Fig. 4

Microscopic examination of cellular internalization of 100 nm PLGA nanoparticles in monoculture and co-culture cells. Single type of cells or mixed cells was treated with 100 nm PLGA nanoparticles for 24 h at 37 °C at a concentration of 10 µg/mL. Cells were observed under bright-field (a, d, g) and fluorescent channels (b, e, and h) with particles observed at the green channel and cell nuclei in the blue channel after stained with Hoechst. Massive cellular uptake of 100 nm PLGA nanoparticles can be visualized in magnified images (c, f, i) for monoculture THP-1 macrophages (yellow arrows) and laryngeal cancer cells UM-SCC-17A (red arrows). In the co-culture system, 100 nm PLGA nanoparticles were still highly ingested by macrophages but less efficient for cancer cells compared to single cultured cells