Environmental Behavior And Bioavailability Of Ag And Ceo2 Nanoparticles: The Role Of Surface Functionalization and its Interaction with Natural Organic Substances and Iron OxohydroxidesEPA Grant Number: R834857
Title: Environmental Behavior And Bioavailability Of Ag And Ceo2 Nanoparticles: The Role Of Surface Functionalization and its Interaction with Natural Organic Substances and Iron Oxohydroxides
Investigators: Unrine, Jason M. , Bertsch, Paul M. , Graham, Ursula M. , Tsyusko, Olga V. , Butterfield, Allan
Institution: University of Kentucky
EPA Project Officer: Klieforth, Barbara I
Project Period: August 1, 2010 through July 31, 2014
Project Amount: $599,840
RFA: Increasing Scientific Data on the Fate, Transport and Behavior of Engineered Nanomaterials in Selected Environmental and Biological Matrices (2010) RFA Text | Recipients Lists
Research Category: Chemical Safety for Sustainability
The objective of this project is to investigate the role of nanoparticle surface chemistry and environmental modifications of nanoparticle surfaces in determining their aggregation, deposition and dissolution in environmental matrices, as well as bioavailability and toxicity, including phototoxicity, to a model organism (Caenorhabditis elegans). This objective will be met by testing the following hypotheses.
Hypothesis 1: Surface chemistry of engineered nanomaterials controls environmental surface modification with natural organic matter and iron oxohydroxides.
Hypothesis 2: Aggregation and dissolution of nanomaterials is heavily influenced by interactions with natural organic matter and iron oxohydroxides.
Hypothesis 3: Bioavailability and toxicity of nanomaterials in soil invertebrates are modified by interaction with natural organic matter and iron oxohydroxides.
Hypothesis 4: Surface modification of nanomaterials with natural organic matter and iron oxohodroxides can alter the response of molecular biomarkers of exposure as well as the nature and extent of damage to biomolecules.
We will synthesize 5 nm Ag and CeO2 particles and surface functionalize them to confer a range of positive and negative surface charge properties (Ag) and surface coating molecular weights (CeO2). The functionalized nanomaterials will then be suspended in media of varying pH, ionic strength and composition containing either humic acid or alginic acid at varying concentrations of particles and the organic matter. We will also suspend particles in the presence of Fe2+ under reducing conditions and subsequently oxidize Fe2+ to Fe3+ in a variety of media. The surface properties, stability, reactivity, bioavailability and toxicity to C. elegans of “as prepared” and modified particles will then be characterized using a variety of advanced analytical techniques. Aggregation, dissolution and surface chemistry of as prepared and surface modified particles will be studied using an array of advanced analytical techniques including asymmetrical flow and sedimentation field flow fractionation (FFF), dynamic and multi-angle light scattering, inductively coupled plasma mass spectrometry, UV-Vis, fluorescence, infra-red, and Raman spectroscopies, thermogravimetric analysis, phase analysis light scattering and X-ray absorption spectroscopy. Imaging techniques to characterize bioavailability will include laser ablation-inductively coupled plasma mass spectrometry, scanning synchrotron X-ray and transmission and scanning electron microscopy (TEM/STEM) (including electron energy loss spectroscopy (EELS)). Biological responses will include mortality, transcriptomic responses and oxidative stress-specific proteomics.
We expect this project to provide vital information on how surface chemistry of nanomaterials dictates interactions with naturally occurring organic and mineral components of aquatic and soil environments. These data will be critical for the paramaterization of models relating the structure of nanomaterials to their fate, transport and toxicity, including a proposed project (Call # FP7-NMP- 2010-EU-USA) by collaborators in the European Union entitled “Modeling nanoparticle relationships with toxicity (ModelPART)”. We expect that such models need to take into account environmental modifications of surface chemistry in order to make accurate predictions.