Polydopamine-Coated Magnetic Nanoplatform for Magnetically Guided Penetration and Enhanced Antibacterial Efficacy in Root Canal Biofilm Elimination

Clinical root canal therapy which takes place through mechanical and chemical strategies is faced with challenges in eliminating bacteria owing to the intricate and curved nature of the root canal system. Moreover, the plaque biofilm within the root canal hinders drug penetration and limits treatment efficacy. Hence, efficient root canal therapy hinges on penetrating into the root canal and overcoming the barriers presented by the plaque biofilms. To penetrate and eradicate biofilms effectively at the root canal, we designed a novel magnetic nanoparticle (MN)-based nanoplatform which was synthesized by the self-polymerization of dopamine on the surface of Fe₃O₄ MNs, and then loaded minocycline through the electrostatic interaction. The therapeutic efficacy of minocycline-loaded magnetic nanoparticles (FDM MNs) under a magnetostatic field was observed by various antibacterial experiments. The synthesized FDM MNs exhibited favorable biocompatibility and robust anti-biofilm efficacy. The designed nanoparticles could effectively navigate biofilms to eradicate bacteria residing deep with the assistance of magnetic force. Furthermore, FDM MNs penetrated into dentin tubules under a magnetic field, effectively disrupting biofilms for deep sterilization. The significant results offered valuable experimental evidence to support the potential clinical utility of magnetic nanoparticles for managing pulpitis and periapical inflammation.