Cytotoxicity of carbon nanotube variants: A comparativein vitroexposure study with A549 epithelial and J774 macrophage cells

Abstract

While production of engineered carbon nanotubes (CNTs) has escalated in recent years, knowledge of risk associated with exposure to these materials remains unclear. We report on the cytotoxicity of four CNT variants in human lung epithelial cells (A549) and murine macrophages (J774). Morphology, metal content, aggregation/agglomeration state, pore volume, surface area and modifications were determined for the pristine and oxidized single-walled (SW) and multi-walled (MW) CNTs. Cytotoxicity was evaluated by cellular ATP content, BrdU incorporation, lactate dehydrogenase (LDH) release, and CellTiter-Blue (CTB) reduction assays. All CNTs were more cytotoxic than respirable TiO2 and SiO2 reference particles. Oxidation of CNTs removed most metallic impurities but introduced surface polar functionalities. Although slopes of fold changes for cytotoxicity endpoints were steeper with J774 compared to A549 cells, CNT cytotoxicity ranking in both cell types was assay-dependent. Based on CTB reduction and BrdU incorporation, the cytotoxicity of the polar oxidized CNTs was higher compared to the pristine CNTs. In contrast, pristine CNTs were more cytotoxic than oxidized CNTs when assessed for cellular ATP and LDH. Correlation analyses between CNTs' physico-chemical properties and average relative potency revealed the impact of metal content and surface area on the potency values estimated using ATP and LDH assays, while surface polarity affected the potency values estimated from CTB and BrdU assays. We show that in order to reliably estimate the risk posed by these materials, in vitro toxicity assessment of CNTs should be conducted with well characterized materials, in multiple cellular models using several cytotoxicity assays that report on distinct cellular processes.

Chemical and Toxicological Evolution of Carbon Nanotubes During Atmospherically Relevant Aging Processes

“…Bottini et al 65 found that MWCNTs oxidized by concentrated HNO 3 exhibited a stronger cytotoxic effect to human T lymphocytes than fresh MWCNTs. Kumarathasan et al 8,9 also observed an increase in cytotoxicity (A549 and J774 cells) for CNTs oxidized by a 3:1 (v/v) mixture of H 2 SO 4 /HNO 3 . In those studies, the increase in toxicity was attributed to surface modification (carboxylic acids) which resulted in a transformation from hydrophobic to hydrophilic CNTs.…”

“…Detailed descriptions of these assays are given elsewhere. 8,9 Functional Group Characterization of SWCNT. Functional groups were characterized before and after oxidant/ambient air exposures by Fourier transform infrared (FTIR) spectroscopy.…”

Differential cytotoxic and inflammatory potency of amorphous silicon dioxide nanoparticles of similar size in multiple cell lines

“…The total acidity of the surface of SiNPs was quantified following the acid-base titration procedure reported earlier (Eitan et al, 2003;Kumarathasan et al, 2015).…”

“…The cytotoxicity of SiNPs was assessed using the integrated bioassay which enabled the analysis of the redox state (resazurin reduction), energy metabolism (cellular ATP) and cell membrane integrity (LDH release) and was conducted as previously described (Kumarathasan et al 2015). Cell proliferation was assessed separately, using the BrdU incorporation assay.…”

Role of microRNA-4458 in patients with non-small-cell lung cancer

“…The cells (50 µl) were transferred to an opaque white plate (Beyotime Institute of Biotechnology) at 24, 48 and 72 h. The fluorescence value was tested using a fluorescence luminometer (F97Pro; Shanghai Lengguang Technology Co. Ltd, Shanghai, China). Relative proliferative activity = appreciation rate of fluorescence value of treatment group / appreciation rate of fluorescence value of control group (28). qPCR assay.…”