Ultrasound-triggered drug release via acoustic droplet vaporization (ADV) represents a paradigm shift compared to conventional drug delivery methods. Central to this approach is ADV, which leverages ultrasound-induced phase transition of liquid droplets into gas bubbles for controlled drug release. We investigate whether ADV can be monitored acoustically in ultrasound-responsive platforms for precise, localized drug activation with tunable payload release. Experiments were conducted in fibrin-based hydrogels incorporating perfluorohexane droplets (diameter: ∼6 μm) at 2.5 MHz, varying droplet concentration, ultrasound pressure, and burst number. Acoustic emissions (100–500 kHz) and bubble cloud formation were recorded during exposure, using a hydrophone and camera, while a fluorometer was used to quantify drug release. ADV generated distinct acoustic emissions whose amplitude correlated with the number of bubbles formed per burst, and thus with the payload release. Stable bubble clouds formed at droplet concentrations ≥0.05% (v/v) which coincided with acoustic amplitude plateauing around ™30 dB from the peak amplitude measured at the initial burst, indicating maximum release. Maximum release occurred after 35 bursts at 0.05% (v/v) droplet concentrations, and after 15 bursts at 0.5% (v/v). Our findings suggest that acoustic emissions from ADV can provide real-time feedback for ultrasound-triggered drug release.
Spiekhout et al. (Wed,) studied this question.