Monocore vs. multicore magnetic iron oxide nanoparticles: uptake by glioblastoma cells and efficiency for magnetic hyperthermia

PEGylated magnetic iron oxide nanoparticles (IONPs) were synthesised with the aim to provide proof of concept results of remote cancer cell killing by magnetic fluid hyperthermia. The IONPs were produced by the polyol synthetic route also called the "forced hydrolysis pathway", yielding highly superparamagnetic, readily-dispersible, and biocompatible IONPs. As shown previously, adjusting the parameters of the reaction led to either monocore or multicore IONPs, with an on-demand morphology and magnetic properties. Polyethylene glycol (PEG) was grafted onto the nanoparticles in a single final step, using a phosphonic acid-terminated PEG synthesised separately, a strategy named "convergent". The magnetic properties of the IONPs were preserved in physiological media, thanks to this biocompatible shell. The interaction of the PEGylated IONPs with a glioblastoma cell line was studied, from the stability of IONPs in an appropriate cell culture medium to the remotely magnetically triggered cell death. Cellular internalisation of the IONPs was studied, along with their fate after application of an alternating magnetic field (AMF). This investigation highlights the superior efficiency of multicore (nanoflowers) vs. monocore (nanospheres) IONPs for magnetic hyperthermia, leading to 80% cancer cell death in medically translatable conditions.