2.14. Antitumor Efficacy In Vivo

To investigate the antitumor efficacy of DTX/RGD NPs in vivo, the in vivo 4T1 breast tumor model was established. The female BALB/c mice were subcutaneously injected with 5 × 10⁵ 4T1 cells into the fourth mammary fat pad. Five days after inoculation, tumor-bearing mice were randomly divided into 5 groups (n = 6) and treated with saline, blank NPs, DTX, PLGA NPs or DTX/RGD NPs via vein at a dose of 5 mg/kg DTX every four days for five times. The tumor volumes and body weights were measured every 2 days. The tumor volumes of the mice were measured and calculated using the following formula: V = 1/2 (L × W²), in which L (length) is the longest diameter and W (width) is the shortest diameter perpendicular to length. After the termination of the therapy, all mice were sacrificed, and the tumors and lungs were collected for photo imaging, weighing and histopathologic examination. The remaining tumors were homogenized, and the DTX concentration in the tumors was determined using LC-MS/MS (AB SCIEX Qtrap5500, Shimadzu, Kyoto, Japan).