ABSTRACT
Objectives: Carbon nanotubes [CNTs] have powerful oxidative properties that influence their biomedical applications. This study addresses the oxidative potential of both single-walled carbon nanotubes [SWCNTs] and multiwalled carbon nanotubes [MWCNTs] by functionalizing them with tannic acid [TA] and gallic acid [GA], and an in vitro evaluation of their antioxidant properties is presented. Their effective role as antioxidants is influenced by their dual functions of reducing toxicity and inducing antioxidant effects
Methods: Functionalization was confirmed by Fourier transform infrared spectroscopy [FTIR], and the total phenolic content was assessed. The antioxidant properties were analyzed by scavenging di[phenyl]-[2,4,6- trinitrophenyl] iminoazanium, lipid peroxidation, reactive oxygen species [ROS] quantification and quenching externally generated hydroxyl and superoxide radicals
Results: The functionalization of nanotubes with antioxidants was conformed via FTIR and measurement of total phenolic compounds. Higher radical scavenging was observed for TA-functionalized SWCNTs than for other functionalizations and MWCNTs. The lipid peroxidation results revealed that the functionalization of nanotubes with the antioxidant TA significantly decreased lipid peroxidation [36%] compared with naked nanotubes [85%] and the positive control [94%]. Furthermore, antioxidant-functionalized nanotubes showed negligible production of ROS after being irradiated under different conditions, and externally generated hydroxyl and superoxide radicals were quenched
Conclusion: This study showed, using in vitro models, that effective functionalization of CNTs with TA and GA leads to remarkable antioxidant properties. Antioxidantfunctionalized nanotubes showed a reduction in cell lethality correlated with negligible ROS production under different irradiation conditions and quenching of externally generated hydroxyl and superoxide radicals. Further, antioxidant-functionalized nanotubes were more compatible with the cell membrane