiO2 NPs suspensions with different HA and NaCl concentrations toward zebrafish (Danio rerio) was evaluated by monitoring the changes of superoxide dismutase, catalase, malonaldehyde and glutathione in gill, liver and intestine. The results showed that the aggregations formation and hydrodynamic diameter of TiO2 NPs in suspensions are not essential characteristics to decide toxicity. The varied oxidative stress responses detected in gill, liver and intestine derived from different toxicity mechanisms of TiO2 NPs. Nevertheless, the oxidative stress could be suppressed by the adding of HA and/or the increase of ionic strength, which can decrease the bioavailability of TiO2 NPs in water. The study suggests that the environmental factors, such as HA and ionic strength, are important for the fate (aggregation and sedimentation) and toxicity of nanomaterials in aquatic environment.
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, Hubei, China. fangt@ihb.ac.cn.
authors.forename: T
authors.initials: T
authors.lastname: Fang
authors.affiliation: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.|Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: L P
authors.initials: LP
authors.lastname: Yu
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, Hubei, China.
authors.forename: W C
authors.initials: WC
authors.lastname: Zhang
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, No. 7 Donghu South Road, Wuchang District, Wuhan, Hubei, China.|Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: S P
authors.initials: SP
authors.lastname: Bao
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D019015:Geologic Sediments / Q000032:analysis; D006812:Humic Substances / Q000633:toxicity*; D053768:Metal Nanoparticles / Q000633:toxicity*; D009994:Osmolar Concentration; D014025:Titanium / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D006812:Humic Substances; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium
keywords: Humic acid; Ionic strength; Oxidative stress; TiO2 NPs; Zebrafish