Direct Labeling of Gold Nanoparticles with Iodine-131 for Tumor Radionuclide Therapy.

Purpose: Gold nanoparticles (Au NPs) are widely used as versatile templates to develop multifunctional nanosystems for disease diagnosis and treatment. Iodine can bind to gold via chemisorption, making this a simple method for labeling Au NPs with radioactive iodine. However, the evaluation of tumor radionuclide therapy is insufficient. In this study, we investigated the feasibility of ¹³¹I-adsorbed Au NPs as novel nanoprobes for tumor radionuclide therapy.

Materials and methods: Radiolabeling was performed by mixing Au NPs and ¹³¹I, and the radiochemical purity (RCP) and in vitro stability of ¹³¹I-adsorbed Au NPs were analyzed under different conditions, including various temperatures, pH values, and ¹³¹I concentrations. The tumor accumulation and therapeutic potential of ¹³¹I-adsorbed Au NPs were assessed using a subcutaneous tumor model after intratumoral injection.

Results: The data showed that the chemisorption of the Au NPs onto ¹³¹I was instant, specific, and quantitative. The ¹³¹I-adsorbed Au NPs exhibited high in vitro stability in different media, distinct inhibitory effects on tumor cells in vitro, good retention ability, and therapeutic effects after intratumoral injection into tumor-bearing mice in vivo.

Conclusion: Our work demonstrates that chemisorption of Au NPs and radioiodine has great potential as a strategy for constructing various nanosystems for theranostic applications.