BME Frontiers / 2022 / Article / Fig 4

Review Article

Ultrasound-Mediated Drug Delivery: Sonoporation Mechanisms, Biophysics, and Critical Factors

Figure 4

Schematic overview of major biophysical effects occurring during sonoporation generated by microbubbles. (a) A microbubble that is undergoing stable cavitation (SC), as triggered by low acoustic pressure, would exhibit symmetrical linear oscillations; in contrast, inertial cavitation (IC), which results in violent microbubble collapse and fragmentation, is excited by ultrasound exposures at even higher driving pressures. (b) A stably cavitation microbubble would generate volumetric oscillations to exert radiation force and microstreaming-induced shear forces. (c) An inertially cavitating microbubble would produce microjets. These physical forces can result in cell membrane permeabilization, cytoskeleton rearrangement, and transmembrane ion transport such as K+ efflux and Ca2+ influx.