Magnetically driven BiOI/MnFe₂O₄ micro/nanorobots for capture, aggregation, and on-site decontamination of biological warfare agents

Biological warfare agents (BWAs) can be misused for military, terrorist, or criminal purposes. It is urgently required to develop effective, recyclable, and on-site removal techniques to eliminate BWAs from the contaminated environment to safeguard national defense security and public health. Although photocatalysis has been regarded as a promising decontamination technique, its practical application is handicapped by limited solar energy utilization, rapid recombination of photogenerated electron-hole pairs, tardy carrier-transfer kinetics, and confined photocatalytic reaction at the catalyst-solvent interface. The integration of photocatalytic materials into magnetically propelled micro/nanorobots (MNRs) helps to address these limitations by leveraging the synergistic benefits of heterojunction engineering and a dynamically photocatalytic platform enabled by magnetic propulsion. Herein, we develop magnetically propelled BiOI/MnFe₂O₄ MNRs by integrating layered BiOI and magnetic MnFe₂O₄ photocatalysts. This not only allows the dynamic capture and accumulation of BWAs and their subsequent effective on-site removal, but also enables the magnetic recycling of MNRs. Given their critical threat characteristics, such as toxin production, multidrug resistance, and low infectious dose risks, pathogenic S. aureus and E. coli were selected as representative BWAs simulants for evaluation. Thanks to the synergistic effect of heterojunction engineering and “on-the-fly” chemistry, the photocatalytic reaction, the optimized photocatalytic MNRs (i.e., BM-0.5) achieve ∼99 % and 95 % antibacterial removal efficiency within 1 h, respectively. This study presents a promising solution for efficient photocatalytic removal of BWAs from contaminated environments, paving the way for the future development of autonomous decontamination systems.