Physicochemical and biological characterization of oxidized multi-walled carbon nanotubes on HepG2 liver cells

Functionalization of multi-walled carbon nanotubes (MWCNTs) is a growing area in the field of materials with biological applications; due that their surface characteristics could determine their biocompatibility and therapeutic uses. This research is focused on the evaluation of the effect of oxidized MWCNTs on the cell cultures of a hepatic carcinoma cell line (HepG2). Pristine MWCNTs (p-MWCNT) with an external diameter of 8–15 nm and a length in the range of 10–50 μm were oxidized with (a) nitric acid/hydrogen peroxide, (b) nitric acid, and (c) nitric acid/sulfuric acid solutions, and their physicochemical properties and biological effects were examined. The findings demonstrated that MWCNT oxidation produced different surface moieties and structural changes depending on the oxidation process, in particular, the oxidation with nitric acid/sulfuric acid generates a high grade of cell toxicity compared to the other types of oxidized MWCNTs. Interestingly, the p-MWCNTs exhibited slight cytotoxic and genotoxic effects but without affecting cell viability, which requires further analysis. The results open the possibility of using oxidized MWCNT with nitric acid/sulfuric acid to promote cytotoxic effects on cancer cells, as well as to explore different oxidative methods in medical applications.