Reviewed by Lexie CornerMar 7 2025
Researchers from the Japan Advanced Institute of Science and Technology (JAIST) have developed magnetic nanoparticles that can be directed to tumors using a magnet and then heated with a laser to destroy cancer cells. This targeted approach was shown to completely remove tumors in mouse models, offering a more accurate and less harmful alternative to traditional treatments.
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Traditional cancer treatments, such as radiation, chemotherapy, and surgery, often harm healthy cells, leading to significant side effects. As a result, new methods are being developed to target cancer cells more accurately while minimizing damage to surrounding tissues.
At JAIST, Professor Eijiro Miyako and his research group are leading the development of these advanced cancer treatments. Previously, the team created tumor-targeting bacteria that stimulate the immune system to attack cancer cells.
The new approach relies on photothermal therapy, which uses photothermal nanoparticles—particles that absorb light and convert it into heat—to selectively destroy cancer cells. When exposed to near-infrared (NIR) laser light, the nanoparticles generate heat that destroys the tumor.
For this study, the team used biocompatible carbon nanohorns (CNHs) as the photothermal agents. CNHs are spherical graphene-based nanostructures that have been previously utilized in bioimaging and drug delivery. However, a key challenge is ensuring that the nanoparticles accumulate efficiently in tumor sites.
The team addressed this issue by coating the CNHs with magnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate ([Bmim][FeCl4]). This added magnetic properties and anticancer capabilities, allowing the nanoparticles to be directed to the tumor using an external magnet.
To improve the particles' water solubility and dispersibility in the body, the researchers applied a polyethylene glycol coating, as [Bmim][FeCl4] is hydrophobic and CNHs are inherently insoluble in water. To monitor the nanoparticles in real time, they also incorporated indocyanine green, a fluorescent dye, to serve as a visual tracker.
This study's innovative approach to nanocomplex design allows us to apply magnetic ionic liquids to cancer treatment for the first time. This represents a significant advancement, offering a new avenue for cancer theranostics.
Eijiro Miyako, Professor, Japan Advanced Institute of Science and Technology (JAIST)
The nanoparticles, measuring just 120 nm in size, were sufficient to kill cancer cells and demonstrated a 63 % photothermal conversion efficiency, which is higher than many traditional photothermal agents. When applied to mouse-derived colon carcinoma (Colon26) cells in lab tests, the nanoparticles successfully induced cell death after five minutes of exposure to an 808 nm NIR laser set at 0.7 W (approximately 35.6 mW mm−2). The researchers used a magnet to direct the nanoparticles to the tumor site after injecting them into mice with Colon26 tumors.
Once the nanoparticles accumulated in the tumor, they heated the tumors to 56 °C, a temperature high enough to kill cancer cells. The results were promising: after six laser treatments, the mice that received magnet-guided nanoparticles had their tumors completely eradicated, with no recurrence over the following 20 days. In contrast, when the nanoparticles were not guided by magnets, the tumors regrew after the laser treatment was stopped, suggesting that insufficient nanoparticles had accumulated to effectively destroy the cancer cells.
This novel treatment combines three powerful mechanisms: magnetic guidance, the tumor-targeting chemotherapeutic effect of the ionic liquid, and heat-based destruction of cancer cells. In comparison, conventional therapies that typically rely on a single mode of action are less effective. The study also suggests the potential for new therapeutic strategies by demonstrating the use of magnetic ionic liquids in cancer treatment.
This simple yet highly effective nanoplatform, which leverages multiple tumor-killing mechanisms, has significant potential for future clinical applications in cancer diagnosis and treatment. However, further safety testing and the development of an efficient endoscopic laser system will be necessary for treating deeper tumors.
Eijiro Miyako, Professor, Japan Advanced Institute of Science and Technology (JAIST)
Journal Reference:
Qi, Y., and Miyako, E., (2025) Multifunctional Magnetic Ionic Liquid-Carbon Nanohorn Complexes for Targeted Cancer Theranostics. Small Science. doi.org/10.1002/smsc.202400640