title: Aggregation, dissolution, and stability of quantum dots in marine environments: importance of extracellular polymeric substances.
abstract: There is an increasing concern that a considerable fraction of engineered nanoparticles (ENs), including quantum dots (QDs), will eventually find their way into the marine environment and have negative impacts on plankton. As ENs enter the ocean, they will encounter extracellular polymeric substances (EPS) from microbial sources before directly interacting with plankton cells. In this study, EPS harvested from four phytoplankton species, Amphora sp., Dunaliella tertiolecta, Phaeocystis globosa, and Thalassiosira pseudonana, were examined for potential interactions with CdSe nonfunctionalized and functionalized (carboxyl- and amine-) QDs in artificial seawater. Our results show that EPS do not reduce the solubility of QDs but rather decrease their stability. The degradation rate of QDs was positively correlated to the protein composition of EPS (defined by the ratio of protein/carbohydrate). Two approaches showed significant inhibition to the degradation of carboxyl-functionalized QDs: (1) the presence of an antioxidant, such as N-acetyl cysteine, and (2) absence of light. Owing to the complexity in evaluating integrated effects of QDs intrinsic properties and the external environmental factors that control the stability of QDs, conclusions must be based on a careful consideration of all these factors when attempting to evaluate the bioavailability of QDs and other ENs in the marine environments.
authors: Department of Marine Science, Texas A&M University at Galveston, Galveston, Texas 77553, United States. zhangs@tamug.edu
authors: Saijin
authors: S
authors: Zhang
authors: Yuelu
authors: Y
authors: Jiang
authors: Chi-Shuo
authors: CS
authors: Chen
authors: Jessica
authors: J
authors: Spurgin
authors: Kathleen A
authors: KA
authors: Schwehr
authors: Antonietta
authors: A
authors: Quigg
authors: Wei-Chun
authors: WC
authors: Chin
authors: Peter H
authors: PH
authors: Santschi
mesh_terms: D008027:Light; D009994:Osmolar Concentration; D018384:Oxidative Stress; D010839:Phytoplankton / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D045663:Quantum Dots; D012623:Seawater; D012995:Solubility
chemical_list: D011108:Polymers