Unique pumping-out fracturing mechanism of a polymer-shelled contrast agent: An acoustic characterization and optical visualization
2014 (English)In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 62, no 3, 451-462 p., 7055440Article in journal (Refereed) Published
This work describes the fracturing mechanism of air-filled microbubbles (MBs) encapsulated by a cross-linked poly(vinyl alcohol) (PVA) shell. The radial oscillation and fracturing events following the ultrasound exposure were visualized with an ultrahigh-speed camera, and backscattered timedomain signals were acquired with the acoustic setup specific for harmonic detection. No evidence of gas emerging from defects in the shell with the arrival of the first insonation burst was found. In optical recordings, more than one shell defect was noted, and the gas core was drained without any sign of air extrusion when several consecutive bursts of 1 MPa amplitude were applied. In acoustic tests, the backscattered peak-to-peak voltage gradually reached its maximum and exponentially decreased when the PVA-based MB suspension was exposed to approximately 20 consecutive bursts arriving at pulse repetition frequencies of 100 and 500 Hz. Taking into account that the PVA shell is porous and possibly contains large air pockets between the cross-linked PVA chains, the aforementioned acoustic behavior might be attributed to pumping gas from these pockets in combination with gas release from the core through shell defects. We refer to this fracturing mechanism as pumping-out behavior, and this behavior could have potential use for the local delivery of therapeutic gases, such as nitric oxide.
Place, publisher, year, edition, pages
2014. Vol. 62, no 3, 451-462 p., 7055440
Medical Equipment Engineering Medical Image Processing Medical Materials
IdentifiersURN: urn:nbn:se:kth:diva-159768DOI: 10.1109/TUFFC.2014.006732ISI: 000351446800006ScopusID: 2-s2.0-84924942910OAI: oai:DiVA.org:kth-159768DiVA: diva2:787417
The study was financed by EU-grants (3MiCRON ) and strategic money from the Karolinska Institutet.
QC 201504092015-02-102015-02-102015-08-26Bibliographically approved