Cell Membrane-Coated Magnetic Nanocubes with a Homotypic Targeting Ability Increase Intracellular Temperature due to ROS Scavenging and Act as a Versatile Theranostic System for Glioblastoma Multiforme

In this study, hybrid nanocubes composed of magnetite (Fe3 O4 ) and manganese dioxide (MnO2 ), coated with U-251 MG cell-derived membranes (CM-NCubes) are synthesized. The CM-NCubes demonstrate a concentration-dependent oxygen generation (up to 15%), and, for the first time in the literature, an intracellular increase of temperature (6 °C) due to the exothermic scavenging reaction of hydrogen peroxide (H2 O2 ) is showed. Internalization studies demonstrate that the CM-NCubes are internalized much faster and at a higher extent by the homotypic U-251 MG cell line compared to other cerebral cell lines. The ability of the CM-NCubes to cross an in vitro model of the blood-brain barrier is also assessed. The CM-NCubes show the ability to respond to a static magnet and to accumulate in cells even under flowing conditions. Moreover, it is demonstrated that 500 µg mL-1 of sorafenib-loaded or unloaded CM-NCubes are able to induce cell death by apoptosis in U-251 MG spheroids that are used as a tumor model, after their exposure to an alternating magnetic field (AMF). Finally, it is shown that the combination of sorafenib and AMF induces a higher enzymatic activity of caspase 3 and caspase 9, probably due to an increment in reactive oxygen species by means of hyperthermia.