Phase-shift droplets provide a flexible and dynamic platform for therapeutic and diagnostic applications of ultrasound. The spatiotemporal response of phase-shift droplets to focused ultrasound, via the mechanism termed acoustic droplet vaporization (ADV), can generate a range of bioeffects. Although ADV has been used widely in theranostic applications, ADV-induced bioeffects are understudied. Here, we integrated ultra-high-speed microscopy, confocal microscopy, and focused ultrasound for real-time visualization of ADV-induced mechanics and sonoporation in fibrin-based, tissue-mimicking hydrogels. Three monodispersed phase-shift droplets—containing perfluoropentane (PFP), perfluorohexane (PFH), or perfluorooctane (PFO)—with an average radius of ∼6 μm were studied. Fibroblasts and tracer particles, co-encapsulated within the hydrogel, were used to quantify sonoporation and mechanics resulting from ADV, respectively. The maximum radial expansion, expansion velocity, induced strain, and displacement of tracer particles were significantly higher in fibrin gels containing PFP droplets compared to PFH or PFO. Additionally, cell membrane permeabilization significantly depended on the distance between the droplet and cell (d), decreasing rapidly with increasing d. Significant membrane permeabilization occurred when d was smaller than the maximum radius of expansion. Both ultra-high-speed and confocal images indicate a hyper-local region of influence by an ADV bubble, which correlated inversely with the bulk boiling point of the phase-shift droplets. The findings provide insight into developing optimal approaches for therapeutic applications of ADV.

1.
J. B.
Fowlkes
,
O. D.
Kripfgans
, and
P. L.
Carson
, “
Microbubbles for ultrasound diagnosis and therapy
,” in
2004 2nd IEEE International Symposium on Biomedical Imaging: Nano to Macro
, IEEE Cat. No. 04EX821 (IEEE, 2004), pp.
29
32
.
2.
A. L. Y.
Kee
and
B. M.
Teo
, “
Biomedical applications of acoustically responsive phase shift nanodroplets: Current status and future directions
,”
Ultrason. Sonochem.
56
,
37
45
(
2019
).
3.
P. G.
Durham
and
P. A.
Dayton
, “
Applications of sub-micron low-boiling point phase change contrast agents for ultrasound imaging and therapy
,”
Curr. Opin. Colloid Interface Sci.
56
,
101498
(
2021
).
4.
M.
Aliabouzar
and
M. L.
Fabiilli
, “
Building blood vessels and beyond using bubbles
,”
Acoust. Today
18
(
2
),
14
23
(
2022
).
5.
N. Y.
Rapoport
,
K.-H.
Nam
,
Z.
Gao
, and
A.
Kennedy
, “
Application of ultrasound for targeted nanotherapy of malignant tumors
,”
Acoust. Phys.
55
,
594
601
(
2009
).
6.
K.
Kalayeh
,
J. B.
Fowlkes
,
J.
Claflin
,
M. L.
Fabiilli
,
W. W.
Schultz
, and
B. S.
Sack
, “
Ultrasound contrast stability for urinary bladder pressure measurement
,”
Ultrasound Med. Biol.
49
(
1
),
136
151
(
2023
).
7.
J.-M.
Escoffre
and
A.
Bouakaz
,
Therapeutic Ultrasound
(
Springer
,
2015
).
8.
K.
Kalayeh
,
J. B.
Fowlkes
,
A.
Chen
,
S.
Yeras
,
M. L.
Fabiilli
,
J.
Claflin
,
S.
Daignault-Newton
,
W. W.
Schultz
, and
B. S.
Sack
, “
Pressure measurement in a bladder phantom using contrast-enhanced ultrasonography—A path to a catheter-free voiding cystometrogram
,”
Invest. Radiol.
58
(
3
),
181
189
(
2023
).
9.
O. D.
Kripfgans
,
J. B.
Fowlkes
,
D. L.
Miller
,
O. P.
Eldevik
, and
P. L.
Carson
, “
Acoustic droplet vaporization for therapeutic and diagnostic applications
,”
Ultrasound Med. Biol.
26
(
7
),
1177
1189
(
2000
).
10.
O.
Shpak
,
T. J.
Kokhuis
,
Y.
Luan
,
D.
Lohse
,
N.
de Jong
,
B.
Fowlkes
,
M.
Fabiilli
, and
M.
Versluis
, “
Ultrafast dynamics of the acoustic vaporization of phase-change microdroplets
,”
J. Acoust. Soc. Am.
134
(
2
),
1610
1621
(
2013
).
11.
D. S.
Li
,
O. D.
Kripfgans
,
M. L.
Fabiilli
,
J.
Brian Fowlkes
, and
J. L.
Bull
, “
Initial nucleation site formation due to acoustic droplet vaporization
,”
Appl. Phys. Lett.
104
(
6
),
063703
(
2014
).
12.
O. D.
Kripfgans
,
M. L.
Fabiilli
,
P. L.
Carson
, and
J.
Fowlkes
, “
Acoustic vaporization micrometer-sized droplets
,”
J. Acoust. Soc. Am.
116
(
1
),
272
281
(
2004
).
13.
O.
Shpak
,
L.
Stricker
,
M.
Versluis
, and
D.
Lohse
, “
The role of gas in ultrasonically driven vapor bubble growth
,”
Phys. Med. Biol.
58
(
8
),
2523
(
2013
).
14.
O.
Shpak
,
M.
Verweij
,
H. J.
Vos
,
N.
de Jong
,
D.
Lohse
, and
M.
Versluis
, “
Acoustic droplet vaporization is initiated by superharmonic focusing
,”
Appl. Phys. Sci.
111
(
5
),
1697
1702
(
2014
).
15.
M.
Aliabouzar
,
O. D.
Kripfgans
,
J. B.
Fowlkes
, and
M. L.
Fabiilli
, “
Bubble nucleation and dynamics in acoustic droplet vaporization: A review of concepts, applications, and new directions
,”
Z. Medizinische Phys.
(
2023
).
16.
M. T.
Burgess
and
T. M.
Porter
, “
On-demand cavitation from bursting droplets
,”
Acoust. Today
11
(
4
),
35
41
(
2015
).
17.
P. S.
Sheeran
and
P.
Dayton
, “
Phase-change contrast agents for imaging and therapy
,”
Curr. Pharm. Des.
18
(
15
),
2152
2165
(
2012
).
18.
M.
Aliabouzar
,
O. D.
Kripfgans
,
J. B.
Estrada
,
J. B.
Fowlkes
, and
M. L.
Fabiilli
, “
Multi-time scale characterization of acoustic droplet vaporization and payload release of phase-shift emulsions using high-speed microscopy
,”
Ultrason. Sonochem.
88
,
106090
(
2022
).
19.
M. T.
Burgess
,
M.
Aliabouzar
,
C.
Aguilar
,
M. L.
Fabiilli
, and
J. A.
Ketterling
, “
Slow-flow ultrasound localization microscopy using recondensation of perfluoropentane nanodroplets
,”
Ultrasound Med. Biol.
48
(
5
),
743
759
(
2022
).
20.
M.
Aliabouzar
,
C. D.
Davidson
,
W. Y.
Wang
,
O. D.
Kripfgans
,
R. T.
Franceschi
,
A. J.
Putnam
,
J. B.
Fowlkes
,
B. M.
Baker
, and
M. L.
Fabiilli
, “
Spatiotemporal control of micromechanics and microstructure in acoustically-responsive scaffolds using acoustic droplet vaporization
,”
Soft Matter
16
(
28
),
6501
6513
(
2020
).
21.
X.
Lu
,
X.
Dong
,
S.
Natla
,
O. D.
Kripfgans
,
J. B.
Fowlkes
,
X.
Wang
,
R.
Franceschi
,
A. J.
Putnam
, and
M. L.
Fabiilli
, “
Parametric study of acoustic droplet vaporization thresholds and payload release from acoustically-responsive scaffolds
,”
Ultrasound Med. Bio.
45
(
9
),
2471
84
(
2019
).
22.
T. O.
Matsunaga
,
P. S.
Sheeran
,
S.
Luois
,
J. E.
Streeter
,
L. B.
Mullin
,
B.
Banerjee
, and
P. A.
Dayton
, “Phase-change nanoparticles using highly volatile perfluorocarbons: Toward a platform for extravascular ultrasound imaging,”
Theranostics
2
(
12
),
1185
(
2012
).
23.
D. R.
Evans
,
D. F.
Parsons
, and
V. S.
Craig
, “
Physical properties of phase-change emulsions
,”
Langmuir
22
(
23
),
9538
9545
(
2006
).
24.
R.
Suzuki
,
T.
Takizawa
,
Y.
Negishi
,
N.
Utoguchi
, and
K.
Maruyama
, “
Effective gene delivery with novel liposomal bubbles and ultrasonic destruction technology
,”
Int. J. Pharm.
354
(
1–2
),
49
55
(
2008
).
25.
S.
Mitragotri
, “
Healing sound: The use of ultrasound in drug delivery and other therapeutic applications
,”
Nat. Rev. Drug Discov.
4
(
3
),
255
260
(
2005
).
26.
M.
Wang
,
Y.
Zhang
,
C.
Cai
,
J.
Tu
,
X.
Guo
, and
D.
Zhang
, “
Sonoporation-induced cell membrane permeabilization and cytoskeleton disassembly at varied acoustic and microbubble-cell parameters
,”
Sci. Rep.
8
(
1
),
3885
(
2018
).
27.
R.
Haugse
,
A.
Langer
,
E. T.
Murvold
,
D. E.
Costea
,
B. T.
Gjertsen
,
O. H.
Gilja
,
S.
Kotopoulis
,
G.
Ruiz de Garibay
, and
E.
McCormack
, “
Low-intensity sonoporation-induced intracellular signalling of pancreatic cancer cells, fibroblasts and endothelial cells
,”
Pharmaceutics
12
(
11
),
1058
(
2020
).
28.
J. H.
Hwang
,
J.
Tu
,
A. A.
Brayman
,
T. J.
Matula
, and
L. A.
Crum
, “
Correlation between inertial cavitation dose and endothelial cell damage in vivo
,”
Ultrasound Med. Biol.
32
(
10
),
1611
1619
(
2006
).
29.
C. F.
Caskey
,
S. M.
Stieger
,
S.
Qin
,
P. A.
Dayton
, and
K. W.
Ferrara
, “
Direct observations of ultrasound microbubble contrast agent interaction with the microvessel wall
,”
J. Acoust. Soc. Am.
122
(
2
),
1191
1200
(
2007
).
30.
A. D.
Maxwell
,
T.-Y.
Wang
,
C. A.
Cain
,
J. B.
Fowlkes
,
O. A.
Sapozhnikov
,
M. R.
Bailey
, and
Z.
Xu
, “
Cavitation clouds created by shock scattering from bubbles during histotripsy
,”
J. Acoust. Soc. Am.
130
(
4
),
1888
1898
(
2011
).
31.
P.
Qin
,
T.
Han
,
C.
Alfred
, and
L.
Xu
, “
Mechanistic understanding the bioeffects of ultrasound-driven microbubbles to enhance macromolecule delivery
,”
J. Controlled Release
272
,
169
181
(
2018
).
32.
R.
Seda
,
D. S.
Li
,
J. B.
Fowlkes
, and
J. L.
Bull
, “
Characterization of bioeffects on endothelial cells under acoustic droplet vaporization
,”
Ultrasound Med. Biol.
41
(
12
),
3241
3252
(
2015
).
33.
C.-H.
Fan
,
Y.-T.
Lin
,
Y.-J.
Ho
, and
C.-K.
Yeh
, “
Spatial-temporal cellular bioeffects from acoustic droplet vaporization
,”
Theranostics
8
(
20
),
5731
(
2018
).
34.
W. W.
Liu
,
S. H.
Huang
, and
P. C.
Li
, “
Synchronized optical and acoustic droplet vaporization for effective sonoporation
,”
Pharmaceutics
11
(
6
),
279
(
2019
).
35.
D.
Qin
,
L.
Zhang
,
N.
Chang
,
P.
Ni
,
Y.
Zong
,
A.
Bouakaz
,
M.
Wan
, and
Y.
Feng
, “
In situ observation of single cell response to acoustic droplet vaporization: Membrane deformation, permeabilization, and blebbing
,”
Ultrason. Sonochem.
47
,
141
150
(
2018
).
36.
S. Y.
Wu
,
S. M.
Fix
,
C. B.
Arena
,
C. C.
Chen
,
W.
Zheng
,
O. O.
Olumolade
,
V.
Papadopoulou
,
A.
Novell
,
P. A.
Dayton
, and
E. E.
Konofagou
, “
Focused ultrasound-facilitated brain drug delivery using optimized nanodroplets: Vaporization efficiency dictates large molecular delivery
,”
Phys. Med. Biol.
63
(
3
),
035002
(
2018
).
37.
S.-T.
Kang
,
Y.-C.
Lin
, and
C.-K.
Yeh
, “
Mechanical bioeffects of acoustic droplet vaporization in vessel-mimicking phantoms
,”
Ultrason. Sonochem.
21
(
5
),
1866
1874
(
2014
).
38.
K.
Duval
,
H.
Grover
,
L.-H.
Han
,
Y.
Mou
,
A. F.
Pegoraro
,
J.
Fredberg
, and
Z.
Chen
, “
Modeling physiological events in 2D vs. 3D cell culture
,”
Physiology
32
(
4
),
266
277
(
2017
).
39.
H.
Jin
,
C.
Quesada
,
M.
Aliabouzar
,
O. D.
Kripfgans
,
R. T.
Franceschi
,
J.
Liu
,
A. J.
Putnam
, and
M. L.
Fabiilli
, “
Release of basic fibroblast growth factor from acoustically-responsive scaffolds promotes therapeutic angiogenesis in the hind limb ischemia model
,”
J. Controlled Release
338
,
773
783
(
2021
).
40.
L.
Huang
,
C.
Quesada
,
M.
Aliabouzar
,
J. B.
Fowlkes
,
R. T.
Franceschi
,
Z.
Liu
,
A. J.
Putnam
, and
M. L.
Fabiilli
, “
Spatially-directed angiogenesis using ultrasound-controlled release of basic fibroblast growth factor from acoustically-responsive scaffolds
,”
Acta Biomater.
129
,
73
83
(
2021
).
41.
M.
Aliabouzar
,
O. D.
Kripfgans
,
W. Y.
Wang
,
B. M.
Baker
,
J.
Brian Fowlkes
, and
M. L.
Fabiilli
, “
Stable and transient bubble formation in acoustically-responsive scaffolds by acoustic droplet vaporization: Theory and application in sequential release
,”
Ultrason. Sonochem.
72
,
105430
(
2021
).
42.
M.
Aliabouzar
,
C.
Quesada
,
Z. Q.
Chan
,
J. B.
Fowlkes
,
R. T.
Franceschi
,
A. J.
Putnam
, and
M. L.
Fabiilli
, “
Acoustic droplet vaporization for on-demand modulation of microporosity in smart hydrogels
,”
Acta Biomater.
164
,
195
208
(
2023
).
43.
M.
Aliabouzar
,
A.
Jivani
,
X.
Lu
,
O. D.
Kripfgans
,
J. B.
Fowlkes
, and
M. L.
Fabiilli
, “
Standing wave-assisted acoustic droplet vaporization for single and dual payload release in acoustically-responsive scaffolds
,”
Ultrason. Sonochem.
66
,
105109
(
2020
).
44.
P. S.
Sheeran
,
T. O.
Matsunaga
, and
P. A.
Dayton
, “
Phase change events of volatile liquid perfluorocarbon contrast agents produce unique acoustic signatures
,”
Phys. Med. Biol.
59
(
2
),
379
(
2014
).
45.
A. A.
Doinikov
,
P. S.
Sheeran
,
A.
Bouakaz
, and
P. A.
Dayton
, “
Vaporization dynamics of volatile perfluorocarbon droplets: A theoretical model and in vitro validation
,”
Med. Phys.
41
(
10
),
102901
(
2014
).
46.
J. B.
Estrada
,
H. C.
Cramer
III
,
M. T.
Scimone
,
S.
Buyukozturk
, and
C.
Franck
, “
Neural cell injury pathology due to high-rate mechanical loading
,”
Brain Multiphysics
2
,
100034
(
2021
).
47.
J. B.
Estrada
,
C.
Barajas
,
D. L.
Henann
,
E.
Johnsen
, and
C.
Franck
, “
High strain-rate soft material characterization via inertial cavitation
,”
J. Mech. Phys. Solids
112
,
291
317
(
2018
).
48.
S.
Le Gac
,
E.
Zwaan
,
A.
van den Berg
, and
C.-D.
Ohl
, “
Sonoporation of suspension cells with a single cavitation bubble in a microfluidic confinement
,”
Lab Chip
7
(
12
),
1666
1672
(
2007
).
49.
Y.
Zhou
,
K.
Yang
,
J.
Cui
,
J.
Ye
, and
C.
Deng
, “
Controlled permeation of cell membrane by single bubble acoustic cavitation
,”
J. Controlled Release
157
(
1
),
103
111
(
2012
).

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