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

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_0.65Fe_1.30P_0.65Si_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.