title: Iron oxide nanoparticle-containing microbubble composites as contrast agents for MR and ultrasound dual-modality imaging.
abstract: Magnetic resonance (MR) and ultrasound (US) imaging are widely used diagnostic modalities for various experimental and clinical applications. In this study, iron oxide nanoparticle-embedded polymeric microbubbles were designed as multi-modal contrast agents for hybrid MR-US imaging. These magnetic nano-in-micro imaging probes were prepared via a one-pot emulsion polymerization to form poly(butyl cyanoacrylate) microbubbles, along with the oil-in-water (O/W) encapsulation of iron oxide nanoparticles in the bubble shell. The nano-in-micro embedding strategy was validated using NMR and electron microscopy. These hybrid imaging agents exhibited strong contrast in US and an increased transversal relaxation rate in MR. Moreover, a significant increase in longitudinal and transversal relaxivities was observed after US-induced bubble destruction, which demonstrated triggerable MR imaging properties. Proof-of-principle in vivo experiments confirmed that these nanoparticle-embedded microbubble composites are suitable contrast agents for both MR and US imaging. In summary, these magnetic nano-in-micro hybrid materials are highly interesting systems for bimodal MR-US imaging, and their enhanced relaxivities upon US-induced destruction recommend them as potential vehicles for MR-guided US-mediated drug and gene delivery.
authors.affiliation: Department of Experimental Molecular Imaging (ExMI), Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.forename: Twan
authors.initials: T
authors.lastname: Lammers
authors.forename: Josef
authors.initials: J
authors.lastname: Ehling
authors.forename: Stanley
authors.initials: S
authors.lastname: Fokong
authors.forename: Jörg
authors.initials: J
authors.lastname: Bornemann
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.forename: Jessica
authors.initials: J
authors.lastname: Gätjens
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D045423:Microbubbles; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D011108:Polymers; C000499:ferric oxide