Fig. 4.

Toxicity and permeability of Lf-PEG-AuNP through the intestinal Caco-2 cell monolayer and endothelial cells. (a) Morphology of the intestinal Caco-2 cells and human umbilical vein endothelial cells (HUVECs) after treatment of AuNP or Lf-PEG-AuNP for 24 h. Magnification: × 100. Scale bar: 100 μm. (b) The viability of Caco-2 cells and HUVECs after treatment of AuNP or Lf-PEG-AuNP for 24 h. Data were expressed as means ± SEM (n = 6). (c) TEER values through Caco-2 cell monolayer after treatment of each group for 24 h. Data were expressed as means ± SEM (n = 3). (d) TEM images of the Caco-2 cell monolayer after AuNP and Lf-PEG-AuNP. Orange arrows: Lf-PEG-AuNP through LfR endocytosis. Scale bar: 500 nm. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)