A Smart Bacteria-Capture-Killing Vector for Effectively Treating Osteomyelitis Through Synergy Under Microwave Therapy

Osteomyelitis caused by deep tissue infections is difficult to cure through phototherapy due to the poor penetration depth of the light. Herein, Cu/C/Fe3O4-COOH nanorod composites (Cu/C/Fe3O4-COOH) with nanoscale tip convex structures are successfully fabricated as a microwave-responsive smart bacteria-capture-killing vector. Cu/C/Fe3O4-COOH exhibited excellent magnetic targeting and bacteria-capturing ability due to its magnetism and high selectivity affinity to the amino groups on the surface of Staphylococcus aureus (S. aureus). Under microwave irradiation, Cu/C/Fe3O4-COOH efficiently treated S. aureus-infected osteomyelitis through the synergistic effects of microwave thermal therapy, microwave dynamic therapy, and copper ion therapy. It is calculated the electric field intensity in various regions of Cu/C/Fe3O4-COOH under microwave irradiation, demonstrating that it obtained the highest electric field intensity on the surface of copper nanoparticles of Cu/C/Fe3O4-COOH due to its high-curvature tips and metallic properties. This led to copper nanoparticles attracted more charged particles compared with other areas in Cu/C/Fe3O4-COOH. These charges are easier to escape from the high curvature surface of Cu/C/Fe3O4-COOH, and captured by adsorbed oxygen, resulting in the generation of reactive oxygen species. The Cu/C/Fe3O4-COOH designed in this study is expected to provide insight into the treatment of deep tissue infections under the irradiation of microwave. As a smart bacteria-capture-killing vector, microwave-responsive Cu/C/Fe3O4-COOH nanorods composites with good biocompatibility can eliminate 99.99 +/- 0.009% of Staphylococcus aureus. Cu/C/Fe3O4-COOH has excellent bacteria-capturing and magnetic targeting ability. Under microwave irradiation, Staphylococcus aureus is efficiently eradicated by the synergetic effect of microwave thermal therapy, microwave dynamic therapy, and copper ion therapy.image

Automated summary

This study successfully fabricated Cu/C/Fe3O4-COOH nanorod composites with nanoscale tip convex structures as a smart bacteria-capture-killing vector for the treatment of osteomyelitis caused by deep tissue infections. The composites showed excellent magnetic targeting and bacteria-capturing ability and effectively treated Staphylococcus aureus-infected osteomyelitis through the synergistic effects of microwave thermal therapy, microwave dynamic therapy, and copper ion therapy under microwave irradiation.