Facile Preparation of Double Rare Earth-Doped Carbon Dots for MRI/CT/FI Multimodal Imaging

The integration of different imaging functions into an ultrasmall nanoplatform with excellent biocompatibility and metabolic performance to fabricate multimodal imaging probes has been a tremendous challenge. Herein, a novel kind of gadolinium- and ytterbium-doped carbon dots (Gd/Yb@CDs) with diameter of 5.26 ± 0.93 nm was obtained by the convenient one-step hydrothermal process for magnetic resonance imaging (MRI), X-ray computed tomography (CT), and fluorescent imaging (FI). The obtained Gd/Yb@CDs exhibited not only the excitation-dependent emission and superhigh photostability but also higher longitudinal relaxivity (r1 = 6.65 mM–1 s–1) and excellent X-ray absorption performance (45.43 HU L g–1). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, tissue section assessment, and body weight investigation shed light on the superior biocompatibility of these Gd/Yb@CDs. MRI/CT imaging demonstrated these multimodal nanoprobes could give rise to obviously enhanced contrast effect on the xenografted tumor model. Furthermore, biodistribution analysis demonstrated that these nanoprobes could be easily removed from the mice through the kidney elimination pathway. Therefore, the present Gd/Yb@CDs could be served as promising MRI/CT/FI multimodal nanoprobes to provide more accurate and comprehensive diagnosis information.