title: TiO2 Nanoparticle Uptake by the Water Flea Daphnia magna via Different Routes is Calcium-Dependent.
abstract: Calcium plays versatile roles in aquatic ecosystems. In this study, we investigated its effects on the uptake of polyacrylate-coated TiO2 nanoparticles (PAA-TiO2-NPs) by the water flea (cladoceran) Daphnia magna. Particle distribution in these daphnids was also visualized using synchrotron radiation-based micro X-ray fluorescence spectroscopy, transmission electron microscopy, and scanning electron microscopy. At low ambient Ca concentrations in the experimental medium ([Ca]dis), PAA-TiO2-NPs were well dispersed and distributed throughout the daphnid; the particle concentration was highest in the abdominal zone and the gut, as a result of endocytosis and passive drinking of the nanoparticles, respectively. Further, Ca induced PAA-TiO2-NP uptake as a result of the increased Ca influx. At a high [Ca]dis, the PAA-TiO2-NPs formed micrometer-sized aggregates that were ingested by D. magna and concentrated only in its gut, independent of the Ca influx. Our results demonstrated the multiple effects of Ca on nanoparticle bioaccumulation. Specifically, well-dispersed nanoparticles were taken up by D. magna through endocytosis and passive drinking whereas the uptake of micrometer-sized aggregates relied on active ingestion.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Ling-Yan
authors.initials: LY
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Shen
authors.initials: S
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Zhong-Bo
authors.initials: ZB
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Liu-Yan
authors.initials: LY
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu Province 210023, China.
authors.forename: Ai-Jun
authors.initials: AJ
authors.lastname: Miao
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D033361:Cladocera; D003621:Daphnia / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D002118:Calcium