BME Frontiers / 2022 / Article / Fig 6

Review Article

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

Figure 6

(a) The extent of sonoporation depends on bubble size and the number of bubbles adjacent to the cell. (I-III) Bright-field and propidium iodide (PI; model drug marker) fluorescence images of sonoporated cells at different times before and after a single 10 μs, 1 MHz ultrasound pulse at 0.6 MPa peak negative pressure. When the bubble had a diameter () smaller than 5.5 μm and the bubble-cell distance () was smaller than D, PI uptake (red fluorescence) shows positive correlation with bubble size and bubble number, referenced to literature [131]. (b) Real-time fluorescence observations on cellular responses induced by microbubble-mediated sonoporation at different values. Higher PI uptake and significant cytoskeleton disassembly (green fluorescence) are observed when the ratio between and () was reduced from 2 to 0, referenced to literature [95].