TY  - JOUR
AU  - Wang, W.
AU  - Dong, H.
AU  - Pacheco, V.
AU  - Willbold, D.
AU  - Zhang, Y.
AU  - Offenhäusser, A.
AU  - Hartmann, R.
AU  - Weirich, T.
AU  - Ma, P.
AU  - Krause, H. J.
AU  - Gu, Z.
TI  - Relaxation behavior study of ultra-small superparamagnetic iron oxide nanoparticles at ultra-low and ultra-high magnetic fields
JO  - The journal of physical chemistry  / B
VL  - 115
SN  - 1520-6106
CY  - Washington, DC
PB  - Soc.
M1  - PreJuSER-18219
SP  - 14789 - 14793
PY  - 2011
N1  - We would like to thank F. Dorn for TEM imaging, J. Bachhausen for IR measurements, and H. Lippert for the ICP-OES measurements. This work is supported by the Research Center Juelich, the China Scholarship Council (CSC), and the German Helmholtz Association.
AB  - Ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) have attracted attention because of their current and potential usefulness as contrast agents for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). USPIOs are usually used for their significant capacity to produce predominant proton relaxation effects, which result in signal reduction. However, most previous studies that utilized USPIOs have been focused on the relaxation behavior at commonly used magnetic fields of clinical MRI systems (typically 1-3 T). In this paper, magnetic relaxation processes of protons in water surrounding the USPIOs are studied at ultralow (≤10 mT) and ultrahigh magnetic fields (14.1 T). USPIOs used in our experiments were synthesized with a core size of 6 nm, and transferred from organic to water by ligand exchange. The proton spin-lattice relaxation time (T(1)) and spin-spin relaxation time (T(2)) were investigated at ultralow (212 μT for T(2) and 10 mT for T(1)) and at 14.1 T with different iron concentrations. At all of the fields, there is a linear relationship between the inverse of relaxation times and the iron concentration. The spin-spin relaxivity (r(2)) at 14.1 T is much larger than that value of the ultralow field. At ultralow field, however, the spin-lattice relaxivity (r(1)) is larger than the r(1) at ultrahigh field. The results provide a perspective on potential in vivo and in vitro applications of USPIOs in ultralow and ultrahigh field NMR and MRI.
KW  - Contrast Media: chemistry
KW  - Ferric Compounds: chemistry
KW  - Magnetic Fields
KW  - Magnetite Nanoparticles: chemistry
KW  - Solubility
KW  - Water: chemistry
KW  - Contrast Media (NLM Chemicals)
KW  - Ferric Compounds (NLM Chemicals)
KW  - Magnetite Nanoparticles (NLM Chemicals)
KW  - ferric oxide (NLM Chemicals)
KW  - Water (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:21972868
UR  - <Go to ISI:>//WOS:000297608600051
DO  - DOI:10.1021/jp2066138
UR  - https://juser.fz-juelich.de/record/18219
ER  -