Fullerene Nanoparticle Counter Using Quartz Crystal Microbalance National Exposure Research Laboratory U.S. Environmental Protection Agency Katrina Varner presenting
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Office of Research and Development National Exposure Research Laboratory Project Goals
• 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
Office of Research and Development 1 National Exposure Research Laboratory 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
(I) Toluene 0.7 (II)Toluene+424 ng C60 (III)Toluene + 212 ng C70 0.6
0.5
0.4
0.3 (III)
Absorbance(AU) 0.2
0.1 (II)
0 (I)
-0.1 270 320 370 420 470 520 570
wavelength(nm)
Office of Research and Development 2 National Exposure Research Laboratory Method
• Explore the solubility & electrochemistry of fullerenes by manipulating electrochemical properties in order to develop an electrochemical detection method.
Sensor design protocol scheme
Office of Research and Development 3 National Exposure Research Laboratory 89569000 QCM-S-(CH2)2 –CO-NH- -CD + CONTROL(TOLUENE) 89568000 t=60 min 89567000 Figure shows : QCM (Au)-S –(CH2)2- t=30 CONH- –CD frequency vs. Time changes 89566000 ϐ A of (A) 1.9 mM C60 Freq.Hz in presence of 200 μL 89565000 t=0 in toluene and (B) absence of C60 (toluene 89564000 only) 89563000 0 200 400 600 800 Time(s)
89744800 QCM-S-(CH2)2 –CO-NH- -CD + C60 89744600 89744400 t=0 min 89744200 89744000 B 89743800 t=30 min
Freq.Hz 89743600 89743400 t=60 min 89743200 89743000 89742800 0 200 400 600 800 Office of Research and Development 4 National Exposure Research Laboratory Time(s)
2000 C70 y 0 Control -2000 -4000 -6000 -8000 -10000 -12000 C60 Change in Frequenc in Change -14000 0 100 200 300 400 500 600 700 Time(s)
Frequency vs time for QCM (Au)-S–(CH2)2-CONH-beta–CD sensor, in presence of fullerene C60, C70 and control (toluene)
Office of Research and Development 5 National Exposure Research Laboratory 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.
Office of Research and Development 6 National Exposure Research Laboratory 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.
Office of Research and Development 7 National Exposure Research Laboratory 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.
Office of Research and Development 8 National Exposure Research Laboratory