Magnetic hyperthermia in focus: emerging non-cancer applications of magnetic nanoparticles

Magnetic hyperthermia (MH), which leverages the ability of magnetic nanoparticles (MNPs), located in the tumor, to generate heat upon exposure to an alternating magnetic field (AMF), has long been synonymous with cancer therapy. However, recent advancements highlight emerging applications of MH beyond oncology, including neuromodulation, tissue engineering, biosensing, catalysis, and environmental remediation. All these applications intelligently harness the same principle to achieve a wide range of new functionalities in MNPs besides local heating, including drug release, eradication of pathogens, manipulation of cell membranes, mechanical responses for novel non-invasive therapies, boosting chemical reactions, intensifying processes and degrading or desorbing pollutants like CO₂, just to name a few. This review provides a comprehensive overview of the latest breakthroughs in non-cancer applications of MH. While some fields, ranging from infection control and organ cryopreservation to nanorobotics in biomedicine, require non-toxic biocompatible and biodegradable MNPs (iron oxides) and AMFs restricted to radiofrequencies in the range of 100-300 kHz and an appropriate field intensity (few tens of kA m^-1) to avoid tissue damage, some other areas, like sustainable catalysis, sensing, etc., open up the possibility of using diverse chemical elements besides iron (e.g., cobalt, nickel, carbon) mainly in the form of alloys, and AMFs of higher frequencies (well above 300 kHz) and amplitudes (well above 10-20 kA m^-1). Indeed, engineering of MNPs with suitable catalytically active elements (gold, nickel, ruthenium, palladium, etc.), support materials (silica, aluminium/magnesium oxide, etc.) or surface coating with appropriate (bio)molecules (enzymes, RNA/DNA fragments, etc.) is crucial for each application, as well as considering the effect of local temperature (for instance, achieving the Curie temperature, T_c, of the nanomaterial, provoking the de-swelling of polymers, activating/deactivating enzymes or boosting the efficiency of a catalytic process). Furthermore, this work discusses the current limitations and future directions required to expand the reach of MH. Finally, this review serves as a critical resource for researchers seeking to harness MH beyond cancer treatment and integrate it into novel scientific and technological frontiers.