Construction of multifunctional nanoparticles (NPs) with near-infrared (NIR) plasmonic responses is considered a versatile and multifaceted platform for several biomedical applications. Herein, a double layer of Au/Ag
alloy on the surface of truncated octahedral
iron oxide NPs (IONPs) was prepared and the distance between the layers was controlled to exhibit broad and strong NIR absorption. The rattle-shaped IONP@shell-in-shell nanostructure showed light-response to the NIR biological window from 650 to 1300 nm for
photothermal therapy (PTT) and magnetic guidance for
hyperthermia and magnetic resonance imaging (MRI) diagnosis. Exposing the aqueous
solution of IONP@shell-in-shell to a 1064 nm
diode laser, its heat conversion efficiency was ∼28.3%. The in vitro cell viability at a
gold concentration of 100 ppm was ∼85%, and decreased to ∼16% when the cells were treated with the NIR irradiation and magnetic attraction. T2-weighted MRI images showed a clear accumulation of IONP@shell-in-shell at the
tumor site with magnetic attraction. In vivo luminescence
tumor images explained that the IONP@shell-in-shell could reduce the U87MG-luc2
cancer cell proliferation in mice with the NIR irradiation and magnetic attraction. These results indicate the IONP@shell-in-shell as a promising nanomedicine for PTT, magnetic targeting, and magnetic resonance imaging (MRI).