Electron spin-polarized effect in ferromagnetic heterojunction enhances photocatalytic antibacterial therapy of...

Photocatalytic therapy (PCT) has emerged as a promising strategy for treating implant-related bacterial infections. While the antibacterial activity of photocatalysts is highly dependent on their electronic structure, the impact of electron spin polarization on this catalytic activity remains underexplored. Herein, a ferromagnetic heterojunction (TiO₂@CoFe₂O₄) is developed with electron spin-polarized properties, which is then thoroughly blended with poly-L-lactic acid powders to prepare a light-responsive scaffold by selective laser sintering. Mechanistically, CoFe₂O₄ induces an asymmetric distribution of electronic spin states in TiO₂, thereby enhancing the density of spin-polarized electrons and increasing the total magnetic moment by up to 60.7% per supercell. Under light irradiation, the synergistic effect of spin-polarized electrons and built-in electric field in TiO₂@CoFe₂O₄ inhibits the recombination of photogenerated carriers and promotes reactive oxygen species (ROS) generation. Furthermore, the micro-magnetic field from spin-polarized electrons enhances membrane permeability, combining with chemical damage induced by ROS to ultimately cause bacterial death. Consequently, the scaffold presents a potent antibacterial effect, with inhibition rates reaching 94.8% against S. aureus and 97.5% against E. coli. This study offers a novel strategy for enhancing PCT against implant-related infections by regulating spin-polarized electrons.