Biodistribution on Day 10 after 4T1 cells inoculation and tumor targeting capacity of different preparations. (A) Fluorescent images of tumors and major organs at 1, 8, 24 h after the administration of DOX, DD/DOX or FD/DOX. (B) Semiquantitative analysis of mean fluorescence intensity of tissues at 24 h after the administration. Data are presented as mean ± SD (n = 3), ∗∗P < 0.01, ∗∗∗P < 0.001. (C) The amount of DOX in tumors and major organs quantified by LC‒MS at 24 h after the administration. Data are presented as mean ± SD (n = 3), ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001. (D) Fluorescent images of tumor sections at 24 h after the administration. Green: DOX; blue: DAPI for staining cell nucleus. Scale bar = 100 μm. (E) Fluorescent images of blood collected from tumor-bearing mice at 1, 8, 24 h after the administration. (F) Semiquantitative analysis of mean fluorescence intensity of blood at 1, 8, 24 h after the administration. Data are presented as mean ± SD (n = 3), ∗∗P < 0.01, ∗∗∗P < 0.001.