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Mechanistic investigations of horseradish peroxidase-catalyzed degradation of single-walled carbon nanotubes.

Authors
Allen-BL; Kotchey-GP; Chen-Y; Yanamala-NV; Klein-Seetharaman-J; Kagan-VE; Star-A
Source
J Am Chem Soc 2009 Dec; 131(47):17194-17205
NIOSHTIC No.
20036298
Abstract
Single-walled carbon nanotubes (SWNTs) have been investigated for a variety of applications including composite materials, electronics, and drug delivery. However, these applications may be compromised depending on the negative effects of SWNTs to living systems. While reports of toxicity induced by SWNTs vary, means to alleviate or quell these effects are in small abundance. We have reported recently the degradation of carboxylated SWNTs through enzymatic catalysis with horseradish peroxidase (HRP). In this full Article, we investigated the degradation of both carboxylated and pristine SWNTs with HRP and compared these results with chemical degradation by hemin and FeCl(3). The interaction between pristine and carboxylated SWNTs with HRP was further studied by computer modeling, and the products of the enzymatic degradation were identified. By examining these factors with both pristine and carboxylated SWNTs through a variety of techniques including atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS), degradation pathways were elucidated. It was observed that pristine SWNTs demonstrate no degradation with HRP incubation but display significant degradation when incubated with either hemin or FeCl(3). Such data signify a heterolytic cleavage of H(2)O(2) with HRP as pristine nanotubes do not degrade, whereas Fenton catalysis results in the homolytic cleavage of H(2)O(2) producing free radicals that oxidize pristine SWNTs. Product analysis shows complete degradation produces CO(2) gas. Conversely, incomplete degradation results in the formation of different oxidized aromatic hydrocarbons.
Keywords
Nanotechnology; Nanotubes; Nanoparticles; Biological-effects; Biochemical-tests; Toxic-effects; Enzymatic-effects; Analytical-chemistry; Microscopy; Chromatographic-analysis; Spectrographic-analysis; Peroxidases
Contact
University of Pittsburgh, Department of Chemistry, Chevron Science Center, 219 Parkman Avenue, Pittsburgh, PA 15260
CODEN
JACSAT
Publication Date
20091202
Document Type
Journal Article
Email Address
astar@pitt.edu
Funding Type
Grant
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-008282
Issue of Publication
47
ISSN
0002-7863
Source Name
Journal of the American Chemical Society
State
PA
Performing Organization
University of Pittsburgh at Pittsburgh
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