Novel Ferrite Nanoparticles for Hyperthermic Cancer Therapeutics

A novel type of nontoxic magnetic nanoparticles shows potential for treating malignant tumor cells through controlled hyperthermia.

For hyperthermia to be used under clinical conditions for cancer therapeutics the temperature regulation needs to be precise and accurately controllable. In the case of the metal nanoparticles used for such activities, a high coercivity is a prerequisite in order to couple more energy in a single heating cycle for efficient and faster differential heating. Coercivity is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized.

Ferromagnetic materials with high coercivity are called magnetically hard materials, and are used to make permanent magnets. Materials with low coercivity are said to be magnetically soft. The latter are used in transformer and inductor cores, recording heads, microwave devices, and magnetic shielding.

Chemically stable Co–Zn ferrite nanoparticles have typically not been used in self-regulating hyperthermia temperature applications to date due to their low Curie temperature (the temperature at which certain materials lose their permanent magnetic properties), usually accompanied by a poor coercivity.

Tumor cells can be attacked and killed by hyperthermic nanoparticles without affecting normal tissue if the temperature of the particles can be controlled accurately within a range of 42°C to 45°C. To accomplish this task, investigators at the University of Surrey (United Kingdom) developed novel Cr3+ substituted Co–Zn ferrite nanoparticles, whose Curie temperature was 45.7 °C. Under clinically acceptable magnetic field conditions, the temperature of these nanoparticle suspensions could be self-regulated to 44.0°C.

The investigators reported in the October 7, 2017, issue of the journal Nanoscale that evaluation of the in vitro cytotoxicity of the nanoparticles showed a low toxicity, which indicated that this novel set of magnetic nanoparticles should be appropriate for use in self-regulating hyperthermia therapeutics.

Senior author Dr. Ravi Silva, head of the advanced technology institute at the University of Surrey, said, "This could potentially be a game changer in the way we treat people who have cancer. If we can keep cancer treatment sat at a temperature level high enough to kill the cancer, while low enough to stop harming healthy tissue, it will prevent some of the serious side effects of vital treatment. It is a very exciting development which, once again, shows that the University of Surrey research is at the forefront of nanotechnologies - whether in the field of energy materials or, in this case, healthcare."

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