Title page for ETD etd-09072011-225305

Type of Document Dissertation
Author Hull, Matthew Scott
Author's Email Address mahull@vt.edu
URN etd-09072011-225305
Title Factors influencing the uptake and fate of metallic nanoparticles in filter-feeding bivalves
Degree PhD
Department Environmental Engineering
Advisory Committee
Advisor Name Title
Vikesland, Peter J. Committee Chair
Love, Nancy C. Committee Co-Chair
Hochella, Michael F. Jr. Committee Member
Marr, Linsey C. Committee Member
Schreiber, Madeline E. Committee Member
  • fate and transport
  • persistence
  • aquatic biota
  • filter-feeders
  • nanotechnology
  • nanomaterials
  • iron nanoparticles
  • gold nanoparticles
  • Corbicula fluminea
  • iron nanoparticles
  • quantum dots
Date of Defense 2011-08-11
Availability unrestricted
Metallic nanoparticles (MetNPs) with unique nanoscale properties, including novel optical behavior and superparamagnetism, are continually being developed for biomedical and industrial applications. In certain biomedical applications where extended blood half-lives are required, MetNPs are surface-functionalized using polymers, proteins, and other stabilizing agents to facilitate their resistance to salt-induced aggregation. Given their colloidal stability in high ionic-strength matrices, functionalized MetNPs are anticipated to be persistent aquatic contaminants. Despite their potential environmental significance, the persistence of surface- functionalized MetNPs as individually-stabilized nanoparticles in aquatic environments is largely unknown. Further, few studies have investigated the fundamental factors that influence MetNP uptake and fate/transport processes in ecologically susceptible aquatic biota, such as filter- feeding bivalves, which ingest and accumulate a broad range of dissolved- and particulate-phase contaminants.

The present study describes a comprehensive approach to prepare and rigorously characterize MetNP test suspensions to facilitate fundamental examinations of nanoparticle uptake and fate/transport processes in freshwater and marine bivalves. We demonstrate the importance of accurately characterizing test suspensions in order to better understand MetNP persistence as individually-stabilized nanoparticles within aquatic test media, and define an optical-activity metric suitable for quantifying and comparing the persistence of variable MetNP formulations as National Nanotechnology Initiative (NNI) definable nanoscale materials. We also show that individually-stabilized MetNPs of variable elemental composition, particle diameter, and surface coating are accessible to bivalves in both freshwater and marine environments. Clearance rates for MetNPs are positively related to the diameter and initial concentration of MetNP suspensions. The observed size-dependence of particle filtration rates facilitates ‘size-selective biopurification’ of particle suspensions with nanoscale resolution, and may have applicability in future sustainable nanomanufacturing processes. Filtered MetNPs are retained for extended periods post-exposure primarily within the bivalve digestive tract and digestive gland, but migration to other organ systems was not observed. Clusters of MetNPs were recovered in concentrated form from excreted feces, suggesting that biotransformation and biodeposition processes will play an important role in transferring MetNPs from the water column to benthic environments.

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