Proteomic analysis in cells treated with pristine carbon nano-onions and its subcellular localization

Nanoparticles toxicity and cellular uptake are substantial factors that regulate the utility of nanoparticles for biomedical applications in diagnostic imaging and therapy. In this work, the cellular uptake of pristine carbon nano-onions (CNOs) produced by submerged arc discharge was confirmed by transmission electron microscopy (TEM) analysis. Carbon nano-onions were localized within early and late endosomes of human keratinocyte cells. TEM images suggest the possible degradation of these structures, in late endosomes of keratinocyte cells after 24 h. Proteomic shotgun analysis revealed that carbon nano-onions cause statistically significant protein abundance changes in a total of 168 proteins. Most of the differentially expressed proteins are involved in biological processes such as metabolic, cellular and immune system processes. Treated cells showed increased expression of clathrin heavy chain 1, calnexin and isoforms beta/alpha, epsilon and sigma 14-3-3 protein, which are related to clathrin-mediated endocytosis. Thus changes in protein abundance concerning clathrin-mediated endocytosis may suggest this as a plausible way by which the carbon nano-onions intracellular traffic occurs.