Gd3+/Yb3+-Doped Zinc Oxide Quantum Dots For Dual Modal Magnetic Resonance Imaging/Computed Tomographic Imaging

The oleate. stabilized ZnO : Gd/Yb QDs was first prepared by doping rare earth ions into ZnO host matrix in ethanol solution, and then amido was grafted onto the surface by a covalent bond. These nanoprobes, with exceptionally small size and good water-dispersability, exhibited a longitudinal relaxivity r(1) of 6. 06 mmol/(L . s), which was higher than that of clinic contrast agent Gd-diethylenetriaminepentaacetic acid (DTPA) (4. 3 mmol/(L . s)). In magnetic resonance imaging (MRI) studies, they exerted strong positive contrast effect when the Gd concentration was 1. 5 mmol/L. Furthermore, computed tomography (CT) imaging showed that these nanoprobes could induce an efficient contrast enhancement when the Yb concentration was at least equal to 5. 0 g/L. These nanoprobes presented relatively low toxicity or adverse affect on cell growth even at the concentration up to 1. 5 mmol/L Gd3+.