Nearly complete regression of tumors via collective behavior of magnetic nanoparticles in hyperthermia.

One potential cancer treatment selectively deposits heat to the tumor through activation of magnetic nanoparticles inside the tumor. This can damage or kill the cancer cells without harming the surrounding healthy tissue. The properties assumed to be most important for this heat generation (saturation magnetization, amplitude and frequency of external magnetic field) originate from theoretical models that assume non-interacting nanoparticles. Although these factors certainly contribute, the fundamental assumption of 'no interaction' is flawed and consequently fails to anticipate their interactions with biological systems and the resulting heat deposition. Experimental evidence demonstrates that for interacting magnetite nanoparticles, determined by their spacing and anisotropy, the resulting collective behavior in the kilohertz frequency regime generates significant heat, leading to nearly complete regression of aggressive mammary tumors in mice.