Figure 2

The cell penetration of FITC-SiO2-COOH NPs in different cell types. (a) The dispersion of FITC-SiO₂-COOH and FITC-SiO₂-NH₂ NPs at two doses after 30 min of incubation with the cell culture medium. (b) The different distributions of two NP types in hUVECs, hFBs, and HeLa cells. The red arrows indicated the localization of NPs outside the cells.