Comparison of Iron Oxide Nanoparticles in Photothermia and Magnetic Hyperthermia: Effects of Clustering and Silica Encapsulation on Nanoparticles' Heating Yield

Featured Application Superparamagnetic iron oxide nanoparticles (SPIONs) have a recognized potential for magnetic hyperthermia, and they are also being increasingly proposed as agents for photothermal treatment (photothermia), a biomedical modality where nanoparticles are excited by light to generate local hyperthermia. While it is known that endosomal internalization of SPIONs negatively affects magnetic hyperthermia, photothermia is not decreased. In an attempt to mimic nanoparticles clustering in endosomes, we herein investigate the effects of silica encapsulation and SPION clustering on both magnetic hyperthermia and photothermia. Photothermal therapy is gathering momentum. In order to assess the effects of the encapsulation of individual or clustered superparamagnetic iron oxide nanoparticles (SPIONs) on nanoparticle light-to-heat conversion, we designed and tested individual and clustered SPIONs encapsulated within a silica shell. Our study compared both photothermia and magnetic hyperthermia, and it involved individual SPIONs as well as silica-encapsulated individual and clustered SPIONs. While, as expected, SPION clustering reduced heat generation in magnetic hyperthermia, the silica shell improved SPION heating in photothermia.