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Fullerene Nanoparticle Counter Using Quartz Crystal Microbalance

National Exposure Research LaboratoryU.S. Environmental Protection Agency

Katrina Varner presenting

1Office of Research and DevelopmentNational Exposure Research Laboratory

• Our research addresses the issues of how best to apply identification, quantitation, and size characterization of fullerene nanomaterials in environmental media which is key to:

– establishing a baseline for the distribution of these materials and trends in concentration as engineered nanomaterials are increasingly introduced into the environment– understanding transport and fate of fullerene nanomaterials, as well dose metrics for exposure, bioaccumulation, and toxicity studies– providing inputs to environmental models, as well as verification of those models– monitoring environmental concentration and migration of fullerenes used in remediation.

• Electrochemical project goals:• Conduct electrochemical detection analysis (a highly sensitive and rapid method) to measure:

– mass change– charge change– current potential– resistance change

Project Goals

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Approach

• Directly monitor double-gyroid nanostructured material (DGN) polymers for:– Chemical interactions– Time-dependent changes in series resonant frequency using QCM sensor–Quantity of nanomaterial comparison via TEM and HRSEM

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Method

• Explore the solubility & electrochemistry of fullerenes by manipulating electrochemical properties in order to develop an electrochemical detection method.

Sensor design protocol scheme

4Office of Research and DevelopmentNational Exposure Research Laboratory

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QCM-S-(CH2)2 –CO-NH-�-CD + CONTROL(TOLUENE)

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QCM-S-(CH2)2 –CO-NH-�-CD + C60

Figure shows : QCM (Au)-S –(CH2)2-CONH-ϐ –CD frequency vs. Time changes in presence of 200 μL of (A) 1.9 mM C60 in toluene and (B) absence of C60 (toluene only)

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Frequency vs time for QCM (Au)-S–(CH2)2-CONH-beta–CD sensor, in presence of fullerene C60, C70 and control (toluene)

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Time of Flight Secondary Ion Mass Spectrometry

False color ToF-SIMS chemical image of QCM (Au)-S-(CH2)2-CONH-beta-CD after soaking in fullerene/toluene solution (a-d) or soak in toluene solution (e-h) (a) C60 (b) Gold (Au) (c) Cyclodextrin (d) Overlay of three colored images. Colored overlay image prepared using IonImage® Software Package, scale bar added using ImageJ.

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Implication

Using a quartz crystal microbalance (QCM), one can measure fullerenes. Measurement of mass changes as well as the in-situ measurements of charge, current, potential and the resistance changes following the isolation of the particles to determine the presence of nanomaterials were identified. Determination is made by frequency decrease or mass increase used to measure the adsorption of C60 fullerenes by the beta-cyclodextrin cavity attached on the QCM.

Successful demonstrations of the synthesis of ß–CD-NH2, its attachment and modification of QCM transducer via DCC/NHS chemistry were shown. The QCM sensor showed specificity to C60 extraction when compared to the control. Current work is focusing on selective surfaces for both natural and synthetic particles.

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Acknowledgements

• Samuel Kikandi, PhD under EPA Student Services Contract EP08D000465

• Professor Omowuni Sadik, PhD SUNY-Binghamton

Notice: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.