Fig. 4.

Acoustic droplet vaporization (ADV) in acoustically-responsive scaffolds (ARSs) resulted in stable bubble formation in sufficiently-sized perfluorohexane (PFH) emulsion and transient bubble formation in perfluorooctane (PFO) emulsion at 2.5 MHz (pulse duration: 5.4 µs). (A) Maximum intensity projection of confocal z-stacks of an ARS containing PFH emulsion. The fibrin matrix contained Alexa Flour 647-labeled fibrinogen (shown in red) while the phase-shift double emulsion contained Alexa Flour 488-labeled dextran (AF₄₈₈, shown in green). (B) ADV resulted in stable bubble formation in ARSs containing PFH emulsion. ARSs with PFO emulsion (C) before and (D) after ADV behaved differently (no stable bubble formation). Similar acoustic settings were used in (B) and (D). (E) Repeated ultrasound (US) exposures (3x) in ARSs with PFO emulsion resulted in more AF₄₈₈ release, thus indicating repeated vaporization and recondensation during US pulses. AF₄₈₈ intensity measurements, comparing payload release from PFO over multiple US exposures, is shown in F. Scale bar for all panels: 5 µm. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)