Liu, Xinyuan and Guo, Lin and Morris, Daniel and Kane, Agnes B. and Hurt, Robert H. (2008) Targeted removal of bioavailable metal as a detoxification strategy for carbon nanotubes. CARBON, 46 (3). pp. 489-500.
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Official URL: http://dx.doi.org/10.1016/j.carbon.2007.12.018
There is substantial evidence for toxicity and/or carcinogenicity upon inhalation of pure transition metals in fine particulate form. Carbon nanotube catalyst residues may trigger similar metal-mediated toxicity, but only if the metal is bioavailable and not fully encapsulated within fluid-protective carbon shells. Recent studies have documented the presence of bioavailable iron and nickel in a variety of commercial as-produced and vendor ``purified'' nanotubes, and the present article examines techniques to avoid or remove this bioavailable metal. First, data are presented on the mechanisms potentially responsible for free metal in ``purified'' samples, including kinetic limitations during metal dissolution, the re-deposition or adsorption of metal on nanotube outer surfaces, and carbon shell damage during last-step oxidation or one-pot purification. Optimized acid treatment protocols are presented for targeting the free metal, considering the effects of acid strength, composition, time, and conditions for post-treatment water washing. Finally, after optimized acid treatment, it is shown that the remaining, non-bioavailable (encapsulated) metal persists in a stable and biologically unavailable form up to two months in an in vitro biopersistence assay, suggesting that simple removal of bioavailable (free) metal is a promising strategy for reducing nanotube health risks. (c) 2007 Elsevier Ltd. All rights reserved.
|Subjects:||Material Science > Functional and hybrid materials|
Risk > Environment, health and safety aspects of nanotechnology
|Deposited By:||Farnush Anwar|
|Deposited On:||23 Dec 2008 15:38|
|Last Modified:||09 Jan 2009 15:04|
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