Composite nanoparticles consisting of a magnetic iron oxide core and a special thermoresponsive polymeric shell are promising materials for multimodal cancer therapy, negating many of the drawbacks of conventional therapies. Drug targeting is achieved by loading these tiny particles with potent anti-cancer drugs, injecting them into the bloodstream and using an external magnetic field gradient to accurately guide them to the tumor. This minimizes systemic distribution and toxicity, and ensures sufficient drug concentration in the tumor.

After the particles are localized in the tumor, an external alternating magnetic field is applied to generate heat in the magnetic nanoparticles. This heat raises the temperature of the surrounding polymer shell, resulting in thermoresponsive behaviour that causes the polymer to shrink and release the anti-cancer drug. Thus, simultaneous hyperthermia and chemotherapy can be achieved, thereby utilizing the synergistic effect. An on-off controlled drug release can also be achieved.

Particles with a purpose

Researchers at Nanyang Technological University, Singapore, and Singapore General Hospital have developed composite magnetic nanoparticles for this purpose. The particles consist of a magnetic core of iron oxide and a shell of the thermoresponsive polymer poly-n-isopropylacrylamide loaded with the anti-cancer drug doxorubicin.

In vivo magnetic targeting of drug-loaded nanoparticles to a liver tumor in a rat model was demonstrated and visualized by MRI. Histology confirmed the localization of the particles to the liver tumor with no occurrence in other organs. In vitro experiments showed that the particles simultaneously generate heat as well as release therapeutically relevant quantities of drugs when exposed to an alternating magnetic field, making them promising materials for multimodal cancer therapy.

The researchers presented their work in Nanotechnology.