Several drugs for breast cancer and Fe3O4 NPs were co-encapsulated into PLGA or PLGA-PEG shells to form the magnetic nanocapsules to carry the drugs to the breast cancer cells, such as Methotrexate (MTX) [114,115], Doxorubicin (DOX) [116,117], Salvigenin (Sal) [118], Gemcitabine (Gem) [119,120], Paclitaxel (PTX) and Transferrin (Tf) [121], Docetaxel (DTX) [122], Vitamin C (Vc) [123], Olaparib (Olb) [124], and Chlorin E6 (Ce6) [125]. This evidence concerns the gene TF and breast cancer.