Fig. 6
4T1 cells were cultured in an ultra-low attachment plate to form tumor spheroids, followed by treatment with different materials in the culture medium over time. (A) The volume of 4T1 tumor spheroids after treatment with PBS (Ctrl), mPDA NPs, mPDA@CuO2 NRs, AbPD−L1-mPDA@CuO2 NRs, AbCD24-mPDA@CuO2 NRs, and dAbPD−L1/CD24-mPDA@CuO2 NRs. Scale bar = 500 μm. (B) In vitro CBIT efficiency tested by blocking PD-L1–PD1 signaling between cancer cells and T cells using dAbPD−L1/CD24-mPDA NPs. (C) Generation of IFN-γ from T cells after co-culturing with 4T1 cells treated with dAbPD−L1/CD24-mPDA NPs. The values are expressed as means ± SD (n = 3). Asterisks indicate a significant difference between the T cells treated and dAbPD−L1/CD24-mPDA NPs + T cells treated groups (Student’s t-test, *p ≤ 0.05). Note: The absence of black and red bars is due to their values being extremely low, almost equivalent to 0