All samples were first

coated with a 35-nm layer of platinum before imaging. The cells were approximately 10 to 25 μm in diameter and heterogeneous in nature. Figure  4A showed what is likely to be variability in surface coating of the platinum layer. When comparing the left and right images of the SNU449 cellular structures in Figure  4A, the left side has what looks like a thicker layer of platinum, which seems to be filling more of the space between adjacent pseudopodia structures. Comparing Figure  4A and Figure  #Evofosfamide purchase randurls[1|1|,|CHEM1|]# 4B, it can clearly be seen that a relatively large structure is protruding out of a SNU449 cell in two locations. These structures appear to be graphite (i.e., multiple stacked SGS) of thickness approximately 500 nm which the cell has internalized. Figure  4C depicts another large nanoplatelet of stacked SGS, which is effectively compressing a Hep3B cell and deforming the cellular structure. Figure  4D and Figure  4E are the most interesting figures since they display evidence of cellular internalization, folding, and compartmentalization buy OSI-906 of SGS. Figure 4 SEM images of the interactions of completely exfoliated SGS and partially exfoliated SGS (i.e., graphite). With the surface of SNU449 (A, B) and Hep3B (C to F) liver cancer cell lines. In Figure  4D, it appears as

if the Hep3B cell is actively internalizing multiple, stacked SGS of height approximately 35 nm, but is most likely a single SGS which looks thicker due to the platinum layer. The folding phenomenon is also evident in Figure  4E where folding of SGS can be seen in the bottom left corner and bottom midsection of the image, as indicated by the white arrows. There is also evidence of slightly

deformed SGS on top of the cellular surface in the upper right-hand section. Finally, Figure  4F depicts the images of both SGS deformation and internalization of large pieces Chloroambucil of graphitic materials. The appearance of pseudopodia over the surface of the SGS is indicated by the red arrows. Cellular internalization of the SGS using microtome high-resolution TEM was then investigated, as shown in Figure  5. Uranyl acetate was used as a negative staining agent. Although single-sheet graphene should appear close to transparent in TEM imaging, we believe visualization of the SGS in the TEM images is due to uranyl ions binding to the functionalized graphene sheets (which would result in a darker image) or that they are stacked graphene layers which are reducing the optical transparency. From the outset, we suspected that there was some cellular internalization of submicron-sized amorphous carbonaceous materials present in the initial graphite material from which the SGS were obtained. Evidence of this can be found in the Additional file 1: Figure S1.