Stable and transient bubble formation in acoustically-responsive scaffolds by acoustic droplet vaporization: theory and application in sequential release

Mitra Aliabouzar; Oliver D. Kripfgans; William Y. Wang; Brendon M. Baker; J. Brian Fowlkes; Mario L. Fabiilli

Ultrasonics Sonochemistry (Apr 2021)

Stable and transient bubble formation in acoustically-responsive scaffolds by acoustic droplet vaporization: theory and application in sequential release

Mitra Aliabouzar,
Oliver D. Kripfgans,
William Y. Wang,
Brendon M. Baker,
J. Brian Fowlkes,
Mario L. Fabiilli

Affiliations

Mitra Aliabouzar: Department of Radiology, University of Michigan, Ann Arbor, MI, USA
Oliver D. Kripfgans: Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA
William Y. Wang: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
Brendon M. Baker: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
J. Brian Fowlkes: Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA
Mario L. Fabiilli: Department of Radiology, University of Michigan, Ann Arbor, MI, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Applied Physics Program, University of Michigan, Ann Arbor, MI, USA; Corresponding author at: University of Michigan, 3226A Medical Sciences Building I, 1301 Catherine Street, Ann Arbor, MI 48109-5667, USA.

Journal volume & issue: Vol. 72
p. 105430

Abstract

Read online

Acoustically-responsive scaffolds (ARSs), which are fibrin hydrogels containing monodispersed perfluorocarbon (PFC) emulsions, respond to ultrasound in an on-demand, spatiotemporally-controlled manner via a mechanism termed acoustic droplet vaporization (ADV). Previously, ADV has been used to control the release of bioactive payloads from ARSs to stimulate regenerative processes. In this study, we used classical nucleation theory (CNT) to predict the nucleation pressure in emulsions of different PFC cores as well as the corresponding condensation pressure of the ADV-generated bubbles. According to CNT, the threshold bubble radii above which ADV-generated bubbles remain stable against condensation were 0.4 µm and 5.2 µm for perfluoropentane (PFP) and perfluorohexane (PFH) bubbles, respectively, while ADV-generated bubbles of any size in perfluorooctane (PFO) condense back to liquid at ambient condition. Additionally, consistent with the CNT findings, stable bubble formation from PFH emulsion was experimentally observed using confocal imaging while PFO emulsion likely underwent repeated vaporization and recondensation during ultrasound pulses. In further experimental studies, we utilized this unique feature of ADV in generating stable or transient bubbles, through tailoring the PFC core and ultrasound parameters (excitation frequency and pulse duration), for sequential delivery of two payloads from PFC emulsions in ARSs. ADV-generated stable bubbles from PFH correlated with complete release of the payload while transient ADV resulted in partial release, where the amount of payload release increased with the number of ultrasound exposure. Overall, these results can be used in developing drug delivery strategies using ARSs.

Published in Ultrasonics Sonochemistry

ISSN: 1350-4177 (Print); 1873-2828 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Chemistry; Science: Physics: Acoustics. Sound
Website: https://www.journals.elsevier.com/ultrasonics-sonochemistry

About the journal

Abstract

Keywords