Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7703694 | Ultrasonics Sonochemistry | 2017 | 10 Pages |
Abstract
This paper compared the effects of flowing phase-shift nanodroplets (NDs) and lipid-shelled microbubbles (MBs) on subsequent cavitation during focused ultrasound (FUS) exposures. The cavitation activity was monitored using a passive cavitation detection method as solutions of either phase-shift NDs or lipid-shelled MBs flowed at varying velocities through a 5-mm diameter wall-less vessel in a transparent tissue-mimicking phantom when exposed to FUS. The intensity of cavitation for the phase-shift NDs showed an upward trend with time and cavitation for the lipid-shelled MBs grew to a maximum at the outset of the FUS exposure followed by a trend of decreases when they were static in the vessel. Meanwhile, the increase of cavitation for the phase-shift NDs and decrease of cavitation for the lipid-shelled MBs had slowed down when they flowed through the vessel. During two discrete identical FUS exposures, while the normalized inertial cavitation dose (ICD) value for the lipid-shelled MB solution was higher than that for the saline in the first exposure (p-value <0.05), it decreased to almost the same level in the second exposure. For the phase-shift NDs, the normalized ICD was 0.71 in the first exposure and increased to 0.97 in the second exposure. At a low acoustic power, the normalized ICD values for the lipid-shelled MBs tended to increase with increasing velocities from 5 to 30 cm/s (r > 0.95). Meanwhile, the normalized ICD value for the phase-shift NDs was 0.182 at a flow velocity of 5 cm/s and increased to 0.188 at a flow velocity of 15 cm/s. As the flow velocity increased to 20 cm/s, the normalized ICD was 0.185 and decreased to 0.178 at a flow velocity of 30 cm/s. At high acoustic power, the normalized ICD values for both the lipid-shelled MBs and the phase-shift NDs increased with increasing flow velocities from 5 to 30 cm/s (r > 0.95). The effects of the flowing phase-shift NDs vaporized into gas bubbles as cavitation nuclei on the subsequent cavitation were inverse to those of the flowing lipid-shelled MBs destroyed after focused ultrasound exposures.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Chemistry (General)
Authors
Siyuan Zhang, Zhiwei Cui, Tianqi Xu, Pan Liu, Dapeng Li, Shaoqiang Shang, Ranxiang Xu, Yujin Zong, Gang Niu, Supin Wang, Xijing He, Mingxi Wan,