Grantee Research Project Results
Final Report: Environmental Transport, Biodegradation, and Bioaccumulation of Quantum Dots and Oxide Nanoparticles
EPA Grant Number: R833861Title: Environmental Transport, Biodegradation, and Bioaccumulation of Quantum Dots and Oxide Nanoparticles
Investigators: Aga, Diana S. , Watson, David , Colon, Luis , Banerjee, Sarbajit
Institution: University of Buffalo
EPA Project Officer: Aja, Hayley
Project Period: July 1, 2008 through June 30, 2011
Project Amount: $400,000
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Fate, Transport, Transformation, and Exposure of Engineered Nanomaterials: A Joint Research Solicitation - EPA, NSF, & DOE (2007) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
Objective:
This research aimed to investigate the influence of size and surface chemistry of quantum dots (QDs) (i.e., CdS and CdSe) and engineered metal oxide (MO) nanomaterials (i.e. CeO2, HfO2, ZrO2, TiO2) on their environmental mobility, biodegradation, and bioaccumulation. The specific goals are to: (1) characterize the influence of natural organic matter (NOM) on the surface functionalization, solubility, and stability of QD and MO suspensions; (2) examine the effects of NOM on the transport behavior and degradation of various formulations of QD and MO in soil columns; and (3) measure the bioaccumulation of QD and MO as a function of size and NOM concentration in a model organism (Eisenia). We hypothesize that size, surface chemistry, bioavailability, and solubility of QD and MO are closely related parameters that affect the environmental fate and potential ecological impacts of QD and MO nanomaterials.
Summary/Accomplishments (Outputs/Outcomes):
Finally, we investigated the bioaccumulation behavior of QD by Eisenia andrei earthworms in a terrestrial environment. Earthworms were exposed to QD-treated soil for up to 4 weeks and analyzed for cadmium and selenium concentration using inductively coupled plasma mass spectrometry. Results were compared with those from earthworms exposed to cadmium nitrate and selenious acid, as positive controls, and those exposed in untreated soil (negative control). Earthworms exposed to QD showed significant bioaccumulation of cadmium and selenium (5.3- and 1.5-fold higher concentration over negative controls, respectively) after 4 weeks. Over the same 4 weeks, positive control earthworms accumulated 9.2- and 2.2-fold higher cadmium and selenium, respectively, than negative controls for a much more substantial final body burden of the two elements. The concentrations also increased with exposure time, suggesting that further bioaccumulation may take place with even longer exposure time. The molar ratio of cadmium to selenium in the QD-exposed worms was closer to the ratios seen in positive control worms than to the pure QD. The results observed in this study indicate that QDs are taken up predominantly in the degraded form.
Conclusions:
In conclusion, our studies suggest that chemical modification of QD to protect them from environmental degradation could potentially reduce accumulation of the nanoparticles by earthworms, and potentially by other soil biota. Plant uptake experiments also suggest that QD is not translocated from roots to other parts of the plant. Results from this study suggest that the potential deleterious effects of QD, MO, and perhaps other engineered nanomaterials may be reduced if the surface coatings are made stable, protecting the release of heavy metals into the environment. Finally, results from the phase-transfer experiments revealed that NOM and other chelating agents in the environment could provide a means by which hydrophobic nanoparticles can enter the aquatic environment, and release toxic elements such as Cd2+ and/or Se2-. These studies demonstrate the importance of having stable surface capping ligands on the surfaces of engineered nanoparticles to reduce their potential negative impacts once they are released into the environment.
Journal Articles on this Report : 10 Displayed | Download in RIS Format
| Other project views: | All 36 publications | 10 publications in selected types | All 10 journal articles |
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Akaighe N, MacCuspie RI, Navarro DA, Aga DS, Banerjee S, Sohn M, Sharma VK. Humic acid-induced silver nanoparticle formation under environmentally relevant conditions. Environmental Science & Technology 2011;45(9):3895-3901. |
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Celiz MD, Colon LA, Watson DF, Aga DS. Study on the effects of humic and fulvic acids on quantum dot nanoparticles using capillary electrophoresis with laser-induced fluorescence detection. Environmental Science & Technology 2011;45(7):2917-2924. |
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Depner SW, Kort KR, Banerjee S. Precursor control of crystal structure and stoichiometry in twin metal oxide nanocrystals. CrystEngComm 2009;11(5):841-846. |
R833861 (2009) R833861 (Final) |
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Navarro DA, Watson DF, Aga DS, Banerjee S. Natural organic matter-mediated phase transfer of quantum dots in the aquatic environment. Environmental Science & Technology 2009;43(3):677-682. |
R833861 (2009) R833861 (Final) |
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Navarro DA, Banerjee S, Aga DS, Watson DF. Partitioning of hydrophobic CdSe quantum dots into aqueous dispersions of humic substances: influence of capping-group functionality on the phase-transfer mechanism. Journal of Colloid and Interface Science 2010;348(1):119-128. |
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Navarro DA, Banerjee S, Watson DF, Aga DS. Differences in soil mobility and degradability between water-dispersible CdSe and CdSe/ZnS quantum dots. Environmental Science & Technology 2011;45(15):6343-6349. |
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Navarro DA, Depner SW, Watson DF, Aga DS, Banerjee S. Partitioning behavior and stabilization of hydrophobically coated HfO2, ZrO2 and HfxZr1-xO2 nanoparticles with natural organic matter reveal differences dependent on crystal structure. Journal of Hazardous Materials 2011;196:302-310. |
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Navarro DA, Bisson MA, Aga DS. Investigating uptake of water-dispersible CdSe/ZnS quantum dot nanoparticles by Arabidopsis thaliana plants. Journal of Hazardous Materials 2012;211-212:427-435. |
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Stewart DT, Noguera-Oviedo K, Lee V, Banerjee S, Watson DF, Aga DS. Quantum dots exhibit less bioaccumulation than free cadmium and selenium in the earthworm Eisenia andrei. Environmental Toxicology and Chemistry 2013;32(6):1288-1294. |
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Stewart DTR, Celiz MD, Vicente G, Colon LA, Aga DS. Potential use of capillary zone electrophoresis in size characterization of quantum dots for environmental studies. TrAC Trends in Analytical Chemistry 2011;30(1):113-122. |
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Supplemental Keywords:
bioavailability, soil contamination, UV, IR Raman, Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, laser-induced fluorescence, heavy metals, capillary zone electrophoresis, Health, Scientific Discipline, Health Risk Assessment, Risk Assessments, bioavailability, nanomaterials, manufactured nanomaterials, ecological risk assessment, biogeochemistry, biological pathways, bioaccumulation, nanotechnology, nanochemistry, nanoparticle toxicity, quantum dots, cellular response to nanoparticles, toxicologic assessment, quantification of non-cancer risk, biochemical researchProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.