Mastering the Shape and Composition of Dendronized Iron Oxide Nanoparticles To Tailor Magnetic Resonance Imaging and Hyperthermia

The current challenge in the field of nano-medicine is the design of multifunctional nano-objects effective both for the diagnosis and treatment of diseases. Here, dendronized FeO1-x@Fe3-xO4 nanoparticles with spherical, cubic, and octopode shapes and oxidized Fe3-xO4 nanocubes have been synthesized and structurally and magnetically characterized. Strong exchange bias properties are highlighted in core shell nanoparticles (NPs) due to magnetic interactions between their antiferromagnetic core and ferrimagnetic shell. Both in vitro relaxivity measurements and nuclear magnetic resonance (NMR) distribution profiles have confirmed the very good in vitro magnetic resonance imaging (Mm) properties of core shell and cubic shape NPs, especially at low concentration. This might be related to the supplementary anisotropy introduced by the exchange bias properties and the cubic shape. The high heating values of core shell NPs and oxidized nanocubes at low concentration are attributed to dipolar interactions inducing different clustering states, as a function of concentration. In vivo MRI studies have also evidenced a clustering effect at the injection point, depending on the concentration, and confirmed the very good in vivo MRI properties of core shell NPs and oxidized nanocubes in particular at low concentration. These results show that these core shell and cubic shape dendronized nano-objects are very suitable to combine MRI and hyperthermia properties at low injected doses.