Fig. 2.

Potential antimicrobial mechanisms during US stimulation. (A) Generation of ROS. ROS generated in response to US can be directly involved in mediating cytotoxicity. ROS have a large diffusion radius and can cross the mitochondrial membrane, participating in electron transfer and oxidation, thus affecting the mitochondrial respiratory chain of bacteria. (B) Thermal damage. US irradiation of nanosonosensitizers increases the temperature, and the bacteria are killed directly when the temperature rises under US irradiation. (C) Ultrasonic cavitation effects. A rapid increase in mechanical pressure caused by the acoustic energy of nanosonosensitizers under US irradiation, results in the creation of microbubbles in the tissue fluid, disrupting the cytoskeleton, cell membranes and the activity of biological enzymes. (D) Sonoporation effects. Under the induction of US, temporary pores are created in the cell membrane of bacteria, thus facilitating the penetration of more nanosonosensitizers into the cells.