Biophysical insight into mechanisms of sonoporation

Significance Gas-filled microbubbles physically oscillate in an ultrasound field and have been shown to potentiate the delivery of therapeutic payloads. The biophysical mechanisms by which vibrating microbubbles stimulate macromolecule uptake across the cell membrane, however, remain unknown. With a coupled microscopy system capable of bright-field imaging up to 25 million frames per second, we show correlations between microsecond-scale bubble oscillations and second-to-minute–scale macromolecule diffusion, uniquely highlighting that microbubble-induced shear stress is a threshold indicator for membrane pore generation. Further insight into membrane reorganization using real-time confocal microscopy demonstrates that ultrasound-triggered microbubbles create resealing pores through both layers of cellular membrane, and gaps between confluent cells. This work presents mechanistic, biophysical insight into sonoporation as a tool for local delivery of therapeutic macromolecules.