Colloidal assemblies of oriented maghemite nanocrystals and their NMR relaxometric properties

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 clust...

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Bibliographic Details
Published in:Dalton transactions : an international journal of inorganic chemistry 2014-06, Vol.43 (22), p.8395-8404
Main Authors: Kostopoulou, Athanasia, Velu, Sabareesh K P, Thangavel, Kalaivani, Orsini, Francesco, Brintakis, Konstantinos, Psycharakis, Stylianos, Ranella, Anthi, Bordonali, Lorenzo, Lappas, Alexandros, Lascialfari, Alessandro
Format: Article
Language:English
Subjects:
Animals
Assemblies
Cell Culture Techniques
Cell Proliferation - drug effects
Cell Survival - drug effects
Clusters
Colloids
Contrast agents
Ferric Compounds - chemistry
Ferric Compounds - toxicity
Hydrophobic and Hydrophilic Interactions
Magnetic Phenomena
Magnetic resonance
Magnetic Resonance Spectroscopy
Magnetization
Mice
Microscopy, Electron, Transmission
Nanocrystals
Nanoparticles - chemistry
Nanoparticles - toxicity
NIH 3T3 Cells
Nuclear magnetic resonance
Particle Size
Surface Properties
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Summary: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.
ISSN:1477-9226
1477-9234
DOI:10.1039/c4dt00024b