title: Spectroscopic probe to contribution of physicochemical transformations in the toxicity of aged ZnO NPs to Chlorella vulgaris: new insight into the variation of toxicity of ZnO NPs under aging process.
abstract: Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly applied nanomaterials in nanotechnology-based industries and they may cause unexpected environmental and health risks with their physicochemical transformations in the environment. Currently, there is still a lack of the in-depth understanding of the toxicity of aged ZnO NPs to aquatic organisms, particularly demanding quantitative analysis of the physicochemical transformations to distinguish their contributions in the toxicity assessment. For this purpose, therefore, we initiated the study of the toxicity of aged ZnO NPs to the model aquatic microalga, i.e. Chlorella vulgaris, and with the aid of spectroscopic tools for characterization and quantification of the physicochemical transformations, we scrutinized the toxicity variations for ZnO NPs with different aging times. As a result, we found that the toxicity altered in an abnormal manner with the aging time, i.e. the toxicity of aged ZnO NPs for 30 days showed the higher toxicity to the green alga than the fresh ZnO NPs or the ZnO NPs aged for longer time (e.g. 120 and 210 days). Through spectroscopic tools such as XRD, FTIR and Raman spectroscopy, we made both the qualitative and quantitative assessments of the physicochemical changes of the ZnO NPs, and confirmed that in the early stage, the toxicity mainly stemmed from the release of zinc ions, but with longer aging time, the neoformation of the nanoparticles played the critical role, leading to the overall reduced toxicity due to the less toxic hydrozincite and zinc hydroxide in the transformed compounds.
authors.affiliation: a Institute of Technical Biology and Agriculture Engineering, Key Laboratory of Ion Beam Bioengineering, Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei , China , and.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: a Institute of Technical Biology and Agriculture Engineering, Key Laboratory of Ion Beam Bioengineering, Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei , China , and.|b National Synchrotron Radiation Laboratory, and School of Nuclear Science and Technology, University of Science & Technology of China , Hefei , China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Huang
authors.affiliation: a Institute of Technical Biology and Agriculture Engineering, Key Laboratory of Ion Beam Bioengineering, Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei , China , and.
authors.forename: An
authors.initials: A
authors.lastname: Xu
authors.affiliation: a Institute of Technical Biology and Agriculture Engineering, Key Laboratory of Ion Beam Bioengineering, Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei , China , and.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
mesh_terms: D048408:Chlorella vulgaris / Q000187:drug effects*; D006878:Hydroxides / Q000032:analysis; D007477:Ions; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D012995:Solubility; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*; D015032:Zinc / Q000032:analysis; D017967:Zinc Compounds / Q000032:analysis; D015034:Zinc Oxide / Q000737:chemistry / Q000633:toxicity*
chemical_list: D006878:Hydroxides; D007477:Ions; D014874:Water Pollutants, Chemical; D017967:Zinc Compounds; C417308:hydrozincite; D015032:Zinc; C052745:zinc hydroxide; D015034:Zinc Oxide
keywords: Algal cells; Raman spectroscopy; ZnO nanoparticles; nanotoxicology; physicochemical transformation