Fig. 3
Cell uptake of Rubipy-SiO2 NPs observed by TEM. TEM images were obtained after 6 h exposure of CaCo-2 cells to 30 and 80 nm Rubipy-SiO2 NPs, either freshly added to cell medium or pre-incubated in the complete medium for 24 h (agglomerates); on the images we can observe clusters of NPs (black arrows), endosomes (E) and lysosomes (L) containing NPs, membrane ruffling typical for macropinocytosis (M), membrane invaginations (Asterisk). Note the flask-shaped endosomes on the right-bottom image (80 nm aggl)