Figure 2

Rapid endosomal escape and subsequent intracellular distribution of nanodiamonds.

(a) Representative confocal microscopy images showing the fluorescent signals of lysotracker/endosome marker (green) and nanodiamonds (red) in HepG2 cells after cell incubation with nanodiamonds in serum-free medium for 1 or 4 hours. The yellow color indicates the overlap between red (nanodiamonds) and green (endosomes/lysosomes). (b) Representative confocal microscopy images showing the intracellular expression of cleaved caspase-3 in HepG2 cells as revealed by their fluorescence intensity (green). The cells treated with normal medium was chosen as control and the positive control could be found in Supplementary Fig. S2. The nuclei were stained by DAPI (blue). (c) TEM images showing the typical intracellular distributions of nanodiamonds in HepG2 cells after their incubation with cells in serum-free medium for 24 hours. (d–f) Representative confocal microscopy images showing the fluorescent signals of (d) nanodiamonds (red) and (e) endosome marker (green) and (f) the overlap image of (d) and (e). (g–i) Representative confocal microscopy images showing the fluorescent signals of (g) nanodiamonds (red) and (h) lysotracker (green) and (i) the overlap image of (g) and (h). (j–l) Representative confocal microscopy images showing the fluorescent signals of (j) nanodiamonds (red) and (k) mitotracker (green) and (l) the overlap image of (j) and (k). (All images were taken from HepG2 cells after their incubation with nanodiamonds in serum-free medium for 24 hours for Fig. 2d–l.)