Figure 2

Analysis of the particle uptake by the epithelial cells (STC-1, BNL CL.2) as a function of size and concentration. Analysis was performed using confocal laser scanning microscopy (CLSM, A), scanning electron microscopy (SEM, B), and flow cytometry (C,D). (A) Size and number of added particles per cell: 0.2 µm: 750,000, 0.5 µm: 48,000, 1 µm: 2000, 2 µm: 700, 3 µm: 200, 6 µm: 25. Actin filaments were stained with rhodamine-phalloidin (red), nuclei were stained with DAPI (blue); FITC-fluorescent MPP are shown in green. Scale bars: 40 µm. (B) Representative SEM images are shown for each cell line in the presence of 2 µm MPP. Additional images are shown in Supplementary Fig. S2. Scale bars: 4 µm. (C,D) Results of flow cytometry measurements of STC-1 (light color) and BNL CL.2 (dark color) at low (C) and high (D) particle concentrations. The added number of particles per cell are given in the graph as p/c. No data are available for 0.2 and 0.5 µm particles due to lacking resolution of the flow cytometer. Data represent mean ± SD, n = 3. Stars represent statistically significant data points (p < 0.05) between both cell lines. For better clarity, no differentiation of significance level is shown.