In vivo Near-Infrared Imaging and Biodistribution

The tumor-bearing BALB/c nude mice model was prepared through the subcutaneous injection of 0.1 mL HepG2 cell suspension (5 × 10⁷ cells/mL) into the right sides of their backs. For the in vivo distribution, tumor-bearing mice were randomly assigned to two groups with three mice per group: ICG and MLPs. ICG and MLPs were administered in amounts of 200 μL through the tail vein. In vivo near-infrared imaging was taken using an IVIS Lumina XR Imaging System (Caliper Life Sciences, PerkinElmer, Inc.). To further monitor tumor accumulation, mice were anesthetized with 1.5% isoflurane at 1:2 O₂/N₂; the IVIS imaging system (excitation of 745 nm) was used to view the tumor accumulation profile. Mice were sacrificed after 24 h and the tumor, heart, liver, kidney, lung, and spleen were excised. These organs were also imaged at the aforementioned excitation wavelength.