Determination of the elasticity of protein-polymer microbubbles by nanoindentation

Abstract

In order to increase the resolution of medical ultrasound survey of the vascular system, dispersions of rigid-shelled microbubbles are used, which are able to oscillate nonlinearly under the action of pressure differences and generate an acoustic response, thereby increasing the contrast of blood vessels against the background of other tissues. The key characteristics of such contrast agents for ultrasound are the mechanical properties of their shell.
The elasticity of microbubbles with an air core and a shell made of an electrostatic complex of bovine serum albumin and copolymer N-vinylpyrrolidone with acrylic acid, used as contrast agents in medical ultrasound of blood vessels, has been experimentally investigated. Investigations were carried out by atomic force spectroscopy of microbubbles immobilised on a polyelectrolyte layer. Calculations of Young's modulus of the walls of a series of microbubbles were carried out on the basis of the model of hollow shell deformation under axial loading - according to Reissner's theory. This technique is useful for determining the factors influencing the difference of acoustic response and duration of circulation in the bloodstream of dispersions of microbubbles of different composition, thus it is significant in selecting the optimal ratio of precursors for the synthesis of the most stable and acoustically active contrast agents for ultrasound.

Speaker

Pavel S. Kuzmin
Skolkovo Institute of Science and Technology, Moscow, Russia
Russia

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