Fe3O4@TiO2‑laden neutrophils activate innate immunity via photosensitive reactive oxygen species release

Although a variety of advanced sterilization materials and treatments haveemerged, the complete elimination of bacterial infection, especially drug-resistantbacterial infection, remains an immense challenge. Here, we demonstrate the use ofneutrophils loaded with photocatalytic nanoparticles to reduce bacterial infection. Thismethod activates the immune system to achieve an anti-infection response. We preparedthe photocatalytic nanoparticle-laden neutrophils in vivo through neutrophilphagocytosis. The resulting loaded cells retained the cell membrane functionality ofthe source cell, as well as the complete immune cell function of neutrophils, particularlythe ability to recruit macrophages to the target area. Photocatalytic nanoparticle-ladenneutrophils can target infection sites and release reactive oxygen species to induce thesecretion of chemokines, leading to the targeted recruitment of macrophages andenhancing a powerful immune cascade. In a severe mouse infection model induced bypathogenic bacteria, small doses of photocatalytic nanoparticle-laden neutrophils showeda remarkable therapeutic effect by enhancing macrophage recruitment and the immune cascade