Photocatalytic microrobots for treating bacterial infections deep within sinuses

Microrobotic techniques are promising for treating biofilm infections located deep within the human body. However, the presence of highly viscous pus presents a formidable biological barrier, severely restricting targeted and minimally invasive treatments. In addition, conventional antibacterial agents exhibit limited payload integration with microrobotic systems, further compromising therapeutic efficiency. In this study, we propose a photocatalytic microrobot through a magnetically guided, optical fiber–assisted therapeutic platform specifically designed to treat bacterial infections in deep mucosal cavities. The microrobots comprising copper (Cu) single atom–doped bismuth oxoiodide (BiOI), termed CBMRs, can be guided and tracked by real-time x-ray imaging. Under external magnetic actuation, the illuminated region from the magnetically guided optical fiber synchronously follows the CBMR swarm, enabling effective antibacterial action at targeted infection sites. Upon continuous visible-light irradiation, the resultant photothermal effect substantially reduces the viscosity of pus on inflamed mucosal tissues, enhancing the penetration capability of the CBMR swarm by more than threefold compared with baseline conditions. Concurrently, atomic-level design of CBMRs facilitates robust generation of reactive oxygen species, enabling efficient biofilm disruption and reductions in bacterial viability. We validated the effectiveness of this integrated optical fiber–assisted microrobotic platform in a rabbit sinusitis model in vivo, demonstrating its potential for clinically relevant infection therapy.