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Nanotechnology Research

Detecting, quantifying and characterizing nanomaterials

Tools to detect, quantify, and characterize engineered nanomaterials in environmental samples and biological tissue.

Issue
Due to the unique characteristics of engineered nanomaterials (ENMs) compared to other environmental contaminants, limited information concerning their transport, fate, exposure, dose, and potential effects is available.  A 2009 expert workshop sponsored by the International Council on Nanotechnology identified improving methods for quantification, detection, and inherent physicochemical characterization of ENM as the most important research area needed to inform sustainable development of nanotechnology.  These metrology tools are critical to an integrated assessment of risk posed by ENM. Although the production and use of ENM is rapidly increasing, reports of environmental contamination have been limited, allowing a window of opportunity to avoid potential legacy contamination. However, few effective metrology techniques have been reported for measuring these materials in environmental settings or understanding their environmental processes related to transport, fate, and bioavailability.

Actions
Detecting, quantifying, and characterizing metal-containing ENMs in environmental media.  Practical methods for detecting, quantifying, and characterizing metal-containing nanomaterials in ambient environmental media will be produced.  Specific approaches will involve single particle-inductively coupled plasma mass spectrometry (SP-ICPMS), flow- and sedimentation- field flow fractionation, hydrodynamic chromatography, quantitative methods for scanning electron microscopy, and various combinations of these techniques. 

Geophysical detection of select engineered nanoparticles in saturated granular media.
This task builds on feasibility experiments which showed a spectral induced polarization response to nano silver and nano zero valent iron in a saturated sand matrix.  These findings are important to the goal of detecting nanoparticle impacted environmental media in-situ using geophysical methods.  The research attempts to determine if geophysical methods can be used to detect nanoparticles in the environment and at what concentration is the detection dependent.  This is important to understanding the environmental impact of nanomaterials because if there is a large release of such material from an industrial setting or transportation incident the location of nano sized materials in the subsurface will be very difficult to determine.  This research continues the effort of determining if there is a geophysical response to nanoparticles so that geophysical methods may be used to detect and characterize such environmental exposures.  Research in this task will investigate the spectral induced polarization and seismic response of various nanoparticles at various concentrations and in variable geologic settings.  Initial results from each of the methods show promise to detecting nanometals and some nanooxides.  Increasing the complexity of the experiments will aid in the understanding of the geophysical response and identify if geophysical methods are efficient and effective for this application.

Separation of nanoparticles from environmental matrices and sample integrity maintenance. Increased manufacture, marketing, and use of silver nanoparticles in household products has prompted concerns about the potential for environmental and human exposure. Work will be conducted using radiolabeled silver as a tracer to follow silver nanoparticles during the spinning disk apparatus and other separations and address the systematic characterization of both ionic and nanoscale forms of silver and silver compounds, with respect to environmental matrices selected from the following, in expected increasing difficulty:  surface water, ground water, wastewater, plants and fish tissues, biosolids, sediments, and soils.   Particle size distributions, aggregation and dissolution will be determined through scanning electron microscope or transmission electron microscopy and chemical integrity verified by elemental analysis using ICP-MS.  This project will measure the distribution and speciation of nanoscale silver environmental samples using the above mentioned techniques.

Comparison of analytical tools for measurement of nanomaterials in the environment. The primary emphasis will be in analyzing and comparing electrochemistry techniques and liquid chromatography/mass spectroscopy (LC/MS) instrumentation for nanomaterial identification, providing methods of analysis for definitive characterization and quantitation of nanomaterials.  LC/MS provides a comprehensive chemical analysis based on accurate mass measurements and determination compound structure and daughter fragments. Voltammetric determination will be used to build upon completed work of a prototype nanosensor from the laboratory to the field using off-the-shelf, plug-and-play components. 

Results and Impact
Detecting, quantifying, and characterizing metal-containing ENMs in environmental media. 
Application of these new metrology methods will be demonstrated in studies on the influence of nanomaterial-specific ICP on the transport, transformation, and fate of metal-containing ENMs.

Comparison of analytical tools for measurement of nanomaterials in the environment.
The study is expected to assemble the basic physicochemical information of nanomaterials. These sensitive and rapid techniques can be used to provide much needed data to monitor, detect, and quantify nanomaterials for a more comprehensive understanding of nanomaterials needed for regulatory support, water quality and land restoration support, and ecological assessment; that lead to more complete characterization of stressor content. Once potential exposure data estimates are available then quantitative structure-activity relationships (QSARs) may provide some indication of the potential risk levels.