Burn‐Safe Biodegradable Magnetocaloric Composites for Temperature‐Controlled Biomedical Applications

This work investigates a magnetocaloric (Mn,Fe)2(P,Si) compound tailored for precise, self‐regulating heating in biomedical use. With a Curie temperature tuned at 43 °C, it enables therapeutic activation without overheating. Encapsulation in a composite ensures controlled temperature rise under an alternating magnetic field (AMF), with high biocompatibility and stability, hinting at a new frontier in safe, localized thermal medical treatments. Abstract Magnetothermal stimulation is key in biomedical applications like tumor ablation, drug delivery, and regenerative therapies. A common method involves injecting magnetic particles that heat under an alternating magnetic field (AMF). However, uncontrolled heating can damage healthy tissues. Maintaining temperatures below 45 °C is critical. Using materials with a Curie temperature (Tc) near this limit offers a self‐regulating solution, as magnetization—and thus heating—drops sharply at Tc. This study explores Mn0.65Fe1.30P0.65Si0.37 (MCM), a magnetocaloric material composed of non‐toxic elements and featuring a tunable Tc. It is engineered to exhibit a Tc of 43 °C, close to the safe physiological threshold. MCM particles are encapsulated in a wax matrix to form a composite that responds to AMF exposure. Heat generated by MCM particles triggers the wax phase transition, while the obtained Tc enables the composite to achieve self‐limiting thermal regulation under magnetic field exposure. Biocompatibility tests using human umbilical vein endothelial cells (HUVECs) show over 90% cell viability in direct and indirect contact. Stability tests in phosphate buffers at 37 °C confirm controlled degradation over 28 days. These results demonstrate that MCM is a promising, burn‐free magnetic material for safe, localized heating, supporting its use in self‐regulating, temperature‐responsive biomedical systems. This work investigates a magnetocaloric (Mn,Fe) 2 (P,Si) compound tailored for precise, self-regulating heating in biomedical use. With a Curie temperature tuned at 43 °C, it enables therapeutic activation without overheating. Encapsulation in a composite ensures controlled temperature rise under an alternating magnetic field (AMF), with high biocompatibility and stability, hinting at a new frontier in safe, localized thermal medical treatments. Abstract Magnetothermal stimulation is key in biomedical applications like tumor ablation, drug delivery, and regenerative therapies. A common method involves injecting magnetic particles that heat under an alternating magnetic field (AMF). However, uncontrolled heating can damage healthy tissues. Maintaining temperatures below 45 °C is critical. Using materials with a Curie temperature ( T c ) near this limit offers a self-regulating solution, as magnetization—and thus heating—drops sharply at T c. This study explores Mn 0.65 Fe 1.30 P 0.65 Si 0.37 (MCM), a magnetocaloric material composed of non-toxic elements and featuring a tunable T c. It is engineered to exhibit a T c of 43 °C, close to the safe physiological threshold. MCM particles are encapsulated in a wax matrix to form a composite that responds to AMF exposure. Heat generated by MCM particles triggers the wax phase transition, while the obtained T c enables the composite to achieve self-limiting thermal regulation under magnetic field exposure. Biocompatibility tests using human umbilical vein endothelial cells (HUVECs) show over 90% cell viability in direct and indirect contact. Stability tests in phosphate buffers at 37 °C confirm controlled degradation over 28 days. These results demonstrate that MCM is a promising, burn-free magnetic material for safe, localized heating, supporting its use in self-regulating, temperature-responsive biomedical systems. Advanced Science, EarlyView.