Blood and tissue pharmacokinetics of Zol in Zol-Ca@bi-lipid NPs. Mice were i.v. injected with Zol-Ca@bi-lipid NPs or free Zol with an equivalent amount of Zol (with 2% Zol-AF647) and euthanized 0.5, 2.5, 6 or 24 h after injection. Fluorescence intensity in blood, right hind leg bone, and major organs were measured. The results are expressed as values after subtracting mean values from the PBS group. (A) Blood, (B) leg bone, (C) fluorescent images of the right rear leg bone and major organs from mice euthanized 24 h after i.v. injection, (D) kidneys, (E) liver, and (F) spleen. Data are mean ± S.D. (n = 3, * p < 0.05, ** p < 0.01).