Investigations into the physicochemical properties of dextran small particulate gadolinium oxide nanoparticles.
OBJECTIVE
Relatively few studies involving the physicochemical properties of crystalline, nanometer-sized particulate gadolinium complexes have been reported. This is in part because of the challenges associated with making nanoparticulate gadolinium suspensions that are stable in aqueous solution. Small particulate gadolinium oxide (SPGO) and SPGO embedded in albumin microspheres (gadolinium oxide albumin microspheres, GOAM), have been used experimentally as prototype contrast agents for multimodality imaging.


METHODS
In the present study, an initial attempt was made to better solubilize SPGO, prevent particle aggregation, and investigate the physicochemical properties of dextran SPGO relevant to its use as a high-field magnetic resonance contrast agent in aqueous solution.


RESULTS
Dextran SPGO demonstrates regular crystalline lattices and has a gadolinium oxide electron diffraction pattern consistent with that of published X-ray powder diffraction (XPD) patterns. The subtraction XPD pattern of dextran SPGO shows diffraction angles and intensities similar, but not identical, to that of published Gd2O3 diffraction patterns. High r2/r1 ratios and magnetic susceptibility studies indicate dextran SPGO can be classified as a superparamagnetic compound. Enhanced relaxivity is observed at high magnetic field strength; largely because of solubilization of SPGO via the surface adherent carbohydrate. Perhaps also contributing to the observed relaxivity enhancement is the ideal lattice structure of the central gadolinium oxide crystal and the effects of sonochemical preparation on nanoparticle physicochemical properties.


CONCLUSIONS
It is anticipated that these studies will help provide a basis for the development of novel nanoparticulate contrast agent platforms capable of improving T1 and T2/T2* contrast for high-field magnetic resonance imaging and molecular imaging.
Stanford University, Department of Radiology, Lucas Center for MR Spectroscopy and Imaging, Radiological Sciences Laboratory, Stanford, CA 94305-5488, USA. mamcdona@stanford.edu
Michael Alexander
MA
McDonald
Kenneth L
KL
Watkin
D003287:Contrast Media / Q000032:analysis* / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D005682:Gadolinium / Q000032:analysis* / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008422:Materials Testing; D010316:Particle Size
D003287:Contrast Media; D003911:Dextrans; C030581:gadolinium oxide; D005682:Gadolinium