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Magnetic Material Cooks Cancer

An extraordinary self-regulating heating effect produced by a particular type of magnetic material may lead to the use of hyperthermia as a cancer treatment.

Temperatures that can be tolerated by healthy body cells have long been known to destroy cancerous cells. While the use of magnetic particles introduced into tissue and heated remotely has found some success in treating cancer, the technique is still some way from becoming a standard procedure.

One of the problems hindering progress is the insufficient heating capacity of magnetic particles. However, researchers led by Prof Kiyonori Suzuki at Monash University have found a material that not only heats rapidly, it also stops quickly and cannot get any hotter. Fortunately, the temperature it reaches is high enough to destroy tumours but too low to affect normal healthy tissue.

“This strong, self-regulated heating effect is unmatched by other materials,” Suzuki said. “It opens a novel design strategy for realising in vivo hyperthermia therapy.”

Suzuki’s team is investigating magnetocaloric materials that have so far only attracted research into magnetic refrigeration. The exciting qualities of these materials are tied to their Curie temperature. This is the point at which magnetic properties undergo change, and it varies for different materials. “We chose these materials for our study because the Curie point resides in the ideal temperature range for hyperthermia treatment of cancer cells,” Suzuki said.

A critical factor in the material’s heating power is the first order Curie transition. This is unlike the conventional Curie transition in that two magnetic states co-exist. For complex reasons tied to this co-existence, the conversion of external magnetic fields to heat is maximised near the Curie temperature and the conversion effect abruptly stops above this temperature.

The researchers are hoping that their proof-of-concept study, which was published in Applied Physics Letters, could pave the way for enhanced cancer therapies. “Thanks to its extraordinary heating effect, these first-order magnetic materials could prove to be a minimally invasive and inexpensive way of achieving intracellular hyperthermia treatment,” Suzuki said.