In vitro toxicity of carbon nanotubes, nano-graphite and carbon black, similar impacts of acid functionalization

Abstract

Carbon nanotubes (CNT) and nano-graphite (NG) are graphene-based nanomaterials which share exceptional physicochemical properties, but whose health impacts are unfortunately still not well understood. On the other hand, carbon black (CB) is a conventional and widely studied material. The comparison of these three carbon-based nanomaterials is thus of great interest to improve our understanding of their toxicity. An acid functionalization was carried out on CNT, NG and CB so that, after a thorough characterization, their impacts on RAW 264.7 macrophages could be compared for a similar surface chemistry (15 to 120 μg·mL(-1) nanomaterials, 90-min to 24-h contact). Functionalized nanomaterials triggered a weak cytotoxicity similar to the pristine nanomaterials. Acid functionalization increased the pro-inflammatory response except for CB which did not trigger any TNF-α production before or after functionalization, and seemed to strongly decrease the oxidative stress. The toxicological impact of acid functionalization appeared thus to follow a similar trend whatever the carbon-based nanomaterial. At equivalent dose expressed in surface and equivalent surface chemistry, the toxicological responses from murine macrophages to NG were higher than for CNT and CB. It seemed to correspond to the hypothesis of a platelet and fiber paradigm.

Preparation and Characterization of Polypropylene/Carbon Nanotubes (PP/CNTs) Nanocomposites as Potential Strain Gauges for Structural Health Monitoring

“…However, even if the electrical conductivity of cementitious materials is significantly increased while maintaining or even improving their mechanical properties, their implementation is limited due to several environmental factors (such as humidity and temperature) affecting the measurement [26][27][28][29][30]. Moreover, the huge amount of fillers to be used in the bulk matrix as well as, the potential toxicity of functionalized CNTs when mixed on-site [31], discourages their diffusion. For this reason, a viable strategy can be the use of polymer/CNTs nanocomposites as sensing materials.…”

Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs)

“…Membrane damage assessed by the lactate dehydrogenase (LDH) leakage assay was only induced by the pristine and -COOH MWCNTs. No significant reduction in cell viability was observed at concentrations deemed environmentally relevant (b1 ppm; Figarol et al, 2015). DNA damage was observed for all MWCNTs tested, with induction increased in functionalized exposures.…”

“…DNA damage was observed for all MWCNTs tested, with induction increased in functionalized exposures. Overall, acid functionalization of the MWCNTs frequently, but not always, resulted in greater toxicity (Figarol et al, 2015;Dong et al, 2012;Wang et al, 2012).…”

“…Due to the various physicochemical properties of CNTs, it is necessary to fully characterize them before their toxicity can be evaluated (Figarol et al, 2015). To date, limited few studies have attempted to compare consequences of surface modifications and surface chemistries of MWCNTs in vitro.…”

“…More notably, surface modifications have been shown to affect exposure and toxicity of MWCNTs (Ursini et al, 2012;Figarol et al, 2015). Understanding how chemical and physical modifications influence MWCNT toxicity is necessary to accurately assess risks associated with exposure to these and other CNTs (Ursini et al, 2012).…”