Figure 4.

Uptake of trehalose‐loaded nanoparticles by NK cells. A) Viability of NK‐92 cells in the presence of chitosan–TPP nanoparticles. Cells were incubated with various concentrations of nanoparticles, ranging from 0.1 to 8 mg mL⁻¹, at 37 °C in culture media, and the viability of the cells measured over a period of 72 h. B) Confocal imaging of uptake of chitosan:TPP nanoparticles by NK cells. Nanoparticles were loaded with FITC (green), and the cells were stained with propidium iodide (PI, red) to distinguish dead cells. NK cells alone showed no uptake of either nanoparticles of red fluorescence due to PI. Uptake of free FITC (NK + FITC) is seen only for cells which appear to also show red fluorescence, while NK cells incubated with nanoparticles (NK + FITC‐nano) show green fluorescence with no red fluorescence, indicating nanoparticle internalization. Scale bars: 50 µm (top three rows) and 10 µm (bottom row); *p < 0.05, **p < 0.01.