Confocal microscopic image of A549 cells showing SiO
NP uptake. (A) A549 cells growing on Permanox® chamber slide were incubated with Rhodamine labelled SiO2NP (30 nm) for 24 h. After this time, culture media was carefully removed, cells were washed in PBS and cells were fixed in 3% paraformaldehyde. Nuclei were stained with Hoechst (blue). A representative sample population of cells were visualized by confocal microscopy using a 63 X oil immersion lens. (B) Three dimensional image stacks showing cytosolic accumulation of 30 nm SiO2NP (Z-stack = 27 slices at 0.45 μm per slices, Z-height 12.15 μm), (top image = x-z plane; centre image = x-y plane; right image = y-z plane). (C) Transmission Electron Microscope (TEM) image shows SiO2NP cytoplasmic accumulation, particle size distribution within an A549 epithelial lung cell (magnification 10 x and 120 KeV accelerating voltage).