Fig. 3.

In vitro cellular uptake of IR820-SS-CPT NPs. A LSCM images of 4T1 cells incubated with IR820 or IR820-SS-CPT NPs for 0.5, 2, and 4 h. Red represents the fluorescence of IR820 (scale bar = 20 µm). The wavelength of excitation laser was set at 633 nm. B Flow cytometry analysis of 4T1 cells incubated with free IR820 and IR820-SS-CPT NPs for 0.5, 2, and 4 h. C Mean fluorescent intensity of free IR820 and IR820-SS-CPT NPs internalized by 4T1 cells after incubation for 0.5, 2, and 4 h