Exchange-coupled magnetic nanoparticles for efficient heat induction

The conversion of electromagnetic energy into heat by nanoparticles has the potential to be a powerful, non-invasive technique for biotechnology applications such as drug release 1 , 2 , 3 , disease treatment 4 , 5 , 6 and remote control of single cell functions 7 , 8 , 9 , but poor conversion efficiencies have hindered practical applications so far 10 , 11 . In this Letter, we demonstrate a significant increase in the efficiency of magnetic thermal induction by nanoparticles. We take advantage of the exchange coupling between a magnetically hard core and magnetically soft shell to tune the magnetic properties of the nanoparticle and maximize the specific loss power, which is a gauge of the conversion efficiency. The optimized core–shell magnetic nanoparticles have specific loss power values that are an order of magnitude larger than conventional iron-oxide nanoparticles. We also perform an antitumour study in mice, and find that the therapeutic efficacy of these nanoparticles is superior to that of a common anticancer drug. The properties of core–shell nanoparticles can be tuned so that they efficiently convert radiation into heat, leading to therapeutic results that are competitive with commercial drug treatments.