title: Interactions of CuO nanoparticles with the algae Chlorella pyrenoidosa: adhesion, uptake, and toxicity.
abstract: The potential adverse effects of CuO nanoparticles (NPs) have increasingly attracted attention. Combining electron microscopic and toxicological investigations, we determined the adhesion, uptake, and toxicity of CuO NPs to eukaryotic alga Chlorella pyrenoidosa. CuO NPs were toxic to C. pyrenoidosa, with a 72 h EC50 of 45.7 mg/L. Scanning electron microscopy showed that CuO NPs were attached onto the surface of the algal cells and interacted with extracellular polymeric substances (EPS) excreted by the organisms. Transmission electron microscopy (TEM) showed that EPS layer of algae was thickened by nearly 4-fold after CuO NPs exposure, suggesting a possible protective mechanism. In spite of the thickening of EPS layer, CuO NPs were still internalized by endocytosis and were stored in algal vacuoles. TEM and electron diffraction analysis confirmed that the internalized CuO NPs were transformed to Cu2O NPs (d-spacing, ∼0.213 nm) with an average size approximately 5 nm. The toxicity investigation demonstrated that severe membrane damage was observed after attachment of CuO NPs with algae. Reactive oxygen species generation and mitochondrial depolarization were also noted upon exposure to CuO NPs. This work provides useful information on understanding the role of NPs-algae physical interactions in nanotoxicity.
authors.affiliation: a Institute of Costal Environmental Pollution Control, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China , Qingdao , China .|b Laboratory for Marine Ecology and Environmental Science , Qingdao National Laboratory for Marine Science and Technology, China , Qingdao , China .
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.affiliation: a Institute of Costal Environmental Pollution Control, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China , Qingdao , China .
authors.forename: Xuesong
authors.initials: X
authors.lastname: Cao
authors.affiliation: c Institute of Materials Science and Engineering, Ocean University of China , Qingdao , China .
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: a Institute of Costal Environmental Pollution Control, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China , Qingdao , China .|b Laboratory for Marine Ecology and Environmental Science , Qingdao National Laboratory for Marine Science and Technology, China , Qingdao , China .
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: a Institute of Costal Environmental Pollution Control, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China , Qingdao , China .
authors.forename: Chenchen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: d Department of Analytical Chemistry , The Connecticut Agricultural Experiment Station , New Haven , CT , USA , and.
authors.forename: Jason C
authors.initials: JC
authors.lastname: White
authors.affiliation: e Stockbridge School of Agriculture, University of Massachusetts , Amherst , MA , USA.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002708:Chlorella / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D003300:Copper / Q000737:chemistry / Q000633:toxicity*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D003300:Copper; C030973:cupric oxide
keywords: Aquatic toxicity; extracellular polymeric substances; internalization; membrane damage; reactive oxygen species