Quantifying Carbon Nanotubes in Biological Samples: Techniques, Applications, and Considerations

Transcription

1 Quantifying Carbon Nanotubes in Biological Samples: Techniques, Applications, and Considerations Shannon K. Hanna, Miller, RJ, Adeleye, AS, Keller, AA, and Hunter S. Lenihan SNO 2013 Copyright 2013 UC Center for Environmental Implications of Nanotechnology. The Regents of the University of California. All Rights Reserved. Contact to obtain permission to use copyrighted material. DBI DBI

2 CNTs Made from graphene sheets or carbon containing gas Metal impurities Comparable to asbestos Non biodegradable Bentoncleanair.org

3 CNT Toxicity Increased mortality in Daphnia 1 Increased mortality, reduced fertilization and molting in copepod 2 Increased ventilation rate, gill pathology, and CNT precipitation in rainbow trout 3 Accumulate in Daphnia 4 and rainbow trout 3 1 Roberts et al 2007, 2 Templeton et al 2006, 3 Smith et al 2007, 4 Petersen et al 2009

4 CNT Quantification Techniques Technique Microscopy Raman Spectroscopy Infrared imaging Thermogravimetric Radio labeling Potential issues Alteration of CNTs Expense of synthesis Quantitative? No Semi Semi Semi Yes 1 Roberts et al 2007, 2 Templeton et al 2006, 3 Smith et al 2007, 4 Petersen et al 2009

5 What about the metals? CoMoCat Cobalt/Molybdenum ARC Yttrium/Nickel Purified ARC CNTs contain ~ 0.16% Y and 0.58% Ni Synthesized from carbon containing gas = δ 13 C CNTs 35.5

6 Purpose Utilize inherent properties (metals content and 13 C) of purified CNTs to quantify uptake and excretion in a marine mussel to help explain toxicity results Predictions: 1) Mussels will decrease feeding rate in the presence of CNTs 2) Decreased feeding will lead to decreased growth 3) Mussels will deposit CNTs in feces and pseudofeces (biodeposits) and accumulate CNTs

7 Mytilus galloprovincialis Sentinel organisms Large groups that support diverse community Prey for fish, gastropods, birds, mammals Filter feeders (>1L/hr) Maricultured globally Indicators of pollution Concentrate and accumulate contaminants

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9 Methods Expose mussels to CNTs over 4 weeks 0, 1, 2, and 3 mg L -1, with feed, water changed every other day 5 cups / concentration 1 mussel / cup 3 cm shell length Collect biodeposits/mussels, measure feeding weekly Analyze 13 C and Y and Ni content Use mixing model and CNT [metals] to estimate [CNT]

10 Results 1) Mussels will decrease feeding rate in the presence of CNTs Feeding rate (% phytoplankton min -1 ) CNT exposure (mg L -1 ) Feeding = (CNT) p < 0.05, r 2 = 0.08

11 Results 2) Decreased feeding will lead to decreased growth 0.08 Growth rate (mm day -1 ) CNT exposure (mg L -1 ) p > 0.1, r 2 < 0.01

12 Results [CNT] via [Metals] CNTs ~ 0.16% Yttrium 3) Deposition and accumulation of CNTs CNTs ~ 0.58% Nickel

13 Results [CNT] via 13 C δ 13 C CNTs 35.5 Tissue 19 Feed 30

14 Results Metal Leeching

15 Summary Increasing CNT exposure resulted in: Decreased feeding rate (24%) Increased deposition and accumulation of CNTs (138,000 μg g -1, 600 μg g -1 ) No impact on growth rate Able to quantify CNT rejection and accumulation via metal concentration and 13 C content

16 Acknowledgements Funding: CEIN (EPA, NSF), Center for Nanotechnology in Society (CNS), Taylor Shellfish Farms, Bren School UCSB, Materials Research Lab UCSB, Marine Science Institute UCSB Ashley Wachtell, Jon Conway, Tyronne Martin, Ivy Ji This material is based upon work supported by the National Science Foundation and the Environmental Protection Agency under Cooperative Agreement Number DBI and DBI Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Environmental Protection Agency. This work has not been subjected to EPA review and no official endorsement should be inferred.

17 Tissue Yttrium (mg g -1 ) Biodeposits Yttrium (mg g -1 ) Results 138 mg CNTs g CNTs ~ 0.16% Yttrium Viscera Remaining tissue CNT exposure (mg L -1 ) 0.65 mg CNTs g CNT exposure (mg L -1 ) 0.2 mg CNTs g -1