TY - JOUR
T1 - Controlled permeation of cell membrane by single bubble acoustic cavitation
AU - Zhou, Y.
AU - Yang, K.
AU - Cui, J.
AU - Ye, J. Y.
AU - Deng, C. X.
N1 - Funding Information:
This work was supported by the National Institutes of Health ( R01CA116592 to C. X. Deng).
PY - 2012/1/10
Y1 - 2012/1/10
N2 - Sonoporation is the membrane disruption generated by ultrasound and has been exploited as a non-viral strategy for drug and gene delivery. Acoustic cavitation of microbubbles has been recognized to play an important role in sonoporation. However, due to the lack of adequate techniques for precise control of cavitation activities and real-time assessment of the resulting sub-micron process of sonoporation, limited knowledge has been available regarding the detail processes and correlation of cavitation with membrane disruption at the single cell level. In the current study, we developed a combined approach including optical, acoustical, and electrophysiological techniques to enable synchronized manipulation, imaging, and measurement of cavitation of single bubbles and the resulting cell membrane disruption in real-time. Using a self-focused femtosecond laser and high frequency ultrasound (7.44 MHz) pulses, a single microbubble was generated and positioned at a desired distance from the membrane of a Xenopus oocyte. Cavitation of the bubble was achieved by applying a low frequency (1.5 MHz) ultrasound pulse (duration 13.3 or 40 μs) to induce bubble collapse. Disruption of the cell membrane was assessed by the increase in the transmembrane current (TMC) of the cell under voltage clamp. Simultaneous high-speed bright field imaging of cavitation and measurements of the TMC were obtained to correlate the ultrasound-generated bubble activities with the cell membrane poration. The change in membrane permeability was directly associated with the formation of a sub-micrometer pore from a local membrane rupture generated by bubble collapse or bubble compression depending on ultrasound amplitude and duration. The impact of the bubble collapse on membrane permeation decreased rapidly with increasing distance (D) between the bubble (diameter d) and the cell membrane. The effective range of cavitation impact on membrane poration was determined to be D/d = 0.75. The maximum mean radius of the pores was estimated from the measured TMC to be 0.106 ± 0.032 μm (n = 70) for acoustic pressure of 1.5 MPa (duration 13.3 μs), and increased to 0.171 ± 0.030 μm (n = 125) for acoustic pressure of 1.7 MPa and to 0.182 ± 0.052 μm (n = 112) for a pulse duration of 40 μs (1.5 MPa). These results from controlled cell membrane permeation by cavitation of single bubbles revealed insights and key factors affecting sonoporation at the single cell level.
AB - Sonoporation is the membrane disruption generated by ultrasound and has been exploited as a non-viral strategy for drug and gene delivery. Acoustic cavitation of microbubbles has been recognized to play an important role in sonoporation. However, due to the lack of adequate techniques for precise control of cavitation activities and real-time assessment of the resulting sub-micron process of sonoporation, limited knowledge has been available regarding the detail processes and correlation of cavitation with membrane disruption at the single cell level. In the current study, we developed a combined approach including optical, acoustical, and electrophysiological techniques to enable synchronized manipulation, imaging, and measurement of cavitation of single bubbles and the resulting cell membrane disruption in real-time. Using a self-focused femtosecond laser and high frequency ultrasound (7.44 MHz) pulses, a single microbubble was generated and positioned at a desired distance from the membrane of a Xenopus oocyte. Cavitation of the bubble was achieved by applying a low frequency (1.5 MHz) ultrasound pulse (duration 13.3 or 40 μs) to induce bubble collapse. Disruption of the cell membrane was assessed by the increase in the transmembrane current (TMC) of the cell under voltage clamp. Simultaneous high-speed bright field imaging of cavitation and measurements of the TMC were obtained to correlate the ultrasound-generated bubble activities with the cell membrane poration. The change in membrane permeability was directly associated with the formation of a sub-micrometer pore from a local membrane rupture generated by bubble collapse or bubble compression depending on ultrasound amplitude and duration. The impact of the bubble collapse on membrane permeation decreased rapidly with increasing distance (D) between the bubble (diameter d) and the cell membrane. The effective range of cavitation impact on membrane poration was determined to be D/d = 0.75. The maximum mean radius of the pores was estimated from the measured TMC to be 0.106 ± 0.032 μm (n = 70) for acoustic pressure of 1.5 MPa (duration 13.3 μs), and increased to 0.171 ± 0.030 μm (n = 125) for acoustic pressure of 1.7 MPa and to 0.182 ± 0.052 μm (n = 112) for a pulse duration of 40 μs (1.5 MPa). These results from controlled cell membrane permeation by cavitation of single bubbles revealed insights and key factors affecting sonoporation at the single cell level.
KW - Cavitation
KW - Intracellular delivery
KW - Membrane permeability
KW - Microbubbles
KW - Sonoporation
KW - Ultrasound
UR - http://www.scopus.com/inward/record.url?scp=84855828861&partnerID=8YFLogxK
U2 - 10.1016/j.jconrel.2011.09.068
DO - 10.1016/j.jconrel.2011.09.068
M3 - Article
C2 - 21945682
AN - SCOPUS:84855828861
SN - 0168-3659
VL - 157
SP - 103
EP - 111
JO - Journal of Controlled Release
JF - Journal of Controlled Release
IS - 1
ER -