Fig. 1

Cellular uptake of chitosan NCs. a \({\text{M}}{\upphi }{\text{s}}\) were incubated for 4 h with 10, 50, and 100 µg/ml Nile-Red-labelled CS-NCs. Particle internalization was assessed by FACS and the results expressed as the mean fluorescence intensity (MFI). b \({\text{M}}{\upphi }{\text{s}}\) were cultured for 1, 4, or 18 h in the presence of 100 µg/ml fluorescent CS-NCs and particle internalization was quantitatively assessed by FACS. c \({\text{M}}{\upphi }{\text{s}}\) were treated with 100 µg/ml fluorescent CS-NCs (red) for 1, 4, or 18 h and NC internalization visualized by confocal microscopy. DAPI (blue) was used to visualize nuclei. d 100 µg/ml Nile-Red-labelled CS-NC were incubated for 4 h with \({\text{M}}{\upphi }{\text{s}}\), A549 epithelial cells, or HepG2 hepatocytes. NP uptake was quantitatively analyzed by FACS. e \({\text{M}}{\upphi }{\text{s}}\) were incubated with 100 µg/ml fluorescent CS-NCs for 2 h with or without the pharmacological inhibitors nystatin, colchicine, cytochalasin D, or chlorpromazine. NC uptake was analyzed as previously described. Error bars represent the mean ± SD and significant differences between treatments are indicated by an asterisk, in which **p < 0.01 and ***p < 0.001