Thermal self-regulating nanoparticles that seek out and destroy cancer cells may sound like something pulled from the new Blade Runner movie script, but researchers at the University of Surrey have developed the therapy for use today. The “intelligent” nanoparticle, which heats up to a temperature high enough to kill cancerous cells, self-regulate and lose heat before they get hot enough to harm healthy tissue. Findings from the new study—published today in Nanoscale in an article entitled “Novel Nanoparticles with Cr3+ Substituted Ferrite for Self-Regulating Temperature Hyperthermia”—could soon be used as part of hyperthermic thermotherapy to treat patients with cancer.

“This could potentially be a game changer in the way we treat people who have cancer,” noted senior study investigator Ravi Silva, Ph.D., head of the Advanced Technology Institute at the University of Surrey. “If we can keep cancer treatment 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.”

Thermotherapy has long been used as a treatment method for cancer, but it is difficult to treat patients without damaging healthy cells. However, tumor cells can be weakened or killed without affecting normal tissue if temperatures can be controlled accurately within a range of 42°C to 45°C.

Scientists from Surrey's Advanced Technology Institute have worked with colleagues from the Dalian University of Technology in China to create nanoparticles which, when implanted and used in a thermotherapy session, can induce temperatures of up to 45°C.

“We report a novel Cr3+ substituted Co–Zn ferrite (Zn0.54Co0.46Cr0.6Fe1.4O4), whose Curie temperature and coercivity values are 45.7 °C and 174 Oe, respectively,” the authors wrote. “Under clinically acceptable magnetic field conditions, the temperature of these nanoparticle suspensions can be self-regulated to 44.0 °C and, most importantly with a specific absorption rate (SAR) of 774 W kg−1, which is two-fold higher than the SAR standard for magnetic nanoparticles used in hyperthermia (300 W kg−1). The evaluation of the in vitro cytotoxicity of the nanoparticles reports a low toxicity, which points to a novel set of magnetic nanoparticles for use in self-regulating hyperthermia.”

The Zn–Co–Cr ferrite nanoparticles produced for this study are self-regulating, meaning that they self-stop heating when they reach temperatures over 45°C. Importantly, the nanoparticles are also low in toxicity and are unlikely to cause permanent damage to the body.

“Magnetic induced hyperthermia is a traditional route of treating malignant tumors,” explained lead study investigator Wei Zhang, Ph.D., associate professor from the Dalian University of Technology. “However, the difficulties in temperature control have significantly restricted its usage. If we can modulate the magnetic properties of the nanoparticles, the therapeutic temperature can be self-regulated, eliminating the use of clumsy temperature monitoring and controlling systems.”

Dr. Zhang continued, concluding that “by making magnetic materials with the Curie temperature falling in the range of hyperthermia temperatures, the self-regulation of therapeutics can be achieved. For  most magnetic materials, however, the Curie temperature is much higher than the human body can endure. By adjusting the components, as we have, we have synthesized the nanoparticles with the Curie temperature as low as 34oC. This is a major nanomaterials breakthrough.”

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