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Magnetic and relaxation properties of multifunctional polymer‐based nanostructured bioferrofluids as MRI contrast agents
Author(s) -
Amiri Houshang,
Bustamante Rodney,
Millán Angel,
Silva Nuno J.O.,
Piñol Rafael,
Gabilondo Lierni,
Palacio Fernando,
Arosio Paolo,
Corti Maurizio,
Lascialfari Alessandro
Publication year - 2011
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22959
Subject(s) - ferrofluid , superparamagnetism , materials science , relaxation (psychology) , nuclear magnetic resonance , mri contrast agent , nanoparticle , magnetization , magnetic nanoparticles , relaxometry , contrast (vision) , polymer , magnetic field , nanotechnology , magnetic resonance imaging , spin echo , composite material , optics , radiology , physics , medicine , psychology , social psychology , quantum mechanics
A series of maghemite/polymer composite ferrofluids with variable magnetic core size, which show a good efficiency as MRI contrast agents, are presented. These ferrofluids are biocompatible and can be proposed as possible platforms for multifunctional biomedical applications, as they contain anchoring groups for biofunctionalization, can incorporate fluorescent dyes, and have shown low cellular toxicity. The magnetic properties of the ferrofluids have been determined by means of magnetization and ac susceptibility measurements as a function of temperature and frequency. The NMR dispersion profiles show that the low frequency behavior of the longitudinal relaxivity r 1 is well described by the heuristic model of 1 H nuclear relaxation induced by superparamagnetic nanoparticles proposed by Roch and co‐workers. The contrast efficiency parameter, i.e., the nuclear transverse relaxivity r 2 , for samples with d > 10 nm assumes values comparable with or better than the ones of commercial samples, the best results obtained in particles with the biggest magnetic core, d = 15 nm. The contrast efficiency results are confirmed by in vitro MRI experiments at ν = 8.5 MHz, thus allowing us to propose a set of optimal microstructural parameters for multifunctional ferrofluids to be used in MRI medical diagnosis. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.