Precision cancer treatment using magnet-induced thermally activated nanoparticles

Traditionally, radiation, chemotherapy, and surgery have been the most common methods of removing and destroying malignant cells. However, these treatments can also damage healthy cells, and often have serious side effects. Today, more accurate and targeted therapies are emerging, designed to attack cancer cells while saving normal tissue.

Professor Miyako and his research team at the Japan Institute of Advanced Science and Technology (JAIST) are pioneering such innovative approaches to cancer treatment. Previously, his team developed tumor target bacteria, triggering an immune system that attacks tumor cells.

In their study published in Small Science on March 3, 2025, Professor Miyako and his team developed nanoparticles that were magnetically directed to tumor cells, which were then heated with a laser to destroy tumor cells.

This treatment is based on photothermal therapy and involves selectively destroying photothermal nanoparticles (particles that absorb light and convert them to heat) cancer cells. When exposed to near-infrared (NIR) laser light, nanoparticles produce heat and destroy tumors.

The team used biocompatible carbon nanohorns (CNHS) as photothermal agent. CNHS is a spherical graphene-based nanostructure that was previously used for drug delivery and bioimaging. However, the key challenge of using CNHS is to ensure that nanoparticles accumulate effectively in the tumor.

To address this, the team modified the CNHS by adding a magnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate ((BMIM)(FECL4)) to the surface. Ionic liquids have anti-cancer properties, which impart magnetic properties to nanoparticles and can be directed to tumor sites using external magnets. However, CNH is naturally water-insoluble, and (BMIM) (FECL4) is hydrophobic (water reflection), which challenges its use in the body.

To improve the dispersibility of particles in the body, researchers added a polyethylene glycol coating to improve the water solubility and dispersibility of the particles. In addition, the fluorescent dye indocyanine green has been incorporated into the nanoparticles and acts as a visual tracker, allowing real-time monitoring of nanoparticles.

“The innovative approach to nanocomplex design in this study will enable the first time that magnetic ionic liquids can be applied to cancer treatments,” explains Professor Miyako. “This represents an important advancement and provides a new avenue for cancer theranostix.”

The photothermal conversion efficiency of nanoparticles, only 120 nanometers in size, was 63%, which is better than many traditional photothermal agents, and was sufficient to kill cancer cells. Clinical tests showed that when added to mouse-derived colon cancer (Colon26) cells, nanoparticles effectively induced cell death upon exposure to 0.7 W (~35.6 mW mm-2) 808 nm NIR laser for 5 min.

When injected into mice with corono26 tumors, the nanoparticles were directed at the tumor using a magnet. These accumulated nanoparticles heated the tumor to 56°C. This is sufficient temperature to destroy cancer cells.

The results were promising. Mice treated with magnet-induced nanoparticles showed complete tumor removal after six laser treatments, but did not recur for the next 20 days. In contrast, if the nanoparticles are not induced by the magnet, the tumors regenerate after the laser treatment has stopped, indicating that insufficient nanoparticles have accumulated and completely eradicated cancer cells.

This innovative therapy combines three powerful mechanisms: heat-based destruction of cancer cells, tumor-targeted chemotherapy effects of ionic fluids, and magnetic guidance. This multimodal approach provides a more effective alternative to traditional therapies that typically rely on a single mode of action. Furthermore, this study highlights the potential of magnetic ionic liquids in cancer treatment, paving the way for new therapeutic strategies.

“This simple yet highly effective nanoplatform that leverages multiple tumor killing mechanisms has important potential for future clinical applications in cancer diagnosis and treatment,” says Professor Miyako. “However, treatment of deeper tumors will require further safety testing and the development of efficient endoscopic laser systems.”