Magnetic Janus Nanomotor for Dentin Hypersensitivity Treatment

Reoccluding the exposed dentinal tubules is crucial for treating dentin hypersensitivity (DH). However, the narrow structure and high-density negative charges of dentinal tubules impede the penetration of filling repair materials to effectively achieve deep-induced mineralization for DH treatment. Herein, a morphologically controllable Fe₃O₄@SiO₂ magnetic Janus nanomotors (MJNs) were synthesized via a seeded emulsion-mediated surface growth strategy. The as-achieved MJNs exhibit magnetic response, with a head diameter of about 200 nm, and snake-like morphology with a tunable tail length regulated 200 nm-4 µm. By adjusting the magnetic field variations, it is permitted to control and transform the cluster structure of MJNs, forming vortex and ribbon clusters. Induced by the magnetic field, the MJNs can infiltrate into narrow dentinal tubules and reaching depths of up to ∼36 µm. To enhance the interaction with dentin, polycatechol group was introduced onto the surface of MJNs to promote mineral formation within the tubules. As a result, dentinal tubule occlusion could be achieved within 3 days under the tested conditions, indicating the potential of this approach for DH treatment.