RT Journal Article SR Electronic T1 Characterisation of Gas Vesicles as Cavitation Nuclei for Ultrasound Therapy using Passive Acoustic Mapping JF bioRxiv FD Cold Spring Harbor Laboratory SP 2024.09.24.614126 DO 10.1101/2024.09.24.614126 A1 Smith, Cameron A. B. A1 Bar-Zion, Avinoam A1 Wu, Qiang A1 Malounda, Dina A1 Bau, Luca A1 Stride, Eleanor A1 Shapiro, Mikhail G. A1 Coussios, Constantin C. YR 2024 UL http://biorxiv.org/content/early/2024/09/26/2024.09.24.614126.abstract AB 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 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, whilst 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.Competing Interest StatementProfessor Constantin Coussios is a Founder, Director, Shareholder and receives consultancy income from OxSonics Therapeutics Ltd, a company spun out from the University of Oxford commercializing cavitation-enhanced drug delivery monitored by Passive Acoustic Mapping. Professor Coussios is also the lead inventor of granted patents on Passive Acoustic Mapping (US9238152B2 and EP2349483B8) which have been commercially licensed.