title: Colloidal assemblies of oriented maghemite nanocrystals and their NMR relaxometric properties.
abstract: An elevated-temperature polyol-based colloidal-chemistry approach allows for the development of size-tunable (50 and 86 nm) assemblies of maghemite iso-oriented nanocrystals, with enhanced magnetization. (1)H-nuclear magnetic resonance (NMR) relaxometric experiments show that the ferrimagnetic cluster-like colloidal entities exhibit a remarkable enhancement (4-5 times) in transverse relaxivity when compared to that of the superparamagnetic contrast agent Endorem®, over an extended frequency range (1-60 MHz). The marked increase in the transverse relaxivity r2 at a clinical magnetic field strength (∼1.41 T), which is 405.1 and 508.3 mM(-1) s(-1) for small and large assemblies, respectively, makes it possible to relate the observed response to the raised intra-aggregate magnetic material volume fraction. Furthermore, cell tests with a murine fibroblast culture medium confirmed cell viability in the presence of the clusters. We discuss the NMR dispersion profiles on the basis of relaxivity models to highlight the magneto-structural characteristics of the materials for improved T2-weighted magnetic resonance images.
authors.affiliation: Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion, Greece. lappas@iesl.forth.gr.
authors.forename: Athanasia
authors.initials: A
authors.lastname: Kostopoulou
authors.forename: Sabareesh K P
authors.initials: SK
authors.lastname: Velu
authors.forename: Kalaivani
authors.initials: K
authors.lastname: Thangavel
authors.forename: Francesco
authors.initials: F
authors.lastname: Orsini
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Brintakis
authors.forename: Stylianos
authors.initials: S
authors.lastname: Psycharakis
authors.forename: Anthi
authors.initials: A
authors.lastname: Ranella
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bordonali
authors.forename: Alexandros
authors.initials: A
authors.lastname: Lappas
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lascialfari
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003102:Colloids; D005290:Ferric Compounds / Q000737:chemistry* / Q000633:toxicity; D057927:Hydrophobic and Hydrophilic Interactions; D060328:Magnetic Phenomena; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D046529:Microscopy, Electron, Transmission; D041681:NIH 3T3 Cells; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D010316:Particle Size; D013499:Surface Properties
chemical_list: D003102:Colloids; D005290:Ferric Compounds; C000499:ferric oxide