Electron Spin Polarization Engineering in Ferromagnetic Bioheterojunction for Sonotherapy of Osteomyelitis

Abstract Electron spinning polarization has garnered increased attention for its potential to enhance device properties. However, its application in life health, specifically in anti‐infection and tissue repair, remains under‐explored. In this study, a ferromagnetic heterojunction CF (Fe₃O₄/TiO₂) is constructed with spin‐polarized electrons, demonstrating efficient antibiosis performance with ultrasound (US) assistance. The antibacterial mechanism is elucidated as follows: spin‐polarized metallic states of Fe₃O₄ induce an asymmetric distribution in the electron spin state of TiO₂, increasing the density of states of spin‐polarized electrons near the Fermi level of CF. Under US treatment, the built‐in electric field and spin‐polarized electrons in CF synergistically suppress the recombination of sono‐activated carriers, promoting reactive oxygen species (ROS) production. Simultaneously, the bacterial membrane is influenced by the micromagnetic field induced by spin‐polarized electrons, causing a severe disturbance in the bacterial respiratory chain. The combined damage from ROS and disturbed respiratory chain results in bacterial death. Fortunately, the micromagnetic field built by CF activates specific mechanosensitive ion channels, including TREK1, Piezo1, and related pathways, enhancing osteoblast differentiation. Sonotherapy using CF exhibits an excellent therapeutic effect in treating osteomyelitis. This study provides novel insights into manipulating spin electrons for applications in life health.