Cancer cells, like normal cells, begin to perish as soon as the temperature hits 43°C. So, the obvious challenge is to find out how cancer cells can be heated up without affecting the normal, healthy cells. One idea to deal with it, is known as magnetic hyperthermia. This involves injecting magnetic nanoparticles into the targeted tumors (For another nanoparticle approach to cancer, click here). Subsequently, the patient is put into a magnetic field that reverses direction several thousands of times each second. This excites the nanoparticles, heating them. Since the magnetic particles are only found in the tumors, the healthy tissue is exempt from the damaging heat.
However, there is a problem with this approach. Conventional nanoparticles interact only modestly with the magnetic field. To counteract this, larger doses are required. While the used nanoparticles usually aren’t really toxic, large doses can activate the immune system, which might result in allergic reactions.
Now, a new nanoparticle has been developed that gets hotter than conventional nanoparticles. These nanoparticles have two layers, a core of one magnetic material, and a surface layer of another one (see figure 1). This appears to make these particles interact more strongly with the magnetic field, releasing up to 10 times more heat, meaning that only 10% of the usual dose of nanoparticles is required to achieve the same amount of heat as in previously used particles.
Figure 1: The new nanoparticles. (Source: Lee et al., 2011)
The research team, at Yonsei University in Seoul, tested their new technique on mice. After injecting their newly designed nanoparticles, they put the mice inside a coil of wire (see figure 2) and alternated the current, creating a quickly alternating magnetic field. Ten minutes later, the mice were removed, and their tumors were monitored for a four week period. All traces of cancer disappeared in the mice, and no apparent side-effects were noticed. This discovery might spur new research into the development of magnetic nanoparticle therapies for cancer, which has been struggling due to the low interaction with a magnetic field by conventional particles.
Figure 2: Mouse in coil of wire. (Source: Lee et al., 2011)
Lee, J.-H.; Jang, J.-T.; Choi, J.-S.; Moon, S.H.; Noh, S.-H.; Kim, J.-W.; Kim, J.-G.; Kim,I.-S.; Park, K.I. and Cheon, J. (2011). Exchange-coupled magnetic nanoparticles for efficient heat induction. Nature Nanotechnology. doi:10.1038/nnano.2011.95.