Effect of single-walled carbon nanotubes on the structural, physical, and mechanical properties of rat glial cell surface

Carbon nanotubes are a very promising class of nanomaterials for biological and medical applications. The work aims at studying the interaction of rat C6 glioma cells with single-walled carbon nanotubes in complex with DNA (DNA-SWCNTs) paying the special attention to the changes in the structural, mechanical, and physical properties of the cell surface layer and the parameters of the DNA-SWCNT accumulation in cells. The properties of cells incubated with DNA-SWCNTs for 1–24 h were studied by atomic force microscopy, patch-clamp method, and Raman spectroscopy. The surface of glioma cells exposed to DNA-SWCNTs for 1 h had invaginations of size similar to the length of nanotubes (100–250 nm). The parameters of sliding friction force measured between the AFM tip and cell surface and the resting membrane potential were significantly reduced during the initial phase of DNA-SWCNT uptake (1–2 h) by cells. With further increase in incubation time (18–24 h), when DNA-SWCNTs were accumulated in the cytoplasm, the friction force parameters increased and became higher than the corresponding parameters for control cells. Using the decision tree algorithm for classification, the difference in the spatial distribution of the cell surface mechanical properties for C6 glioma cells exposed to DNA-SWCNTs during 1 or 24 h was shown with high classification accuracy. Our results prove that endocytosis is the main mechanism of DNA-SWCNT uptake by C6 rat glioma cells. The reorganization of the cell surface layer accompanying nanotube endocytosis leads to changes in the mechanical and physical properties of the cell surface.