Liu Lingling, Fan Wenhong, Lu Huiting, Xiao Wei
Department of Environmental Science and Engineering, School of Chemistry and Environment, Beihang University, Beijing 100191, Beijing, P. R.China.
Department of Environmental Engineering, School of Resource &Environmental Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China.
Sci Rep. 2015 Aug 5;5:11121. doi: 10.1038/srep11121.
Anatase TiO2 nanosheets (NSs) with exposed {001} facets have been widely used because of their high activity and particular surface atomic configuration. However, investigations on their biotoxicity are rare. In this study, bioaccumulation of five different TiO2 (with 10%, 61%, 71%, 74% and 78% exposed {001} facets), as well as copper and enzyme activities in Daphnia magna, are systematically investigated and rationalized. The results indicated that the addition of Cu(2+) enhanced agglomeration-sedimentation of TiO2, resulting in the reduction of TiO2 bioaccumulation by 10% to 26%. TiO2 nanoparticles (NPs) increased copper bioaccumulation by 9.8%, whereas the other four TiO2 nanosheets (NSs) decreased it by 43% to 53%, which depended on TiO2 variant adsorption and free Cu(2+) concentrations in the supernatant. The levels of superoxide dismutase (SOD) enzyme and Na(+)/K(+)-ATPase activities suggested that oxidative stress, instead of membrane damage, was the main toxicity in D. magna. Meanwhile, the SOD enzyme activities increased with decreasing Cu accumulation and increasing Ti accumulation because of the different functions of Cu and Ti in organisms. This research highlighted the important role of the percentage of exposed {001} facets in nanostructured TiO2 on bioaccumulation and biotoxicity of TiO2 and Cu(2+) in Daphnia magna.
具有暴露{001}晶面的锐钛矿型二氧化钛纳米片（NSs）因其高活性和特殊的表面原子构型而被广泛应用。然而，关于其生物毒性的研究却很少。在本研究中，系统地研究并分析了五种不同的二氧化钛（暴露{001}晶面的比例分别为10%、61%、71%、74%和78%）在大型溞中的生物累积情况，以及铜含量和酶活性。结果表明，添加Cu(2+)会增强二氧化钛的团聚-沉淀作用，导致二氧化钛的生物累积量降低10%至26%。二氧化钛纳米颗粒（NPs）使铜的生物累积量增加了9.8%，而其他四种二氧化钛纳米片（NSs）则使其降低了43%至53%，这取决于二氧化钛变体的吸附情况以及上清液中游离Cu(2+)的浓度。超氧化物歧化酶（SOD）和Na(+)/K(+)-ATP酶的活性水平表明，氧化应激而非膜损伤是大型溞中的主要毒性。同时，由于铜和钛在生物体内的功能不同，SOD酶活性随着铜累积量的减少和钛累积量的增加而升高。本研究强调了纳米结构二氧化钛中暴露{001}晶面的比例对大型溞中二氧化钛和Cu(2+)的生物累积及生物毒性的重要作用。
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