Low frequency vibrating magnetic field-triggered magnetic microspheres with a nanoflagellum-like surface for cancer therapy

The magneto-mechanical force killing cancer cells is an interesting and important strategy for cancer therapy.Novel magnetic microspheres composed of a Fe3O4 nanocore, a bovine serum albumin (BSA) matrix, and a rod-like SiO2 nanoshell, which had flagellum-like surface for force-mediated cancer therapy were developed. One such magnetic microsphere (Fe3O4/BSA/rSiO2) at a cancer cell (not leave the cell surface) under a low frequency vibrating magnetic field (VMF) could generate 6.17 pN force. Interestingly, this force could induce cancer cell to generate reactive oxygen species (ROS). The force and force-induced ROS could kill cancer cells. The cell killing efficiency of Fe3O4/BSA/rSiO2 exposed to a VMF was enhanced with increasing silica nanorod length, and the microspheres with straight nanorods exhibited stronger cell killing ability than those with curled nanorods. Fe3O4/BSA/rSiO2 triggered by a VMF could efficiently inhibit mouse tumor growth, while these microspheres without a VMF had no significant effect on the cell cycle distribution, cell viability, tumor growth, and mouse health.These microspheres with unique morphological characteristics under VMF have great potential that can provide a new platform for treating solid tumors at superficial positions whether with hypoxia regions or multidrug resistance.