DCs were generated as previously described.27 (link) Briefly, bone marrow cells obtained from mouse femurs were cultured in 6-well plates (5×106 cells/well) in culture medium supplemented with 40 ng/mL granulocyte macrophage-colony stimulating factor and 40 ng/mL IL-4 (both from CreaGene, Seongnam, South Korea). After 3 days, the non-adherent cells were removed by gently shaking the dish and then replacing the medium. On day 4, the non-adherent cells were again removed by the same method. On day 6, half the culture medium was replaced with fresh medium. To induce maturation, DCs were exposed to 50 ng/mL interferon (IFN)-γ and 50 ng/mL tumor necrosis factor (TNF)-α (both from PeproTech Inc., Rocky Hill, NJ, USA), or treated with the indicated NPs for 48 h. The DCs were harvested by gentle pipetting on day 8.