Mechanisms of toxicity by carbon nanotubes

Abstract

Carbon nanotubes (CNTs) consist of a family of carbon built nanoparticles, whose biological effects depend on their physical characteristics and other constitutive chemicals (impurities and functions attached). CNTs are considered the twenty first century material due to their unique physicochemical characteristics and applicability to industrial product. The use of these materials steadily increases worldwide and toxic outcomes need to be studied for each nanomaterial in depth to prevent adverse effects to humans and the environment. Entrance into the body is physical, and usually few nanoparticles enter the body; however, once there, they are persistent due to their limited metabolisms, so their removal is slow, and chronic cumulative health effects are studied. Oxidative stress is the main mechanism of toxicity but size, agglomeration, chirality as well as impurities and functionalization are some of the structural and chemical characteristic contributing to the CNTs toxicity outcomes. Among the many toxicity pathways, interference with cytoskeleton and fibrous mechanisms, cell signaling, membrane perturbations and the production of cytokines, chemokines and inflammation are some of the effects resulting from exposure to CNTs. The aim of this review is to offer an up-to-date scope of the effects of CNTs on biological systems with attention to mechanisms of toxicity.

Applicability of rat precision-cut lung slices in evaluating nanomaterial cytotoxicity, apoptosis, oxidative stress, and inflammation

“…Mechanisms of action reported for MWCNT are 'frustrated phagocytosis' (i.e. stiff, non-degradable MWCNT overwhelming the phagocytic capacity of tissue macrophages thereby causing chronic tissue inflammation) and DNA oxidative injury, generation of ROS due to the metal impurities trapped inside the carbon nanotubes, pro-inflammatory effects due to oxidant injury, and pro-fibrogenic responses, and the intensitiy of these effects is reported to change with differing fiber sizes (Damoiseaux et al, 2011;Meng et al, 2009;Nel et al, 2009Nel et al, , 2013aRodriguez-Yanez et al, 2013).…”

“…Physico-chemical properties of nanomaterials that have been recognized to influence their inhalability, deposition efficiency, and toxicology are their airborne and hydrodynamic size, size distribution, shape (and aspect ratio), their state of agglomeration, surface properties and functionalization (surface area, porosity, charge, reactivity, chemistry/ coatings, contaminants), as well as solubility and crystallinity (Kuempel et al, 2012;Nel et al, 2013a;Oberdörster, 2009;Oberdörster et al, 1994;Rodriguez-Yanez et al, 2013;Zhu et al, 2013). Also in in vitro cytotoxicity assays, particle size, surface chemistry and coating, as well as chemical composition have been recognized as key determinants of nanoparticle adverse effects (Feltis et al, 2012;Horev-Azaria et al, 2011;Kroll et al, 2011).…”

Multi-walled carbon nanotube dispersion by the adsorbed humic acids with different chemical structures

“…Many studies have observed CNTs to be toxic in a number of ways, such as inducing pulmonary toxicity (Lam et al, 2006), inhibiting root growth and elongation (Canas et al, 2008) as well as generating oxidative stress (Rodriguez-Yanez et al, 2013). Strong associations between CNTs and various pollutants significantly alter the bioavailability and toxicity of both CNTs and associated pollutants (Sheng et al, 2010).…”

Therapeutic applications of low-toxicity spherical nanocarbon materials

“…141 It is proposed that the geometry and agglomeration of carbon nanotubes, in addition to their metallic impurities, contribute to their toxicity. 142 Still, we should be cautious to believe that spherical nanoparticles are always safer than tubular structures because the toxicological properties of nanomaterials are very complicated and depend on many different factors. Nonetheless, many current studies on spherical nanocarbon materials support the idea that the spherical shape may be advantageous in many biological systems.…”