Nano Archive

Size and surface effects on the MRI relaxivity of manganese ferrite nanoparticle contrast agents

Tromsdorf, Ulrich I. and Bigall, Nadja C. and Kaul, Michael G. and Bruns, Oliver T. and Nikolic, Marija S. and Mollwitz, Birgit and Sperling, Ralph A. and Reimer, Rudolph and Hohenberg, Heinz and Parak, Wolfgang J. and Forster, Stephan and Beisiegel, Ulrike and Adam, Gerhard and Weller, Horst (2007) Size and surface effects on the MRI relaxivity of manganese ferrite nanoparticle contrast agents. NANO LETTERS, 7 (8). pp. 2422-2427.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/nl071099b

Abstract

Superparamagnetic MnFe2O4 nanocrystals of different sizes were synthesized in high-boiling ether solvent and transferred into water using three different approaches. First, we applied a ligand exchange in order to form a water soluble polymer shell. Second, the particles were embedded into an amphiphilic polymer shell. Third, the nanoparticles were embedded into large micelles formed by lipids. Although all approaches lead to effective negative contrast enhancement, we observed significant differences concerning the magnitude of this effect. The transverse relaxivity, in particular r(2)*, is greatly higher for the micellar system compared to the polymer-coated particles using same-sized nanoparticles. We also observed an increase in transverse relaxivities with increasing particle size for the polymer-coated nanocrystals. The results are qualitatively compared with theoretical models describing the dependence of relaxivity on the size of magnetic spheres.

Item Type:Article
Subjects:Material Science > Nanofabrication processes and tools
Physical Science > Nanomagnetics
Material Science > Nanostructured materials
ID Code:2477
Deposited By:Farnush Anwar
Deposited On:07 Jan 2009 13:14
Last Modified:07 Jan 2009 13:14

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