Tumor inhibition via magneto-mechanical oscillation by magnetotactic bacteria under a swing MF

Since magnetic micro/nano-materials can serve as multifunctional transducers for remote control of cell functions by applying diverse magnetic fields, magnetic cell manipulation provides a highly promising tool in biomedical research encompassing neuromodulation, tissue regeneration engineering and tumor cell destruction. Magnetotactic bacteria (MTB), which contain natural magnetic materials, can sensitively respond to external magnetic fields via their endogenous magnetosome chains. Here, we developed a technique for magnetotactic bacteria-based cell modulation and tumor suppression combined with a swing magnetic field. We enabled MTB cells to recognize and bind to mammalian tumor cells via functional modification with RGD peptides onto the surfaces of MTB cells, and RGD-modified MTB bacteria could interact with the targeted tumor cells effectively. The magnetic torque, which was due to the interaction of the long magnetosome chain inside the MTB bacterial cell and the applied swing magnetic field, could result in obvious swing magnetic behaviors of the modified MTB bacteria bound to tumor cell surfaces and thus subsequently exert a sustained magnetomechanical oscillation on the tumor cell surfaces, which could induce a significant activation of Ca²⁺ ion influx in vitro and tumor growth inhibition in vivo. These findings suggest that MTB cells mediated magnetomechanical stimulation, which is remotely controlled by dynamic magnetic fields, as an effective way to regulate cell signaling and treat tumor growth, which will shed the light on further biomedical applications utilizing whole magnetotactic bacteria.