Fig. 3
A–D Confocal microscopy images of NSC34 (A, B) and MCF7 (C, D) cells cultured on glass coverslips or on PAN/G10 membranes and counterstained with FITC-conjugated Phalloidin to reveal F-actin distribution. E, F Morphometric analysis of MCF7 and NSC34 cells 2 days after culture on glass coverslips (Ctrl) or on PAN/G10 membranes. Fluorescence images were taken from cells counterstained with Phalloidin-FITC and the surface area (E) and the shape factor (F) were measured from at least 50 cells of each experimental group. Bars represent means ± SD. G Apoptosis assay was performed by using TUNEL staining of MCF7 and NSC34 cells grown for 2 days on glass coverslips (Ctrl) or on PAN/G10 membranes. Cells were counterstained with DAPI (red signal) and the percentage of TUNEL-positive cells (green signal) was calculated. A detail of a normal nucleus and a typical apoptotic TUNEL-positive cell are shown. Bars represent mean ± SD. H Schematic depiction of the points A and B (separated by 70 μm in distance over the membrane surface) and altitudes (with the laser focusing at Z = 0 μm meaning at the level of the membrane surface and at Z = 15 μm over the membrane surface level) where Raman spectra were acquired for a PAN/G10 membrane with MCF7 clusters formed on top after 2 days of cell culture. I, J Raman spectra of the point A and B, respectively. I Point A spectrum shows a region of the membrane surface (Z = 0 μm) with low concentration of graphene (G band) relative to polymer (CN peak intensity). Characteristic bands representative of biomolecules present on cells are not detected at Z = 15 μm in point A. J Point B spectra at Z = 0 μm is representative of a region with high agglomeration of graphene (low ICN/IG ratios) where, otherwise, at Z = 15 μm typical bands of biomolecules in cells were clearly appreciated. *p < 0.05, **p < 0.005, ***p < 0.0005, n.s: not significant. Scale bars: 10 µm (A–D and G)