Iodine-131-labeled, transferrin-capped polypyrrole nanoparticles for tumor-targeted synergistic photothermal-radioisotope therapy

Combining different therapeutic functions within single tumor-targeted nanoscale delivery systems is promising to overcome the limitations of conventional cancer therapies. Herein, transferrin that recognizes transferrin receptors up-regulated on tumor cells is pre-labeled with iodine-131 (¹³¹I) and then utilized as the stabilizer in the fabrication of polypyrrole (PPy) nanoparticles. The obtained transferrin-capped PPy@Tf-¹³¹I nanoparticles could be used for tumor-targeted radioisotope therapy (RIT) and photothermal therapy (PTT), by employing beta-emission from ¹³¹I and the intrinsic high near-infrared (NIR) absorbance of PPy, respectively. Owing to the transferrin-mediated tumor targeting, PPy@Tf-¹³¹I nanoparticles exhibit obviously enhanced in vitro cancer cell binding and in vivo tumor uptake compared to its non-targeting counterpart. The combined RIT and PTT based on PPy@Tf-¹³¹I nanoparticles is then conducted, achieving a remarkable synergistic therapeutic effect. This work thus demonstrates a rather simple one-step approach to fabricate tumor-targeting nanoparticles based on protein-capped conjugated polymers, promising for combination cancer therapy with great efficacy and high safety.