Enhancement and tunability of plasmonic-magnetic hyperthermia through shape and size control of Au:Fe3O4 Janus nanoparticles

Abstract

Nanohyperthermia therapies have appeared as a promising alternative for the treatment of diverse cancer tumors. Multifunctional nanosystems offer a step forward in these therapies. They harness more efficient and multistimuli hyperthermia for low-dose application, as well as supplementary functions for imaging, targeting, controlled release, and sensing. Among them, Janus Au:Fe3O4 nanoparticles (JNPs) are highly versatile and a prominent example for dual photo- and magneto-thermia capabilities. To achieve the highest efficiencies of these nanomaterials, which allow low-dose applications, optimization in terms of size and shape is imperative. Here, we have expanded the synthesis of Janus nanostructures and carried out a systematic study to understand the structure–performance relationship and improve their hyperthermia efficiency. JNPs were synthesized by seed-mediated growth processes to obtain Janus nanostars (JNSs) and Janus nanospheres (JNSphs) with controlled sizes, together with initial heterodimers and indented F3O4 NPs. The hyperthermia abilities were then evaluated using AC magnetometry and under near-infrared laser irradiation. The results showed a clear effect of size and shape on the tuning of both magnetothermia and photothermia. Iron oxide size showed the biggest effect on magnetothermia, which could be tuned by the size and shape of the gold component. Likewise, for photothermia, JNSs offered the best performance and a clear correlation between the proximity of the plasmonic band to the irradiation source and their photothermal performance, modulated by the presence of iron oxide. A SARmax of 3 kW g–1 for the strongest field and frequency tested, 0.48 kW g–1 for biological safety limits in magnetothermia, and 8.3 kW g–1 per W cm–2 of applied light for photothermia were obtained. The acquired results support the proper selection of the best JNPs for dual hyperthermia and allow one to set up the design rules for obtaining more efficient multifunctional nanosystems, opening new avenues toward advanced heating-based therapies.