Dynamic and Structural Behavior of Magnetic PVA-Shelled Microbubbles: Acoustic Characterization
2013 (English)In: IEEE International Ultrasonics Symposium / [ed] Dr. AHMAD SAFARI, 2013, 1509-1512 p.Conference paper (Refereed)
Combination of superparamagnetic iron oxide nanoparticles (SPOINs) and the polymer-shelled microbubble (MB) are proposed to be a contrast agent for both magnetic resonance and ultrasound imaging. The introduction of nanoparticles into MBs changes the material properties of encapsulating shell, which further influences on MBs performance as an ultrasound contrast agent. Magnetic MBs were prepared in two following strategies: 1. SPIONs were attached on the surface of MBs (Type A) and 2. SPIONs were physically entrapped in the MBs shell during the initial formation of PVA shell (Type B). A modified Church model was used to fit the attenuation coefficient spectra acquired experimentally. This allowed to recalculate the viscoelastic properties, i.e. storage and loss modulus, and dynamical properties, i.e. resonance frequency and damping coefficient of two types of magnetic MBs. The cross-correlation analysis of the time-domain response from the MBs suspension was used to identify pressure threshold at which MBs shell fractures. Higher values of both viscoelastic and dynamic characteristic were identified for MBs Type B. The estimated total damping ratio above 1 suggested that the MBs Type B behave as an overdamped harmonic oscillator whereas MBs Type A with total damping ratio below 1 possess underdamped harmonic oscillator nature. The predicted resonance frequencies are approximately 13 and 27 MHz for MBs Type A and B respectively. Moreover, the fracture pressure threshold measurements revealed that, higher peak negative pressure is required to fracture MBs Type B than Type A. When the driving pulse consists of 12 cycles, pressure threshold was 1.1 MPa and 1.3 MPa for MBs Type A and B respectively. In conclusion, MBs with nanoparticles loaded on the surface (Type A) appear to be more acoustically active, demonstrate lower resonance frequency, damping and fracture pressure threshold, than MBs with nanoparticles incorporated in the shell (Type B).
Place, publisher, year, edition, pages
2013. 1509-1512 p.
ultrasound contrast agent; polymer-shelled microbubbles; superparamagnetic nanoparticle; dual modal contrast agent
Mechanical Engineering Medical Engineering
IdentifiersURN: urn:nbn:se:kth:diva-134219DOI: 10.1109/ULTSYM.2013.0385ISI: 000336665300382ScopusID: 2-s2.0-84894353879ISBN: 978-1-4673-5686-2OAI: oai:DiVA.org:kth-134219DiVA: diva2:665583
2013 Joint UFFC, EFTF and PFM Symposium
FunderEU, FP7, Seventh Framework Programme, 245572
QC 201406272013-11-202013-11-202014-06-27Bibliographically approved