Fig. 5

Microscopic examination of cellular internalization of 500 nm PLGA nanoparticles in monoculture and co-cultured cells. Single type of cells or mixed cells was treated with 500 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, h) with particles observed at the green channel and cell nuclei in the blue channel after stained with Hoechst. Massive cellular ingestion of 500 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 cells (red arrows). In the co-culture system, 500 nm PLGA nanoparticles were still highly uptake by macrophages, while cancer cells had inadequate particle internalization