Investigation of mechanical and dynamic characteristics for multifunctional contrast agents using atomic force microscopy and acoustic assessments

Abstract

Although multi-parameter fitting algorithms are often used for the characterization of coated-bubbles, it is inevitable to introduce uncertainty into the results. Therefore, it is urgent to develop some improved techniques to analyze the mechanical properties of the multifunctional microbubbles (MBs) accurately and systematically. By combining the measurements of atomic force microscopy, optical and acoustic detection with the simulations of coated-bubble dynamics, a comprehensive technology was developed to determine the size distribution, shell thickness, elasticity, and viscosity of multifunctional MBs precisely. Moreover, the impact of magnetic nanoparticles (MNPs) concentration on the multifunctional MBs' dynamic properties was studied systematically. It is demonstrated that, with the increasing MNPs concentration, the MB mean diameter and shell stiffness increased and ultrasound scattering response and inertial cavitation activity could be significantly enhanced. Although the shell thickness does not depend on the MNPs concentration, the increased MNPs concentration would generally result in enhanced bulk modulus and reduced bulk viscosity. The results of current studies demonstrate that the proposed single-parameter evaluation method could be helpful for further design and development of MB agents in clinic applications.