In vivo Biodistribution

For In vivo biodistribution experiments, tumors were allowed to develop for 2 to 3 weeks until they were at least 200 mm³ in volume. Tumor-bearing mice were randomized into 2 groups (n = 3 for each group). They were intravenously injected with 0.1 mmol/kg (equivalent to Gd) of Gd-Dox@PEG/PCL -cy5.5 (group 1) or Anti-Gd-Dox@PEG/PCL -cy5.5 (group 2) via tail vein. At 1, 2, 4, and 24 h after the injection, tumor-bearing mice were anaesthetized at a vaporizer and in vivo fluorescence imaging was performed using an in-vivo optical imager (InVivo Smart-LF, VIEWORKS Co., KOREA). At 24 h after injection, mice were euthanized, and ex vivo fluorescence images of various organs (heart, liver, lung, kidney, and spleen) and excised tumors were acquired using in vivo optical imager. All of the fluorescence images were adjusted to optimal threshold for displaying tumors.