Bioavailability, Environmental Transformation, and Detoxification of Core/Shell NanomaterialsEPA Grant Number: R833862
Title: Bioavailability, Environmental Transformation, and Detoxification of Core/Shell Nanomaterials
Investigators: Hurt, Robert H. , Kane, Agnes B.
Institution: Brown University
EPA Project Officer: Klieforth, Barbara I
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
Many engineered nanomaterials possess a core containing a chemical toxicant with known adverse health effects, surrounded by a more biocompatible shell. Materials in this class include quantum dots and catalytically synthesized carbon nanotubes, which are both high priority materials for large scale commercial development. The protective properties of these shells are highly uncertain due to nanoscale dimension, and as a result, the bioavailability of the core toxicant becomes a key property governing health risk. We hypothesize that core toxicant bioavailability will depend on shell structure, environmental transformation, processing stresses, and intra/extra-cellular biological modifications that influence toxicant release profiles in environmental organisms and humans. We further hypothesize that these relationships, once understood, will offer opportunities to synthesize, handle, reformulate, and/or post-process the nanomaterials in a way that minimizes environmental and human health risk.
A suite of commercial carbon nanotubes and a set of prototype quantum dots for the LED consumer market will be extensively characterized and subjected to a common set of bioavailability assays, both chemical and cellular. Toxicant bioavailability will be measured on the materials as-produced and after three types of processing: (i) environmental stresses relevant to device fabrication, consumer use, and disposal, (ii) biological stresses in cellular compartments and physiological simulant fluids, and (iii) intentional post-processing to increase material safety. Longer term biopersistence will be assessed using an intracellular simulant fluid in a continuous flow assay.
The proposed research is targeted at minimizing environmental and health risks associated with commercial nanotubes and quantum dots by proper management of core chemical toxicants. The work will lead to validated chemical screening assays for bioavailability assessment, data on environmental degradation and toxicant release throughout the product lifecycle, and practical protocols for material detoxification through coatings, surface treatment, or targeted removal of bioavailable (free) metal.