Grantee Research Project Results
2008 Progress Report: Bioavailability and Fates of CdSe and TiO2 Nanoparticles in Eukaryotes and Bacteria
EPA Grant Number: R833323Title: Bioavailability and Fates of CdSe and TiO2 Nanoparticles in Eukaryotes and Bacteria
Investigators: Holden, Patricia , Nadeau, Jay L. , Stucky, Galen
Institution: University of California - Santa Barbara , McGill University
EPA Project Officer: Aja, Hayley
Project Period: May 15, 2007 through May 14, 2010
Project Period Covered by this Report: May 15, 2007 through May 14,2008
Project Amount: $399,986
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: a Joint Research Solicitation-EPA, NSF, NIOSH, NIEHS (2006) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Safer Chemicals
Objective:
To fully characterize cellular-scale fate and transport processes and to learn how CdSe quantum dot (QD) and TiO2 nanoparticles are toxic to eukaryotic cells and bacteria. The objectives include addressing: 1) nanoparticle uptake as it relates to nanoparticle size, conjugation, reactive oxygen species (ROS) generation, and specific cellular receptors for nanoparticle conjugates, 2) nanoparticle and conjugate stability related to breakdown inside and outside cells and how this might occur, 3) cellular responses that mediate nanoparticle uptake including glutathione production, membrane potential changes, free radical scavenging and resulting toxicological patterns, 4) nanoparticle chemistry influences on cellular uptake and effects including toxicity of constituent metals, and the possibility of a “nanoparticle effect” that is hypothesized by as yet uncharacterized.Progress Summary:
Bare QDs are partially biotically decomposed into constituent metals by Pseudomonas, explaining how Cd(II) and QDs are similarly toxic at specified concentrations of total cadmium. The fate of metals include cellular bioaccumulation of Cd(II). Se(II) liberated from biotic decomposition of QDs is oxidized to Se(0) and mostly remains associated with cells. QDs disfigure cell envelopes, similarly to what has been observed with ROS-generating compounds, yet Cd(II) did not disfigure membranes. CdTe QDs are differently growth inhibitory, depending on bacterial strain over a range of gram positive to gram negative. Working with TiO2 nanoparticles from industry (Evonik P25) and from research collaborators we showed a dose-response relationship in the growth of Pseudomonas bacteria such that the relationship was strongest for the smallest (7 nm) particles. The other particles (14 nm from laboratory synthesis and the industrial 25 nm particle) were also somewhat inhibitory but less than the 7 nm nanoparticle, and the dose-response relationship was relatively moderate. Also with TiO2 nanoparticles, we observed (using environmental scanning electron microscopy or ESEM) disagglomeration of initially agglomerated titania nanoparticles which is being quantified and independently verified by additional methods.Future Activities:
1) Complete studies of bare QD effects on growing P. aeruginosa including evaluation of membrane damage and ROS association. 2)Complete mass balance assessment of QD fate in P. aeruginosa study system including dissolution and bioaccumulation of QDs and metals / metalloid. 3) Submit publications for peer-review on both the breakdown and effects of QDs in P. aeruginosa, with one oriented towards planktonic growth and the other oriented towards biofilms with comparisons to planktonic growth. 4) Finish study of CdTe QD effects on bacterial growth and assess strain dependencies. 5) Assess relationship between membrane association and nanopariticle effects on membranes plus growth inhibition. 6) Develop and apply approaches for assessing energy state of membranes (depolarization, potential) and energy generation activity (dehydrogenase activity), in coordination with energy integrity assays, for studying the nanoparticle effect.7) Complete initial studies of TiO2 toxicity and dissagglomeration, submitting the latter for publication in a peer-reviewed journal.Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 44 publications | 15 publications in selected types | All 13 journal articles |
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Clarke S, Koshy S, Zhang J, Cohen N, Nadeau J. Power and wavelength dependence of photoenhancement in (CdSe)ZnS-dopamine in aqueous solution and live cells. Zeitschrift fur Physikalische Chemie 2008;222(5-6):851-863. |
R833323 (2008) R833323 (Final) |
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Conti JA, Killpack K, Gerritzen G, Huang L, Mircheva M, Delmas M, Harthorn BH, Appelbaum RP, Holden PA. Health and safety practices in the nanomaterials workplace: results from an international survey. Environmental Science & Technology 2008;42(9):3155-3162. |
R833323 (2008) R833323 (Final) |
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Kaats AJ, Galiana HL, Nadeau JL. Standardizing the atomic description, axis and centre of biological ion channels. Journal of Neuroscience Methods 2007;165(1):135-143. |
R833323 (2008) R833323 (Final) |
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Khatchadourian R, Bachir A, Clarke SJ, Heyes CD, Wiseman PW, Nadeau JL. Fluorescence intensity and intermittency as tools for following dopamine bioconjugate processing in living cells. Journal of Biomedicine & Biotechnology 2007;2007:70145 (10 pp.). |
R833323 (2008) R833323 (Final) |
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Supplemental Keywords:
bioavailability, cadmium, selenium, selenite, heavy metals, titanium, biofilm, endocytosis, titania, conjugate, bioconjugate, fate, transport, bioaccumulation.Progress 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.