Carbon nanotubes have distinctive and remarkable material properties,different from bulk materials with the same chemical composition, and potentialtechnological applications, including those in biology and medicine (He et al., 2013; Prylutska et al., 2013; Guo et al., 2017;Harvey et al., 2017). These nanotubes have recently emerged as a newoption for cancer treatment, bioengineering, as well as gene therapy, butinconsistent data on cytotoxicity and limited control over functionalizedcarbon nanotubes behavior currently restrict predictability of such applications(Firme and Bandaru, 2010).
Carbon nanotubes have ahighly hydrophobic surface and a non-biodegradable nature that contributes totheir reduced biocompatibility, limiting their biomedical applications, withgrowing concerns about their chronic toxicity (Prylutska et al., 2008; Tejral etal., 2009; Yang et al., 2009; Minchenko et al., 2016; Kobayashi et al., 2017). It wasreported that different variants of these nanotubes exhibit different toxicity both in vitro and in vivo andthat intratracheal administration of single-walled carbon nanotubes (SWCNTs)resulted in inflammation (Uo et al.
, 2011). The toxicity of carbon nanotubes is attributed totheir physicochemical properties, including structure, length and aspect ratio,surface area, degree of aggregation, extent of oxidation, surface topology,bound functional groups, concentration, and dose offered to cells or organisms (Tejral et al., 2009; Uo et al., 2011). It isinteresting to note that carbonnanotubes can elicit toxicity through numerous mechanisms: membrane damage, DNAdamage, oxidative stress, changes in mitochondrial activities, alteredintracellular metabolic routes, and protein synthesis Yuan et al., 2011, 2012; Shvedovaet al.
, 2012; Ahmadi et al., 2017; Guo et al., 2017). Recently, it wasshown that functionalized SWCNTs induce oxidative stress in human circulating leukocytes (Kermanizadeh et al., 2018). However,their cytotoxicity is significantly controversial, with a large number ofstudies reporting altered toxic responses to SWCNTs both in vitro and in vivo (Uo et al., 2011).