Shape-Control in Microwave-Assisted Synthesis: A Fast Route to Size-Tunable Iron Oxide Nanocubes with Benchmark Magnetic Heat Losses

Iron oxide nanocubes (IONCs) are among the most promising materials in magnetic hyperthermia (MHT) for tumor therapy as they can efficiently convert magnetic energy into heat under alternating magnetic field (AMF). Conventional IONCs syntheses are based on thermal decomposition methods, limited by the long reaction time (hours) and milligram-scale production; while, solvothermal methods produce gram-scale amount of high quality IONCs, but, reaction times are of the orders of hours. In this work, a microwave-assisted route to shape-control IONCs in which the reaction time is reduced to minutes while achieving a high iron conversion yield up to 80% is reported. The size of the IONCs (range 13–30 nm) is coarse-tuned by adjusting the amount of benzaldehyde ligand, while fine-size tuning is achieved by changing temperature and minute-reaction time. IONCs exhibit superparamagnetic behavior at 298 K with saturation magnetization over 80 emu g_IONC⁻¹ and possess high specific absorption rate values (SAR) up to 400 W g_Fe⁻¹ at clinical AMF conditions. These results mark a milestone for rapid synthesis of IONCs at high yield conversion of well-defined size and shape nanocubes with benchmark MHT heat performance while using a fast route, with limited energy consumption which makes this method greener and cheaper than previous ones.