Impact/Purpose:

Nanoscale forms of magnetic Fe₃O₄ and the photocatalysts TiO₂ and ZnO have a wide range of current and proposed applications, and rank among the highest production volume nanoparticles (NPs). Many applications of these NPs require surface functionalization. Nanoparticle surface chemistry influences uptake and toxicity, as well as interactions with environmental media. Microbially mediated redox processes have the potential to alter the surface chemistry of functionalized TiO₂, ZnO, and Fe₃O₄, thereby impacting their toxicity and fate. Fundamental information on changes in the surface chemistry of these commercially important metal oxide NPs under environmentally relevant oxidative and reductive conditions is currently lacking. Furthermore, the influence of surface coatings on metal oxide NP toxicity has not been thoroughly studied, and little information exists on the effects of environmentally induced changes in surface chemistry on toxicity. The objectives of this study are to determine (1) the extent to which the surface chemistry of functionalized metal oxide NPs is altered under oxidative and reductive environmental conditions, and (2) the degree to which such transformations modify their inherent and photo-enhanced toxicity.

Description:

This study will provide fundamental information on alterations in the surface chemistry of commercially important functionalized metal oxide NPs under environmentally relevant oxidative and reductive conditions, as well as needed data on the inherent and photo-enhanced toxicity of these same materials as synthesized and after transformation. This research will enable the development of environmentally benign nanomaterials and facilitate environmental risk assessment of these materials.

Record Details:

Record Type:PROJECT( ABSTRACT )

Start Date:07/01/2008

Completion Date:06/30/2011

Record ID: 201101

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Project Information:

Approach :

The surfaces of TiO₂, ZnO and Fe₃O₄ NPs will be coated using a variety of strategies (e.g., ligand exchange through different anchoring groups, silica shells, polymer wrapping) and extensively characterized. Alterations in the surface chemistry of the coated metal oxide NPs will be investigated using in vitro biomimetic assays modeled after important microbially mediated redox processes. Oxidative transformations will be examined using methoxyhydroquinone-driven Fenton’s reaction as chemical model for reactive oxygen species produced by lignolytic fungi. Reductive transformations will be studied using reduced cobalamin as a model for microbial reduction processes. The inherent and photo-enhanced toxicity of the as-synthesized functionalized NPs and their transformation products will be investigated using the embryonic zebrafish model. Mortality, sublethal morphological and functional endpoints of toxicity, oxidative stress and metallothionein induction will be examined.

Cost :$382,345.00

Research Component :Nanotechnology

Project IDs:

ID Code :R833860

Project type :EPA Grant