作者： Walsh, Martin Phillip

Drexel University

摘要：The ability of ultrasound-induced cavitation of microbubbles to impact cells is firmly established, but the mechanism by which the acoustic phenomena affects the phospholipid bilayers are not fully understood. Here, we examine the interactions of acoustically driven microbubbles by themselves and in two other different architectures: microbubbles mixed with liposomes and microbubbles tethered to liposomes. Using a combination of ultrasound acoustic spectra and the Wrenn modified RPNNP colloidal model, we observe the effects of microbubble size distribution, radius, and shell chemistry, along with ultrasound frequency and peak negative pressure on the cavitation behavior of the microbubble. We identify the ultrasound intensities corresponding to stable and inertial cavitation and concomitant acoustic microstreaming and shockwave to reversible and irreversible pore formation, respectively, for each architecture.

The size distribution of microbubbles are similar between the two different chemistries, but with the use of size isolation by differential centrifugation, different size distribution and polydispersity were observed. The decrease in the polydispersity of the microbubbles increased the growth rate of microbubbles destroyed, while the microbubbles with a higher concentration of microbubbles above a micron had a higher amount of acoustic activity. The increase in the frequency slowed the growth rate of microbubbles destroyed from inertial cavitation, while shifting the onset of inertial cavitation to a higher pressure and as the acoustic activity decreased. The addition of polyethylene glycol increased the shell’s area expansion modulus which had a similar effect as an increase in frequency.