title: Surface functionalization of single superparamagnetic iron oxide nanoparticles for targeted magnetic resonance imaging.
abstract: Magnetic resonance imaging (MRI), a non-invasive, non-radiative technique, is thought to lead to cellular or even molecular resolution if optimized targeted MR contrast agents are introduced. This would allow diagnosing progressive diseases in early stages. Here, it is shown that the high binding affinity of poly(ethylene glycol)-gallol (PEG-gallol) allows freeze drying and re-dispersion of 9 +/- 2-nm iron oxide cores individually stabilized with approximately 9-nm-thick stealth coatings, yielding particle stability for at least 20 months. Particle size, stability, and magnetic properties of PEGylated particles are compared to Feridex, a commercially available untargeted negative MR contrast agent. Biotin-PEG(3400)-gallol/methoxy-PEG(550)-gallol stabilized nanoparticles are further functionalized with biotinylated human anti-VCAM-1 antibodies using the biotin-neutravidin linkage. Binding kinetics and excellent specificity of these nanoparticles are demonstrated using quartz crystal microbalance with dissipation monitoring (QCM-D). These MR contrast agents can be functionalized with any biotinylated ligand at controlled ligand surface density, rendering them a versatile research tool.
authors.affiliation: Laboratory for Surface Science and Technology ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Esther
authors.initials: E
authors.lastname: Amstad
authors.forename: Stefan
authors.initials: S
authors.lastname: Zurcher
authors.forename: Alireza
authors.initials: A
authors.lastname: Mashaghi
authors.forename: Joyce Y
authors.initials: JY
authors.lastname: Wong
authors.forename: Marcus
authors.initials: M
authors.lastname: Textor
authors.forename: Erik
authors.initials: E
authors.lastname: Reimhult
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide