title: Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs).
abstract: Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics-based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100ng/mL of MWCNTs for 24 and 48h; MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for (1)H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure experiments were extremely low (i.e. [Ni]≤2×10(-10)g/mL). Preliminary data suggested that MWCNT exposure causes perturbations in biochemical processes involved in cellular oxidation as well as fluxes in amino acid metabolism and fatty acid synthesis. Dose-response trajectories were apparent and spectral peaks related to both dose and MWCNT dispersion methodologies were determined. Correlations of the significant changes in metabolites will help to identify potential biomarkers associated with carbonaceous nanoparticle exposure.
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA, United States. Electronic address: Henderson.Matt@epa.gov.
authors.forename: W Matthew
authors.initials: WM
authors.lastname: Henderson
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA, United States.
authors.forename: Dermont
authors.initials: D
authors.lastname: Bouchard
authors.affiliation: Grantee to U.S. Environmental Protection Agency via National Research Council Cooperative Agreement, Athens 30605, GA, United States.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Chang
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 Martin Luther King Dr. W, Cincinnati, OH 45268, United States.
authors.forename: Souhail R
authors.initials: SR
authors.lastname: Al-Abed
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA, United States.
authors.forename: Quincy
authors.initials: Q
authors.lastname: Teng
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D004781:Environmental Exposure; D004784:Environmental Monitoring; D056945:Hep G2 Cells; D006801:Humans; D055442:Metabolome; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000633:toxicity*; D010084:Oxidation-Reduction; D010316:Particle Size; D013054:Spectrophotometry, Atomic; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D015415:Biomarkers; D037742:Nanotubes, Carbon; D013501:Surface-Active Agents
keywords: Biomarker profiling; Carbon nanotubes; Liver toxicity; MWCNT suspension; Metabolomics