Biocompatible Folate-modified Gd³⁺/Yb³⁺-Doped ZnO Nanoparticles For Dualmodal MRI/CT Imaging

The development of multimodal imaging probes is highly desirable for clinical diagnosis and therapy because they combine the advantages of different imaging functionalities within a single nanoplatform and can provide complementary information from each imaging modality. Herein, we demonstrated our efforts to the fabrication of ZnO:Gd,Yb probe for MRI/CT imaging on the basis of the paramagnetic property of Gd3+ and the high X-ray absorption property of Yb3+. To increase the stability and biocompatibility, these nanoprobes were functionalized with folate (FA). The cytotoxicity and histological analysis show these nanoparticals (NPs) present low cytotoxicity even at a Gd3+concentration as high as 30 μgml-1 and have no obvious injury or inflammation in the susceptible organs (heart, liver, spleen, lung and kidney). Upon intravenously injected, the uptake and deposition of FA-modified nanoprobes take place primarily in spleen, lung and liver, and but these NPs can be completely excreted out from the body of mice as time prolonged. These nanoprobes not only exhibit a relatively higher longitudinal relaxivity (n) of 6.29 mM-1 s-1 over the commercial Gd(III)-diethylenetriamine pentaacetic acid complexes, but also keep strong X-ray attenuation property. In T1-weighted magnetic resonance imaging (MRI) and X-ray computed tomography (CT) studies, they can efficiently induce positive contrast enhancement, demonstrating the potential of the as-prepared ZnO:Gd,Yb-FA NPs for the development of dualmodal MRI/CT molecular imaging probes.