Polyethylene glycol-cover ultra-small Gd2O3 nanoparticles for positive contras at 1.5 T magnetic resonance clinical scanning
The size distribution and magnetic properties of ultra-small gadolinium oxide crystals (US-Gd 2 O 3 ) were studied, and the impact of polyethylene glycol capping on the relaxivity constants ( r 1 , r 2 ) and signal intensity with this contrast agent was investigated. Size distribution and magnetic p...
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Published in | Nanotechnology Vol. 18; no. 39; p. 395501 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
2007
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Subjects | |
Online Access | Get full text |
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Summary: | The size distribution and magnetic properties of ultra-small gadolinium oxide crystals (US-Gd 2 O 3 ) were studied, and the impact of polyethylene glycol capping on the relaxivity constants ( r 1 , r 2 ) and signal intensity with this contrast agent was investigated. Size distribution and magnetic properties of US-Gd 2 O 3 nanocrystals were measured with a TEM and PPMS magnetometer. For relaxation studies, diethylene glycol (DEG)-capped US-Gd 2 O 3 nanocrystals were reacted with PEG-silane (MW 5000). Suspensions were adequately dialyzed in water to eliminate traces of Gd 3+ and surfactants. The particle hydrodynamic radius was measured with dynamic light scattering (DLS) and the proton relaxation times were measured with a 1.5 T MRI scanner. Parallel studies were performed with DEG–Gd 2 O 3 and PEG-silane–SPGO (Gd 2 O 3 ,< 40 nm diameter). The small and narrow size distribution of US-Gd 2 O 3 was confirmed with TEM (~3 nm) and DLS. PEG-silane–US-Gd 2 O 3 relaxation parameters were twice as high as for Gd–DTPA and the r 2 / r 1 ratio was 1.4. PEG-silane–SPGO gave low r 1 relaxivities and high r 2 / r 1 ratios, less compatible with positive contrast agent requirements. Higher r 1 were obtained with PEG-silane in comparison to DEG–Gd 2 O 3 . Treatment of DEG–US-Gd 2 O 3 with PEG-silane provides enhanced relaxivity while preventing aggregation of the oxide cores. This study confirms that PEG-covered Gd 2 O 3 nanoparticles can be used for positively contrasted MR applications requiring stability, biocompatible coatings and nanocrystal functionalization. |
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ISSN: | 0957-4484 1361-6528 |
DOI: | 10.1088/0957-4484/18/39/395501 |