Magnetically driven thermoelectric-ROS cascade conversion in a scaffold for bone tumor and infection therapy

Thermoelectric materials enabled thermoelectric-reactive oxygen species (ROS) conversion under temperature gradients, offering a promising strategy for suppressing postoperative recurrence of bone tumors and associated bacterial infections. However, their clinical translation was hindered by the inability to achieve spatiotemporally controlled ROS release within bone tissue. To address this, a magnetothermal-thermoelectric heterojunction (Bi₂Te₃-MnFe₂O₄) was constructed by in situ growth of manganese ferrite (MnFe₂O₄) on bismuth telluride (Bi₂Te₃) nanosheets, and was then incorporated into poly-L-lactic acid (PLLA) scaffold using additive manufacturing. Under an alternating magnetic field, the magnetothermal effect of MnFe₂O₄ induced a localized temperature increase, which activated the thermoelectric effect of Bi₂Te₃. This process drove the separation of electron-hole pairs and catalyzed ROS generation to antitumor and antibacterial. Furthermore, the multivalent metal ions (Mn²⁺/Mn³⁺ and Fe²⁺/Fe³⁺) in MnFe₂O₄ mediated Fenton-like reactions, further enhancing ROS production and depleting glutathione via chemodynamic therapy. The magnetothermal heating also accelerated the kinetics of these processes, forming a synergistic therapeutic outcome. Experimental results demonstrated that the ROS produced by the scaffold induced mitochondrial dysfunction and apoptosis in tumor cells, and effectively killed bacteria by causing intracellular content leakage. This study integrated the magnetothermal, thermoelectric, and chemodynamic effects into a bone scaffold, providing an innovative strategy for comprehensive postoperative treatment of bone tumors.