Figure 7.

Internalization of TiO₂ P25 and P25/LPS. Raw264.7 cells were preincubated for 1 h in the absence (A,C) or in the presence of cytochalasin B [20 µM (B,D)] and then exposed to P25 [16 µg/ml (A,B)] or P25/LPS [nominal dose 16 µg/ml (C,D)] for further 24 h. At the end of the incubation, cell monolayers were stained with calcein-AM, for cytoplasm and nucleus, and LysoTracker^®, for lysosomes, as reported in “Materials and Methods.” For each condition, a single horizontal confocal section of a representative field is shown. P25 or P25/LPS, white; cells, green; lysosomes, red. The experiment has been performed twice with similar results. Arrows, internalized NP aggregates. Arrowheads, extracellular NP aggregates in contact with the cell membrane. Bar = 20 µm.