Jump to main content
Jump to site search


High-precision acoustic measurements of the nonlinear dilatational elasticity of phospholipid coated monodisperse microbubbles

Author affiliations

Abstract

The acoustic response of phospholipid-coated microbubble ultrasound contrast agents (UCA) is dramatically affected by their stabilizing shell. The interfacial shell elasticity increases the resonance frequency, the shell viscosity increases damping, and the nonlinear shell viscoelasticity increases the generation of harmonic echoes that are routinely used in contrast-enhanced ultrasound imaging. To date, the surface area-dependent interfacial properties of the phospholipid coating have never been measured due to the extremely short time scales of the MHz frequencies at which the microscopic bubbles are driven. Here, we present high-precision acoustic measurements of the dilatational nonlinear viscoelastic shell properties of phospholipid-coated microbubbles. These highly accurate measurements are now accessible for the first time by tuning the surface dilatation, that is, the lipid packing density, of well-controlled monodisperse bubble suspensions through the ambient pressure. Upon compression, the shell elasticity of bubbles coated with DPPC and DPPE-PEG5000 was found to increase up to an elasticity of 0.6 N m−1 after which the monolayer collapses and the elasticity vanishes. During bubble expansion, the elasticity drops monotonically in two stages, first to an elasticity of 0.35 N m−1, and then more rapidly to zero. Integration of the elasticity vs. surface area curves showed that, indeed, a phospholipid-coated microbubble is in a tensionless state upon compression, and that it reaches the interfacial tension of the surrounding medium upon expansion. The measurements presented in this work reveal the detailed features of the nonlinear dilatational shell behavior of micron-sized lipid-coated bubbles.

Graphical abstract: High-precision acoustic measurements of the nonlinear dilatational elasticity of phospholipid coated monodisperse microbubbles

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 May 2018, accepted on 15 Oct 2018 and first published on 16 Oct 2018


Article type: Paper
DOI: 10.1039/C8SM00918J
Citation: Soft Matter, 2018, Advance Article
  •   Request permissions

    High-precision acoustic measurements of the nonlinear dilatational elasticity of phospholipid coated monodisperse microbubbles

    T. Segers, E. Gaud, M. Versluis and P. Frinking, Soft Matter, 2018, Advance Article , DOI: 10.1039/C8SM00918J

Search articles by author

Spotlight

Advertisements