Using Passively Detected Acoustic Signals to Characterize Ultrasound Gated Nanoparticles

Focused ultrasound (FUS) can concentrate energy noninvasively through the skull to elicit neuromodulation. Although the natural response of neurons to ultrasound has been explored, acoustically active drug loaded nanoparticles have the benefit of yielding a pharmacological response that may be more predictable than the effects of FUS alone. Researchers have developed drug delivery vehicles that release small molecule neuromodulatory drugs without opening blood brain barrier. It is desirable to increase drug release, and drug release typically increases with increased peak negative pressure (PNP). However, the likelihood of undesirable bioeffects, such as cavitation-induced focal hemorrhages increases with increasing PNP. Here, we examined echoes from propofol-containing nanoparticles during ultrasound exposures known to uncage propofol from the vehicle. Our goals were to 1) increase drug release without generating cavitation and 2) identify echoes that may be related to propofol release.