Fig. 3
The cellular uptake, endosomal escape and cytotoxicity of SFN1/BQR1@MSPION3. a, CLSM images of 4T1 cells showing intracellular uptake of R6G@MSPION3 and R6G@SFN/BQR1@MSPION3 at 4.0 h time point. Green fluorescence: FITC-Phalloidin for cytoskeleton. Red fluorescence: R6G for nanoparticles. Blue fluorescence: DAPI for nuclei. b, CLSM images of 4T1 cells treated without or with R6G@MSPION3 or R6G@SFN/BQR1@MSPION3 for 4.0 h, showing lysosomal escape of the nanoparticles. Green fluorescence: Lysotracker Green for lysosomes. Red fluorescence: R6G for nanoparticles. Blue fluorescence: DAPI for nuclei. c, TEM images of 4T1 cells treated with SFN/BQR1@MSPION3 for 4.0 h, indicating escaped MSPION3 from lysosomes (red arrows) and remaining (yellow arrows) MSPION3 in lysosomes. d, 4T1 cell viabilities after incubation with PBS (control), MSPION3, SFN1@MSPION3, BQR1@MSPION3, or SFN/BQR1@MSPION3 (CFe = 10 µg/mL) for 24 h. e, 4T1 cell viabilities treated with PBS (control), SFN, BQR, SFN + BQR, or SFN/BQR1@MSPION3 (CFe = 10 µg/mL) for 24 h. f, Cell viabilities of 4T1 cells treated with SFN1/BQR1@MSPION3 (CFe = 10 µg/mL) without or with addition of ferroptosis inhibitors including Fer-1 (2.0 µM), DFO (100 µM), or NAC (2.0 mM). g, CLSM images of 4T1 cells with calcein-AM and PI staining incubated with PBS (control), MSPION3, SFN1@MSPION3, BQR1@MSPION3, or SFN/BQR1@MSPION3 (CFe = 10 µg/mL) for 24 h. h, CLSM images of 4T1 cells with calcein-AM and PI staining incubated with PBS (control), SFN, BQR, SFN + BQR, or SFN/BQR1@MSPION3 (CFe = 10 µg/mL) for 24 h. i, Apoptosis of 4T1 cells with Annexin V-FITC/PI double staining after various treatments for 24 h measured by flow cytometry. **P < 0.01