Metallic phase enabling MoS 2 nanosheets as an efficient sonosensitizer for photothermal-enhanced sonodynamic antibacterial therapy

Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets (e.g., MoS 2 ) with metallic phase (1T or 1T´ phase) have been proven to exhibit superior performances in various applications as compared to their semiconducting 2H-phase counterparts. However, it remains unclear how the crystal phase of 2D TMD nanosheets affects their sonodynamic property. In this work, we report the preparation of MoS 2 nanosheets with different phases (metallic 1T/1T´ or semiconducting 2H) and exploration of its crystal-phase effect on photothermal-enhanced sonodynamic antibacterial therapy. Interestingly, the defective 2D MoS 2 nanosheets with high-percentage metallic 1T/1T´ phase (denoted as M-MoS 2 ) present much higher activity towards the ultrasound-induced generation of reactive oxygen species (ROS) as compared to the semiconducting 2H-phase MoS 2 nanosheets. More interestingly, owing to its metallic phase-enabled strong absorption in the near-infrared-II (NIR-II) regime, the ultrasound-induced ROS generation performance of the M-MoS 2 nanosheets can be further enhanced by the photothermal effect under a 1064 nm laser irradiation. Thus, after modifying with polyvinylpyrrolidone, the M-MoS 2 nanosheets can be used as an efficient sonosensitizer for photothermal-enhanced sonodynamic bacterial elimination under ultrasound treatment combining with NIR-II laser irradiation. This study demonstrates that metallic MoS 2 nanosheets can be used as a promising sonosensitizer for antibacterial therapy, which might be also promising for cancer therapies. Graphical Abstract