Regulatory Peptides Are Susceptible to Oxidation by Metallic Impurities within Carbon Nanotubes

In this article, we show that the redox properties of the regulatory peptide L-glutathione are affected by the presence of nickel oxide impurities within single-walled carbon nanotubes (SWCNTs). Glutathione is a powerful antioxidant that protects cells from oxidative stress by removing free radicals and peroxides. We show that the L-cysteine moiety in L-glutathione is responsible for the susceptibility to oxidation by metallic impurities present in the carbon nanotubes. These results have great significance for assessing the toxicity of carbon-nanotube materials. The SWCNTs were characterized by Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy.