NIS-mediated I-131 radiolabeled polylactic-co-glycolic acid (PLGA) nanoparticle (NINP) with excellent particle stability was designed with non-chelated radioiodine in the inner core to preserve the nanomaterial integrity, and mediated with a sodium/iodide symporter to assist in radioiodine uptake by MDA-MB-231 triple-negative breast cancer cells. The gene discussed is SLC5A5; the disease is triple-negative breast carcinoma.