Fig. 5. Combined extracellular and intracellular photodynamic therapy for improved therapeutic outcome.

a Spatially controllable Ce6/SOG activation of MRITN. Top panel: intracellular Ce6/SOG activation. Cells were incubated with MRITN at 37 °C, followed by the removal of extracellular MRITN. Middle panel: extracellular Ce6/SOG activation. Bottom panel: Combined intracellular and extracellular Ce6/SOG activation. Cells were incubated with MRITN at 4 °C (Middle panel) and 37 °C (Bottom panel) without removal of extracellular MRITN. Scale bar =20 μm. b In vitro cytotoxicity of MRITN with spatially controllable PDT activation. 4T1 cells were irradiated with a 660 nm laser (100 mW cm⁻² for 3 min) at 4 °C under dark conditions (n = 3 biologically independent cell samples). c Flow cytometry analysis of 4T1 cells apoptosis under 660 nm irradiation by spatially controllable PDT therapy. d Quantitative apoptotic percentage of 4T1 cells based on flow cytometry (n = 3 biologically independent cell samples). Statistical analysis by two-sided Student t-test. e Tumor growth curves in subcutaneous 4T1 tumor-bearing mice with different irradiation treatments. Mice were irradiated with 660 nm laser at 400 mW cm⁻² for 10 min at 3 h post-injection of MRITN (Ce6 dose of 0.75 mg kg⁻¹). The PDT treatment was given twice separately at day 1 and day 5 (n = 8 biologically independent mice). Two-way analysis of variance (ANOVA). f Photographic images of excised tumors in different treatment groups at the end of antitumour study. g The survival rates of mice bearing 4T1 tumors after different irradiation treatments (n = 8 biologically independent mice). Survival analysis was performed by the log-rank (Mantel–Cox) test. All data are presented as mean ± s.d.