title: Assessment of the viscoelastic and oscillation properties of a nano-engineered multimodality contrast agent.
abstract: Combinations of microbubbles (MBs) and superparamagnetic iron oxide nanoparticles (SPIONs) are used to fabricate dual contrast agents for ultrasound and MRI. This study examines the viscoelastic and oscillation characteristics of two MB types that are manufactured with SPIONs and either anchored chemically on the surface (MBs-chem) or physically embedded (MBs-phys) into a polymer shell. A linearized Church model was employed to simultaneously fit attenuation coefficients and phase velocity spectra that were acquired experimentally. The model predicted lower viscoelastic modulus values, undamped resonance frequencies and total damping ratios for MBs-chem. MBs-chem had a resonance frequency of approximately 13 MHz and a damping ratio of approximately 0.9; thus, MBs-chem can potentially be used as a conventional ultrasound contrast agent with the combined functionality of MRI detection. In contrast, MBs-phys had a resonance frequency and damping of 28 MHz and 1.2, respectively, and requires further modification of clinically available contrast pulse sequences to be visualized.
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH, Royal Institute of Technology, Sweden.
authors.forename: Satya V V N
authors.initials: SV
authors.lastname: Kothapalli
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Oddo
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, Italy.
authors.forename: Gaio
authors.initials: G
authors.lastname: Paradossi
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH, Royal Institute of Technology, Sweden.
authors.forename: Lars-Åke
authors.initials: LÅ
authors.lastname: Brodin
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH, Royal Institute of Technology, Sweden; Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute, Huddinge, Sweden; Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden. Electronic address: dmitryg@kth.se.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Grishenkov
mesh_terms: D000162:Acoustics; D003287:Contrast Media / Q000737:chemistry*; D055119:Elastic Modulus; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D045423:Microbubbles; D008956:Models, Chemical; D011142:Polyvinyl Alcohol / Q000737:chemistry; D055682:Viscoelastic Substances / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles; D055682:Viscoelastic Substances; D011142:Polyvinyl Alcohol
keywords: Fe(3)O(4) nanoparticles; Harmonic oscillation; Magnetic microbubbles; Ultrasound contrast agent; Viscoelastic properties