Fig. 3: TTAP NPs-mediated synergistic immunotherapy.

a A schematic illustration of the in vivo study of TTAP NPs-mediated prodrug photoactivation with checkpoint blockade the α-PD-L1 antibody to realize synergistic immunotherapy in a bilateral model of 4T1 tumor-bearing BALB/c mice. The right-side tumor stands for primary tumor meanwhile the left side tumor stands for distant tumor or “metastatic tumor”. b A schematic illustration of the experimental immunotherapy process. At first, the 4T₁ cells were seeded at both right back and left back of mice. When the right-side tumor volume reached to 100 mm³, the TTAP NPs was injected into the right-side tumor, which was then illuminated by NIR LED (20 mW cm⁻², 650 nm). This day was called as Day 1. At Day 7–9, the α-PD-L1 was intraperitoneally (i.p.) injected for mice of groups 3 and 6. Finally, the tumor of mice was isolated on Day 15. c The growth curves of primary tumors. d The growth curves of distant tumors. The red arrow stands for i.p. injection α-PD-L1 for groups 3 and 6 at 7th, 8th, and 9th day. e The primary tumor weight of mice. f The distant tumor weight of mice. “G” is the abbreviation of group, values are means ± s.e.m. (n = 5 mice per group). ^*p < 0.05, ^**p < 0.01, and ^***p < 0.001.