Hedgehog-Like Gold-Coated Magnetic Microspheres that Strongly Inhibit Tumor Growth through Magnetomechanical Force and Photothermal Effects.

Using magnetomechanical force to kill cancer cells has attracted great attention recently. This study presents novel hedgehog-like microspheres composed of needle-like magnetic nanoparticles with carbon and gold double shells. Using a novel low-frequency vibrating magnetic field (VMF), these microspheres with sharp surfaces can seriously damage cancer cells and strongly inhibit mouse tumor growth through mechanical force. The cell killing efficiency depends on VMF exposure time, frequency, strength, and microsphere concentration. The maximum mechanical force generated by one microsphere acting on a cancer cell under a VMF is about 35.79 pN. The microspheres also induce photothermal ablation after being triggered by near-infrared laser irradiation. Mouse tumors could not be detected after treatment with the synergistic stimuli of mechanical force and photothermal ablation. These results reveal a simple and highly efficient strategy using magnetic microspheres for local treatment of solid tumors in a remote and noninvasive manner.