Single walled carbon nanotubes in high concentrations is cytotoxic to the human neuronal cell LN18

Single walled carbon nanotubes have been used in biological applications for targeted drug delivery, and as scaffolds for regeneration and diagnosis of diseases due to their excellent properties. However, their extensive application in biology is stifled by toxicity issues. The present study focuses on the effect of pristine single walled carbon nanotubes (P-SWCNT) and carboxylic functionalized single walled carbon nanotubes (C-SWCNT) on the human neuronal cell line LN18 at concentrations of 5, 10, 20, 40 µgmL-1 and time durations of 0-48 h. Cytotoxicity was evaluated by measuring the viability using Trypan Blue, MTT, and Live Dead Cell Assays, and oxidative stress was evaluated by the ROS and Lipid Peroxidation Assays. The IC70 values as measured by the cell viability assay at 12 h were found to be 20 and 10 µgmL-1 for P-SWCNT and C-SWCNT respectively. A significant amount of ROS was produced with P-SWCNT and C-SWCNT at 40 µgmL-1 and 6 h incubation onwards. At 24 and 48 h, a three-fold increase in MDA concentration was observed at 40 µgmL-1 of P-SWCNT and C-SWCNT and was measured to be 0.814±0.0042 nM. Analysis of the cellular outcomes revealed that the toxicity of P-SWCNT and C-SWCNT was dose-time dependent with higher toxicity observed for the latter as compared to the former. Hence, it can be concluded that P-SWCNT and C-SWCNT are toxic to LN18 cells at higher concentrations.