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Ultrafast Microscopy Imaging of Acoustic Cluster Therapy Bubbles: Activation and Oscillation

Abstract

Acoustic Cluster Therapy (ACT®) is a platform for improving drug delivery and has had promising pre-clinical results. A clinical trial is ongoing. ACT® is based on microclusters of microbubbles–microdroplets that, when sonicated, form a large ACT® bubble. The aim of this study was to obtain new knowledge on the dynamic formation and oscillations of ACT® bubbles by ultrafast optical imaging in a microchannel. The high-speed recordings revealed the microbubble–microdroplet fusion, and the gas in the microbubble acted as a vaporization seed for the microdroplet. Subsequently, the bubble grew by gas diffusion from the surrounding medium and became a large ACT® bubble with a diameter of 5–50 μm. A second ultrasound exposure at lower frequency caused the ACT® bubble to oscillate. The recorded oscillations were compared with simulations using the modified Rayleigh–Plesset equation. A term accounting for the physical boundary imposed by the microchannel wall was included. The recorded oscillation amplitudes were approximately 1–2 µm, hence similar to oscillations of smaller contrast agent microbubbles. These findings, together with our previously reported promising pre-clinical therapeutic results, suggest that these oscillations covering a large part of the vessel wall because of the large bubble volume can substantially improve therapeutic outcome.
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Category

Academic article

Language

English

Author(s)

  • Annemieke van Wamel
  • Melina Mühlenpfordt
  • Rune Hansen
  • Andrew Healey
  • Flordeliza S. Villanueva
  • Spiros Kotopoulis
  • Catharina de Lange Davies
  • Xucai Chen

Affiliation

  • SINTEF Digital / Health Research
  • University of Bergen
  • Norwegian University of Science and Technology
  • University of Pittsburgh
  • Andre institusjoner

Year

2022

Published in

Ultrasound in Medicine and Biology

ISSN

0301-5629

Volume

48

Issue

9

Page(s)

1840 - 1857

View this publication at Norwegian Research Information Repository