An ultrasound-activated heterojunction as ROS generator given scaffolds sonodynamic antibacterial effect

Potassium niobate (KNbO3) with favorable biocompatibility presented a great potential in the sonodynamic therapy of implant-related infection due to its superior piezoelectric performance. However, the rapid electron-hole pair recombination weakened its sonodynamic therapy effect. In this work, Au@KNbO3 heterojunctions were synthesized by depositing Au nanoparticles on KNbO3, and then mixed with poly-l-lactic acid (PLLA) powder to prepare scaffold by laser additive manufacturing. Herein, Au with lower Fermi level acted as electron trap to capture the ultrasonic-excited electrons from KNbO3. Subsequently, Au formed Schottky barrier with KNbO3 to prevent electrons backflow. As a result, the electron-hole was expected to be separated. EIS curves indicated that Au@KNbO3 presented a smaller arc radius than that of KNbO3, confirming the electron-hole separation efficiency of Au@KNbO3 was enhanced. Following that, ROS generation ability of the scaffold was significantly strengthened. Antibacterial tests revealed that the generated ROS could not only trigger protein leakage by disrupting bacterial cell membranes, but also deplete glutathione to weaken the antioxidant defense of bacteria. As a consequence, the scaffold exhibited excellent antibacterial abilities of 92% and 90% against S. aureus and E. coli, respectively. Collectively, this work provided a promising countermeasure to fight the implant-related infection.