Biochemical and histopathological evaluation of functionalized single-walled carbon nanotubes in Swiss-Webster mice

With their unique physicochemical properties, single-walled carbon nanotubes (SWCNTs) have many potential new applications in medicine and industry. A biomedical application of single-wall carbon nanotubes such as drug delivery requires a fundamental understanding of their fate and toxicological profile after administration. However, the toxicity of SWCNT is barely known when they are introduced into the blood circulation, which is especially vital for their biomedical applications. The aim of this study was to assess the effects, after intraperitoneal injection, of functionalized SWCNTs (carboxyl groups) on reactive oxygen species (ROS) induction and various hepatotoxicity markers (ALT, AST, ALP, LPO and morphology of liver) in the mouse model. We exposed mice to three different concentrations of functionalized SWCNTs (0.25, 0.5 and 0.75 mg kg⁻¹ b.w.) and two controls (negative and positive). Samples were collected 24 h after the last treatment following standard protocols. Exposure to carboxylated functionalized SWCNT induced ROS and enhanced the activities of serum amino-transferases (ALT/AST) and alkaline phosphatases (ALP) and the concentration of lipid hydroperoxide compared with control. Histopathology of the exposed liver showed a statistically significant effect in the morphological alterations of the tissue compared with controls. The cellular findings reported here do suggest that purified carboxylated functionalized SWCNT has the potential to induce hepatotoxicity in Swiss-Webster mice through activation of the mechanisms of oxidative stress, which is of sufficient significance to warrant in vivo animal exposure studies. However, more studies to clarify the role of functionalization in the in vivo toxicity of SWCNTs are required and parallel comparison is preferred.