Sonodynamic Bacterial Inactivation Enhanced by an Actuator-Integrated Mechanism

Sonodynamic bacterial inactivation, a reactive oxygen species (ROS)-empowered approach featuring high penetration depth and low health risk, is explored for antibiotic-free antibacterial treatment. However, the low yield and insufficient diffusion of ROS negatively affect the antibacterial efficacy of sonodynamic treatment, thus hindering its further development. Here an actuator-integrated mechanism is proposed for enhancing the sonodynamic efficacy of loaded sonosensitizers through motion-induced hydrodynamic effects, demonstrated by a porphyrin-decorated gold nanomotor, which can produce ROS for bacterial inactivation while performing multimodal motion via actuation using low-frequency ultrasound. Corroborated by numerical simulation, the experimental results show that the motor's stirring motion significantly increases the yield and diffusion of ROS through fluid flow and frequent interactions between the motor and bacterial targets, resulting in doubled antibacterial efficiency in comparison to a stationary motor. Furthermore, the flow-induced shear forces combined with the frequent interactions constitute a source of mechanical damage and can form a synergy with the antibacterial properties of ROS, enabling an efficient biofilm eradication that is inaccessible by freely suspended porphyrin. In conclusion, this study reports a motion-based strategy to enhance sonodynamic efficacy and provides proof of concept using a sonodynamic gold nanomotor powered by ultrasound.