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Zhang S, Jiang Y, Chen CS, Spurgin J, Schwehr KA, Quigg A, Chin WC, Santschi PH. Aggregation, dissolution, and stability of quantum dots in marine environments: importance of extracellular polymeric substances. Environ Sci Technol 2012; 46:8764-8772. [PMID: 22834414 DOI: 10.1021/es301000m] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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.
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Affiliation(s)
- Saijin Zhang
- Department of Marine Science, Texas A&M University at Galveston, Galveston, Texas 77553, United States.
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Chen CS, Anaya JM, Zhang S, Spurgin J, Chuang CY, Xu C, Miao AJ, Chen EYT, Schwehr KA, Jiang Y, Quigg A, Santschi PH, Chin WC. Effects of engineered nanoparticles on the assembly of exopolymeric substances from phytoplankton. PLoS One 2011; 6:e21865. [PMID: 21811550 PMCID: PMC3140995 DOI: 10.1371/journal.pone.0021865] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 06/10/2011] [Indexed: 11/19/2022] Open
Abstract
The unique properties of engineered nanoparticles (ENs) that make their industrial applications so attractive simultaneously raise questions regarding their environmental safety. ENs exhibit behaviors different from bulk materials with identical chemical compositions. Though the nanotoxicity of ENs has been studied intensively, their unintended environmental impacts remain largely unknown. Herein we report experimental results of EN interactions with exopolymeric substances (EPS) from three marine phytoplankton species: Amphora sp., Ankistrodesmus angustus and Phaeodactylum tricornutum. EPS are polysaccharide-rich anionic colloid polymers released by various microorganisms that can assemble into microgels, possibly by means of hydrophobic and ionic mechanisms. Polystyrene nanoparticles (23 nm) were used in our study as model ENs. The effects of ENs on EPS assembly were monitored with dynamic laser scattering (DLS). We found that ENs can induce significant acceleration in Amphora sp. EPS assembly; after 72 hours EN-EPS aggregation reached equilibrium, forming microscopic gels of ∼4-6 µm in size. In contrast, ENs only cause moderate assembly kinetic acceleration for A. angustus and P. tricornutum EPS samples. Our results indicate that the effects of ENs on EPS assembly kinetics mainly depend on the hydrophobic interactions of ENs with EPS polymers. The cycling mechanism of EPS is complex. Nonetheless, the change of EPS assembly kinetics induced by ENs can be considered as one potential disturbance to the marine carbon cycle.
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Affiliation(s)
- Chi-Shuo Chen
- Bioengineering, University of California, Merced, Merced, California, United States of America
| | - Jesse M. Anaya
- Bioengineering, University of California, Merced, Merced, California, United States of America
| | - Saijin Zhang
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Jessica Spurgin
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Chia-Ying Chuang
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Chen Xu
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Ai-Jun Miao
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, Jiangsu Province, People's Republic of China
| | - Eric Y-T. Chen
- Bioengineering, University of California, Merced, Merced, California, United States of America
| | - Kathleen A. Schwehr
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Yuelu Jiang
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Antonietta Quigg
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Marine Biology, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Peter H. Santschi
- Department of Marine Science, Texas A & M University at Galveston, Galveston, Texas, United States of America
- Department of Oceanography, Texas A & M University, College Station, Texas, United States of America
| | - Wei-Chun Chin
- Bioengineering, University of California, Merced, Merced, California, United States of America
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