Biomimetic MnO2 micromotors with asymmetric sea urchin architecture for synergistic mechano-chemical eradication of endodontic biofilms

Abstract

Effective treatment of apical periodontitis remains challenging due to the persistent bacterial biofilms within the complex root canal anatomy. To address the limitations of conventional disinfectants regarding penetration depth and tissue irritation, this study developed a self-propelled hollow “urchin-like” MnO₂ micromotor via a facile one-step hydrothermal method. The micromotors are propelled by oxygen bubbles generated through catalytic decomposition of H₂O₂, demonstrating remarkable autonomous motion at 33.8 ± 2.5 μm s⁻¹ in 2% H₂O₂, enabling deep penetration into the complex root canal architecture. Their unique spiny architecture not only enhanced H₂O₂ catalytic efficiency for reactive oxygen species generation but also physically disrupted biofilms (67% disruption rate) through mechanical friction. This synergistic mechano-chemical action achieved 93.6% antibacterial efficacy against Enterococcus faecalis while oxygenating the anaerobic microenvironment in deep root canal regions, with superior biocompatibility to sodium hypochlorite. This work presents an innovative disinfection strategy combining superior penetration, synergistic antibacterial activity, and clinical safety, offering a promising alternative to current disinfection methods in endodontics.