Fig. 2

Cellular uptake and cancer cell-specific cytotoxicity of F68-FDOX. a The cathepsin B expression levels in the HT29, MDA-MB231, KPC960 and H9C2 cells. b Cellular uptake of FRRG-DOX, F68-FDOX and DOX in the HT29, MDA-MB231, KPC960 and H9C2 cells after 48 h of incubation. c Quantitative analysis for the amount of F68-FDOX in the cytosol or nucleus in different cells after 48 h of incubation. d Fluorescence images of HT29 cells labeled with Rab5a-RFP (endosomes) or Lamp1-RFP (lysosomes) after 48 h of F68-FDOX treatment. e, f The cell viability of HT29, MDA-MB231, KPC960 and H9C2 cells after 48 h treatment with e F68-FDOX or f DOX. g The IC50 values of F68-FDOX and DOX in the HT29, MDA-MB231, KPC960 and H9C2 cells. Significance was determined by Tukey − Kramer post-hoc test