*2.1. Cell Lines and Reagents*

The human acute myelogenous leukemia (AML) cell KG1a and the human acute promyelocytic leukemia (APL) cell HL60 were obtained by the China Center for Type Culture Collection (Shanghai, China). Dulbecco Modified Eagle Medium (DMEM) and fetal bovine serum (FBS) were acquired from Invitrogen Gibco (Carlsbad, CA, USA). Double antibiotics (penicillin plus streptomycin) were purchased from Beyotime Biotech (Shanghai, China). Counting Kit-8 and phosphate buffer saline were purchased from Sangon Biotech Co., Ltd. (Shanghai, China). The FeNPs and PBNPs were supplied by the Biological and Biomedical Nanotechnology Group of the State Key Lab of Bioelectronics, Southeast University (Nanjing, China) [15,17]. The size and potential of nanoparticles were measured again with a Malvern Particle size analyzer, Zetasizer Nano (Malvern Instruments, Malvern, UK).
