Development and biodistribution of 131I-radiolabeled silver-doped indium oxide nanoparticles as a novel nanoplatform for tumor targeting in tumor bearing mice.

Cancer remains a leading global cause of mortality, with approximately 20 million new cases and 9.7 million deaths reported in 2022. Traditional treatments, including chemotherapy and external beam radiotherapy, are often limited by non-specific targeting, systemic toxicity, and resistance. Targeted radionuclide therapy using iodine-131 (131I), which emits both β-particles for therapeutic effects and γ-rays for imaging, offers a promising alternative. This study developed 131I-radiolabeled silver-doped indium oxide nanoparticles (131I-Ag-In2O3 NPs) as a novel nanoplatform for enhanced permeability and retention (EPR) mediated tumor accumulation for radionuclide therapy. For comparison, undoped In2O3 nanoparticles were also radiolabeled with 131I under identical conditions to evaluate the effect of silver doping on radiolabeling efficiency and biological performance. Ag-In2O3 NPs were synthesized via photodeposition, characterized by XRD, FTIR, and TEM (revealing quasi-spherical particles of 15-25 nm), and radiolabeled with 131I using chloramine-T, achieving a radiochemical yield of 94.02 ± 0.21 % under optimized conditions (200 μg/ml NPs, pH 7, 50 μg/ml CAT, 30 min at room temperature). The formulation demonstrated excellent in vitro stability (94.02 ± 0.21 % % up to 24 h). Biodistribution studies in Ehrlich ascites carcinoma (EAC) bearing mice showed preferential tumor accumulation (peak 11.2 ± 0.8 % ID/g at 2 h post-injection), prolonged retention (t½ = 30.41 h), and high tumor-to-muscle ratios (up to 22.67 ± 0.07 at 24 h), mediated by the EPR effect. These findings demonstrate favorable biodistribution characteristics, tumor accumulation, and retention of 131I-Ag-In2O3 NPs in the EAC model, supporting their potential for further investigation as a radiolabeled nanoparticle platform.