Loss of gas from echogenic liposomes exposed to pulsed ultrasound.
The destruction of echogenic liposomes (ELIP) in response to pulsed ultrasound excitations has been studied acoustically previously. However, the mechanism underlying the loss of echogenicity due to cavitation nucleated by ELIP has not been fully clarified. In this study, an ultra-high speed imaging approach was employed to observe the destruction phenomena of single ELIP exposed to ultrasound bursts at a center frequency of 6 MHz. We observed a rapid size reduction during the ultrasound excitation in 139 out of 397 (35%) ultra- high-speed recordings. The shell dilation rate, which is defined as the microbubble wall velocity divided by the instantaneous radius, [Formula: see text] /R, was extracted from the radius versus time response of each ELIP, and was found to be correlated with the deflation. Fragmentation and surface mode vibrations were also observed and are shown to depend on the applied acoustic pressure and initial radius. Results from this study can be utilized to optimize the theranostic application of ELIP, e.g. by tuning the size distribution or the excitation frequency.
Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3940, 231 Albert Sabin Way, Cincinnati, OH 45267-0586, USA.
Jason L
JL
Raymond
Ying
Y
Luan
Tao
T
Peng
Shao-Ling
SL
Huang
David D
DD
McPherson
Michel
M
Versluis
Nico
N
de Jong
Christy K
CK
Holland
D003287:Contrast Media / Q000737:chemistry*; D005740:Gases / Q000737:chemistry / Q000528:radiation effects*; D008081:Liposomes / Q000737:chemistry* / Q000528:radiation effects*; D045423:Microbubbles; D011312:Pressure; D011829:Radiation Dosage; D000069453:Ultrasonic Waves
D003287:Contrast Media; D005740:Gases; D008081:Liposomes