Synthesis of urchin-like nickel nanoparticles with enhanced rotating magnetic field-induced cell necrosis and tumor inhibition

Magnetic nanoparticles (MNPs)-induced cell necrosis under rotating magnetic field (RMF) has attracted a great deal of attention in recent years. However, the smooth structure of MNPs largely limits their necrosis efficiency. In this study, we aimed to synthesize novel urchin-like nickel nanoparticles (UNNPs) and evaluate their high efficiency in cell necrosis and tumor inhibition under a low-frequency RMF. The unique UNNPs were prepared via a one-step solvothermal process under an external magnetic field of 0.6 T. The as-synthesized UNNPs exhibited a size distribution from 350 to 700 nm with a peak of 450 nm and ferromagnetic behavior with a magnetization saturation of 49.88 emu/g. The in vitro results showed that the as-prepared UNNPs induced much higher rate of necrotic cell death than sphere-like nickel nanoparticles under the same RMF. Both in vitro and in vivo testing revealed that the UNNPs possessed nontoxic properties. Furthermore, the UNNPs showed obvious suppression against tumor cell growth in a mouse model of malignant breast cancer under the induction of low-frequency RMF.