Smith Cameron A B, Bar-Zion Avinoam, Wu Qiang, Malounda Dina, Bau Luca, Stride Eleanor, Shapiro Mikhail G, Coussios Constantin C
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, United Kingdom.
AIP Adv. 2025 Feb 7;15(2):025016. doi: 10.1063/5.0239607. eCollection 2025 Feb.
Genetically encodable gas-filled particles, known as gas vesicles (GVs), have shown promise as a biomolecular contrast agent for ultrasound imaging and have the potential to be used as cavitation nuclei for ultrasound therapy. In this study, we used passive acoustic mapping techniques to characterize GV-seeded cavitation, utilizing 0.5 and 1.6 MHz ultrasound insonation over peak rarefactional pressures ranging from 100 to 2200 kPa. We found that GVs produce cavitation for the duration of the first applied pulse, up to at least 5000 cycles, but that bubble activity diminishes rapidly over subsequent pulses. At 0.5 MHz, the frequency content of cavitation emissions was predominantly broadband in nature, while at 1.6 MHz, narrowband content at harmonics of the main excitation frequency dominated. Simulations and high-speed camera imaging suggest that the received cavitation emissions come not from individual GVs but instead from the coalescence of GV-released gas into larger bubbles during the applied ultrasound pulse. These results will aid the future development of GVs as cavitation nuclei in ultrasound therapy.
基因编码的充气颗粒，即气荚膜（GVs），已显示出作为超声成像生物分子造影剂的前景，并有可能用作超声治疗的空化核。在本研究中，我们使用被动声学映射技术来表征GV引发的空化，利用0.5和1.6兆赫的超声照射，峰值负压范围为100至2200千帕。我们发现，GVs在第一个施加脉冲的持续时间内会产生空化，至少持续5000个周期，但在随后的脉冲中气泡活动会迅速减弱。在0.5兆赫时，空化发射的频率成分主要是宽带性质的，而在1.6兆赫时，主要激发频率谐波处的窄带成分占主导。模拟和高速相机成像表明，接收到的空化发射并非来自单个GVs，而是来自在施加超声脉冲期间GV释放的气体聚合成更大的气泡。这些结果将有助于GVs作为超声治疗中空化核的未来发展。
